United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-R-00-005
July 2000
www.epa.gov/tio
clu-in.org
EPA A Resource for MGP Site
Characterization and
Remediation
Expedited Site Characterization and
Source Remediation at Former
Manufactured Gas Plant Sites
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EPA-542-R-00-005
July 2000
A Resource for MGP Site Characterization and
Remediation
Expedited Site Characterization and Source Remediation
at Former Manufactured Gas Plant Sites
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Technology Innovation Office
Washington, DC 20460
Walter W. Kovalick, Jr., Ph.D., Director
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Notice
This report was prepared by CH2M Hill, 1111 Broadway, Suite 1200, Oakland, CA 94607 with editorial
support by Environmental Management Support, Inc., 8601 Georgia Avenue, Suite 500, Silver Spring,
MD 20910 under contract 68-W6-0014, work assignment 87, with the U.S. Environmental Protection
Agency. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
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Abstract
The United States Environmental Protection Agency (USEPA), in conjunction
with states, industry trade associations (the Edison Electric Institute [EEI], the
Utility Solid Waste Activities Group [USWAGj, and American Gas
Association [AGA]), and individual utilities, has compiled a summary of
innovative strategies and. technical approaches for expediting site characterization
and source material remediation at former manufactured gas plant (MGP) sites.
Former MGP sites, as a category of inactive industrial waste disposal sites, contain
many similarities in historical industrial activities and the types and distribution of
MGP wastes and related contaminants. This trend, coupled with the fact that
today's utilities are often the primary owners of (or accept remedial responsibility
for) these sites, allows both the regulatory agencies and the utilities to develop
approaches to achieving economies of scale and effort in addressing contamination
at former MGP sites. Unlike remediation sites of other industries, MGP sites are
typically not found at locations where utilities operate today, are often located in
the midst of residential communities that have developed around these abandoned
industrial locations, and are owned by entities unrelated to the modern utility.
This document was prepared by the USEPA to provide current information on
useful approaches and tools being applied at former MGP sites to the regulators
and utilities characterizing and remediating these sites. The document outlines site
management strategies and field tools for expediting site characterization at MGP
sites; presents a summary of existing technologies for remediating MGP wastes in
soils; provides sufficient information on the benefits, limitations, and costs of each
technology, tool, or strategy for comparison and evaluation; and provides, by way
of case studies, examples of the ways these tools and strategies can be implemented
at MGP sites.
Innovative strategies for managing former MGP sites, as discussed in Chapter 3 of
this document, include multi-site agreements, dynamic work-planning, teaming
approaches to expedite remedial action planning and execution, and methods for
dealing with uncertainty at these sites. Technical innovations for site
characterization (Chapter 4) include the availability of direct push and other field
screening technologies to complement traditional analytical approaches. Finally, a
variety of approaches and technologies have been employed to provide cost-
effective solutions to treating the wastes remaining at former MGP sites (Chapter
5).
The information presented in this document is applicable to the characterization
and remediation of former MGP sites conducted under traditional remediation
programs as well as the large number of MGP sites which are likely to be addressed
under voluntary cleanup programs.
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Contents
Foreword i
Abstract ; ii
Contents iii
List of Acronyms and Abbreviations v
1 Introduction 1-1
1.1 Background 1-1
1.2 Purpose and Scope of Document 1-2
2 Creating an Expedited Site Characterization and Remediation Program 2-1
2.1 Introduction 2-1
2.2 Expedited Site Characterization and Remediation 2-1
2.3 Creating the Expedited Site Characterization and
Remediation Program 2-5
2.4 Management Tools for Expediting Characterization and Remediation 2-7
2.5 Tools for Site Characterization :. 2-8
2.6 Technologies for Cleaning up MGP Wastes 2-8
2.7 Conclusion 2-9
3 Management for Expediting Site Characterization and Remediation ... 3-1
3.1 Introduction 3-1
3.2 Management Tools for Expediting Site Characterization and
Remediation ''.... i 3-4
3.2.1 Site Bundling 3-4
3.2.2 Multi-Site Agreements 3-8
3.2.3 Generic Work Plans and Reports 3-13
3.2.4 Program/High Performance/Design Plan 3-15
3.2.5 Early Land Use Determination/Brownfields 3-20
3.2.6 Managing Uncertainty (Observational Approach) 3-24
3.2.7 Expedited Site Characterization 3-30
3.2.8 Legislative Innovation 3-36
3.2.9 Dovetailing Business Decisionmaking and Remediation
Planning 3-40
3.2.10 Establishing Background PAH Concentrations 3-43
3.2.11 Generic Administrative Orders 3-49
ii
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Contents
4 Tools and Techniques for Expediting Site Characterization 4-1
4.1 Introduction , 4-1
4.2 Tools and Techniques for Expediting Site Characterization 4-10
4.2.1 Direct-Push Methods/Limited Access Drilling 4-10
4.2.2 Analytical Field Screening 4-26
4.2.3 Geophysical Surveys 4-36
4.2.4 Soil Gas Surveys 4-52
4.2.5 Contaminant Migration Evaluation 4-56
4.2.6 Other Tools 4-61
5 Technologies for Source Material Treatment 5-1
5.1 Introduction 5-1
5.2 Technologies for Source Material Treatment 5-1
5.2.1 Co-Burning 5-5
5.2.2 Thermal Treatment Processes 5-8
5.2.3 Asphalt Batching 5-24
5.2.4 Bioremediation/Chemically Enhanced Bioremediation 5-32
5.2.5 Containment , 5-45
5.2.6 Stabilization/Solidification 5-49
5.2.7 Soil Washing 5-55
5.2.8 Soil Vapor Extraction 5-61
6 References 6-1
7 Additional Sources of Information 7-1
iii
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List of Acronyms and Abbreviations
AFB Air Force Base
AFCEE Air Force Center for Environmental Excellence
ASTM American Society of Testing and Materials
atm atmospheres ,
bgs below ground surface
BTEX benzene, toluene, ethylbenzene, and xylenes
Btu British thermal unit
CERCLA Comprehensive Environmental Response, Compensation and
Liability Act of 1980
CERCLIS Comprehensive Environmental Response Compensation, and
Liability Act Information Systems
cis-l,2-DCE cis-l,2-dichloroethylene
CO carbon monoxide
cPAH carcinogenic polycyclic aromatic hydrocarbon
CPT cone penetrometer
CROW™ Contained Recovery of Oily Wastes
CWM Ghico/Willows/Marysville
DCE dichloroethylene
DCI Dust Coating, Inc.
DEC Department of Environmental Conservation
DEP Department of Environmental Protection
DEQ Department of Environmental Quality
DMLS™ diffusion multi-layer sampler
DNAPL dense non-aqueous phase liquid
DNR Department of Natural Resources
DQO data quality objective
DRE destruction removal efficiency
DTSC Department of Toxic Substance Control
DUS dynamic underground stripping
EEI Edison Electric Institute
ELISA enzyme-linked immunosorbent assay
EMS ' electromagnetic survey
EPA Environmental Protection Agency
EPRI Electric Power Research Institute
ERAP Expedited Remedial Action Program
ESC expedited site characterization
iv
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List of Acronyms and Abbreviations
FS feasibility study
ft/min feet per minute
GC gas chromatography
GCL geosynthetic clay liner
GIS geographic information system
gpm gallons per minute
GPR ground-penetrating radar
GRI Gas Research Institute
ha hectare
HASP health and safety plan
HC1 hydrogen chloride
HDPE high-density polyethylene
HPO hydrous pyrolysis oxidation
HPT high-performance team
IDW investigation-derived waste
|GT Institute of Gas Technology
ISM in situ bio-geochemical monitor
ISTD in situ thermal desorption
ISU Iowa State University
kg kilogram
LIF ' laser-induced fluorescence
LNAPL light nonaqueous phase liquids
LTTD low-temperature thermal desorption
LTU land treatment unit
MART Mid Atlantic Recycling Technologies, Inc.
MCL Maximum Contaminant Level
MEC MidAmerican Energy Corporation
MEW Missouri Electric Works
Hg/L micrograms per liter
|4.rh micrometer
mg milligram
mg/kg milligrams per kilogram
MGP manufactured gas plant
mm millimeter
MSE microscale solvent extraction
NAPL nonaqueous phase liquid
NCP National Contingency Plan
NJDEP New Jersey Department of the Environment
NMPC Niagra Mohawk Power Corporation
NOX nitrogen oxide
NPL National Priorities List
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List of Acronyms and Abbreviations
NTU nephelometric turbidity unit ;
NYSDEC New York State Department of Environmental Conservation
OUR oxygen uptake rate
PAH polycyclic aromatic hydrocarbon
PA preliminary assessment
PCB polychlorinated biphenyl
PCE perchloroethylene
PCP pentachlorophenol
PEA preliminary endangerment assessment
PGE Portland General Electric
PG&E Pacific Gas and Electric Company
PITT Partitioning Interwell Tracer Test •
PNA polynuclear aromatic hydrocarbon
ppb parts per billion
PP&L Pennsylvania Power & Light Company
ppm parts per million
PQL practical quantitation limit
PSE&G Public Service Electric and Gas Company
psi pounds per square inch
PVC polyvinyl chloride
QA quality assurance
QAPP quality assurance project plan
QC quality control
RA remedial action
RAGS Risk Assessment Guidance for Superfund
RAP remedial action plan
RCRA Resource Conservation and Recovery Act of 1976
RD remedial design
RG&E Rochester Gas and Electric
RI remedial investigation
ROD Record of Decision
ROST™ Rapid Optical Screening Tool
RP responsible party
SCAPS site characterization analysis penetrometer system
SI site investigation
SITE Superfund Innovative Technology Evaluation
SoCal Gas Southern California Gas Company
SO2 Sulfur dioxide
SPLP synthetic precipitation leaching procedure
SRP site remediation program
S/S solidification and stabilization
VI
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List of Acronyms and Abbreviations
SVE soil vapor extraction
SVOC semivolatile organic compound
TCE trichloroethylene
TCLP toxicity characteristic leaching procedure
TEPH total extractable petroleum hydrocarbons
3-D/3-C three-dimensional, three-component
TPH total petroleum hydrocarbons
TSCA Toxic Substance Control Act
2D two-dimensional - > ...-•
UCS ultimate compressive strength
USEPA United States Environmental Protection Agency
USWAG Utility Solid Waste Activities Group
VOC volatile organic compound
WEPCO Wisconsin Energy Power Company
WRI Western Research Institute
XRF X-ray fluorescence
Vll
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Chapter 1
Introduction
1.1 Background
From the early 1800s through the mid-19003, manufactured gas plants (MGPs)
were operated nationwide to provide gas from coal or oil for lighting,
heating, and cooking. The gas manufacturing and purification processes at
these plants yielded by-products or gas plant residues that included tars, sludges,
lampblack, light oils, spent oxide wastes, and other hydrocarbon products.
Although many of these by-products were recycled, excess residues remained at
MGP sites. These residues contain polycyclic aromatic hydrocarbons (PAHs),
petroleum hydrocarbons, benzene, cyanide, metals, and phenols.
Almost every city in the United States had an MGP; an estimated 3,000 to 5,000
former MGP sites exist across the country, some of, which are still owned by the
successors to the utilities that founded them. MGPs were typically built on the
outskirts of cities that have since grown. As a result, the sites are now often
located in inner city areas that are being redeveloped.
MGPs were constructed nationwide with similar facilities and generated similar
wastes using defined manufacturing processes. In general, MGPs produced gas by
cracking the hydrocarbon chains of feedstocks, primarily oil and coal, and
releasing lighter carbon products. These lighter products were given off in the
form of gas that was used for household needs. MGP residues were solid or liquid
and included creosote, tars, spent oxide residues, and lampblack. The feedstocks
and manufacturing processes used at a site, the size of the manufacturing
operations, and a site's physical constraints (e.g., proximity to wetlands or vacant
lots) were some of the factors that governed the manufacturing and disposal
practices at each site.
Although many former MGP sites have been or are currently being investigated
and/or remediated, a large number remain unaddressed. In some cases, the same
party may be responsible for numerous former MGP sites in a region. The
similarities in the configuration and contaminants at these sites provide
opportunities to apply innovative approaches that benefit from economies of scale.
Former MGP sites offer an ideal opportunity to apply tools and technologies that
expedite site characterization and source remediation.
Residues often occur in the same locations at former MGP sites, e.g., near the
former gas holders, tar sumps, and lampblack separators. These wastes contain a
number of known or suspected carcinogens and other potentially hazardous
chemicals. Because of the nature of these residues, there is a limited subset of
technologies that are likely to be effective in treating them.
For additional background and historical information on the operations of former
manufactured gas plants, the reader is referred to the Additional Sources of
Information listed in Chapter 7 of this document.
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Chapter 1
Introduction
1.2 Purpose and Scope of Document
There is a general awareness, both in the public and private sectors, of the need
for faster, better, and cheaper methods for site characterization and remediation.
MGP sites as a class provide opportunities to try new methods of site
characterization and waste treatment, and to relate the resulting experiences to
other MGP sites. Utilities and other regulatory agencies are recognizing the
advantages of such programs, and are currently putting these experiences to use.
Three aspects of former MGP site characterization and remediation are addressed
in this document:
• Management tools for expediting site characterization and remediation
(Chapter 3)
» Tools and techniques for expediting site characterization (Chapter 4)
• Technologies for treatment of MGP-related wastes in soil (Chapter 5)
Chapter 3, Management Tools for Expediting Site Characterization, describes
innovative strategies and gives examples of their use at former MGP sites. Because
many of the examples come from ongoing projects, references are provided so
readers can contact representatives for follow-up information.
Chapter 4, Tools and Techniques for Expediting Site Characterization, presents
information on "tried and true" as well as innovative tools that can be used to
expedite characterization of former MGP sites. The following categories of
information are presented for each tool or technique:
» Tool or Technique Description
• Operational Considerations
• Applications and Cost
• Benefits and Limitations
• Case Studies
• Contacts
Chapter 5, Technologies for Source Treatment, focuses on the technologies
currently available for MGP source (soil and/or MGP residue) treatment. The
following information is presented for each technology:
• Tool or Technique Description
• Operation Considerations
• Applications and Cost
• Benefits and Limitations
» Case Studies
• Contacts
1-2
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Chapter 1
Introduction
The costs provided in this document are based on limited data and are dynamic.
Many variables will affect the cost of a tool or technology as applied to a specific
site or set of sites. The cost information provided herein reflects an order-of-
magnitude guide to costs, and is provided on an informational basis.
Case studies are provided, where available. Additional examples of the
application of these strategies, tools, and treatment technologies likely exist.
Typical regional variations in MGP sites are identified where relevant or where
additional information is available.
Detailed information on the history of former MGPs and their disposal practices
is not included in tiiis*dacumeiit.>F0F> background; and histOEisaL-information, the
reader is referred to Chapter 7, Additional Sources of Information.
Finally, this document specifically does not address groundwater remediation
technologies. A limited amount of information is provided on restoration of
non-aqueous phase liquid (NAPL) zones at or below the water table. This is an
area of considerable technological development. These issues may be addressed
in future guidance document volumes.
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ill" i
Chapter 1
Introduction
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Chapter 2
Creating an Expedited Site
Characterization and Remediation
Program
2.1 Introduction
The process of characterizing and remediating an MGP site or sites involves
first determining what contamination is present and where. Once it is clear
what wastes are present and at what locations, a selection of treatment
and/or management alternatives can be evaluated to identify a preferred remedial
approach. Familiarity with the historical operation of MGPs, which was similar at
almost all sites, can further expedite the characterization and remediation process.
This process typically follows that which is outlined by the National Contingency
Plan (NCP) and is often modified by other federal, state, and/or local regulations.
The primary modes by which the site characterization and remediation process
can be modified to save time and costs are:
• How the site is "administered" (i.e., how investigations and cleanups are
organized and managed)
• The use of innovative and survey-level tools and approaches for expediting the
site characterization
• Awareness of and familiarity with the subset of treatment technologies that are
proven or promising for the particular types, of wastes found at MGP sites
This chapter summarizes the process of streamlining the site characterization and
remediation process, by tying together approaches to site management and
contamination assessment (described in Chapters 3 and 4) with proven or
promising treatment technologies for MGP residues and wastes in soil (Chapter 5).
2.2 Expedited Site Characterization and
Remediation
Twenty to twenty-five years ago, in the early days of site characterization and
environmental remediation, contaminated site work was scientific study as new
disciplines were created and refined to address the work at hand. Typically, site
work would begin with the preparation of work plans, followed by a round of
field investigations. Samples collected during the field programs were sent to
analytical laboratories for analyses, and after about a month, laboratory results
were returned and subjected to tabulation, mapping, and other types of data
evaluations. The results of the data analyses were documented in a draft report
which was distributed to the responsible party and regulatory agencies for review.
Meetings typically followed in which detailed discussions were held as to the
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. ; .. . • ,' , ' Chapter 2
Creating an Expedited Site Characterization and Remediation Program
"correct" interpretation of the data. Eventually, a revised report was prepared and
submitted, the conclusion of which typically included recommendations for
additional sampling. And so the whole process of work planning-sampling-
laboratory analyses-data interpretation-reporting would continue until multiple
phases and many years would pass. In all, very large sums of money were spent
on "studying" the site before cleanup activities were planned, much less
implemented.
In response to outside economic influences (including, experience with the
economic impacts of site characterization and remediation on businesses), the
need for additional urban lands for redevelopment (bringing the Brownfields-type.
initiative to the forefront), and the maturation of the environmental marketplace,
new pressures have been brought to bear to accomplish the same tasks in a
smarter, cheaper, and more expeditious manner. For certain types of sites,
including former MGP sites, practitioners now have enough experience that they
can anticipate the nature of work to be accomplished, foresee the problems that
may arise, and select an appropriate remedy from a known subset of treatment
technologies. From a menu of technology options, practitioners can select the site
characterization and analytical methods that are most likely to yield useful
information to support site decisionmaking and remedy selection. When remedial
design options are anticipated during the planning stage, data supportive of
remedy considerations can be gathered concurrently with characterization
information. By involving stakeholders at critical junctures, community .and
regulator satisfaction can be increased, decreasing the likelihood of legal battles
that may delay remedial action and consume financial resources.
Work at former MGP sites can proceed seamlessly from investigation to
remediation and closeout. With careful advance planning and the use of rapid
turnaround on-site analytical technologies, investigation and cleanup objectives
can be achieved in a fraction of the time (and thus at a lower cost) as compared to
traditional approaches which rely on a prescriptive, linear progression of phases
and tasks. Considerable time savings over the life of the project can be realized by
reducing the number of mobilizations to the field and by performing multiple task
simultaneously.
There are a number of key elements that comprise new approaches to performing
site characterization. The most critical is the need for systematic planning prior to
initiating site work. Systematic planning is one of the most cost-effective tasks in
environmental remediation. It markedly increases the likelihood that a project will
be successfully completed the first time, and within budget. It markedly decreases
the probability of unpleasant and costly surprises.
Planning should be performed by a core technical team that contains all the
expertise needed to adequately address the needs of the site, and that will
incorporate the interests and concerns of stakeholders. Expertise vital to nearly all
sites, but frequently overlooked, includes the services of a knowledgeable
analytical chemist and a statistician familiar with the special concerns of
environmental sampling. Planning involves the use of a site conceptual model
which identifies the historical uses of the site, potential exposure pathways,
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Chapter 2
Creating an Expedited Site Characterization and Remediation Program
cleanup concerns, and future land-use options. Clear articulation of the decision(s)
or question (s) that drive the site work is imperative to the planning process. An
appreciation for how much uncertainty or risk is acceptable in site decisions is also
crucial (i.e., how sure must the decisionmaker be that wrong decisions will not be
made). A great deal of time and effort may be consumed reaching consensus on
these two issues, but once done, planning of the actual work to be performed at
the site can begin and proceed without interruption.
Planning then proceeds in an orderly progression: When the site decision (s) is
known, the type of information (data) which is required to inform the
decisionmakers can be identified. When the amount of uncertainty has been
decided, the quality of the data needed to meet the uncertainty goals can be
determined. Once the type of data and the data quality needs have been
determined, then a menu of analytical chemistry methods (for contaminant data)
or sampling tools and techniques (for hydrogeological or contaminant
information) can be surveyed for a cost-effective means of gathering information.
If, during the planning process, it is found that the expense of collecting a data
point to meet very stringent uncertainty goals exceeds available resources, the
team can "go back to the drawing board," and negotiate with stakeholders over
future land use alternatives and the degree of allowable uncertainty.
Selecting an analytical method(s) involves balancing a number of considerations:
the data needs, any regulatory requirements, costs, the ability to optimize sample
throughput to provide real-time decisionmaking and to match the speed of sample
collection, and any anticipated site-specific issues (such as matrix interference).
Method selection should be done by a qualified chemist who can weigh the costs
and benefits of various methods against site-specific data needs.
Field analytical methods hold a significant potential for cost and/or time savings,
and should be included in the pool of analytical options under consideration. The
rapid turnaround time supports a dynamic work plan which can decrease the
collection and analysis of uninformative samples. Again, a knowledgeable chemist
is crucial to avoiding the potential pitfall of the undiscerning use of field analytics.
It is the responsibility of the chemist member of the technical team to stay on top
of rapid advancements being made in analytical environmental chemistry,
especially as they relate to field methods. Depending on the method, the skill of
the operator, and the kinds of calibrations and quality control used, some
currently available field technologies can produce results that are just as
quantitative as those expected from traditional laboratory services. The ability of
field analytical methods to address certain issues, such as defining spatial
variability across the site and minimizing the loss of volatile contaminants during
sample collection and transport, means that field analytical data can sometimes be
more reliable and representative than those generated under traditional scenarios.
Of course, the big question about the use of innovative analytical methods and
sampling tools is "Will the regulators accept the results?" In general, regulators
will often accept results from less-traditional technologies if the rationale for the
collection and use of the data has been clearly documented. It is unfortunately
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Chapter 2
Creating an Expedited Site Characterization and Remediation Program
true, however, that a heavy reliance has been placed on accepted methods,
sometimes to the extent that these methods are viewed as "approved methods"
that mu?t be used to generate analytical data at contaminated sites. However, as
part of their Performance-Based Measurement System initiative, the U.S.
Environmental Protection Agency (USEPA) is attempting to change the focus to
what data quality is required, leaving it up to the regulated entity to select the
analytical method to be used.
Finally, by blending advance planning with field analytical methods capable of
"immediately" available results, it is possible to implement dynamic work plans to
accomplish site work much more efficiently than under traditional approaches.
Dynamic work plans offer structured decision logic, such as decision trees or
contingency planning, that guides the performance of field activities. A key feature
is on-site decisionmaking and direction of field efforts by the technical team based
on an evolving site conceptual model which is constantly updated with new
information as it becomes available. Dynamic work plans use an adaptive
sampling and analysis strategy where subsequent sampling is directly contingent
oh the interpretation of earlier results, which permits the collection of samples or
the installation of wells in locations where the data are truly needed to decrease
uncertainty.
j , ','•, " '" •, t1 "• . ••• ' : '..i1.1
To successfully implement a dynamic work plan, more experienced team members
must take charge of field work. Increased expense is justified by the increased
productivity of field work. For example, there is a decreased need for multiple
mobilizations to the field to redirect work after interpretation of results turned
around from the laboratory three to four weeks later indicate that important data
gaps (and thus uncertainty) still remain; or when it is discovered that some critical
analyses failed quality assurance checks and samples must be recollected if the
data set is to be complete. Most importantly, the quandary of whether to spend
more money on another sampling round to decrease uncertainty or whether to
"make do" with the available data is avoided. "Making do" generally means that
site decisions or remedial design will be based on inadequate information which
increases the risk that the project will ultimately fail to achieve its objectives.
Adequate site characterization is essential to define the nature and extent of
contamination so that decisions regarding site cleanup will be done in a scientific
and legally defensible yet cost-effective manner. The range of experience and
knowledge gained over the past decade is permitting the environmental
remediation field to capitalize on new technologies and new ideas. To maintain
momentum, practitioners must make the effort required to stay current with
developments in their field of expertise. As the pool of available knowledge and
technology tools continues to expand, it also becomes important to recognize that
a single person cannot be relied upon to do it all - a technical team approach
which acknowledges that contributions of geologists, engineers, chemists,
biologists, quality assurance experts, risk assessors, statisticians, and regulatory
experts is crucial to successful projects.
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Chapter 2
Creating an Expedited Site Characterization and Remediation Program
2.3 Creating the Expedited Site Characterization
and Remediation Program
A successful expedited site characterization and remediation program is formed
by careful and thoughtful advance planning. As a whole, the program can be
broken down into the following four steps or phases. Although these steps appear
to be the same basic steps as currently applied at Resource Conversion and
Recovery Act of 1976 (RCRA) or Comprehensive Environmental Response,
Compensation and Liability Act of 1980 (CERCLA) sites, the intent is to do the
project in a better, faster, and less expensive manner. During each step described
below, project implementation and management can be enhanced through the
development of relationships (and trust) between stakeholders, frequent and
effective communication, flexibility, and contingency planning.
Step 1: Preliminary Conceptual Model Formation
The first vital step in expediting site characterization and remediation is to
conduct an initial site evaluation (also known as a Phase I environmental
assessment or Preliminary Assessment) to establish baseline conditions at the site.
In this assessment, historical information about the site's former operations are
gleaned from documents such as:
• Historical aerial photographs
• Sanborn Fire Insurance maps
• As-built site drawings
• Historical operations records
• Historical topographic maps
• Real estate records and title information
Regulatory agency site listings and files are also reviewed as are current site
practices. From this assessment, a preliminary site conceptual model is formed,
identifying what types of contaminants (if any) may be present at the site (e.g.,
petroleum hydrocarbons, PAHs, heavy metals), the possible locations of wastes
(e.g., gas holders, lampblack separators, tar pits and wells), and any immediate
health risks or threats to the environment.
Step 2: Survey-Level Field Program Formulation
Following completion of the preliminary site conceptual model, all possible
stakeholders in the project should be identified, briefed with the preliminary
conceptual model, and interviewed to obtain their input on the overall project
goals and objectives. Possible stakeholders include senior members of the
responsible parties' organizations, regulatory agency representatives, third-party
owners, public officials, and representatives of the public as required for future
. land use determination. A survey-level field program is then formulated to collect
analytical data to answer the following questions:
• What contaminants are present at the site, if any?
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Chapter 2
Creating an Expedited Site Characterization and Remediation Program
• What are the relative concentrations of the detected contaminants?
« What is the approximate extent of contamination at the site?
It is here the 80/20 rule should prevail; that is, practitioners should aim at getting
80 percent of the information ultimately needed for the project in this round of
sampling. The survey-level field program should take advantage of the site
characterization and management tools listed in Chapters 3 and 4 to gather a large
amount of relatively good quality data in order to determine where the majority of
the contamination is located and its chemical composition. A limited site
investigation (SI) is usually required to collect this information.
Dynamic work planning is essential to the successful completion of this phase of
the project. Sampling and field decisionmaking protocols — rather than specific
boring locations — should be outlined in the work plan, allowing an experienced
field team to move and sample at those locations dictated by each previous
sampling point. Innovative tools should be paired and implemented to allow for
real-time on-site analytical data feedback; for example, using direct-push drilling
with grab groundwater samplers and immunoassay or colorimetric testing to
identify the presence/absence and relative concentrations of subsurface and
groundwater contamination, where practicable.
Step 3: Preliminary Treatment Technology Screening, and Focused Field
Investigation Formulation and Implementation
Following completion of the survey-level field investigation, the sampling
program's results are analyzed with an eye toward site remediation. Those
remediation technologies that are the most promising for the site are identified, as
a're the additional data points necessary to:
» Further refine estimates of contamination volume
• Gather the additional data necessary to aid in evaluation and selection of the
best remedial alternative(s) for the site (e.g., geochemical indicators of natural
attenuation to see if active groundwater remediation is necessary, soil sieve
analyses to determine grain size, soil moisture measurements to determine
effectiveness of thermal desorption, etc.)
• Collect additional site-specific data to evaluate uncertainties that may have a
significant effect on the remedy selection (e.g., Is shallow groundwater in
connection with deeper groundwater-bearing zones? May drinking water be
affected?)
From this exercise, one or more focused field investigations are formulated and
subsequently implemented to gather only those data necessary to reduce
uncertainty to a pre-determined level of comfort and as required to complete
remedy selection. Again, work planning should allow for flexibility in the field,
permitting additional data collection as deemed necessary by the experienced
project team.
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Step 4: Remedy Selection and Contingency Planning
Using the results from the focused field investigations or a full-scale subsequent
remedial investigation (RI), remediation remedies for the site are evaluated.
Taking all factors into account, a remediation selection is made. As part of the
remedy selection and remedial design process, contingency planning is conducted
to prepare for unexpected changes in site conditions during remediation. The
selected remedial program is then implemented and modified as needed to adapt
to changing site conditions in order to achieve pre-determined performance-based
standards.
The four steps described above are intended to provide a skeleton for an expedited
site characterization and remediation program. It is the responsibility of the
practitioner to use this as a guide, amending, modifying, and adapting as needed
to meet site- or project-specific conditions. There are many variables that will
influence the form, scope, and level of effort involved for a site characterization
and remediation program. For example, site attributes that may affect the tools
used to characterize the site include:
• Site size
• Hydrogeology complexity
• MGP feedstocks used
• Availability of background and historical information
The tools described in general below and in detail in subsequent sections of this
document have been selected as those most applicable and available for
formulating an expedited program at former MGP sites. Logic and experience will
aid in formulation of an appropriate site-specific program.
2.4 Management Tools for Expediting
Characterization and Remediation
The process of MGP site characterization and remediation can be expedited by a
number of management or administrative approaches. Underlying all these
approaches is the need for trust and communication among those with an interest
in the site: the site owner, responsible party, regulators, consultants, the public,
area residents, etc. Actively involving all stakeholders in the process and creating
teams under conditions that foster genuine cooperation are key to facilitating
cleanup. If there is trust among all parties involved, there can be flexibility to make
decisions in the field as new information is uncovered about the site, without
slowing the process down for repeated reviews of new documentation. Effective,
cooperative relationships can be fostered by establishing administrative structures
and procedures, and/or by chartering teams of stakeholder representatives on a
project-by-project basis.
Practical strategies for streamlining MGP site characterizations and remediations
are discussed in Chapter 3 and include grouping together nearby or similar sites
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and negotiating agreements for groups of sites rather than on a site-by-site basis;
creating templates for work plans, reports and administrative orders; and knowing
early in the process what the eventual use of a site will be so cleanup can be
targeted to levels appropriate to that future use. Risk analyses, in the form of
tiered or probabilistic risk assessments, can also be used to help establish
appropriate cleanup objectives and to aid in the comparison of risks and liability
that could remain if various remedial alternatives were implemented. In addition,
use of the observational approach to site management can help focus the project
on targeting the information needed to assess contamination, getting only as much
information as needed to evaluate remedial alternatives, and planning for new
information that might emerge about the site as cleanup proceeds rather than
trying to eliminate all uncertainties before remediation can begin.
2.5 Tools for Site Characterization
All of the management strategies summarized above rely on targeted field
investigations in which sampling locations are chosen based on knowledge of a
site's past layout, and on the use of tools that are generally faster and give more
immediate results than those used in the past for assessment and cleanup of
wastes. Many samples can be collected, and a large amount of survey-level data
can be generated in a short time using these innovative tools.
Field surveying tools described in Chapter 4, from direct-push drilling to methods
for rapidly sampling soil and groundwater to the use of imaging techniques to
locate underground structures, make the process of collecting data on the types,
concentrations, and locations of MGP wastes much more rapid than in the past. If
management strategies such as site bundling are also used, multiple sites can be
assessed together or sequentially, taking advantages of economies of scale.
After the first phase of an investigation has been completed using field surveying
tools, further, focused investigations can supply additional data about areas of
contamination or uncertainly. This document focuses on tools for rapid field
surveys. In some cases, regulators may require data that these tools cannot provide
(e.g., low concentrations of PAHs in groundwater). However, because effective
field surveying can determine where the majority of the contamination occurs at a
site, traditional, time-intensive monitoring (e.g., fixed monitoring wells) to gather
additional data can be used only where necessary, saving time and money
compared to using these traditional methods to assess the whole site.
2.6 Technologies for Cleaning Up MGP Wastes
Familiarity with the technologies that have proven effective for treating MGP
wastes (as described in Chapter 5) may save time in identifying those candidates
most applicable to a specific former MGP site. Consider the choice between on-site
or off-site asphalt batching and thermal desorption as a treatment for
contaminated soil. Since both technologies will produce approximately the same
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result, considerations such as the amount and types of soil to be treated, the
proximity of the MGP site to an off-site fixed facility, and the costs associated with
these factors will likely motivate the decision.
2.7 Conclusion
The ability to craft an effective, streamlined site characterization and remediation
program comes from both experience and knowledge* Understanding how MGPs
were operated and dismantled is the first step — gaining an understanding of
what might be below the surface of a site is extremely important. Flexibility,
combined with careful planning and the willingness to try something new, can aid
in the formulation and successful implementation of an innovative and
streamlined investigation and remediation program.
The management strategies and field-survey tools described in this guide will
provide information necessary to expedite the site characterization and
remediation process. The technologies described are those most likely to be
effective in remediating MGP wastes in soils, delineated by this streamlined
process.
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Chapters
Management Tools foir Expediting Site
Characterization and Remediation
3.1 Introduction
Because of the similarity of former MGP sites nationwide, innovative site
management tools have been developed to streamline the characterization
and remediation of wastes found at these sites. Using these techniques can
reduce the timescale that has been typical for remedial investigation, feasibility
study, remedial design, and remedial action (RI/FS/RD/RA) cleanup projects at
sites being addressed under traditional programs. These innovative approaches,
described below, have two key features: they take advantage of economies of
scale, emphasizing ways to address multiple sites simultaneously; and they focus
on facilitating communication among the parties involved in cleanup as well as
promoting each party's "ownership" of the process. The table on the following
pages summarizes the components of these programs.
These site management innovations are currently being applied at MGP sites. Case
studies are included below where available. Not every tool will be appropriate in
every situation. Parties responsible for former MGP sites can modify the
approaches to fit their sites. Similarly, responsible parties can select more than one
of the tools discussed below and merge them to tailor a program to a site or set of
sites. Reference information is supplied so that readers can contact representatives
involved in the specific projects.
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Management Tools for Expediting Site Characterization and Remediation
Name
Description
Economies of Scale Advantages
Communication Facilitation
Site Bundling
Bundling multiple MGP sites into one
package" which is then managed,
investigated, and as appropriate, remediated
as a single entity.
• Saves time and money by reducing the volume of
paperwork
• Allows for negotiation of lower unit pricing with vendors
• Reduces project management and accounting costs
through reduction in project administration labor hours
• Reduces regulatory agency oversight costs by
negotiation one order for multiple sites and having one
regulatory project manager
• One regulatory project manager for multiple sites
minimizes downtime from lack of education/project
understanding
• Minimizes duplication in RI/FS/RD/RA program
development
• Builds trust/relationship between stakeholders by
prolonged, multi-site contact
Multi-Site Agreements
Single agreement providing responsible
party(ies) and regulatory agency(les) the
opportunity to address environmental
conditions under a single, cooperative,
mutually beneficial, statewide agreement.
Comprehensive and consistent statewide strategies
Reduced costs of negotiating agreements/orders
Control of year-to-year costs
Optimized risk reduction
• Agreements tailored to company-specific needs
• Central point of contact(s) established within regulatory
agency (ies)
• Proactive environmental mitigation
• Emphasis on cooperation and common sense
Generic Work Plans
and Reports
Preparation of generic documents, such as
work plans and"reports, that can be tailored
to a specific site or set of sites.
• Savings from having to prepare only the site-specific
sections of a document
• Reduced regulatory oversight costs and review time
from having all documents from a single entity be
organized similarly
• Streamlined decisionmaking from "prequalifying"
remediation technologies with local regulatory agencies
• Consistent site characterization and application of quality
assurance project plans and Health and Safety Plan across
multiple sites
• Consistent decisionmaking rationales applied to multiple
MGP sites
Program/
High Performance/
Design Teams
A team or set of teams formed and
chartered to work towards a common goal,
prompting communication, expediting
decisionmaking, streamlining deliverable
preparation, and remediating a site in the
most cost- and time-effective manner
possible with agreement among all parties
involved.
• Shared project vision, mission, and goals for all sites
addressed by the team
• Reduces overall costs by minimizing document
handling and review and project downtime
• Reduces overall regulatory oversight costs
• Minimizes downtime and backsliding resulting from
consultant or regulatory management turnover
• Chartering and common sense of purpose and set of
goals promotes communication
• Success of teamfs) based on development of relationship
and trust
• Nature of team reduces stakeholder conflict
• Team charter formalizes communication process
Early Land-use
Determination/
Brownfields
Identification of future site beneficial use
prior to site characterization, and integration
of the proposed future land use with the
planned site remediation.
• Reduces site characterization costs by identifying only
those data necessary for evaluation of remediation
alternatives to meet proposed future site use
• Minimizes remediation costs by focusing on
alternatives that can successfully meet future beneficial
use needs
• Can turn a challenged property into a money-making
enterprise
• Focuses regulatory agency(ies) and responsible parties
on the project's ultimate goal (site remediation and
redevelopment)
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Name
Managing Uncertainty
Expedited Site
Characterization
Legislative Innovation
Dovetailing Business
Decisionmaking and
Remediation Planning
Establishing
Background PAH
Concentrations
Generic
Administrative Orders
Management Tools for Expediting Site Characterization and Remediation
Description
A method providing a way to determine when
sufficient site characterization data have been
collected and involving managing
uncertainties through the identification of
reasonable deviations from original plans and
the preparation of contingency plans to
address changed site conditions.
The combination of tools, strategies, and
processes that interlink and synergistically
help streamline investigation and remediation
processes.
Alternative regulatory policies for the
remediation of contaminated properties by
providing for a comprehensive program that
includes revised liability, indemnification
processes, risk-based cleanups, streamlined
remediation processes, and dispute
resolution.
Combining site remediation with business
ventures such as developing affiliate
companies or developing joint venture to
create a mobile treatment facility.
Establishing the portion of PAHs at a site that
are the result of non-MGP processes such as
automobile exhaust, crude oil processing, etc.
Preparation of a single generic administrative
order that can be adapted for multiple sites.
Economies of Scale Advantages
• Minimizes downtime during site characterization and/or
remediation through upfront contingency planning to
address potential changes in site conditions
• Reduced costs through streamlined document
preparation and review
• Reduced costs through the use of field screening and
analysis tools
• Minimizes project downtime by allowing flexibility in the
overall site characterization and remediation processes
and through the active management of uncertainty
• Allows risk-based decisionmaking to optimize
remediation alternatives
• Apportionment of liability based on fair and equitable
principles and orphan share funding
• Saves cost by expediting site remediation
• Optimize treatment costs by investing in risk-sharing
treatment ventures
• Optimizes volume of soil to be remediated by
addressing only those portions of PAH-contaminated soil
that are the result of historical MGP processes
• Streamlines the administrative order preparation
process
• Reduces costs in preparing and negotiating
administrative orders
Communication Facilitation
• Requires flexibility to alter a site investigation and/or
remediation in the field based on pre-determined
contingency plans. This requires trust and consistent
communications between regulatory agency(ies) and
responsible party(ies)
• Communication and cooperation among responsible
parties, regulatory agencies, and third party stakeholders
through mediation, facilitation, and high-performance teams
• Uses onsite or rapid decisionmaking capabilities
• Includes a process for reducing team member turnover
and minimizing effects of team member replacement
• Lead agency designation streamlines regulatory agency
communication
• Requires public participation per state regulatory
guidelines
N/A
N/A
• Familiarity with the generic order allows for site-specific
communications/ negotiations on an as-needed basis
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Chapters
Management Tools for Expediting Site Characterization and Remediation
Management Tools for Expediting Site
Characterization and Remediation
The following sections describe each site management tool for expediting site
characterization and remediation. Because different tools will be appropriate for
different sites, no attempt has been made to rank the tools according to their
effectiveness.
3.2.1 Site Bundling
Tool Description
Utility companies typically own or are liable for multiple MGP sites. There are
many methods that can save time and money during site characterization and
remediation. One simple but effective method is bundling multiple MGP sites into
one "package," which is then managed, investigated, and remediated as a single
entity. Site bundling saves time and costs by:
• Reduction in the volume of paper documentation (e.g., one work plan may be
prepared for multiple sites)
» Reduction in project management and accounting costs through a reduction in
the number of labor hours required for project administration
• Reduction in regulatory agency oversight costs by negotiating one order for
multiple sites and by requiring only one regulatory agency representative for
the sites
Additional savings can be achieved by coordinating site investigation and
remediation activities for multiple sites located relatively close together.
Mobilization costs can be reduced by conducting sampling (e.g., quarterly
groundwater monitoring) sequentially at all sites and by purchasing sampling
materials in bulk. When the preferred remedial alternative is the same for multiple
sites and especially in situations where the sites are located near one another,
treatment costs can be reduced by staging treatment processes for all the sites at
one location. Savings result from reduced transportation costs and lower unit costs
for treating larger volumes of material than would be generated by a single site.
Case Study
MidAmerican Energy Company Multi-Site Thermal Desorption
At the end of 1996, MidAmerican Energy Company (MEC) was preparing to
conduct remedial activities at a number of former MQP sites that were relatively
close to each other. These sites had fairly small quantities of waste to be treated
and were of limited size, which posed potential problems for locating treatment
technologies on-site. Because of the sites' proximity, small size, and ownership by
one utility, innovative administrative and technical approaches were chosen.
On-site thermal desorption by a mobile treatment unit was identified as a viable
remedial alternative for all of the sites. MidAmerican Energy worked with the
Iowa Department of Natural Resources (DNR) and USEPA Region VII to locate a
thermal desorber at a National Priorities List (NPL) site in Waterloo, Iowa.
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Management Tools for Expediting Site Characterization and Remediation
Following completion of a rigorous trial burn, the thermal desorption unit was
used to treat MGP wastes at the Waterloo site and from three additional sites in
Charles City, Hampton, and Independence, Iowa.
Project Milestones
Initially, Independence, Iowa, was the only MEC site where contaminated soils
were to be excavated and thermally treated. As the planning for this project
proceeded, it became apparent the thermal desorption unit could not be set up on-
site because of lack of space. A search began to find a treatment location. An
industrial park in Independence appeared to be the first choice. However, the high
costs of this choice meant that another option had to be considered. The Waterloo
former MGP site in Waterloo, Iowa, already had 12,000 cubic yards of soil
removed for treatment, and this site was located 30 miles from Independence. An
open excavation existed at Waterloo, and more soil required excavation.
Concurrently, MEC determined that removal actions at the Charles City and
Hampton former MGP sites would also be beneficial if soil treatment could be
arranged. MEC therefore concluded that treatment of excavated contaminated
soils from all four sites at one on-site location could be a tremendously cost-
effective way to conduct removal actions at all four former MGP sites.
Site
Size (acres)
Service
Years
Current Site
Use
Gas Process
Used
Regulatory
Status
Waterloo
3.4
1901-1954
vacant
coal carbonization,
water gas,
carbureted water gas
Under consent order
with USEPA Region
VII
Hampton
0.6
1906-1937
electric substation/
storage area
Lowe Water Gas
System
Under consent order
with Iowa DNR
Charles City
1
1909-1949
electric
substation
Lowe Water
Gas System
Under consent
order with Iowa
DNR
Independence
0.4
1880-1947
vacant
J.D. Patton Oil
Gas Process,
Tenney Water
Gas Process
Under consent
order with Iowa
DNR
A summary of the projects milestones is shown below:
• January and February of 1997 - MEC contacts the city managers of
Independence, Charles City, and Hampton, Iowa, to discuss the potential
remediation of the former MGP sites.
• March and April 1997 - Additional meetings with Iowa DNR and USEPA take
place to discuss the possibility of locating a thermal desorption unit at the
Waterloo site and thermally treating soils from the other three sites, thermally
desorbing the remaining soil at the Waterloo site, and using all the thermally
treated soil as backfill at Waterloo.
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" May 1997 - MEC adds the Hampton, Charles City, Waverly, and Waterloo sites
to the Independence thermal desorption project, and initiates community
relations activities in preparation for the project.
• July 1997 - A Thermal Desorption Scope of Work and Contract Documents
package is completed. MEC continues to work with the Iowa DNR to develop
work plans for the sites under state regulatory oversight and with the USEPA
concerning the scope of work at the Waterloo site.
• October 1997 - Final changes are made to the work plans for Hampton, Charles
City, and Independence sites. Site preparation begins at Waterloo, with soil
excavation initiated at the Hampton site and soil shipping to Waterloo.
• December 1997 - Thermal desorption operations begin in January 1998. Soil
excavation continues at all four sites, with thermal desorption operations
continuing at the Waterloo site.
• February 1998 - All work, including backfilling, is completed.
Remedial Action Implementation
The cleanup objective at these sites was to remove visibly contaminated soil and to
excavate to physical limits, which were determined by site conditions such as
buildings, property boundaries, railroad tracks, etc. The criteria for stopping the
excavation short of a physical boundary were less than 500 milligrams per
kilogram (mg/kg) total PAHs or less than 100 mg/kg total cPAHs (cPAHs) in the
0- to 6-foot range, or less than 3,000 mg/kg total PAHs or less than 200 mg/kg
cPAHs at depths greater than 6 feet. The cleanup criterion for the thermally
treated soil was less than or equal to 5 mg/kg total PAHs.
The following table shows the amount of soil excavated and treated for each of the
four sites:
Site
Hampton
Charles City
Independence
Waterloo
Total
Tons of Soil Treated
3,651
2,138
4,734
14,167
24,690
Treated soils from all four sites were used to backfill a previous excavation at the
Waterloo site. All contaminated oversized debris was crushed and thermally
treated. Some exceptionally large debris, such as foundations, was decontaminated
in place and left in the excavation. All scrap steel was cleaned and sent to a
recycler. As a result, nearly all materials removed were thermally desorbed or
recycled. A small amount of material, primarily wood debris and tree roots, was
taken to the local landfill.
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The total cost of the project was $2 million. This cost includes site preparation and
installation of utilities; excavation at all the sites; hauling excavated material from
Hampton, Charles City, and Independence to Waterloo; backfill and labor to place
the fill; and the thermal desorption services including the cost of fuel.
The average cost per ton of soil treated was calculated for the project and is shown
in the table below:
Item
Excavation
Thermal Treatment
Transportation
Backfill
Miscellaneous*
Total
^Average ppst per ton ($)*,
4.83
47.87
12.53
4.83
8.62
78.68
* This includes the cost of analysis, engineering services, air monitoring, etc.
Conclusions
Site bundling resulted in total savings of more than $1 million on this project. The
use of a single, central location for treatment of contaminated materials resulted in
significant savings compared to the cost of completing the four projects separately;
MEC has estimated a savings in excess of $150,000 in costs related to project
management. Additional savings of approximately $205,000 were realized by
using the treated soil as backfill at the Waterloo site rather than landfilling the
treated soil and purchasing clean backfill. Setting up the thermal treatment unit in
Waterloo, a central location relative to the other sites remediated, reduced
shipping costs. Previous work at the Waterloo site had included shipping soil to
the Neal Generating Station near Sioux City, Iowa. By setting up the thermal
desorber in Waterloo, MEC saved approximately $575,000 in soil shipping costs.
Reduced regulatory oversight and engineering costs were estimated to be in excess
of $100,000.
Teamwork was a key component to the successful completion of this project. Iowa
DNR and USEPA Region VII personnel reviewed and commented on documents
for this project. Because MEC wrote the work plans in-house, the time required to
make a change to a work plan and send an updated copy to the regulators was
very short. At times a change would be suggested, the pages of the work plan
were modified, and copies of the changes were faxed within hours of the
discussion. This fast pace kept everyone involved focused on completing the task.
Joint effort by state and federal agencies resulted in achieving the goals of site
source removal, thermal treatment, and backfill at four sites in a short time.
Contacts
Johanshir Golchin, Iowa Department of Natural Resources, (515) 281-8925
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Jim Colbert, USEPA Region VII, (913) 551-7489
Sam Nelson, MidAmerican Energy Company, (712) 277-7851
DanKlimek, MidAmerican Energy Company, (712) 277-7930
3.2.2 Multi-Site Agreements
Tool Description
Former MGP sites lend themselves to multi-site agreements. Much like strategic
plans, multi-site agreements provide both the responsible party(ies) and the state
in which the properties are located the opportunity to address environmental
conditions under a single, cooperative, mutually beneficial, statewide agreement.
Benefits of multi-site agreements include:
• Comprehensive and consistent statewide strategies
• Reduced costs of negotiating agreements/orders
• Agreements tailored to company-specific needs
• Control of year-to-year costs
• A central point of contact that may be established within the state regulatory-
agency
• Proactive environmental mitigation
* Optimized risk reduction
• Emphasis on cooperation and common sense
Multi-site agreements have currently been implemented in California, Iowa, New
York, and Pennsylvania. In all cases, multi-site agreements are developed through
negotiations among utilities/companies and regulatory agency(ies) and include a
strategic plan for addressing and completing site investigation and remediation.
The Pennsylvania Department of Environmental Protection Multi-Site
Agreement Program
The state of Pennsylvania has developed a statewide program for multi-site
remediation agreements under the Department of Environmental Protection,
Bureau of Land Recycling and Waste Management. Under the Pennsylvania
Department of Environmental Protection (DEP) Multi-Site Remediation
Agreement program, utilities and other private parties may enter into a form of
consent agreement that is fundamentally different than the agreements enforced
for parcels owned by individual owners. Instead of imposing requirements with
respect to each individual site, the Pennsylvania multi-site agreements require that
a specific minimum increment of work be performed each year at the covered sites
taken as a whole. A point system is used to measure the work completed, thereby
ensuring permit compliance. To a large extent, the volume and type of work
performed during a particular year is within the discretion of the business owner.
The Pennsylvania multi-site agreements include seven primary elements that
distinguish them from other DEP-enforceable remediation agreements:
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Element 1: Planning Process—Under the Pennsylvania DEP Multi-Site
Remediation Agreement program, a company entering into an agreement with
DEP is required to submit an annual and S^ear plan incorporating the following
items:
» Identification of anticipated work during the next 1- and 5-year periods
• A list prioritizing the sites covered by the agreement
• The number of points to be earned by the anticipated work
• The estimated costs to be incurred during the next year of work
Under this program, it is the DEP's responsibility to assemble a team including
representatives from both regional and central DEP offices, to disseminate
information among this team during the course of the agreement, and to respond
to submittals with a single set of comments. Any disagreement within the DEP
team for the sites must be resolved internally to provide consistent regulatory
review and oversight.
An annual planning meeting is held between the party responsible for the sites
and the DEP, providing an opportunity to review the proposed plans in a
cooperative manner, resolve outstanding issues, and discuss implementation of
the agreement. :
Element 2: Prioritization of Sites—As noted above, the annual plan is required to
prioritize the sites to be covered by the agreement. This prioritization is conducted
by evaluating the environmental and human health risks posed by each site and
assigning points based on a scoring system that identifies the features that
potentially pose the greatest risks. The scoring system varies by agreement and is
included as an attachment to the multi-site agreement. This method of risk-based
scoring promotes DEP's goal of risk reduction and helps the party responsible for
the sites address its areas of highest liability first.
Element 3: Point System/Minimum Annual Point Requirement—The key feature
of Pennsylvania DEP's Multi-Site Remediation Agreement program is the point
system that measures success in completing remediation activities. Rather than
dictating which sites require which activities, the DEP and the party responsible
for the site create a list of anticipated components of work required to investigate
and remediate the sites covered by the agreement. Points are assigned to each
component based on various criteria (or combinations of criteria), including level
of effort, cost, environmental benefit, and risk reduction. The DEP and the
responsible party then determine the minimum number of points to be completed
annually under the agreement, which allows the responsible party the freedom to
determine which activities will be conducted! in any given year. Failure to meet the
minimum annual point requirements may result in penalties and the requirement
to "make up" the shortfall in a specified period of time. Conversely, if the
responsible party achieves more than the minimum annual point requirement in a
given year, it may bank or save the "extra" points.and apply them in a subsequent
year.
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Element 4: Cost Cap—The Pennsylvania DEP is willing to include a cost cap in its
multi-site agreements, allowing a responsible party to fall short of its minimum
annual point requirement should its total annual costs meet or exceed the cap. The
costs that are included in this cap are open to negotiation. The cap gives the
responsible party fiscal protection should remediation activities at one particular
site turn out to be significantly more expensive than anticipated. In order to
include the cost cap in a multi-site agreement, the responsible party must make a
financial disclosure.
Element 5: Uniform Process for Review and Approval of Submittals —
Pennsylvania's multi-site agreements, like all enforceable agreements in the state,
must identify the type and contents of plans and reports to be submitted. Because
Multi-Site Remediation Agreement documents require review by a DEP team, a
uniform process for review and approval of submittals is also included in the
multi-site agreement. Establishing this process during the agreement preparation
means that requirements can be applied consistently. The review process can also
be streamlined and potentially contentious issues can be resolved up front.
Element 6: Termination —All multi-site agreements prepared by the DEP allow
for termination of the agreement by either party upon the agreement's fifth
anniversary and every fifth anniversary thereafter. The agreement is limited to a
minimum of 5 years, which allows the responsible party to "test the waters"
without committing to a long-term process.
Element 7: Interaction with Act 2—Act 2, Pennsylvania's Land Recycling and
Environmental Remediation Standards Act, establishes environmental
remediation standards to provide a uniform framework for cleanups. Under this
act, responsible parties can choose from three types of cleanup standards:
background standard, statewide health standard, or site-specific standard. Act 2
describes submission and review procedures to be used under each of the three
cleanup standards and provides releases from liability for owners or developers
where the site has been remediated according to the standards and procedures of
the Act. Under the Pennsylvania DEP's Multi-Site Remediation Agreement
program, interaction with Act 2 has, to date, been agreement specific. The Penn
Fuel Multi-Site Agreement (discussed below) required the achievement of an Act 2
standard but also allowed DEP to issue a no-further-action letter in lieu of an Act 2
release, thereby relieving Penn Fuel from some of the administrative requirements
ofAct2(Rader, 1997).
Benefits achieved under the Pennsylvania DEP Multi-Site Remediation Agreement
program include (Commonwealth of Pennsylvania, 1996a):
« Development of case loads that are manageable by both the DEP and the
responsible parry
• Reduction of review time and inconsistent responses through the development
of the uniform process for review and approval of submissions
• Cost savings from managing multiple sites simultaneously and reducing
redundant administrative tasks
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• Creation of good will among DEP regions and central office and with the
regulated community
The primary disadvantage of the program is the potential deferral of remediation
at some of the covered sites. However, by actively managing the sites requiring
investigation and remediation and providing credits for work completed ahead of
schedule, both DEP and the responsible parties can minimize risk within the
context of limited resources.
Case Studies
Pennsylvania Power & Light Co. Multi-Site Agreement
In 1995, Pennsylvania Power & Light Company (PP&L) entered into a multi-site
agreement with the Pennsylvania DEP. This agreement formed part of the
foundation of Pennsylvania DEP's current Multi-Site Remediation Agreement
program. Under this multi-site agreement, PP&L and DEP agreed to develop a
model to rank almost 130 potential contaminated sites, including utility poles,
substations, power plants, and former MGP sites. To create this model, PP&L and
DEP first developed a uniform polychlorinated biphenyl (PCB) standard for all the
sites so PP&L could manage the project with consistent interpretations from
different DEP regional offices. Next, a system for prioritizing the sites was
devised, and a method for tracking progress was designed. A point system was
developed to ensure that PP&L kept its cleanup efforts on schedule, and an annual
financial cap was set, allowing the compan}^ to allocate financial resources over
several years (Winsor, 1996).
An example of a former MGP site remediated under the PP&L multi-site
agreement is the Lycoming College redevelopment project. At this site, PP&L
worked with the college and DEP to remove coal tar left from two large
underground holders remaining from the original MGP (PP&L, 1996).
Contact
Don Stringfellow, PP&L, (717) 769-7535
Penn Fuel Multi-Site Agreement
Penn Fuel Gas, Inc., (Penn Fuel) arid North Penn Gas Company (North Penn)
entered into a multi-site agreement with the Pennsylvania DEP to investigate, and,
where necessary, remediate 20 former MGP sites using standards from the Land
Recycling Program (Act 2) and to plug 340 abandoned natural gas wells •
(Commonwealth of Pennsylvania, 1996b). Signed on March 27,1997, the
agreement between DEP, Penn Fuel, and North Penn Gas Company stipulated
that, during the following 15 years, Penn Fuel would investigate all 20 of the sites,
cleaning up those that require remediation following a schedule based on the
potential environmental and health risks, if any, posed by each site. North Penn
has also agreed to plug a minimum of 16 abandoned wells per year, with all 340
plugged by the year 2011. Penn Fuel and North Penn have agreed to spend up to a
total of $1.75 million a year on investigation and cleanup operations and well
plugging.
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The Lewistown former MGP site was remediated by Penn Fuel under a multi-site
agreement. Built in the early 1800s, this large MGP stood on the southern end of
Lewistown, Pennsylvania. At the end of 1996, only two of the former MGP's gas
holders remained. Under the multi-site agreement, Penn Fuel removed 100,000
gallons of coal tar and 625,000 gallons of water from inside the two gas holders
and then dismantled the tanks. Water from the gas holders was pumped through
an oil-water separator and treated with a dual carbon treatment system before
disposal. The coal tar was pumped into treatment tanks and blended with a
polymer to dewater the tar. The steel from the-gas-holders was recycled in a steel
foundry.
Niagara Mohawk Multi-Site Agreement
Niagara Mohawk Power Corporation (NMPC) currently owns 24 former MGP
sites, all inherited from predecessor companies when it was founded in 1950.
Twenty-two of the former MGP sites are subject to two consent orders between
NMPC and the New York Department of Environmental Conservation (DEC); the
two other sites are being addressed separately.
The first of two DEC orders between NMPC and DEC calls for NMPC to:
• Investigate, between 1992 and 1999, coal tar and other wastes at 21 of the
former MGP sites currently owned by the company to determine whether any
hazardous substances are present and whether they pose a significant threat to
the environment or to public health.
• Remediate each site where DEC determines that remedial process is required.
Where deemed appropriate, interim measures may be undertaken to remove
or control sources of contamination.
Under the second consent order, NMPC will expand and complete the cleanup
already under way at the Harbor Point former MGP site in Utica, New York, to
include adjacent parcels containing MGP wastes. In addition, the company
committed to operate a research center at Harbor Point to evaluate several new
technologies for remediation of waste-contaminated materials and to fund in
advance DEC's expenses for environmental monitoring, oversight, and
administrative costs (New York State Department of Environmental Conservation,
1992).
Under a third consent order that was executed in 1997, NMPC and the DEC
expanded the first and second orders to include remedial programs for certain
additional sites (including non-MGP sites) to:
• Level future annual costs to be incurred for site investigation and remediation
(SIR) activities
• Minimize the impact upon ratepayers of excessive short-term expenditures for
concentrated SIR activities
• Minimize potentially excessive burdens on staffing and administrative
resources of both NMPC and the DEC
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NMPC and the DEC agreed to implement an annual cost cap for SIR activities
based on the level of annual costs incurred in recent years.
Contacts
Michael Sherman, Niagara Mohawk Power Corporation, (315) 428-6624
Jim Harrington, NY State Department of Environmental Conservation, (518) 457-
0337
3.2.3 Generic Work Plans and Reports
Tool Description
In the site investigation and remediation process, documentation costs leading up
to the remediation can be very high. The traditional RI/FS/RD/RA approach
typically requires the preparation of one or more versions of a work plan and
investigation report (often multiple work plans and reports for multiple phases of
work), feasibility study reports, RA plans, removal action work plans, and closure
reports. For utilities or private parties with portfolios containing multiple MGP
sites, significant savings can come from reducing the costs of documenting and
reporting. These savings can result from either preparing single submittals for
multiple sites and/or multiple phases of work, or from preparing generic
documents that can easily be tailored to a specific site or sites.
Most generic submittal development efforts have focused on field investigative
work plans and feasibility studies. Benefits that can be achieved through the
preparation of generic templates for these documents include:
• Savings from having to prepare only the site-specific sections of a work plan or
feasibility study
• Reduced regulatory oversight costs and review time from having all
documents from a single entity be organized similarly
• Streamlined decisionmaking from "prequalifying" remediation technologies
with local regulatory agencies (e.g., development of presumptive remedies) .
• Consistent site characterization and application of quality assurance project
plans (QAPPs) and Health and Safety Plans (HASPs) across multiple MGP
sites I
• Consistent decisionmaking rationales applied to multiple MGP sites
A key factor in the successful application of generic work plans and feasibility
studies is allowing flexibility to move outside the template as necessary for site-
specific conditions. Combined with other streamlining strategies (e.g., multi-site
agreements), the use of generic deliverables can provide a great time and cost
savings to responsible parties and regulatory agencies.
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Case Studies
Public Service Electric & Gas Company Generic Remedial Investigation
Work Plan
In April and May of 1995, Public Service Electric & Gas Company (PSE&G) met
with the New Jersey Department of Environmental Protection (NJDEP) to discuss
the potential to work with the NJDEP Site Remediation Program (SRP) to
streamline the MGP site remediation process. As a result, an NJDEP/PSE&G
Streamlining Team was established. In partnership, the two organizations defined
and evaluated the process of investigating and remediating MGP sites and
identified opportunities for improvement, consistency of approach, and cost
effectiveness. The Streamlining Team identified the quality of the RI workplan
submittal as a major area for improvement. The inadequacy of the documents
coupled with the separate review and approval cycles of the two organizations
considerably lengthened the RI process. The Streamlining Team's solution was to
develop a boilerplate RI work plan that met or exceeded NJDEP's technical
regulations and guidelines.
In November 1997, PSE&G published a Generic Remedial Investigation Work Plan
(PSE&G, 1997). This work plan outlined a data quality objective (DQO) process
designed to gather and evaluate all the data necessary to complete an RI in one
phase. The DQO process consists of six steps that, when completed, should
provide all the data necessary to meet NJDEP's requirements. The six steps are:
Step 1: Understand the MGP facility's history, construction, and operations as they
relate to the production and disposition of MGP residuals and the potential
for release (s) to the environment.
Step 2: Use the results of Step 1 and the preliminary assessment and site
investigation (PA/SI) to develop a preliminary site conceptual model.
Step 3: Develop a vision for future land use, preferably supported by a well-
researched, site-specific plan.
Step 4: Develop risk-based RA objectives that define the purpose of the
remediation and avoid expenditures on remedial activities that do not meet
these objectives.
Step 5: Identify potential remedial methods, proven to be effective at former MGP
facilities, that will achieve the RA objectives.
Step 6: Identify applicable regulatory requirements.
The Generic Remedial Investigation Work Plan prepared by PSE&G consists of
three volumes. The first volume is the generic work plan itself, containing boiler
plates for the descriptive portion of the work plan (e.g., site background,
environmental setting, and scope of work). Volume 2 of the work plan contains
the QAPP, Standard Operating Procedures for many field activities (e.g., cone
penetrometer surveys, rock coring, and aquifer testing), and a list of the minimum
safety and health plan requirements and specifications. PSE&G is currently
planning to publish a generic RI report in concert with NJDEP.
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Contacts
Rich Blackman, Public Service Electric & Gas, (973) 430-8278
Chris Kanakis, New Jersey Department of Environmental Protection, (609) 633-
1460
Woerner Max, Public Service Electric & Gas, (973) 430-6413
Southern California Edison Generic Feasibility Study
Faced with investigation and remediation of multiple MGP sites, Southern
California Edison (Edison) prepared a "generic FS" to help streamline preparation
of site-specific feasibility studies for their MGP sites. This generic FS template is
organized like a site-specific FS and contains text that can remain in a site-specific
FS, but it also allows the user to "plug-in" site-specific information as appropriate.
For example, the document provides a general history of MGP facilities and then
prompts the user to add site-specific historical information. The generic FS also
provides numerous examples of text and tables to further assist users in preparing
a site-specific FS. In all cases, the generic FS assumes:
• The MGP waste is nonhazardous.
• Onsite ex situ remediation is not feasible because of space limitations at the
sites.
• The cleanup level is 1 ppm total cPAHs (benzo[a]pyrene equivalent).
Contact
Terry Sciarotta, Southern California Edison, (626) 302-9723
3.2.4 Program/High Performance/Design Team
Tool Description
A Program, High Performance, or Design Team is a team of stakeholders brought
together with the intention of creating trust, communication, motivation, and
cooperation to collectively solve a problem. Site characterization and remediation
is one of many fields in which the use of such a team can expedite, streamline, and
reduce the cost of completing a project, with the project being site-specific (as for
an MGP site characterization and remediation) or programmatic (e.g., to establish
methodologies for dealing with multiple MGP sites) in nature.
A team approach is useful because characterization and remediation of sites:
• Is often too complex for any one person to be able to know of or handle
multiple variables.
• Typically has no single solution. The best solution is often one that balances the
needs of all stakeholders involved in the site with federal, state, and local
regulations.
• Requires multiple areas of expertise to reach a preferred solution.
• Requires that all stakeholders work together to efficiently achieve an acceptable
solution.
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A High Performance Team (HPT) must concentrate on three major areas where
team development typically occurs: problem-solving skills, process improvement,
and behavioral performance. The team must learn to work together, be flexible,
and be willing to understand and develop team-related problem-solving skills
(such as Total Quality Management techniques including causal loop diagraming,
popcorn brainstorming, and decision science models). The rules of conduct laid
out in the charter must be followed, and the team must regularly revisit its
purpose, goals, and methods, seeking individual and team feedback for
continuous improvement. At times, a trained facilitator may be required to
manage the team-building process and/or to assist the team in overcoming road
blocks in the consensus-making process.
Building a team requires time and energy. Effective teams create synergistic
results. Beyond pooling skills and understanding, an HPT can speed the
remediation process, reduce overall project costs, minimize conflict and
misunderstanding with regulators, promote acceptance and support in the local
community, minimize downtime and back sliding resulting from consultant or
regulatory management turnover, and create relationships and trust between the
utility and regulators that extend beyond any single site characterization and
remediation. The upfront costs of building the team are typically offset by savings
realized later in the project after the team is formed and trust has been built
between the team members.
Case Studies
Pacific Gas and Electric Company ChicolWillowslMarysville High
Performance Team
In 1994, Pacific Gas and Electric Company (PG&E) initiated the RI/FS/RD/RA
process for three former MGP sites in Chico, Willows, and Marysville, California.
Recognizing the advantages of streamlining the RI/FS process, PG&E combined or
"bundled" the sites into one project. PG&E negotiated one order for the three sites
with California Department of Toxic Substances Control (DTSC) and identified
representatives from PG&E, each of California's primary regulatory agencies
(DTSC and the Regional Water Quality Control Board), along with a PG&E
consultant to serve as primary case managers for all three sites. In 1996, PG&E
initiated a unique streamlining program, the backbone of which was the Chico/
Willows/Marysville (CWM) HPT.
The CWM HPT, as with most similar teams, was made up of a series of focus
groups or sub-teams formed solely to promote the project's successful completion.
The organization of the CWM HPT comprised all potential project stakeholders (in
this case, PG&E, state regulatory agencies, and PG&E's consultant).
The Sponsorship Team was composed of stakeholder representatives with the
authority to "sign on the dotted line." These included persons in charge of
policymaking and budget authorization. Members of this team included DTSC's
Site Mitigation Section Chief and PG&E's vice-president, who oversees all
environmental operations. These are the ultimate "owners" of the project.
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For the CWM project, a Leadership Team was also formed, consisting of senior
representatives from PG&E and the regulatory agencies. California regulatory
agencies generally experience a frequent turnover in project managers. Involving
senior staff in the HPT process helps ensure continuity of project decisionmaking
and regulatory interpretation despite personnel changes. Representatives on this
team included PG&E's Director of Site Remediation and DTSC's Site Mitigation
Unit Chief.
The Management Team of the CWM HPT is composed of persons charged with
actually carrying out the project. Members are PG&E's consultant and regulatory
project managers. Separate Task Teams were also formed to address specific issues
or problems. For example, Task Teams were formed for community relations and
risk assessment.
The first task of the HPT was its charter. This exercise formed the basis for the
team's operations. Steps conducted by the HPT during chartering included:
identifying unifying goals, objectives, and measures by which the team could
evaluate whether it was meeting goals; preparing guidelines for meetings and
communications; and identifying the fundamental rules by which the team(s)
would operate. Because several HPT members were not familiar with either the
RI/FS process or MGP sites, education was also required to ensure that all team
members were comfortable with the process and would support decisions. This
education was conducted during workshops where HPT members reviewed the
operational history and historical documents (MGP facility plans, Sanborn maps,
etc.) available for each site. Applicable state and federal regulations and HPT
member expectations were also discussed.
The second HPT task was the development of conceptual models for each site to
ensure that all HPT members had the same view of site physical conditions, source
delineation, transport pathways, and exposure pathways. The team then jointly
initiated the first steps of the FS, identifying all possible remedial technologies and
screening them to form what all team members (including regulatory agencies)
agreed to as a subset of technologies that could be reasonably applied at the three
sites (i.e., ex situ thermal desorption and asphalt batching). At this time, the HPT
identified two key questions that still needed to be resolved and defined the scope
of an additional focused field investigation designed to collect only the data
necessary for the HPT to complete the FS with a high degree of confidence.
As of July 1998, the CWM. HPT completed site investigations and was in the
middle of preparing FSs for the three sites. Although the CWM HPT has been
operating for only approximately one year, significant gains (both fiscal and non-
fiscal) have been made both on the CWM project and on other PG&E projects with
the same regulatory agency oversight. Specifically, the HPT format has promoted
better communication among the team members and a notable increase in trust
between PG&E and the regulatory agencies. By the completion of the project, the
CWM HPT will have:
• Expedited completion and review of the FS for all three sites. As each step of
the FS process is completed by the HPT, a technical memorandum is prepared
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and reviewed by the team. When the FS is complete, these memoranda will be
compiled along with an introduction to form the body of the FS. Because each
memorandum is reviewed and approved by the HPT as it is prepared, final
review of the FS will be a formality.
• Developed an advisory cleanup standard for remediation. This cleanup
standard is developed with the recognition that it is a target that the HPT is
trying to achieve, and that, given the uncertainties inherent in site remediation,
this target may change. The paradigm shift of recognizing the cleanup
standard as a target and not an absolute gives the HPT "permission" to be
flexible in its remediation and to do what is best for the site, most protective of
human health and the environment, and cost and time effective.
• Evaluated a greater array of remedial alternatives and cost savings, by
evaluating remediation at three sites at once, than would have been possible
for each site if taken individually (i.e., taking advantage of cost savings by
negotiating contracts for work at all three sites rather than for each individual
site).
• Promoted management of uncertainty through contingency planning prior to
remediation, and through HPT communication during remediation to allow
for expedited decisionmaking.
Contacts
Robert Doss, Director of Site Remediation, Pacific Gas and Electric
Company, (415) 973-7601
Francis Anderson, California EPA, Department of Toxic Substances Control,
(916) 255-3733
NJDEPIPSE&G MGP Site Remediation Streamlining Team
In April and May of 1995, PSE&G met with the NJDEP to discuss the potential to
work with the NJDEP SRP to streamline the MGP site remediation program. As
the result of discussions between the two organizations, the NJDEP/PSE&G
Streamlining Team was established with executive sponsors and co-chairs from
each organization. The goals of the Streamlining Team were stated as:
In partnership, NJDEP and PSE&G will identify and evaluate the process of MGP
site investigation and remediation with the objective of streamlining the process.
The Streamlining Team will identify opportunities for improvement, consistency
of approach, and cost effectiveness. The Streamlining Team will develop a model
that will reflect increased cooperation and teamwork between NJDEP and PSE&G
and should provide measurement and oversight of improvement initiatives.
Impediments that exist in achieving the above will be identified with
improvements recommended (NJDEP/PSE&G, 1996).
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The Streamlining Team initially defined major "issues" that are barriers to efficient
and effective site remediation, identifying causes and developing solutions for
each. The solutions were subsequently grouped by relative ease of implementation
and potential for cost and/or time savings. Two basic categories of recommended
solutions resulted:
• Solutions that were within the control and authority of the Streamlining Team
to implement and would result in relatively greater cost or time savings while
ensuring protection of human health and the environment
• Solutions that were beyond the control and authority of the Streamlining Team
to implement but would provide relatively greater cost or time savings while
ensuring protection of human health and the environment
The Streamlining Team then produced detailed implementation plans for the
recommended solutions that were within the control and authority of the team to
implement. Solutions that were beyond the control or authority of the Team were
sent as recommendations to the NJDEP Green & Gold Task Force Site Remediation
Subcommittee.
Using the detailed implementation plan prepared by the Streamlining Team, it
was estimated that the time for the RI phase could be shortened by 30 percent and
costs for RI work plans could be reduced by approximately 40 percent, that
remedial investigation costs could be reduced by 30 to 50 percent, and that
remedial investigation report approval time could be shortened by 30 percent to 40
percent.
Solutions included:
• Establish a dedicated NJDEP case team for PSE&G projects to enhance
communications, encourage empowerment, enhance consistency of application
of regulatory requirements, facilitate increased availability of regulatory staff,
and streamline regulatory agency oversight.
• Establish periodic executive level reviews of program initiatives and results.
• Develop standard report "terms and conditions" for all PSE&G sites.
• Establish standard procedures to ensure proper treatment/disposal of wastes
and/or contamination.
• Establish joint cycle time targets for delivery and approval of plans, reports,
and •work-related activities.
• Develop a generic RI work plan, including standard operating procedures, to
streamline site-specific work plan preparation and review.
Contacts
Rich Blackman, Public Service Electric & Gas, (973) 430-8278 .
Woerner Max, Public Service Electric & Gas, (973) 430-6413
Chris Kanakis, New Jersey Department of Environmental Protection, (609) 633-
1460
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3.2.5 Early Land-Use Determination/Brownfielcls
Whether an environmentally distressed MGP site is a long-abandoned brownfield
or is still owned and operated by a public or private utility, remediation can be
expedited by developing an appropriate, beneficial reuse strategy. The remedial
approach can then focus on cleaning the site up to a level acceptable for its future
use (e.g., residential, industrial or commercial). Early land-use determination
usually requires a multi-faceted team (including real estate professionals, land-use
planners, local redevelopment agencies and environmental groups, financial
analysts, community relations specialists, regulators, insurance professionals,
remediation engineers, and others) and depends, ultimately, on the opportunity
for local real estate development. Successful projects have identified a beneficial
use for former MGP sites that increased their asset value and/or offered multiple
other benefits to the local community. This strategy only works when the
economics of the project are adequate to support both remedial cleanup and
development of the site after cleanup.
The USEPA has recognized that restoring a contaminated property can bring
strength and life to a community. They have defined brownfields as abandoned,
idle, or under-used industrial and commercial facilities where expansion or
redevelopment is complicated by real or perceived environmental contamination.
To promote brownfields redevelopment, the USEPA announced its Brownfields
Action Agenda in January of 1995. This agenda outlined four key areas of action
for returning brownfields to productive use:
• Awarding Brownfields Pilot Grants
• Clarifying liability and cleanup issues
• Building partnerships with all brownfields stakeholders
» Fostering local workforce development and job training initiatives
In May of 1997, the USEPA expanded its Brownfields Initiative by announcing the
Brownfields National Partnership Action Agenda which provided a framework for
cooperation among governments, businesses, and non-governmental
organizations. The Brownfields Partnership addressed all aspects of the
brownfields processes with monetary commitments from federal agencies and
non-governmental organizations. To date, USEPA has funded more than 120
brownfields pilot projects.
A key to the success of the Brownfields program is the clarification of liability and
cleanup issues. To address these issues, USEPA developed guidance promoting
early land-use planning discussions and the use of Prospective Purchasers of
Contaminated Property Agreements under which USEPA agrees not to sue the
buyer of a property for existing contamination. USEPA also developed and issued
policies on:
• The issuance of comfort letters (letters sent to stakeholders who need
information on USEPA's involvement at potentially contaminated properties)
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• Circumstances under which USEPA will not pursue the owners of property
where groundwater contamination has migrated to their property in instances
where the owner did not contribute to the contamination
• Comprehensive Environmental Response Compensation and Liability Act of
1980 (CERCLA) enforcement against lenders and government entities that
acquire property involuntarily
• The Underground Storage Tank Lender Liability Rule
Tool Description
The intent of the early land-use strategy is to evaluate a variety of potential land
reuse options (for one site or a portfolio of sites) and to select reuse options that
meet the following criteria:
• Local market need
Availability of potential developers interested in the reuse option
• Profitable financial analysis
Financial analysis including cost of remediation and liability management
Reasonable profit and return on investment
Insurance products
• Environmental compatibility
Regulatory agencies willing to provide "comfort letters" or "covenants not
to sue" after remediation is complete
Cleanup levels based on reuse approach, limited remediation risks
• Physical feasibility
• Political acceptability (if local community approval is required)
Support of community and local government
Assurance that zoning changes can be achieved for the planned property
use
Typically, real estate reuse specialists evaluate potential reuse options and work
with remedial engineers and regulatory analysts to consider the level of cleanup
and redevelopment necessary for these options. For options with merit, a financial
analysis is developed. The analysis may indicate that the cost of remediation for a
given site exceeds the potential revenue for all reuse options considered. When
this is the case, early land-use determination will no longer be appropriate unless
the owner can include the site within a portfolio of sites that, together, make up a
financially feasible reuse package. There are developers who specialize in
evaluating and purchasing portfolios of environmentally distressed properties.
They evaluate the economics of a portfolio as a whole. If there is sufficient return
on investment from the whole portfolio, the loss associated with individual sites
that cannot be cost effectively redeveloped is acceptable.
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When a site is being considered for a reuse option, the project's success rests on
acceptance and buy-in of all parties. Once all affected parties accept the reuse
option, a reuse-specific risk-based management plan can be developed and
supported by the regulatory agencies with authority over the project. There is
significant support within the USEPA and many state environmental regulatory
agencies for risk-based approaches to remediation and reuse of historically
contaminated industrial properties.
Assuming that stakeholders in the properly all accept a recommended reuse
option, a development plan and marketing package can be prepared to solicit bids,
or the site owner can choose a specific developer for the entire process. Once the
developer is selected, insurance can also be used to limit the remediation cost and
to specify how remaining or future environmental liability will be apportioned
(Daddario, 1997; Voorhees, 1997; Barnett Alexander, 1997).
Case Studies
Bangor Gas Works, Bangor, Maine (Adaptive Reuse of Coal Gasification
Superfund Facility to Supermarket)
Coal gasification processing occurred from 1853 to 1963 at the Bangor Gas Works,
resulting in widespread coal tar contamination of soil and groundwater at the site.
Large quantities of viscous tar had been stored in on-site underground storage
tanks. The property was eventually abandoned. The City of Bangor purchased the
4-acre property, located in a mixed residential and commercial area, in 1978. After
the purchase, the city discovered an underground tank containing 45,000 gallons
of coal tar as well as other underground contamination consisting of subsurface
pools of coal tar and related substances. Within 1 mile of the site there are
wetlands and the Penobscot River, which supports salmon, rainbow trout, and
spring smelt.
In 1978, the City of Bangor alerted the Maine DEP to the site contamination. The
Maine DEP oversaw initial remedial actions, which included:
• Filling the underground tank with clay
» Demolishing the old gasification buildings
• Paving over the site to create a parking lot
Subsequent investigations confirmed that these actions would prevent the coal tar
from migrating off site.
In 1990, USEPA placed the site on the Comprehensive Environmental Response,
Compensation and Liability Act Information Systems (CERCLIS) list. Maine DEP
accessed Superfund monies and performed a preliminary assessment of the
contamination and a site inspection. The studies concluded that the previous
asphalt paving had adequately reduced the potential for migration or direct
contact with the contaminated soil through an airborne release. In 1994, after the
study results were made public, the City of Bangor, Shaw's Supermarket, and
Boulos Developers agreed to build a 60,000-square-foot supermarket on the site
and adjacent properties. The project cost was $9.5 million.
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A partnership was formed between the City of Bangor, USEPA, and Maine DEP to
develop a plan that would permit concurrent cleanup and redevelopment. In 1996,
a multi-layer cap was constructed over the areas where coal tar by-products
remained, so all sources of contamination would be isolated prior to building. The
new supermarket was intended to be the largest in the area and thus would spur
economic expansion and downtown redevelopment (USEPA, 1998a).
The Bangor gas works site consists of a number of parcels. In addition to the
portion that has been the subject of redevelopment to date, a number of parcels are
still being investigated, and as appropriate, remediated.
Site remediation/redevelopment involved a number of actions to address
contamination. In the 1970s, with Maine DEP approval, 430,000 gallons of coal tar
were removed from the site and burned in a paper mill boiler. Analysis of location,
characteristics, and fate and transport aspects of residual contamination indicated
that further excavation was not warranted at the time. The site currently has a cap
and a passive venting system and is subject to deed restrictions. If conditions
warrant, the passive venting can be converted to active extraction.
Contacts
Stan Moses, City of Bangor, Department of Economic Development, (207) 945-4400
John Harris, U.S. Environmental Protection Agency, Office of Emergency
and Remedial Response, (703) 603-9075
Wisconsin Electric Power Company, Racine, Wisconsin (Adaptive Reuse
of Manufactured Gas Plant Site to Mixed Use Development)
Wisconsin Electric Power Company (WEPCO) historically operated a coal
gasification plant on 11 waterfront acres in downtown Racine, Wisconsin.
Contamination requiring remediation was identified at the site.
Prior to initiating remediation, WEPCO decided to hire a consultant to evaluate
potential reuse options for the site. The consultant performed both a physical and
marketing analysis. The analysis determined that the property had significant
value with potential for a variety of multiple uses that would also assist in
revitalization of the city. The reuse option selected was a waterfront community,
now known as Gaslight Pointe.
Remedial actions conducted on the Racine site prior to redevelopment included
the removal of tar holders and highly contaminated soil. The site was then capped,
and a groundwater extraction and treatment system was installed to address
groundwater contamination. A soil venting and vapor extraction system was also
installed to prevent fume buildup in buildings to be constructed on the site.
Gaslight Pointe now includes a marina, towrihouses, a hotel, and retail stores.
The development team agreed on a divestment to a specific developer/builder.
WEPCO assumed no risk and did not need to invest new capital. The remediation
and regulatory approval process focused on the newly recommended
redevelopment use.
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Gaslight Pointe has been a qualified success. It has resulted in reasonable returns
for Wisconsin Energy Corporation as well as providing a source of new jobs and
tax revenues for the community (Barnett Alexander, 1997). Most importantly, it
has completely transformed a previously blighted property into a significant focal
point in the community.
Contact
James W. Lingle, Wisconsin Electric Power Company, (414) 221-2156
3.2.6 Managing Uncertainty (Observational Approach)
Tool Description
Uncertainty is pervasive in the characterization and remediation of all kinds of
contaminated sites, including MGP sites. One approach to managing uncertainty
is the observational method. This method provides a way to determine when
sufficient site characterization data have been collected and involves managing
uncertainties through the identification of reasonable deviations from original
plans if changed conditions materialize, and contingency plans to address these
deviations. The observational approach entails monitoring site conditions during
remediation and implementing contingency plans as needed. Using the
observational method gives the flexibility to modify an RA to address conditions
as they are discovered while still completing the action on time and under budget.
Managing uncertainties when applying one or more remedial technologies at a
manufactured gas plant site requires two important pieces of information:
« The input, process, or environmental variables (e.g., contaminant composition,
temperature, soil structure, moisture content) that affect a remedy's success
* The values of those variables throughout the implementation of the remedy
For ex situ remedial processes (e.g., thermal desorption, catalytic oxidation), this
information can be obtained with relative ease. Process designers can incorporate
the instrumentation and controls necessary to measure the critical process
variables and perform adjustments to optimize process performance.
In situ remedial processes are more difficult. Unless a site is veiy small and/or the
process is incredibly adaptive and robust, it is difficult to have all the information
needed about the values of critical process variables (e.g., soil moisture). For
example, the heterogeneity of subsurface soils and the lack of good subsurface
analytical technologies make it virtually impossible to map the values of process
variables throughout a site. With today's technology, the best achievable result is a
reasonable estimate of the range of these variables.
Scientists and engineers working on subsurface construction problems (e.g.,
foundations, dams, tunnels) have found a way to manage the uncertainties
associated with in situ remediation. Geotechnical engineers have addressed
problems of this nature for decades using the observational method (Peck, 1969).
Karl Terzaghi described the conditions for this application almost 50 years ago:
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"In the engineering for such works as large foundations, tunnels, cuts
and earth dams, a vast amount of effort goes into securing only rough
approximate values for the physical constants that appear in the
equations. Many variables, such as the degree of continuity of important
strata or the pressure conditions of water contained in the soils, remain
unknown. Therefore, the results of computations are not more than
working hypotheses, subject to confirmation or modification during
construction" (quoted by Peck, 1969).
The table on the fofllowing page summarizes the key elements of the
observational approach applied to hazardous waste sites.
Elements of the Observational Approach
Explore to establish general conditions
Assess probable conditions and reasonable deviations
- Depends on remedial technology
Design for probable conditions
- Define remedial end point(s) and how to measure
- Select design/implementation modification for each potential deviation
- Select parameters to observe and define how to measure
- Determine expected values of parameters for remedial
technology under probable conditions and deviations
Implement remedial technology
- Observe parameters and compare to anticipated values
- Implement preplanned actions if deviations detected
Hazardous waste sites involve uncertain subsurface conditions such as those
found by geotechnical engineers at any site but also entail uncertain chemical and
biological parameters. The principal differences from the traditional linear study-
design-build model and the observational methods are the explicit recognition of
uncertainty, characterization of states of uncertainly via scenario development
(i.e., deviations), monitoring for deviations, and preplanning for contingencies.
This is a management approach with feedback loops and preplanned responses.
The success of the observational approach depends upon the ability to alter a site
investigation and/or remediation in the field based on pre-determined
contingency plans. Therefore, the observational approach is not suitable for sites
where there are no available contingent actions for site conditions within an
allowable response time (e.g., a release of contaminants to the atmosphere that
cannot be detected in time to implement a contingency plan).
During the past eight years, the observational method has been increasingly used
for the remediation of hazardous waste sites because it offers two key benefits:
» The method provides a means to determine when sufficient site
characterization data have been collected.
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• The method makes it possible to continue the project by managing uncertainty
through contingency planning rather than trying to overcome it through
additional study or highly conservative remedial design.
Case Studies
An Observational Approach to Removing Light Non-Aqueous Phase
Liquids (LNAPLS)
Background
An operating bulk petroleum products storage and transfer facility, 43 hectares in
size, contained approximately 11 million liters of light non-aqueous phase liquid
(LNAPL) in the vadose zone beneath the site. The LNAPL was composed of
approximately 70 percent gasoline-range hydrocarbons and 30 percent diesel-
range hydrocarbons and had been located under the site for approximately 68
years. The hydrogeology underlying the site was composed of discontinuous
alluvial and eolian Pleistocene deposits of sand, silty sands, silts, clayey silts, and
dense clays. Depth to groundwater was approximately 3 to 6 meters below grade,
and a cyclic rising and lowering water table resulted in LNAPL being trapped
below the water table at some locations and perched above the water table at other
locations, depending upon the small-scale subsurface stratigraphy.
During 10 years of site characterization, more than 100 borings and wells were
installed at the site. Based on the information gathered from these borings, 60
product-extraction wells were installed to remediate the site. Numerous
piezometers and groundwater monitoring wells were also installed to monitoring
the performance of the extraction system.
The extraction system installed following the site characterization operated
ineffectively because of the site's stratigraphic heterogeneities. Some wells in the
system produced LNAPL beyond expectations while other wells extracted
practically no product. After several years of operation, the site owner wanted to
expand the LNAPL removal system to increase overall extraction efficiency, but,
because of the stratigraphic heterogeneities, there was significant uncertainly
regarding how a particular LNAPL removal technology or design would perform
in different portions of the site (Haimann, 1996).
Probable Site Conditions
LNAPL flow in the subsurface occurs in the vadose or unsaturated zone and is
therefore dominated by capillary forces. Capillary forces are, in turn, highly
dependent upon soil type, specifically on pore-throat diameters. Pore-throat
diameters vary substantially among different soil types; in alluvial deposits,
diameters can vary by nearly the scale of the soil particles themselves. In addition,
the soil types above and below LNAPL layer(s) can significantly affect the
efficiency of a removal technology by influencing soil moisture and the ability of
the LNAPL to move within the vadose zone. At this site, a conventional site
remediation approach, where a final remedy with a high likelihood of success is
selected, designed, and implemented, would be unlikely to succeed because of the
small-scale heterogeneities observed in the subsurface. At a site such as this, the
cost and time required to gather sufficient data to fully understand the scale and
location of these heterogeneities could exceed the actual cost for several rounds of
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remediation. Recognizing that such a conventional approach was not an efficient
use of resources, those managing the site selected the observational approach.
In a phased observational approach, remediation is implemented in distinct
phases, without investigating the entire site, to the extent that sufficiently detailed
information is available to design a site-wide system. In effect, each phase of
remediation occurs simultaneously as a phase of investigation. In this case, the
operation of the system and the response of the subsurface to LNAPL removal
were monitored, and data were collected and used to interpret subsurface
stratigraphic features. These features"were then used to update the subsurface
stratigraphic model .and to design expansions and/or modifications to the LNAPL
removal system.
Remedial Technology Design and Implementation
The initial phases of the project were focused on portions of the site where
subsurface stratigraphy was understood well enough to design an LNAPL
removal system. The subsurface stratigraphic information used to design this
initial extraction phase had been gathered during the field investigations and
operations of the early LNAPL removal systems. The effectiveness of the initial
extractions was then monitored using subsurface monitoring points located at the
edges of the extraction zone to determine reasonable deviations in the monitoring
parameters (indicating the relative success of the treatment setup). Subsurface
monitoring points included monitoring wells, piezometers, and soil vapor probes,
and the types and locations of the monitoring points were varied depending upon
the LNAPL removal technology implemented at the specific area (e.g., liquids
extraction, vapor extraction, dual-phase extraction, bioslurping). Data collected
and evaluated during monitoring included drawdown, product thickness,
subsurface vacuum pressures, and vapor concentrations.
The results of the first phases of LNAPL extraction were used to select and design
the extraction system for the second phase; the results of the second phase used to
design a third, and so on (Haimann, 1996). Continuous monitoring of data during
remedial implementation allowed for the implementation of preplanned actions
(e.g., increasing number of extraction points) as needed to address site-specific
subsurface conditions and uncertainties.
Conclusion
One of the key benefits of the phased approach was the immediate
implementation of remediation. Early extraction of the LNAPL prevented further
migration from the source. Under a conventional scenario, the elapsed time that
would have been lost during an extended site characterization could have led to
the additional spread of LNAPL and therefore increased remediation costs.
Several other cost savings were realized by implementing the phased
observational approach, including (Haimann, 1996):
• A significant reduction in investigation costs. Combining remediation and
investigation into one field effort reduced the need for multiple mobilizations
and management costs from an extended project schedule.
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• Savings resulting from a reduction in liabilities. Early and proactive removal of
LNAPL prevented migration in the subsurface and reduced expenses relating
to litigation and additional cleanups from off-site contamination.
A reduction in overall project costs resulting from a shortened project duration.
Combining remediation with investigation reduced the overall number of phases
of field work and reduced the remediation schedule because LNAPL migration
was restricted as a result of early remediation.
Application of the Observational Method to the Cleanup of a PCB Spill
Portland General Electric (PGE) operated a steam-powered electricity generating
plant on a 28-acre site known as the Station L facility between the early 1900s and
1975. The Station L facility is located in Portland, Oregon, on the east bank of the
Willamette River.
As part of a transfer of a portion of the Station L property, PGE initiated an
investigation to identify areas where PCBs might have been released. This
investigation led to the discovery of a historical PCB spill in the Willamette River.
A review of company records showed that a transformer next to the generating
plant had failed in 1971. PGE collected sediment samples to determine the extent
of contamination and found that an approximately 80- by 120-foot area contained
PCB concentrations ranging from non-detect to 286 mg/kg.
During a 2-year period, PGE evaluated different remedial alternatives, submitted
RA plans to the Oregon Department of Environmental Quality (DEQ), and
conducted a limited action to remove near-shore contaminated sediments exposed
during low-flow conditions in the river. In February 1990, DEQ issued a Record of
Decision (ROD) that stated that low-volume, diver-operated, performance-stan-
dard dredging was the preferred remedial alternative. The performance standard
in the ROD was to remove, if practical, up to 2 feet of sediment in areas with PCB
concentrations greater than 10 mg/kg. Dredging was to be conducted in a manner
that would minimize sediment resuspension. The ROD provided for dewatering
and disposal of dredged sediments in an approved disposal facility and water
treatment to applicable standards prior to discharge to the Willamette River.
Following dredging, the spill area was to be isolated by placing a 6-foot sand,
gravel, and rock cap over sediments containing PCB concentrations greater than 1
mg/kg; the cap was to be constructed in a way that would also minimize sediment
resuspension (Brown, 1988).
Early in the remedial design, it was recognized that a conventional engineering
approach could not be used because the following were highly uncertain:
« Sediment characteristics
• Dredging equipment flow rates required for removing two feet of sediment
• The amount of sediment resuspension associated with low-volume, diver-
operated dredging
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• Water treatment system flow rate and influent sediment and PCB
concentrations
• The amount of sediment resuspension associated with cap construction
methods
To manage these uncertainties and meet an the extremely tight project schedule,
the observational method was selected.
The observational method was used to manage virtually all areas of uncertainty.
The most likely outcome, based on available site characterization data and
previous diving contractor experience, was 'that the suction created by the low-
volume, diver-operated dredge would be sufficient to contain any resuspended
sediment. Further, it was assumed that the suction action of the dredge would
prevent PCB concentrations downstream from the site from rising above the acute
aquatic criterion. A reasonable deviation was that dredging would cause
conditions that exceeded the acute aquatic criterion for PCBs.
The parameter selected for observation was turbidity because it could be
measured in the field in time to implement a contingency plan if a deviation was
detected. Direct measurement of PCB concentrations was not selected because
sample results could not be obtained in time to implement a contingency plan. To
satisfy DEQ's concern for aquatic protection, a correlation between turbidity and
PCB concentration in water was developed before dredging was initiated. This
correlation was developed by relating suspended sediment concentrations (using
site-specific sediments) to turbidity, on the basis of the average PCB concentration
in sediments at the site.
Potential contingency plans included increasing the dredge flow rate to increase
the capture of resuspended sediments, modifying diver operations to reduce
sediment resuspension, and, if neither of these plans worked, stopping dredging
and construction of the sand, gravel, and rock cap.
Monitoring conducted during dredging demonstrated that the turbidity did not
increase downstream of the site and the acute aquatic criterion was not exceeded.
Because no deviation was observed, none of the contingency plans was
implemented (Brown, 1988). .
Conclusion
The observational method made it possible to implement a relatively innovative
RA and still complete the project on time and under budget. During a 4-week
period, 22 tons of sediment were removed and more than 500,000 gallons of water
were treated. The average depth of sediment removal was 1 foot. PCB
concentrations were reduced from an average of 12 mg/kg before dredging to
7 mg/kg after dredging. All of this work was conducted without any observable
increase in turbidity, without exceeding the acute aquatic criterion for PCB, and
without any contractor change orders. PGE, DEQ, and the contractor considered
the project a success (Brown, 1988).
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Contact
Dennis M. Norton, Manager, Environmental Services, Portland General Electric,
(503) 464-8522
3.2.7 Expedited Site Characterization
Tool Description
The traditional RI/FS process, as commonly practiced during the 1980s and early
1990s, is a phased approach: Ifconsists of an RTrequiring iterations "of work plan
preparation, review, and approval; field work; and report preparation, review, and
approval. These steps are all designed to characterize the horizontal and vertical
extent of contamination at a site. This phased RI is then followed by the FS to
determine an appropriate remedial scenario and often includes additional phases
of field investigation to acquire additional data. Following the NCP regulations,
the FS leads to preparation of a Remedial Action Plan (RAP) and RD, culminating
in the actual RA, which often uncovers unexpected conditions and/or
contamination, sending the whole process spiraling back to supplemental RIs and
revised FSs. The result is lengthy and costly site investigation/remediation cycles.
Changing regulatory and economic environments requires new strategies to meet
the same needs. Private and public entities must now meet environmental
responsibilities in a time of tightening budgets and greater pressure to work in a
faster and cheaper manner. Thus, processes are being developed to expedite the
way RI/FS/RD/RAs are being conducted.
Expedited site characterization and closure involves a number of tools, strategies,
and processes that interlink and synergistically help streamline investigation and
remediation processes. Components of an expedited site characterization and
closure can include the following:
• On-site or rapid decision-making capabilities
» Use of field sampling and analysis tools (such as mobile laboratories and field
• screening methods) to facilitate real-time data collection and interpretation
" Use of nonintrusive or minimally intrusive geophysical and/or sample
techniques
» Communication and cooperation among responsible parties, regulatory
agencies, and third-party stakeholders through mediation, facilitation, and
HPTs
• Flexibility in the overall site characterization and remediation processes (e.g.,
setting flexible DQOs)
• Active management of uncertainties regarding the location of former MGP
residues and their effects on remediation costs and technologies, through
modeling and contingency planning
• A streamlined document preparation and review process
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• A process for reducing team member turnover and minimizing the effects of
team member replacement
Not all components may be necessary to expedite site characterization. Selections
of those component most directly applicable to a site or set of sites can still yield
cost and time savings.
Argonne National Laboratory Expedited Site Characterization Process
In 1994, Argonne National Laboratory developed an innovative, cost- and time-
effective process for preremedial site characterization. The Expedited Site
Characterization (ESC) process was developed to optimize site characterization
field activities.
The Argonne ESC process:
• Is a process and not a single or specific technology or tool.
• Is flexible and neither site- nor contaminant-dependent.
• Demands the highest levels of accuracy.
• Is scientifically driven within a regulatory framework (i.e., regulatory guidance
does not drive the program without science).
» Requires that all field activities potentially affecting the quality of results be
addressed in a quality assurance and quality control (QA/QC) plan.
The basic steps of the Argonne ESC are:
Step 1: A team is formed, composed of an experienced technical manager with a
broad base of experience and a team of scientists (including geologists,
geochemists, hydrogeologists, biologists, health and safety personnel,
computer scientists, etc.) with diverse expertise and strong field
experience.
Step 2: The technical team critically reviews and interprets existing data for the
site and its contaminants to determine which data sets are technically valid
and can be used in initial design of the field program.
Step 3: After assembling and interpreting the existing data for the site, the
technical team visits the site to identify the site characteristics that may
prohibit or call for any particular technological approach.
Step 4: After the field visit, the team selects a suite, of technologies appropriate to
the problem and completes the design of the field program. Nonintrusive
and minimally intrusive technologies are emphasized to minimize risk to
the environment and public health.
Step 5: A dynamic work plan is prepared, outlining the technical program to be
followed. The work plan must allow flexibility; therefore the HASP and
QA/QC plan must encompass a broad range of possible work plan
alterations.
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Step 6: The team implements the field program. Data are collected, reduced, and
interpreted each day. At the end of each day, the team meets, reviews
results, and modifies the next day's program as necessary to optimize
activities that generate overlapping or confirming site details.
Step 7: Daily results and modifications are transmitted to the project sponsor and
regulators, allowing both to participate in early data review and
decisionmaking for the site.
The ESC is an iterative process that optimizes field activities to produce a high-
quality technical result in a time- and cost-effective manner. Because both on-site
analytical and multiple hydrogeologic techniques are used, there is very little need
to send nearly all samples off-site and to perform massive subsurface sampling in
the absence of local hydrogeologic information. By including on-site
decisionmaking, the ESC process can significantly reduce the probability of having
to return to the site to fill data gaps. As a result, the current multiphase sequence
of environmental data acquisition becomes compressed into a single real-time
phase typically requiring only months to complete (Burton, 1994).
The Argonne ESC process is not the ideal process for all sites. However, the basic
components of the ESC have been applied at other former MGP sites to expedite
site characterization and remediation. These basic components are also included in
the American Society for Testing and Materials' (ASTM) provisional standard
guide for Accelerated Site Characterization for Confirmed and Suspected
Petroleum Releases (PS 3-95) (ASTM, 1996). Although the types of contaminants
found at former MGP sites are typically more complicated than those found at
sites with only petroleum releases, the general process published by ASTM in their
provisional standard guide is similar to that outlined for Argonne's ESC program.
Both published programs involve review of existing site information and
development of a conceptual model prior to sample collection, followed by an
on-site iterative process designed to collect, analyze, and interpret all data in a
single field program.
Case Studies
Marshalltown Former MGP Site
In 1994 and 1995, USEPA's Ames Laboratory adopted the Argonne National
Laboratory's ESC process for demonstration at the Marshalltown former MGP site
in Marshalltown, Iowa. The Marshalltown former MGP site was owned by IBS
Utilities, Inc., and was located in an old industrial area adjacent to an active
railroad switching yard and main lines. Gas manufacturing operations occurred
between the 1880s and 1950s, resulting in the release of a variety of MGP wastes,
including coal tar, petroleum hydrocarbons, condensates, and oxides.
Before the ESC at the Marshalltown site, five rounds of field investigation and/or
reporting had been conducted. Data collected during these investigations
provided the historical and technical information necessary to select technologies
and develop scopes of work for the ESC demonstration.
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The ESC methodology applied at the Marshalltown former MGP site incorporated
on-site decision-support technologies that enabled site characterizations to be
completed in a consolidated package.
The principal characteristics of the Ames ESC were:
• Emphasis on geologic structure and hydrogeology to determine contaminant
fate and transport
• Use of technologies by expert operators with flexible data quality objectives
• On-site data processing using mobile laboratories
• On-site decisionmaking
• Preference for nonintrusive or minimally intrusive geophysical techniques
• Minimization of intrusive sampling techniques
• A single team for planning and managing site work
The use of minimally intrusive survey techniques, on-site analytical technologies,
and innovative sampling and screening technologies (such as the Site
Characterization and Analysis Penetrometer System cone penetrometer unit and
GeoProbe™ soil conductivity probe) to determine the local hydrogeologic setting,
supported the potential for significant time and cost savings. For example,
geophysical survey techniques including ground-penetrating radar, seismic
reflection and refraction, electromagnetic offset logging, and borehole logging
were applied at the site to define the surface of the bedrock and significant
stratigraphic interfaces above the bedrock and to provide information regarding
the distribution of PAH contamination (Bevolo, 1996). By including on-site
decisionmaking, the Ames ESC process significantly reduced the number of
iterations of field investigations that otherwise would have been necessary to fill
data gaps. As a result, the typical cycles of work planning, field investigation, and
reporting, which often take years to complete, were compressed into months.
Site Characterization
The Site Characterization and Analysis Penetrometer System (SCAPS) cone
penetrometer unit, GeoProbe™ soil conductivity probe, and geophysical survey
technologies provided very useful and reliable stratigraphic data. Side-by-side
comparisons of the direct-push technology logs with previous investigation
borehole logs indicated stratigraphic correspondence to within about 1 to 2 feet. It
should be noted, however, that the previous data tended to provide a slightly
deeper granular/lower cohesive unit contact than direct-push data. Usually, the
major unit stratigraphic contacts were easily picked off of both the cone
penetrometer testing (CPT) and soil conductivity logs, and were used to create a
database from which a three-dimensional site stratigraphic model was generated.
Based on previous site characterization work, the lateral and vertical distribution
of the dissolved PAHs and residual NAPL contamination was estimated.
Assessment of the nature and distribution of the PAH contaminants was carried
out using three types of technologies: Phase I screening technologies
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(immunoassays, passive and active soil gas, and chemiluminescence), Phase II
screening technologies (laser-induced fluorescence probe, soil conductivity probe),
and Phase II quantitative technologies (chemical analysis of soil samples with gas
chromatography mass spectrometry instruments in field laboratories).
The Phase I contaminant screening technologies were applied in an effort to
evaluate their ability to identify the approximate boundaries of the contaminated
area. Duplicate soil samples were collected from different depths and analyzed
using three different immunoassay techniques and the. chemiluminescence system.
In addition, passive and active soil gas samples were collected and analyzed from
the approximate depths of the soil samples.
The presence or absence of detectable PAHs and the data from each of the three
immunoassay analyses correlated fairly well with each other. Results from the
chemiluminescence did not correlate as well. Active soil gas measurements for
aromatic hydrocarbons and naphthalene showed good agreement with passive
soil gas and immunoassay measurements. Overall, the results of the Phase I
contaminant screening technologies generally compared well with the previous
investigation results. One significant finding of the screening was that PAH
contamination existed farther to the west than appeared from previous data.
Phase II contaminant screening was performed using the cone penetrometer laser-
induced fluorescence (LIF) sensor system and the GeoProbe™ soil conductivity
profiles. Chemical analysis of soil samples collected adjacent to LIF "hits"
indicated that although the LIF sensor data could not be considered quantitative, it
could reliably detect regions of low, medium, or high contamination. The LIF may
be considered the most direct qualitative methodology for indicating regions of
PAH contamination.
Phase II quantitative plume delineation efforts were planned and implemented
based on results of previous investigations, Phase I and Phase II screening, and an
updated site geologic model. The primary technology evaluation function of this
part of Phase II was the comparison and assessment of five on-site extraction
methods for PAHs in soil (sonication, microscale, microwave-enhanced extraction,
thermal desorption, and supercritical fluid extraction).
Conclusion
A significant finding of the study was the potential for inconsistencies in
procedures and results even with strict adherence to SW846 methods. The
application, versatility, and high quality of data from direct-push technologies
were demonstrated at the site.
The study also indicated the potential for significant variation of chemical analysis
results for PAHs in soils. The uncertainty and potential variability associated with
soil matrix effects, sample selection, and preparation and extraction procedures far
outweigh inaccuracies in the chemical analysis methodologies themselves. The
Phase I and Phase II screening results, including olfactory and visual data, gave a
far better picture of the distribution and extent of contamination than the
quantitative analysis results.
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The Ames ESC team implemented the ESC model using many of the tools that are
essential to ESC, such as a dynamic work plan real-time data analysis and
incorporation of stakeholders in the decisionmaking process. Establishing and
maintaining close communications with the regulators was viewed as critically
important, and significant efforts were made to invite participation from
stakeholder groups including local residents, community organizations, educators,
students, trade press, local media, etc. (Bevolo, 1996).
Contacts
Dr. Al Bevolo, Ames Laboratory, Iowa State University, (515) 294-5992
Bruce Greer, Alliant Energy, (608) 252-3948
Johanshir Golchin, Iowa Department of Natural Resources, (515) 281-8925
Pacific Gas and Electric Company ChicolWillowslMarysville Former MGPs
In 1994, Pacific Gas and Electric Company (PG&E) initiated the RI/FS/RD/RA
process for three of its former MGP sites where Preliminary Endangerment
Assessments (PEAs) had been completed in 1991. PG&E chose the former MGP
sites in Chico, Willows, and Marysville, California, because they had similar
operating histories and MGP-related contaminants, similar geologic settings, and
were in close geographic proximity. Recognizing the advantages of streamlining
the RI/FS process, PG&E initially combined or "bundled" the sites into one
project, negotiating one order for the three sites with the California EPA
Department of Toxic Substances Control (DTSC). Representatives from PG&E and
its consultant as well as the state's primary regulatory agencies (DTSC and the
Regional Water Quality Control Board) were identified to serve as primary case
managers for all three sites. In 1996, an alternative, streamlined approach to the
RI/FS was proposed and adopted in addition to the site bundling implemented
earlier.
Streamlining the RI
By bundling three sites into one "package," PG&E observed immediate cost
savings from reducing the volume of paper documentation and negotiating lower
unit pricing as a result of larger volumes of laboratory analyses and work than
would have applied to a single site. Further cost savings were achieved by
negotiating one order with regulatory agencies and incurring oversight costs for
only one regulatory agency caseworker for all three sites and by preparing one
HASP and one RI work plan for the three sites. This work plan outlined the field
sampling protocols and described the decision process by which field crews
would identify and justify field sampling locations. These protocols were then
used along with a field sampling flowchart in lieu of figures identifying specific
locations for sampling. Such predetermined processes for decisionmaking and
communications enabled the team to actively manage uncertainty about the extent
of onsite contamination. Therefore, the number of field investigations required to
adequately characterize the sites was significantly reduced.
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The RI field programs developed for the three former MGP sites were further
tailored so that field crews went from site to site (Willows and Chico are 45
minutes apart by automobile; Chico and Marysville are approximately one hour
apart), circling back after well seals had cured and wells could be developed and
sampled. Thus, well development and sampling took place in a short time. As part
of the streamlined field program, lower unit pricing was negotiated with
subcontractors (drilling and analytical laboratory) by offering larger volumes of
work than would have been the case for a single site. Field personnel used in situ
samplers (e.g., Hydropunch™ and Simulprobe™ samplers) and field screening
tools (Handby colorimetric kits and Petrosense™ probes) to further aid in field
evaluations of the extent of contamination. Through site bundling and field
decisionmaking (aided by in situ and field screening tools), PG&E saved an
estimated $120,000 during the preliminary phase of the RI/FS alone.
Streamlining the FS
As the Chico/Willows/Marysville (CWM) project continued into the FS stage, the
project team adopted additional measures to streamline the project. The backbone
of these measures was the formation of an HPT, discussed previously in greater
detail in Section 3.2.4.
Significant gains have been made to date as a result of the streamlining at the
CWM sites. Expenditures have been decreased by bundling of sites and by
allowing flexibility to modify field programs during implementation. This
flexibility has reduced the number of phases of field sampling required to
determine the extent of contamination. In addition, both the CWM project and
other PG&E projects with the same regulatory agency oversight have benefitted
from the improved communication and trust between PG&E and the regulatory
agencies as a result of the HPT's work.
Contact
Robert C. Doss, Pacific Gas and Electric Company, (415) 973-7601
3.2.8 Legislative Innovation
Tool Description
Recognition of the need to change the RI/FS/RD/RA process is not limited to
consultants and private organizations; regulatory agencies have also seen the need
to streamline site characterization and remediation. Legislative innovations have
created a range of programs for regulatory agencies to streamline site
remediations in the hope of significantly lessening current and future threats to
human health and the environment in a much shorter time period than possible
using the traditional RI/FS/RD/RA process. An example is the pilot Expedited
Remedial Action Program currently being implemented by the State of California.
California Expedited Remedial Action Program
The California Expedited Remedial Action Program (ERAP) was established under
the authority of the Expedited Remedial Action Reform Act of 1994. Its purpose is
to test alternative regulatory policies for the remediation of contaminated
properties by providing for a comprehensive program that includes revised
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liability based on fair and equitable standards, indemnification protection through
a covenant not to sue, risk-based cleanups based on the ultimate use of sites,
streamlined remediation processes, and a dispute resolution process. Because sites
involved in the ERAP process follow the California Uniform Agency Review
Hazardous Materials Release Sites (California Health and Safety Code Division 20,
Chapter 6.65), permits and certification are issued through one lead oversight
agency, which minimizes duplicate efforts among regulatory agencies
(Cambridge, 1998).
Only 30 sites may participate in the pilot project; participation is voluntary by
responsible parties (RPs) for sites. Participants must agree to pay for all oversight
costs not paid by another RP or the trust fund designated for "orphan shares;"
response costs apportioned to parties that cannot be located, identified, or are
insolvent are considered orphan shares. If monies are available in the trust fund
established for ERAP, these are refunded to the RPs once a site is certified. Only 10
sites in the pilot program may be designated as orphan share sites (Cambridge,
1998).
Case Study
Alhambra Former MGP Site
In Alhambra, California, Southern California Gas Company (SoCal Gas) elected to
participate in the California EPA DTSC and ERAP to expedite cleanup of the
Alhambra MGP site.
Site Background
SoCal Gas entered into a Remedial Action Consent Order with the DTSC on May
5,1994, to perform remedial investigations at the Alhambra MGP. On September
22,1995, SoCal Gas submitted to DTSC a Notice of Intent to have the site
participate in ERAP. The site was admitted into ERAP on November 27,1995, and
thus was no longer subject to the Remedial Action Consent Order. In March 1996,
DTSC and SoCal Gas signed an Enforceable Agreement for performing a site
investigation and remediation. DTSC became the lead agency for the site cleanup.
The site consists of 20 residential lots on 2.4 acres. An MGP operated at the site
from 1906 to 1913. SoCal Gas acquired the property, which had had two previous
owners, in March 1939 after the gas plant had been dismantled, and sold the
property to an individual in September 1939. This owner then subdivided the
property and sold the lots for residential development beginning in 1940.
Investigations prior to the site's inclusion in ERAP had shown MGP
residues—arsenic, lead, and cPAHs—might be present in on-site soils at levels that
would exceed risk-based soil concentration goals. Therefore, a site inspection was
conducted after the site's admission into ERAP.
The SI concluded that there was significant, -widespread contamination in soils at
the site. The level of contamination required excavation and removal to eliminate
threats to public health and the environment. The SI also determined that
groundwater had not been affected by MGP wastes.
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The RA goal for the Alhambra site was to restore the levels of chemical exposure
to background conditions. Values were established using a statistical evaluation of
a background data set, which consisted of 184 samples collected over 20 different
locations in Southern California. The remedial action plan (RAP) proposed the
excavation and removal of all contaminated soil from the front and backyards of
18 of the 20 homes located on-site. The RAP also proposed removing all
contaminated soil in the crawlspaces underneath each home.
A number of public meetings and other community outreach efforts were
undertaken. The site's residential community was multicultural, with the
languages spoken among 20 property owners including English, Spanish,
Vietnamese, Cantonese, and Mandarin. All fact sheets and public notices were
translated into those languages. At the public meeting for the RAP, four
translators were present to address questions from the audience. All one-on-one
meetings held between on-site residents and DTSC and SoCal Gas representatives
had an interpreter present, if needed.
The final RA for the site began on July 23,1997. The excavation portion of the
project was done in phases. Four families would be relocated at a time, and
excavation and removal activities would focus on those four properties. A
relocation company handled details of moving residents. After completion of
excavation activities at each house, backfilling and restoration activities included
replacement of all landscaping and hardscaping removed as a result of the
remedial activities. Remedial activities at the site were completed on February 13,
1998. The total volume of contaminated soil removed was 9,000 tons. DTSC issued
a certificate of completion to SoCal Gas on February 27,1998. The site evaluation
and cleanup under ERAP took just over two years.
Benefits of ERAP
Sites posing the greatest public health or environmental threat are the highest
priority for remediation. The Alhambra property was a natural priority because
the presence of on-site residents created a high probability of direct exposure.
SoCal Gas had reservations about proceeding with remediation in view of
uncertainties about the requirements and effectiveness of the cleanup, the
interruption to residents' lives, the possible liability resulting from cleanup, and
the time and cost involved. The ERAP pilot project provided some assurance that
the cleanup would be efficient and made explicit the potential risks and liabilities
of remediation. SoCal Gas viewed the most beneficial aspects of ERAP as:
» "Lead" Agency Designation—DTSC, as lead agency, communicated with the
other state and local agencies involved with the site. Contacts occurred early,
during the preparation of the application package for the program. At this
stage, DTSC contacted each affected agency to determine its concerns and
anticipated level of involvement so these could be incorporated up front. Once
the site was selected, DTSC invited these agencies to participate in the site
conference that was required within 90 days of site designation. This provided
other agencies with an opportunity to raise issues that could then be
incorporated into work plans. Once site remediation was completed, DTSC
issued a certificate of completion, which provides regulatory clearance from all
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other state and local agencies regarding hazardous substances issues. This
certificate indicates that SoCal Gas's remediation of the site is complete.
• Guidelines for Public Participation and Involvement— ERAP provides that
the party responsible for a site must comjply with DTSC's public participation
manual. Public participation was essential to the success of this project. In
addition to fact sheets and an information repository, many public meetings,
both formal and informal, were conducted to facilitate ongoing discussions.
Most notable were the one-on-one discussions with residents. These contacts
meant that the project managers considered residents' perspectives when
making decisions, such as what types of trees or grass to replant during the
landscaping activities and the timing of each activity. The result of the public
participation efforts was positive community response to the cleanup.
• Risk-Based Decisionmaking—Any remedial action proposed by an RP must
leave a site in a condition appropriate to its planned use without any
significant risk to human health or the environment. Under ERAP, RPs are
provided flexibility when selecting the remedial action; the DTSC does not
give special preference to any particular actions. Evaluation of the remedial
actions is based on their individual merit in light of site-specific conditions.
Although this provision is most applicable to sites that will be used for
commercial or industrial purposes, SoCal Gas demonstrated it could be
applied to residential sites.
• Apportionment of Liability Based on Fair and Equitable Principles and
Orphan Share Funding —The process for apportioning liability among parties
potentially responsible for a site (e.g., previous and current owners) involves
assigning to each a percentage of liability for necessary remedial action at a
site. As an alternative to liability determination through judicial process (cost
recovery under CERCLA), ERAP provides for DTSC to apportion liability to
each RP. For this site, SoCal Gas was able to recover some cleanup costs
through DTSC's apportionment of liability to orphan shares.
• Indemnification through a Covenant Not to Sue — Within the ERAP
enforceable agreement is a requirement for a covenant not to sue under
CERCLA between DTSC and the RPs who are signatories to the agreement.
This covenant is conditional on performance of all obligations of CERCLA and
the conditions outlined in the enforceable agreement. This covenant becomes
effective upon completion of the RAP and receipt of the certificate of
completion. Because the certificate of completion for the site is issued under
the provisions of the Unified Agency Review Law, the RP can qualify for
immunity and protection from future liability. However, the covenant not to
sue does not apply to natural resource damage claims filed pursuant to
CERCLA. SoCal Gas valued the protections afforded by this covenant, which
significantly reduced the risk of future claims being made against the company
because of the Alhambra site. The ERAP process also provides assurance that
other agencies will not take additional enforcement actions in the future.
Conclusion
The Alhambra former MGP site is an example of a site remediated after a
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residential community was established there. Because residents live on-site, direct
exposure to MGP residues was the greatest health risk. The focus of the project
was to restore the site to background exposure levels and return the residents to
their homes in the shortest amount of time with the least amount of disruption. Of
most importance to SoCal Gas was the definition of the time and costs associated
with the project and the determination of the company's liability. The ERAP
program provided SoCal Gas with assurances regarding risks as well as monetary
relief from the ERAP trust fund, which will reimburse costs assigned to orphan
shares.
Contact
Megan Cambridge and Adam Palmer, California EPA DTSC, (916) 255-3773
3.2.9 Dovetailing Business Decisionmaking and Remediation
Planning
Tool Description
Combining remediation strategies with business decisions can, when the
circumstances are appropriate, provide additional opportunities for significant
savings in total remedial cost, the effort required to secure permits, or time
required to complete the project. The greatest cost and time savings are realized
when remediation, land use/reuse, and business considerations can be aligned.
Depending on factors such as the numbers of MGP sites requiring remediation in a
given area and the types of wastes involved, a number of business strategies may
make sense. Parties responsible for one or more MGP sites may want to consider
options such as: entering into a business venture with a local facility that could
treat the MGP wastes; purchasing rather than renting remediation equipment;
developing an affiliate company that markets cleaned and treated soil and/or
provides cleanup services to others after MGP site remediation is complete; or
undertaking a joint venture to create a mobile or fixed treatment facility. These
options may offer significant savings in total time and cost of a remediation
project.
The following list of questions is designed to help determine whether undertaking
a remediation business venture might expedite and reduce the long-term costs of
remediation:
(1) Are there multiple MGP sites in close proximity that have large volumes of
contaminated materials that could be treated using the same remediation
technology? (The sites may have multiple owners as long as they have
similar wastes.)
(2) Are there other sites in the area with large volumes of similar waste that
could also be treated with this remediation technology?
(3) Are there local political, community, and land reuse/redevelopment
conditions that would predispose regulators to approve a remediation
approach targeting multiple sites?
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(4) What are the actual contaminants and their concentration levels?
(5) Do these contaminants lend themselves to off-site remedial treatment that
would meet regulatory cleanup criteria? (e.g., non-hazardous vs. hazardous)
(6) Are there conveniently located facilities that could accept the contaminated
material as supplemental fuel for blending? Examples include utility boilers,
cement kilns, and asphalt batching facilities. Alternatively, is there a local
waste treatment facility that could treat these wastes or incorporate a
process to do so? If so, could this facility-Feadily.;expand»itSfpeFmit to
incorporate the new treatment process? Does this facility have adequate
room to add such a treatment process?
(7) Has the local state environmental regulatory agency approved a permit for
the treatment approach of interest in the past?
(8) Is there a regulatory process in place that would allow testing and
approving the treatment process for the MGP application?
(9) Is the local operating facility or disposal/treatment company willing to
assume financial and other risks in exchange for a guarantee to be given a
specific amount of material for treatment?
(10) If there is no local facility in a position to accept the wastes in question,
what are the economics of purchasing rather than renting remediation
equipment (e.g., thermal desorbers, asphalt batchers)? This-analysis should
take into consideration the long-term costs of treating all MGP sites for
which the party in question is responsible.
(11) Is there a market for cleaned or treated soil from the site(s) (e.g., for clean
fill, asphalt, etc.)?
(12) Is there a market at other sites for the same remediation services required at
the MGP site(s)?
(13) Are there local operating facilities or disposal treatment companies that are
entrepreneurially oriented and willing to assume financial and other risks in
exchange for a guaranteed volume of material for treatment?
Reviewing the answers to these questions can help clarify the opportunities to
combine remediation efforts for several sites and/or to undertake new business
efforts that can continue after remediation of a company's own sites is complete.
Opportunities for off-site remedial treatment at fixed treatment facilities are ideal
because the process of obtaining environmental permits is simplified if the waste
materials are treated at one location. In addition, a fixed facility can draw input
(contaminated materials) from a larger area and operate more efficiently than a
mobile facility, thereby offering its customers a unit cost reduction borne from the
economics of scale. However, it is also possible to form successful business
ventures to treat wastes using mobile facilities at multiple sites.
Remediation business ventures are most promising in a geographical area where
there has been considerable past utility/industrial activity, so large quantities of
contaminated materials requiring remediation are likely to be present. Such areas
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are likely to already have waste or hazardous waste treatment/disposal facilities,
co-burning boilers, cement kilns, and/or asphalt batch plants nearby with whom
joint ventures can be undertaken. If off-site (fixed) treatment facilities are not
readily accessible, however, there is the possibility of purchasing treatment
equipment, developing a mobile facility or entering into a business agreement to
construct an off-site facility. The success of a project like this often hinges on the
local regulatory agency's willingness to consider such ventures. Whenever there is
a local need for redevelopment of several contaminated sites, the area's long-term
cleanup needs can be used as an argument to support a proposal for a remediation
business venture.
Case Study
Several related case examples are provided for co-burning (Section 5.2.1) and
asphalt batching (Section 5.2.3).
Mid Atlantic Recycling Technologies Inc. (MART)
A New Jersey utility owned multiple MGP sites contaminated with typical MGP
wastes. Ten of these sites were scheduled for eventual remediation. In considering
options to reduce overall remediation costs, the utility evaluated its business
options in light of the upcoming remediations. Because the company owned
multiple sites with large volumes of contaminated soil, it sought options that
would take advantage of economies of scale during remediation. The utility also
hoped to return treated soil to the original sites.
In response to the utility's need, two environmental service companies, Casie
Protank and American Eco Corporation, formed Mid Atlantic Recycling
Technologies Inc. (MART). (Casie Protank owns and operates a waste
transportation, transfer, and treatment facility in New Jersey. American Eco
Corporation provides environmental, construction, and industrial services.) The
utility and its remediation contractor negotiated a 5-year agreement with MART
that committed MART to providing financing and then constructing and
operating a thermal desorption facility specifically to treat MGP-contaminated
soil. The facility is located in Vineland, New Jersey. The intent was that the
thermal desorber would also be able to remediate other soils, specifically those
contaminated with total petroleum hydrocarbons (TPHs). Construction of the
facility cost $9 million and took 7 months; it began accepting MGP soils in July,
1997.
The NJDEP approved a permit for the facility's Astec/SPI low-temperature
thermal desorber, requiring it to process contaminated soil to meet risk-based
Residential Direct Contact Soil Cleanup Criteria. The desorber system can treat up
to 45 metric tons/hour and reaches a treatment temperature of 540° C. After
treatment, the soil is analyzed to demonstrate that Residential Direct Contact Soil
Cleanup Criteria have been met. The treated soil can then either be returned to the
generator or kept on-site and reused.
The first MGP site remediation undertaken by the utility was in an urban area. The
site was vacant. Local community leaders wanted to see it converted to a new
office complex. The project started in July, 1997, and was completed in 16 weeks.
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Although 27,000 metric tons of soil and debris were transported to MART for
remediation and the former MGP site is in a high-traffic area, the project did not
disrupt local traffic or create an environmental or health hazard. The desorption
treatment approach was successful; on the first pass all treated materials met the
cleanup criteria specified by NJDEP. Treated soil was returned to the site, and the
land was turned over to the community for beneficial use after treatment was
complete and the site had been seeded (DiAngelo, 1998).
Contact
Brian Home, Mid Atlantic Recycling Technologies Inc., Vineland, New Jersey
(609)696-3435
3.2.10 Establishing Background IPAH Concentrations
Tool Description
PAHs are a by-product of the incomplete combustion of organic material, and are
found in everything from grilled meats to waste oil to MGP wastes. In today's
society, the incomplete combustion of fossil fuels from heating systems,
automobile exhausts, garbage incineration, crude oil processing, and many other
practices release PAHs into the atmosphere where they tend to adhere to particles
in suspension. Some of these suspended particles ultimately fall back on surface
soils or aquatic environments. Establishing the background concentration of PAHs
at MGP sites is therefore a significant challenge because it is necessary to
distinguish the proportion of PAHs that come from MGP site wastes from those
produced elsewhere.
In risk assessment, sample concentrations from a site are compared to background
concentrations to identify non-site-related chemicals that are found at or near a
site. If background risk is a possible concern, it is typically calculated separately in
order to accurately evaluate the additional risk to public health or the environment
posed by contaminants from a site. According to the Risk Assessment Guidance
for Superfund (RAGS), (USEPA, 1989) information collected during a site
characterization can be used to screen for two types of background chemicals:
naturally occurring chemicals (i.e., those that have not been influenced by
humans) and anthropogenic chemicals (i.e., those that are present because of
human activity).
However, RAGS goes on to recommend that anthropogenic background chemicals
not be eliminated from risk calculations as it is typically difficult to show that the
chemicals are present at the site because of operations not related to the site or
surrounding area. This presents a dilemma to those remediating MGP sites located
in urban areas as the risks associated with background PAH concentrations are
often quantified at concentrations above the incremental cancer risk of 10 ~* to 10 "6,
the criterion the USEPA most often uses for site restoration.
An alternative to the development of RA objectives based on traditional risk
assessment practices is the establishment of background levels of anthropogenic
materials and the application of those levels as a standard for site cleanup. This
methodology has been applied at MGP sites and is gaining more acceptance as the
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cost and difficulty of cleaning up to pristine levels, sometimes beyond background
concentrations, becomes clear.
Relatively few studies have been published in which PAH concentrations in soil
have been quantified. According to one review of literature published in the
Journal of Environmental Quality (Edwards, 1983), typical concentrations of
benzo(a)pyrene (a known cPAH) in soils of the world range from 100 to 1,000
micrograms per kilogram (ug/kg). A typical range for total PAHs was about 10
times the value for benzo(a)pyrene alone, with the actual measured concentration
of benzo(a)pyrene ranging from 0.4 ug/kg in remote regions to 650,000 ug/kg in
very highly polluted areas. A second study on the background concentrations of
PAHs in New England urban soils (Bradley, 1994) determined that the upper 95
percent confidence interval on the mean was 3 mg/kg for benzo(a)pyrene toxic
equivalents, 12 mg/kg for total potentially cPAHs, and 25 mg/kg for total PAHs.
The lack of adequate studies on background concentrations of PAHs, along with
the need for site-specific information, indicates the demand for the development
of a standardized procedure for establishing background PAH concentrations,
rather than a single numerical value against which all other PAH values are
measured.
A primary consideration in characterizing background levels of anthropogenic
materials is the establishment of what constitutes background. In some cases,
background has been functionally defined. For example, at CERCLA sites,
background is defined as off-site locations that are comparable to the cleanup site
in outward environmental characteristics such as geological setting and
meteorological conditions. At RCRA sites, background is typically an on-site
location where no facility processing or disposal has been known to occur. At any
site, this definition is subject to opinion, based upon evaluation of the best
available information. Proximity to the facility is a key consideration in specifying
the locations that represent background conditions. Clearly, nearby locations are
optimal in terms of similarities of geological conditions and deposition of
anthropogenic materials, but these locations are also, because of their proximity to
the facility, potentially subject to low-grade contamination from the facility.
Distant locations may result in differing levels, not so much as a function of
facility versus nonfacility contamination but rather as a function of major
differences in native conditions and/or proximity to other sources. Definition of
appropriate background locations must balance these distances based upon
available site history. Once locations are selected to represent background levels,
sampling results from those locations can be evaluated to corroborate expectations
or to identify locations that do not meet assumptions about background
conditions.
The total number of background samples to be collected is the next major
consideration. Sample sizes can be directly estimated to achieve prespecified
statistical power and confidence by making reasonable assumptions about the two
expected "populations" of chemical concentrations (i.e., the site and background).
Alternatively, sample size can be indirectly determined by defining a desired
spatial coverage, then calculating the total number of samples to be collected by
dividing the entire area to be sampled by the predetermined coverage or surface
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area per sample (e.g., collecting samples using a 25-foot grid with one sample
collected per grid element).
The sample size for background characterization should be considered in the
context of the sample size for the site being characterized. Statistical power for
most comparative tests is optimized with a balanced design. That is, to maximize
the ability to differentiate two populations (site versus background), similarly
detailed information is necessary about contaminant distributions from the two
areas. Optimizing statistical power must be balanced against the practical reality
that sampling on the site may already be extensive.
Following collection of samples from background locations or consolidation of
data from various sources, the frequency distribution of observed values can be
examined. Intuitively, background data are expected to be relatively consistent or
at least not to exhibit obviously bi- or multi-modal distributions of observations
over the concentration range observed. Probability plots and statistical testing for
adherence to commonly observed distributions (e.g., Shapiro-Wilk or Shapiro-
Francia for normal or log normal distributions) are common methods to ascertain
that data meet these basic assumptions about background conditions. Where data
are composited from various sources and/or represent different methods or
conditions, preliminary evaluations should also include examining the extent to
which sampling factors (e.g., soil sample depths, analytical methods, specific
locations) could be reasonably expected to result in different levels of the
constituent. Spatial differences are the primary factors in considering background
soils. Tests for trend (e.g., Cox or Sen tests) are useful to detect the presence of
seasonal cycles and/or increasing or decreasing trends which would either
eliminate the location from background designation or indicate the presence of
upgradient effects independent of the site under investigation. If there are no
significant differences among factor levels, data can be considered to represent a
single population that represents background levels of naturally occurring or
anthropogenic constituents.
The issue then becomes how to apply the available background information to
determine which areas of a site represent incremental potential risk. Sample
results from background locations are commonly used to estimate some agreed-
upon proportion of the background population (such as an upper bound tolerance
limit that defines the concentration corresponding to the 95 * of 100 observations,
ranked from lowest to highest concentration). That point estimate is then used as
an upper limit to identify sample results from the site being investigated that
exceed background and therefore require remedial action. The advantage of point
comparisons is the relative simplicity of the method and calculations.
Disadvantages to point comparisons are numerous. First, contrary to the
recommendations on sample size in the discussion above, the number of
observations from background locations is typically smaller than the number of
observations from the site. With the exception of uniform distribution, the
probability of a sample containing extreme values relative to the overall
population is lower than the more commonly occurring values from the center of
the distribution. In other words, less commonly occurring values require increased
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sampling. A reduced sample size may result in an underestimate of variability in
background levels. Because the calculated variance of the sampled population is
integral in the calculation of the tolerance limit, the reduced sample size may
result in a substantial underestimate of the upper concentration levels within the
background population. Second, even when applying an upper bound estimate
from a background sample, a certain proportion of values that truly represents
background will exceed that estimate. For example, 5 percent of background
Values would be expected to exceed a 95 percent tolerance limit based upon true
knowledge of the population. Finally, the statistical power, of point-to-point
comparisons is limited.
Alternative methods are population-to-population comparisons. For example, t-
tests, Kruskal-Wallis tests, or Wilcpxon Ranks Sum tests in which the mean or
median from on-site samples are compared to the mean or median from
background samples; or the Quantile test which compares the upper end of the
two populations (background and site) for statistically significant differences.
Because no single statistical method is adequate to definitively define background
conditions, a combination of tools (population-to-population and point
comparisons) is recommended. Population-to-population comparisons, focusing
on the entire distribution as well as upper portions of the observations, provide a
more sensitive indication of the extent to which background and site populations
compare. Used in conjunction with point estimates (such as tolerance limits or
prediction limits), which establish an upper bound for a sample of a prespecified
size (as would be established in post-remedy verification sampling), these
comparisons optimize application of results from the background sampling effort.
Case Study
Alhambra Former MGP Site
In 1996, SoCal embarked upon the remediation of PAHs at a former MGP site in
Alhambra, California. Because background concentrations of PAHs exceeded
concentrations corresponding to a one-in-one-hundred-thousand cancer risk, the
California EPA agreed that remediation to levels lower than background would
not be practical. The first challenge associated with remediating to background
included building a database of background PAH concentrations that could be
used to characterize background concentrations. In addition, statistical methods
had to be selected to support the site characterization and site remediation
decisions made in the restoration of the site to background conditions.
Site Background
The Alhambra site had only operated as a MGP from 1906 through 1913. Because
oil was the most likely feedstock, the predominant residual expected to be found
was lampblack. Aerial graphs showed that the site sat vacant until about 1940,
when the first house was built. By about 1948, the site had been subdivided into 20
lots, each with a separate residence.
Site investigations revealed the presence of PAHs in shallow soils. Other
chemicals often associated with MGP operations such as metals, cyanides, reduced
sulfur compounds, phenolics, and benzene, however, were not detected in soil
above local background levels, or were present at levels below those that posed a
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health threat. Groundwater and soil investigations demonstrated that chemicals
had not migrated into groundwater. Based on these findings, the remediation of
the site focused on PAHs in soil.
Site remediation was performed under the supervision of the California EPA
DTSC. As a risk management policy, the DTSC generally requires
post-remediation cancer risks to be closer to the 10 "6 end of the 10 ~4 to 10 "6
acceptable risk range recommended in the National Contingency Plan (NCP).
Most remediations approved by the DTSC achieve cleanup to a residual cancer
risk of 10"5 or lower.
Background Database
The database of background PAH concentrations includes analyses of 184 surface
soil samples collected from 20 different sites throughout Southern California. The
data set was subjected to several statistical tests to determine if the data comprised
a homogeneous population. Among the variables probed to explain variations in
the data were urban versus rural setting, analytical method, and sample collection
technique. After evaluating several different variables that might account for
variability in the data, it was concluded that the data could be considered a single
data set with a log normal distribution.
Developing the Remedial Action Goal
Using cancer slope factors recommended by California EPA for cPAHs, the
concentrations of cPAHs (expressed as benzo(a)pyrene [B(a)P] equivalents)
corresponding to 10"6,10"5, and 10"4 cancer risks for a residential exposure
scenario are 0.02,0.2, 2.0 mg/kg, respectively. Using the database of background
PAH concentrations in Southern California soils developed as part of this
project, the 95% upper confidence level estimate of the mean concentration of
cPAHs (expressed as B(a)P equivalents) in soil is 0.24 mg/kg. This concentration
does not correspond to a cancer risk above the 10 "4 upper end of the acceptable
risk level recommended in the NCP, but it does correspond to risks in excess of
10'6 and 10'5.
Remediating soils in Southern California to PAH concentrations corresponding
to cancer risks in the 10"6 to 10"5 range would require reducing concentrations to
levels below background, an impractical goal. Remediating the site to
background concentrations would produce a site that posed no incremental risk
to humans or the environment beyond that posed by background PAHs. The
remediation goal adopted for the site was to restore each residential lot to a
condition such that people living at the site would have no more exposure to
PAHs than they would have had in the absence of the MGP operations.
Achieving the Remedial Action Goal
Given the objective of restoring the site to background conditions, the ideal
remediation would have involved removing all PAHs that originated from the
former MGP operations. Over time, however, some of the PAHs from the MGP
operations had mixed with soil to such an extent that while the PAH
concentrations were elevated above background levels, the soil across much of
the site was not visually distinct. The practical approach developed for
remediating the site relied on field observation to visually identify lampblack
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Chapter 3
Management Tools for Expediting Site Characterization and Remediation
and on statistical evaluations of sampling data to identify areas with PAH
concentrations above background levels.
Because there is no single statistical test that could be applied to soil
concentration data to determine if the PAHs measured in a particular sample
exceed background concentrations, SoCal applied a few different statistical tests
to identify areas where concentrations probably exceeded background levels.
The statistical tests include both comparisons of point estimates as well as
distributions. To evaluate point estimates, the,95.? percentile,; the. upper
tolerance limit, and the upper prediction limit were considered. The appropriate
test for comparing distributions depended on the nature of the background
distribution and the site data. Visual comparisons of plots of the background
data set to the data from each lot were revealing, as were more rigorous
statistical tests such as a t-test or a Mann-Whitney test. Using these statistical
tests, an initial excavation target of 0.9 mg/kg of B(a)P equivalents for the
cPAHs was identified. Using the initial site characterization data, soils with
B(a)P equivalent concentrations above 0.9 mg/kg were initially identified to be
excavated.
Because approximately 5 percent of background soil samples had B(a)P
equivalent concentrations above 0.9 mg/kg, leaving some soil with PAH
concentrations above this level did not necessarily mean that the PAH
concentrations remaining after site remediation exceeded background levels.
This was an important practical consideration because some soil with elevated
PAHs level were in areas where excavation was not practical (e.g., beneath
foundations).
The evaluation of data distributions was particularly important in the
determination of whether contamination had spread off-site. Because there is a
wide range of PAH concentrations in the background, the occasional detection
of a relatively high concentration of PAHs in boundary or off-site samples did
not necessarily mean that contamination had spread off-site. The use of a single
point estimate (e.g., two standard deviations above the mean, the upper
tolerance limit, etc.) as a test for determining whether any single data point
represents contamination beyond background can lead to false conclusions.
Demonstrating Achievement of the Remedial Action Goal
Based on the initial evaluation of the distribution of PAHs in soil at the site, the
excavation of soils meeting the two initial excavation criteria described above
(i.e., visible lampblack and B(a)P equivalent concentrations above 0.9 mg/kg)
was predicted to effectively restore each lot to background conditions.
Excavation was required on 18 of the 20 lots down to an average depth of 4 to 5
feet, including under crawl spaces and concrete slabs. Following excavation, soil
samples were collected from the side walls and bottoms of excavated areas and
statistical analyses were performed to determine if each lot had been restored to
background conditions. Post-remediation concentrations were also compared to
risk-based concentration limits designed to prevent acute or sub-chronic health
effects to ensure that none of the material left behind would pose such health
risks. The same statistical tests described above for determining whether and
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Chapter 3
Management Tools for Expediting Kite Characterization and Remediation
where remediation was needed were applied to the post-remediation data to
confirm that remediation was complete.
Conclusions
Because risk-based remediation goals for cPAHs were below background levels,
a method for developing background-based remediation goals was needed. The
traditional reliance on a single point estimate of background (e.g., two standard
deviations above the mean), however, can provide false indications of
contamination, particularly if there is a substantial overlap in the range of
background concentrations and the range of incremental concentrations
attributable to MGP operations.
By having a database representative of background concentrations over a sizable
geographic region, the characterization of background concentrations coming
from the database can be used at the many sites in the region. The size of the
database (i.e., 184 data points) allows for a high degree of statistical power in
distinguishing background concentrations from elevated concentrations that are
presumably related to MGP operations/In addition, through the use of
distributional comparisons to supplement point estimate definitions of
background levels, this approach can minimize the false identification of
background concentration samples as representing contamination.
Contact
Bob Vogel, Southern California Gas Company, (213) 244-5880
3.2.11 Generic Administrative Orders
Tool Description
Generic administrative orders have been developed to streamline the regulatory
administrative process. Former MGP sites, as a subset of site characterization and
remediation experiences, lend themselves to generic administrative orders and
provide the opportunity to address environmental conditions under a consistent,
cooperative, mutually beneficial statewide agreement. Benefits of generic
administrative orders include:
• Comprehensive and consistent statewide strategies
• Reduced costs in negotiating agreements/orders
• Proactive environmental mitigation
• Emphasis on cooperation and common sense
Case Study
North Carolina MGP Group Generic Administrative Order
In the late 1990s, the North Carolina Manufactured Gas Plant Group (NCMGPG)
entered into a memorandum of understanding (MOU) with the North Carolina
Department of Environment, Health, and Natural Resources, Division of Solid
Waste Management (DSWM) to establish a uniform program and framework for
addressing manufactured gas plant sites in North Carolina. Under the MOU, all
investigations and, if required, remediation of specific MGP sties are to be
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Management Tools for Expediting Site Characterization and Remediation
addressed pursuant to one or more administrative orders of consent. The MOU
did not commit the NCMGPG to investigation and/or remediation any particular
former MGP site; rather it simply set in place the framework to be followed should
such an investigation/remediation be implemented. Implementation is formalized
through the execution of one or more of the generic administrative orders of
consent.
In establishing the generic administrative orders and preparing the MOU, the
NCMGPG and DSWM agreed to coordinate all North Carolina MGP site
investigations and remediations under the authority and jurisdiction of the DSWM
in order to ensure that all characterization activities were completed in a uniform
manner and to ensure that a single, regulatory agency (DSWM) would take control
of oversight of North Carolina former MGP sites. In executing the MOU, the
NCMGPG and DSWM agreed to:
• Negotiate in good faith to develop a uniform program and framework for the
investigation and, if required, remediation of former MGP sites within the
state
• Prioritize MGP sites in the state using the Site Screening and Prioritization
System (SSPS) developed by the Electric Power Research Institute
• Discuss and obtain regulatory acceptance of the most nearly applicable
cleanup standards that would be applied under CERCLA arid Superfund
Amendments and Reauthorization Act of 1986, recognizing the need for
flexibility in addressing site-specific conditions
• Negotiate in good faith to develop appropriate alternatives to the site
assessment and remediation methodologies outlined in the generic
administrative orders
• Organize and sponsor group-funded technical seminar (s) and conference (s)
highlighting state-of-the-art technologies involving assessment and
remediation of former MGP sites
Contact
Brian Nicholson, North Carolina Department of Environment, Health, and Natural
Resources, (917) 733-2801 x353
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Chapter 4
Tools and Techniques for Expediting
Site Characterization
4.1 Introduction
Expedited site characterization (as described in Section 3.2.7) encompasses the
use of tools and methodologies that streamline data collection, increase field
program flexibility, and allow for real-time on-site access to results.
Fundamentals key to an expedited site characterization include:
» On-site or rapid decision-making capabilities .
» Use of field and analytical tools that facilitate real-time data collection and
interpretation.
• Use of non-intrusive or minimally intrusive geophysical and/or sampling
techniques
• Flexibility in the overall site characterization and remediation process
The tools and techniques described in this chapter offer alternatives to, and in
some cases, advantages over more traditional approaches to environmental
assessment of sites. These tools and techniques are less intrusive, and generally
allow completion of data collection in a more expeditious manner. In addition, the
majority of these tools allow practitioners immediate, on-site access to results
rather than requiring samples be sent to analytical laboratories for analysis.
Having the data available in real time while implementing the sampling program
allows the investigator to modify the sampling program based on early results.
The investigator can then make informed decisions about subsequent sampling
locations to cover an area of interest or to define the boundaries of identified
problem areas.
In addition to being faster and less intrusive, these tools and techniques are cost-
effective, taking many samples and producing a large amount of data in a short
time. This is especially useful in expedited site characterizations, where the goal is
to first collect more data points of lesser quality in order to focus resources on
those areas of greatest concern. Subsequent phases of field work can then be
implemented to collect fewer data points of better quality at predetermined
locations, if necessary, to complete the site characterization.
These tools and techniques can be combined to form a site-specific expedited field
program. Prior to developing such a program, however, thought must be given to
the project's data needs and the ways in which the data will be used. Once these
DQOs have been formulated, different site characterization tools and techniques
can then be brought together, as appropriate for different site conditions.
Flexibility in decision-making during the field program will also be required to
ensure that only necessary and useable data points are collected. Each tool and
technique in this chapter has strengths and weaknesses. The following table
summarizes available information. Additional information is presented in the
4-1
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Chapter 4
Tools and Techniques For Expediting Site Characterization
chapter proper for use by the practitioner. The order in which the tools and
techniques discussed in this chapter does not reflect any ranking of their relative
effectiveness.
4-2
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Expedited Site Characterization Tools and Techniques
Name
Description
Benefits
Limitations
Approximate Cost
Direct Push Methods/Limited Access Drilling
Direct Push/Limited Access
Drilling (Geoprobe, Power
Punch, Strataprobe,
Precision Sampling, and
others)
Used to collect soil, groundwater and
soil gas samples and for identifying
stratigraphy and nonaqueous phase
liquids.
• Faster, cheaper way to explore subsurface
characteristics
• Can be linked to on-site analysis for real time
mapping
• Widely available
• Can install small diameter wells and vapor extraction
points
• Less intrusive
• Produces small volume of investigation-derived
waste
• Limited range of use (with refusal/depth limited
to <100 ft max; typically 25 to 30 feet)
• Does not allow for large well installations
• Limited use at locations with buried obstructions
(e.g., foundations and coarse grain materials)
• Potential for cross-contamination from
single-tube rigs.
$1,000-$1,500 per day;
typical production 10-15
shallow (<40 ft) pushes per
day
Cone Penetrometer
Push sampler used for geologic
logging and to collect in situ
measurements of geologic properties
and pore pressure. Can be used to
collect soil gas and groundwater
samples.
• Rapid collection of objective stratigraphic information
• Can penetrate harder zones than most direct push
methods
• Produces small volume of investigation-derived
wastes
• Does not collect soil samples for analysis or
inspection
• Large, heavy rig may limit access
• Cannot install wells
• Potential for cross contamination from
single-tube rigs
Typically one-third that of
conventional soil borings, on
per foot basis
Simulprobe
Driven sampler used to collect soil,
groundwater, and soil gas samples
through a casing or auger advanced
to desired sampling depth.
• Collects soil and either groundwater or soil gas
samples at same stratigraphic interval on the same
push
• Can be used with field instrument to screen for VOCs
while pushing
• Can be used in conjunction with a variety of drilling
methods
• Limited availability
• Multiple moving parts increases potential for
breakage or sticking
* Depth to which sampler can be pushed limited
Tools rent for $150/day or
$650/week, plus rig cost of
about $1,500 per day.
Hydropunch.
Direct push tool used to collect
depth-discrete groundwater samples
at a discrete level in a single push.
• Collects groundwater sample at a discrete depth
• Can be used with field instrument to screen various
depths
• Data subject to interference from turbidity
• Potential for cross-contamination if sampler is
driven across hydrostratigraphic zones
Tools rent for $150/day or
$650/week, plus rig cost of
about $1500 per day.
Waterloo Profiler
Direct push sampler used to collect
depth-discrete groundwater samples
at various levels in a single push.
Useful in identifying thin, high-
concentration plumes that may be
missed or underestimated (via
dilution) with monitoring well
sampling.
• Generates a vertical profile of groundwater quality on
a single push (typical vertical separation of about 2 to 5
feet)
• Faster and less prone to cross-contamination
(vertically) than multiple pushes with conventional push
samplers
• Sampling depth generally limited by drilling
method
• Not applicable to low-permeability settings
• Tool available through limited number of
vendors
$1,500 to $2,000 per day
(2-person crew, including all
decpn and support
equipment); typical
production is 150 - 200 ft per
day. Waterloo sampler
equipment may be
purchased from Solinst
Canada, Inc., for $US 2,700.
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Expedited Site Characterization Tools and Techniques, continued
Name
Description
Benefits
Limitations
Approximate Cost
Multi-Level Groundwater Samplers
Westbay System
Fixed multi-level sampler built for a
specific well installation. Access is
through a single standpipe with
mechanical "ports" that are opened
and closed during sampling. Used to
provide multi-level sampling and
hydraulic head measurements.
Provides direct samples of formation water
Allows head measurements
Mechanically complex
Not adjustable or portable between wells
Requires specially constructed wells
Approximately $30,000 for a
5-level system ranging from
50 feet to 200 feet in depth.
Includes installation but not
sample analysis.
Waterloo Sampler
Fixed multi-level sampler built for a
specific well installation. Access is
through bundled flexible tubes that
are accessible at the surface. Used
to provide multi-level sampling and
hydraulic head measurements in
specially-constructed well. Smaller
"drive point" units available for
shallow installation.
Provides direct samples of formation water
Reduces purge volumes
Removable or permanent systems available
• Mechanically complex
• Specially-ordered materials necessary
• Removable packer system sometimes difficult
to cost-effectively reuse
• Requires trained technician for installation
Approximately $25,000 for a
5-level system ranging from
50 feet to 200 feet in depth.
Includes installation but not
sample analysis.
Diffusion Multi-Layer
Sampler (DMLS)
Portable multi-layer dialysis cell
passive groundwater sampler. Used
to characterize vertical variation in
groundwater quality in either open
rock boreholes or in wells with long
well screens. Can be used to
estimate groundwater flow velocity
using borehole dilution method.
• Portable between wells
• Allows vertical characterization of groundwater in a
single borehole or well
• Requires no purging
• Not widely used
• Does not allow head measurements
• May not be appropriate for zones with strong
vertical gradients
About $3,000 for 2-to
3-meter-long units. Cost
increases with increasing
length. Need to add
additional costs related to
sample analysis and
equipment installation.
Discrete Point Samplers
Discrete Point Samplers
Discrete point sampler used to collect
representative groundwater sample
at a distinct elevation or points of
inflow in either open boreholes or
screened wells.
J_
• Permits groundwater sampling from discrete vertical
depth
• Minimizes mixing of water from different levels during
sample collection
Portable
May require training to operate sampler
May be difficult to obtain complete seal
$15042,000 for purchased
sampler.
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Expedited Site Characterization Tools and Techniques, continued
Name
Description
Benefits
Limitations
Approximate Cost
Analytical Field Screening
Rapid Optical Screening Tool
(ROST)
X-Ray Fluorescence (XRF)
Colorimetric Field Test Kits
Immunoassay Field
Screening
Mobile Laboratory
Sampling and screening technology
used to field screen for petroleum
hydrocarbons and other
contaminants.
Field screening tool used to analyze
trace metals in soil, sludges, and
groundwater.
Field test kits used to detect the
presence or determine the
concentrations of contaminants in soil
and water.
Field test kit used to detect target
chemicals in soil and other samplers.
Most kits use competitive enzyme-
linked immunosorbent assay (ELISA)
type.
Mobile facility providing onsite soil,
water, and air analyses.
• Rapid, real-time geologic and hydrocarbon data
• Can be used to converge on area of interest
• Works for both fuel (aromatic) hydrocarbons and
creosote (polycyclic aromatic hydrocarbons)
• Generates little investigation-derived wastes during
sampling
• No waste generated
• Little sample preparation required
• Easily transported to the field
• Inexpensive and easy to use
• Available for a wide range of concentrations for
hundreds of chemicals
• Can be used for remote sampling
• Produces rapid, real-time analytical data onsite
• Can be used to select samples for laboratory.analysis
and to define limits of contamination
• Rapid onsite detection of contaminants
• May reduce mobilization/demobilization charges for
field projects
• Can rapidly perform time-critical analyses
• Limited availability
• Limited to unconsolidated geology (same as
CRT)
• Provides only relative concentration data
• Limited penetration depths
• Susceptible to interference from water,
petroleum, and soil variability
• Poor detection limits for some metals
• Radioactive source in analyzer
• Relatively high detection limits
• Possible interference by naturally occurring
chemicals and other contaminants
• Possible difficulty in reading colorimetric
matches in low light
• Requires site-specific calibration
• Does not speciate individual PAHs
• Does not work effectively at MGP sites where
crude oil was used -
• Does not produce quantified concentrations of
target chemicals
• Requires test runs to ensure adequacy
• More expensive for standard turn-around
analysis
• Not all mobile laboratories use USEPA
analytical methods
$4,000 to $4,500 per day
(reflects recent cost
reduction). Production up to
300 feet per day.
$2,000/week.
Handby Kits -$1300/30
samples
PetroFLAG- $800/10
samples
Petrosense-$150/week
Quick Testr-$275/week
Approximately $20 -
$5S/sample excluding labor
$2,500 to $3,000 for rental;
$13to$30/samplefor
expendables.
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Expedited Site Characterization Tools and Techniques, continued
Name
Description
Benefits
Limitations
Approximate Cost
Geophysical Surveys
Electromagnetics
Non-intrusive electromagnetic
geophysical tool used to locate
buried drums, landfills, bulk buried
materials, etc. Can be used to
determine depth to the water table
and to delineate eleclrically-
conduclive (high dissolvedsolids)
contaminant plumes.
• Non-intrusive
• Can provide large quantities of detailed data in short
time
• Need expert subconsultant to plan survey and
interpret data
• Data affected by power lines and metal
buildings, cars, or other large metal items
• Problematic in iron-rich soils and fill with large
amounts of diffused metal wastes
Approximately $3,500,
including data collection and
interpretation for a one-acre
site.
Seismic Refraction
Non-intrusive geophysical surveying
tool used to determine depth to
bedrock and/or water table. Can be
used to define bedrock surface,
buried channels, etc.
• Non-intrusive
• Can provide large quantities of detailed data in short
time
• Need expert subconsultant to plan, collect, and
interpret data -
• Data subject to interference from complex
geologic strata
• Needs to be correlated with other site-specific
subsurface data "-
• Heavy traffic or numerous surface obstructions
may be problematic
Approximately $10,000
including data collection and
interpretation for a one week
survey.
Ground Penetratinq Radar
(GPR)
Non-intrusive geophysical surveying
tool used to locate buried waste,
drums, tanks and voids, and to
determine the depth and thickness of
soil and bedrock.
• Non-intrusive source and detectors
• Can provide large quantities of detailed data in short
time
• Need expert subconsullant to plan, collect, and
interpret data 'i
• Data deteriorates with increasing surface
moisture or clay in subsurface
• Problematic in iron-rich, deeply weathered soils
$10,000/weekfor5to7line
miles of interpreted data.
Magnetometry/Melal
Detection
Non-intrusive geophysical survey tool
used to detect and map buried
drums, metallic pipes, utilities and
cables, tanks and piping. Also used
to delineate trenches and landfills
with metal debris.
• Non-intrusive
• Relatively easy for non-expert to use
• Can provide large quantities of detailed data in short
time
• Depth and detail not obtainable
• Cannot distinguish between types of metallic
objects
• Nonferrous metallic objects are invisible
$500/month for equipment
rental costs only.
Electric Logging
Includes electrical resistivity
methods, induction logs, self-
potential logs, and fluid conductivity
logs. Uses electrical resistivity to
identify different hydrogeologic zones
around a borehole.
Rental equipment available
Specialized training not required
Quantitative data may require corrections
• Requires uncased borehole
• Electrical resistivity and self-potential
techniques require conductive borehole fluids
• No quantitative measurements (other than
depth)
• Induction logging requires a dry borehole or
borehole with non-conductive fluids
$1,200-$2,500 day. (Can
log 5-7100-foot wells per
day.)
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Expedited Site Characterization Tools and Techniques, continued
Name
Description
Benefits
Limitations
Approximate Cost
Geophysical Surveys, com
Mechanical Logging
Includes flow-meter and caliper
logging. Used to identify water-
producing zones. Flow-meter logging
provides semi-quantitative flow
measurements when used in
conjunction with caliper log (which
measures borehole size and
roughness and locates fractures and
washouts).
• Provides direct measurement of vertical flow in well
bore
• Flow-meter logging is relative insensitive at low
velocities
• Most applications of flow-meter logging requires
a pumping or flowing well
• Caliper logging is required for interpretation of
flow-meter log
$500-$600 per well, when
run as part of multiple log
suite. Flow-meter only (with
caliper) is approximately
$1,500-$2,500 per well.
Acoustic (Sonic) Logging
Uses acoustic energy to determine
the relative porosity of different
formations. May be used to identify
the top of the water table, locate
perched zones, and assess the seal
between a casing and formation
material.
• Useful for characterizing rock aquifers
• Allows porosity determination without use of
radioactive source
• Not applicable in shallow wells or in unsaturated
conditions
• Relatively complex test; requires skilled
operator for reliable results
$1,500-$4,500 per well.
Radiometric Logging
Includes neutron logging and natural
gamma logging. Used to estimate the
porosity and bulk density of a
formation and to locate saturated
zones outside casing. Gamma
logging is used to evaluate downhole
lithology, slratigraphic correlation,
and clay or shale content.
Rental equipment available
Specialized training not required
Good tool for performing infiltration studies
• Neutron logging requires handling radioactive
source and may be limited to case boreholes
• Natural gamma logging may provide a
non-unique response
• Natural gamma logging may respond to the
presence of phosphate minerals of micas or may
mistake feldspar for clay or shale
For neutron logging, $2,500
to $5,000 per well depending
on well depth and number of
other logs run in conjunction.
For natural gamma logging,
$1,200 - $2,500 day. (Can
Iog5-7100-footwellsper
day).
Thermal Logging
Uses temperature differentials for
flow and injectivity profiling, in
conjunction with flow-meter logging.
• Supplements flow-meter log for identification of
producing zones
• Requires fluid-filled borehole for testing
• Interpretation of log complicated if internal
borehole flow is present
$500-$600 per well, when
run as part of multiple log
suite. Temperature log only
$1,500-$2,500 per well.
Video Logging
Downhole videotaping to provide
visual inspection of a well interior,
detecting damaged sections of
screen and casing, and to detect
fractures, solution cracks and
geologic contacts in uncased holes.
Allows visual inspection of the interior of the well
• Requires very clear water for successful survey
• Not suitable for open boreholes in
unconsolidated formations
$400 to $3,000 per well.
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Expedited Site Characterization Tools and Techniques, continued
Name
Description
Benefits
Limitations
Approximate Cost
Soil Gas Surveys
Passive Soil Gas
Measures relative concentration of
contaminants through subsurface
detectors sensitive to diffusion.
• Can be more sensitive than active soil gas, soil, or
groundwater sampling for detecting presence of trace
contaminants
• Can be used in areas of low-permeability soil
• Does not measure direct concentration
• May be difficult to collect data at depth for
vertical characterization
• Requires 2 to 4 weeks for sample collection
Approximately $250 per
sample location, including
analysis and reporting; about
$50-$100 per location
installation and retrieval.
Active Soil Gas
Uses a vacuum pump to induce
vapor transport in the subsurface and
to instantaneously collect samples of
contaminants in the vapor phase.
• Provides real-time data
• Rapid results allows user to converge on areas of
interest
• Provides direct measure of vapor concentration
• Can be used to evaluate vertical changes in soil gas
concentrations
• Samples must be collected at least 10 to 20 feet
bgs
• Cannot be used in areas of relatively low
permeability
• May be adversely affected by transient
processes (e.g., barometric pressure) and
stationary features (e.g., pavement)
Approximately $3,000 to
$4,000 per day
Contaminant Migration Evaluation
Push-Pull Natural
Attenuation Test
Injection/withdrawal test (single well)
to document and quantify microbial
metabolism.
• Can document microbial metabolism, loss of
degraded contaminants, production of degradation
products, and yield estimates of zero- and first-order
decay constants
• Can use wells already installed
• Provides in situ data
• Not widely used
• Can have difficulty when decay rate is slow
relative to groundwater flow rates
$12,000 to $15,000 for 2 to 3
wells at one site for BTEX.
Costs may be higher for
other contaminants (because
of more expensive analysis).
Partitioning Interwell Tracer
Test (Pin)
Injection/withdrawal test (2 wells) to
quantify volume and estimate
distribution of nonaqueous phase
liquids (NAPLs).
• Can provide quantitative estimates of NAPL volume
• Can be used to design remediation methods
targeting a NAPL source
• Is relatively accurate compared with other in situ tests
that utilize point values or small aquifer volumes
Expensive
Technology is patented
Most experience is with solvents
$100,000 to $400,000
depending on scale of test.
In Situ Bio/Geochemical
Monitor (ISM)
Allows for in situ measurement of
biochemical reaction rates and
retardation factors for both organic
and inorganic compounds through
the subsurface introduction and
monitoring of tracers and reactants.
• Reduces the time and cost of obtaining site-specific
biological and geochemical data
• Provides In situ measurements of biochemical
reaction rates
• Provides estimated rates of denitrification during
biodegradation
• Provides estimated retardation rates for organic and
inorganic compounds
• Testing is complex and requires trained
personnel
• Small aquifer volume tested means results may
be affected by small-scale variations in aquifer
properties
• Typically applicable only with permeabilities
>1fr cm/sec
$3,000 for equipment only.
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Expedited Site Characterization Tools and Techniques, continued
Name
Description
Benefits
Limitations
Approximate Cost
Other Tools
Micro-Scale Extraction (for
PAHs)
PAH Sample Filtration
Inverse Specific Capacity
Method
Hand Augering/Trenching/
Pot Holing
Noise and Fugitive
Emissions Controls
Alternative laboratory extraction
procedure for mono- and polycyclic
aromatic hydrocarbons, chlorinated
phenols, PCBs, mineral oil, and
selected nitrogen- and sulfur-
containing aromatic hydrocarbons
prior to analysis.
In-field or laboratory filtration of water
samples prior to PAH analysis to
estimate the 'true' dissolved
concentration by removing potential
for colloidal contribution of PAHs.
Specific application of push sampler
(Geoprobe and others) to link
groundwater quality data obtained
from push sampler with an estimate
of hydraulic conductivity in the
sampled zone
Field surveying and sampling
technique.
Barriers and controls to minimize
noise and fugitive emissions during
site characterization and remediation.
• Small sample volumes required
• Fast laboratory turnaround times
• Minimal laboratory wastes
• Quantitative results for individual components
• Eliminates high bias in PAH concentration
measurements introduced by artificial colloidal
entrainment
• Inexpensive
• Requires minimal training to implement
• Allows vertical profiling of variations in horizontal
hydraulic conductivity to be assessed
• Inexpensive where labor is cheap
• Can be used to expose buried objects
• Discrete and can get into tight locations
• Protects community and workers
• Limits noise and air pollution
• Minimizes the migration/transport of contaminants
• Relatively new procedure
• Low bias resulting from elimination of
naturally-occurring colloidal transport of PAHs
• Dissolved or colloidal contaminants may adsorb
onto the filter or apparatus
• Provides hydraulic conductivity for only small
volume of aquifer
• Need site-specific permeability data from
conventional means (pumping or slug tests in
wells) to convert specific capacity to hydraulic
conductivity
• Only appropriate for zones having permeability
ranging from 10'1 to 10'5 cm/sec
• Hand augering and test pits are depth limited
• Pot holing and test pits are visible to public
• Borehole/slope stability problems
• Waste management may be a problem
• May be cost- and effort-prohibitive on a large
scale
• Controls may make field work logistically more
complex and/or limit rate of completion
Dependent upon analysis.
Can reduce costs by over
50% in certain situations.
Minimal cost when compared
to overall analytical costs.
(Typical PAH analysis costs
$200to$300/sample.)
Negligible cost, assuming
that a peristaltic pump and
push sampler already are in
use at the site (assumes
typical time for test ranges
from 5 to 10 minutes).
Materials and equipment
costs are minor. Cost is
dependent on local labor
costs.
Ranges from $200-$500/day
for water sweeping to
>$1 0,000 for complete site
enclosure.
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Chapter 4
Tools and Techniques For Expediting Site Characterization
4.2 Tools and Techniques for Expediting Site
Characterization
Described below are 13 categories of new and existing tools and techniques that
are currently available for expediting characterization of former MGP sites. The
cost of using the tools and techniques and the results generated will vary from site
to site depending upon accessibility, cost of labor, types and concentrations of
contaminants found, hydrogeology, and other characteristics. Although many of
these tools and techniques have been used successfully at former MGP sites,
practitioners should choose tools based on the particular conditions at their site(s).
Where possible, references are listed so that readers can contact representatives of
projects where the tools and techniques have been used.
, -I
4.2.1 Direct-Push Methods/Limited Access Drilling
Tools in this category provide faster and cheaper ways to explore subsurface
characteristics than have been available in the past. These methods are typically
less intrusive, generate fewer investigation-derived wastes than past techniques,
and permit sample collection in areas with limited clearance. When combined
with on-site data analysis, these tools provide a powerful way to survey soil (and
groundwater) for contaminants.
Some of the tools described herein may be limited to depths of 25 to 30 feet; others,
however, are not depth-constrained. These tools generally create small-diameter
boreholes and therefore do not allow for the installation of large wells. In addition,
they may only allow for one-time "snapshot" or "grab" sampling. Tools included
in this category are:
• Direct-Push Limited Access Drilling Techniques (such as GeoProbe™, Power
Punch™, Strataprobe™, and Precision Sampling™)
• Cone Penetrometer
• Simulprobe™ Sampler
• Hydropunch™
• Waterloo Profiler
» Westbay System
» Diffusion Multi-Layer Sampler
• Waterloo System
• Point Sampler or Dual Packer Sampling
4.2.1.1 Direct-Push/Limited Access Drilling
Tool Description
A wide range of direct-push and limited access drilling techniques is available for
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Tools and Techniques For Expediting Site Characterization
collecting soil, vapor, and groundwater samples and for identifying stratigraphy
or NAPLs. Some vendors, such as GeoProbe™, have also developed specific
application probes (e.g., the conductivity probe) that can be used in conjunction
with a drilling rig to survey a site or install small-diameter wells. These drilling
methods have been successfully applied at former MGP sites for delineating
source areas, screening aquifers for plumes before well installation, and collecting
subsurface information in hard-to-access areas.
Direct-push drilling rigs typically consist of hydfaulic-ptjwered" "
percussion/probing machines designed specifically for use in the environmental
industry. "Direct push" describes the tools and sensors that are inserted into the
ground without the use of drilling to remove soil and make a path for the
sampling tool. These drilling rigs rely on a relatively small amount of static
(vehicle) weight combined with percussion for the energy to advance a tool string.
The small rig size allows work in limited access areas. Below is a photograph
showing a typical direct-push drilling rig.
Operational Considerations
Direct-push drilling rigs, such as the GeoProbe™, are more efficient at drilling in
shallow, soft areas but are not typically capable of drilling through a thick
subsurface structure such as a gas holder foundation. Although limited in depth
and often unable to drill through buried foundations at an MGP site, this
technology can provide useful information about the location and depth of buried
structures without puncturing them, which would create a route for cross
contamination. In addition, this technique is effective for collecting soil,
groundwater, and soil vapor grab samples. It is most efficient to depths of
approximately 30 to 50 feet (depending on soil type).
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Tools and Techniques For Expediting Site Characterization
Applications and Cost
Vendors of direct-push drilling rigs include GeoProbe™, Power Punch™,
Strataprobe™, and Precision Sampling™. This drilling technology is well
understood and provides reliable results. The cost of a direct-push drilling rig is
approximately $1,000 to $1,500 per day, not including sampling tools and related
expenses.
Benefit
• Small rig size suitable for tight spaces around aboveground structures or utility
areas such as substations
• Small volume of investigation-derived waste (IDW) produced
• Continuous coring or discrete soil samples both possible
• Sampling of soil, groundwater, and vapor possible along with installation of
small-diameter wells
Limitations
• Limited use at locations with buried obstructions (e.g., foundations)
• Potential for cross contamination from single-tube rigs
• Rods can get lost in tight soils
« Small diameter wells installed using these direct-push rigs may be difficult to
develop
• Water samples collected from direct-push tubes typically contain considerable
suspended sediment; may yield biased results for turbidity-sensitive
constituents such as lead and PAHs
• Repeated pushes required from ground surface in order to vertically profile a
site (i.e., collect water samples at different depths at the same location) unless
special equipment (i.e., Waterloo system) is used
• Impractical (because of slow sample collection) in low-permeability soil or
when attempting to collect samples at relatively shallow depths below water
table
Case Study
ChicolWillowslMarysville (CWM) Former MGP Sites
Both GeoProbe™ and Precision Sampling™ direct-push drilling rigs were used at
PG&E's CWM former MGP sites. The rigs were used to:
» Collect deep soil and grab groundwater samples from within active
substations
• Collect grab groundwater samples to delineate the extent of offsite
groundwater contamination so that downgradient monitoring wells could be
placed at the edges of plumes (to act as sentry wells against continued
downgradient plume migration)
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• Quickly establish the extent of lampblack and coal tar in shallow soils at the
locations of former lampblack separators, lampblack dumps, and tar pits
When the rigs were unable to drill through obstructions, this helped verify the
location, depth, and extent of buried foundations. Soil samples from depths
beneath former foundations (collected when the drilling rig was able to push
through the former foundations) provided information about the types and
volume of buried MGP wastes. At locations where cross contamination was a
significant concern, Precision Sampling's dual-tube direct-push drilling rig was
used to minimize the amount of soil and/or waste that may be transported
downward by the driving rod.
4.2.1.2 Cone Penetrometer (CPT)
Tool Description
CPTs were initially developed as engineering tools for determining the capacity of
soils to support foundations and pilings. These tools are a quick, reliable, and well-
tested means to determine the continuity of stratigraphy, the depth to the water
table, and the thickness of stratigraphic layers. More recently, the hydraulic
pushing equipment on a modern CPT rig has been used to advance probes and
samplers into subsurface soils. Examples of such probes/samplers include vapor
samplers, soil samplers, the Hydropunch™, LIF probes, and resistivity probes.
A traditional CPT survey is a continuous penetration test in which a cone-shaped
rod is forcibly pushed into the soil with hydraulic rams. Sensors electronically
measure the resistance at the cone's tip and along the cone's sides. The function of
the relative density of the sediment is then correlated to the soil textures to
determine the site's stratigraphy. A schematic figure of a CPT rig is shown below.
ffi3r;
.tiiujJ--'-'.-'-!-'-.".----.-...., -'
|2 cm/sec
I, i
Oc
FIGURE 1 - SCHEMATIC DIAGRAM OF CFr
(
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Chapter 4
Tools and Techniques For Expediting Site Characterization
Operational Considerations
Modern CPT rigs are capable of collecting the same data as conventional drilling
rigs. CPT data are high quality, most often meeting DQOs, cost effective, and
typically pose minimal health and safety concerns. In addition, CPT testing does
not generate any drill cuttings. CPT drilling rigs can generally penetrate to depths
of 100 to 150 feet below ground surface (bgs) in normally consolidated soils. The
principal disadvantage of CPT rigs is that they cannot penetrate as deeply as
conventional drilling rigs.
Applications and Cost
There are several CPT vendors in the United States, most of whom support both
traditional geotechnical CPT projects and modern environmental investigations.
The types of CPT-mounted sampling equipment and probes vary, however,
among vendors. Costs for CPT are typically about 30 percent (on a per-foot basis)
of the cost of conventional soil borings installed using traditional methods such as
hollow-stem auger drilling. CPT costs are comparable with the modern direct-
push drilling technologies offered by GeoProbe™, Precision Sampling, Inc., and
others.
Benefits
• Can penetrate harder zones better than most direct-push methods
• Produces small volume of ID W
• Can be used for sampling groundwater and soil gas
Limitations
» Potential for cross-contamination from single-tube rigs
• Does not allow continuous coring or discrete soil samples
• Cannot be used to install wells
• Large, heavy rig may preclude access to some locations
4.2.1.3 Simulprobe™ Sampler
Tool Description
The Simulprobe™ sampler is a soil, soil gas, and groundwater sampling tool
designed to be driven by either push or drive sampling technology. The sampler
reduces the potential for cross-contamination by precharging its sample canister
with nitrogen and by covering the sampler with a latex condom. Precharging the
sampler with nitrogen prevents water from entering the sample canister until the
sample is collected. The condom ensures that the sampler remains
uncontaminated until driven into undisturbed soil.
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Chapter 4
Tools and Techniques For Expediting Site Characterization
One significant advantage of the tmm
Simulprobe™ sampler is the ability to
obtain a soil core sample at the exact
depth where the grab groundwater or
soil gas sample was obtained. This allows
the user to determine the lithology at the
point of sampling. In addition, the
Simulprobe™ sample chamber fills at a
slower rate than other samplers
(controlled by the rate at which the
nitrogen is bled off), thereby reducing
turbidity. The sampler also has a settling
chamber so that any excess sediments
that enter the chamber settle out before
the water sample is transferred. The i^^^^^^^^^^^^^^^^^^^^™
adjacent photograph shows a
Simulprobe™ sampler.
The Simulprobe™ provides continuous sampling of soil gas in the vadose zone.
When the probe is pushed through the vadose zone, soil gas is extracted under the
vacuum and measured continuously in an organic vapor analyzer located above
ground surface. If desired, a syringe can be inserted and a sample of soil gas can
be extracted and analyzed by gas chromatography (GC) at any time.
Operational Considerations
Sampling with the Simulprobe™, as with other similar tools, is limited by the
depth to which the tool can be driven. Other geologic conditions, such as flowing
sands, also limit the tool's effectiveness and range.
When a grab groundwater sample is collected using the Simulprobe™ sampler, the
water canister is first charged with nitrogen (usually 60 pounds per square inch
[psi]/100 feet of hydrostatic head), and the entire sample device is covered with a
latex condom. The Simulprobe™ is then slowly lowered to the bottom of a
borehole and hammered 21 inches into the subsurface to collect a soil core. The
device is then pulled back 2 to 3 inches to retract the sliding drive shoe and expose
the circular screen. A valve is opened to allow the nitrogen pressure to bleed off
from the water canister so water can enter the sample chamber under ambient
hydrostatic pressure. After the water sample has been collected, the water canister
is repressurized to prevent leakage into the sampling device, pulled out of the
borehole, and emptied into appropriate sample containers.
Applications and Cost
The latex condom covering the Simulprobe™ sampler is designed to minimize
cross-contamination during sampling, therefore making the Simulprobe™ a tool
for grabbing groundwater samples before well installation, especially in areas
where cross-contamination is of concern. Combined with push- or hammer-driven
sampling (such as GeoProbe™) and in-field analysis, it provides a fast, effective
method for obtaining survey-level data for refining monitoring well and
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Tools and Techniques For Expediting Site Characterization
ground-water plume locations. In addition, collecting soil samples at the same
interval as the sampled groundwater allows for better linkage between
hydrostratigraphy and groundwater and contaminant movement in the
subsurface.
The rental cost of the Simulprobe™ sampler alone (direct from the vendor) is
approximately $150 per day or $650 per week. Drilling costs can add
approximately $1,500 per day to total sample collection costs. Sampling depth and
frequency, site hydrostratigraphy, and buried obstructions can significantly
impact the tool's effectiveness.
Benefits
• Collects soil and either groundwater or soil gas samples at the same
stratigraphic interval in the same push
• Can be used with field instruments to screen for volatile organic compounds
while pushing
• Field tested and proven
• Can be used in conjunction with a variety of drilling tools
• Latex condom minimizes cross-contamination during sampling
"' . , H
• Nitrogen or helium can be used to purge the canister to create an inert
atmosphere before sample collection, thereby improving the quality of
chemical parameters for natural attenuation monitoring
• Canister attachments can be used as pneumatic bailers inside wells or
boreholes (e.g., for sampling below NAPL layers)
Limitations
• Limited availability (though may be available through local drilling firms)
i
« Multiple moving parts increase potential for breakage or sticking
• Depth to which the sampler can be pushed/driven limited
Case Study
Chico Former MGP Site
Field investigations conducted at PG&E's Chico former MGP site identified PAHs
and petroleum hydrocarbons in the shallow water-bearing zone. However, the
hydrostratigraphy below the water-bearing zone was not known, nor was
information available on the water quality of deeper water-bearing zones. In order
to determine the vertical extent of MGP-related constituents in groundwater and
to identify the next deeper, unimpacted zone for monitoring (as a sentry well), the
Simulprobe™ sampler was used with resonant sonic drilling. Grab groundwater
samples were then collected from the two water-bearing zones directly underlying
the shallow groundwater.
The first, deeper water-bearing zone was identified at 47 feet bgs. Grab
groundwater samples were successfully collected from this zone using the
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Simulprobe™. Because naphthalene-like odors •were detected in the field from this
groundwater zone, the Simulprobe™ was advanced to the next deeper water-
bearing zone, identified at 97 feet bgs. Flowing sands encountered at this depth
combined with the vibrations from the resonant sonic drilling jammed the sampler
and prevented collection of a grab groundwater sample. Use of the Simulprobe™
is not recommended with a resonant sonic drilling rig or where flowing sands are
present.
4.2.1.4 Hydropunch™
Tool Description
The Hydropunch™ is a direct-push tool for collecting a depth-discrete
groundwater sample inside a boring without installing a well. The Hydropunch™
has been successfully used for collecting grab groundwater samples at former
MGP sites to quickly delineate the extent of a. groundwater plume without well
installation or to quickly determine the best location or depth for screening a
monitoring well.
The Hydropunch™ sampler is advanced with a hammer-driven tool to collect a
groundwater sample from a particular depth. The sampler is pushed to the proper
groundwater sampling zone and then withdrawn to expose an inlet screen. The
screened interval is approximately 3 to 5 feet long. Groundwater can be collected
from multiple depths within a single borehole although the tool must be
withdrawn between samples. The following figure is a schematic diagram of the
Hydropunch™ sampler.
Sample
ChambeF
Operational Considerations
The key factor affecting the accuracy
of groundwater analytical results
collected via the Hydropunch™
sampler is the turbidity of the grab
sample. Because the sample is
collected from a borehole instead of a
developed well, the sample may be
turbid. If the sample is not filtered
before laboratory analysis,
hydrophobic chemicals (such as PAHs
and metals) sorbed onto the
suspended sediments may cause
erroneously high concentrations. In
addition, the Hydropunch™ sampler
limits the sample volume collected per
push, so this tool is best used in a
permeable zone where there is i^m^^^M^^^m^^^^^^mmmm
reasonable recharge into an area 3 to 5
inches thick. It is possible to attach a
peristaltic pump to the Hydropunch™ sampler to pump larger volumes of
Replaceable
Stainless Steel
Screen
Expendable
Drive Point
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Chapter 4
Tools and Techniques For Expediting Site Characterization
samples if volatilization is not an issue. Finally, as with any single-tube direct-
push probe or sampler, there is a potential for cross-contamination between
groundwater zones. However this concern can be mitigated by using conductor
casings. Floating-layer hydrocarbons may be sampled with a srnall-diameter bailer
lowered through the push rods in one of the Hydropunch™ tools.
Applications and Cost
The Hydropunch™ sampler is a fast and inexpensive method for collecting a
groundwater sample without installing a well. The Hydrbpunch™is well
understood and provides reliable results.
The cost of a Hydropunch™ sampler is approximately $150 per day, in addition to
the drilling rig and associated equipment.
Benefits
• Provides reliable data
• Field tested and proven
Limitations
• Data subject to interference from turbidity
• Potential for cross-contamination if sampler is driven across
hydrostratigraphic zones
Case Study
Stockton Former MOP Site
Grab groundwater sampling at the Stockton former MGP site was performed
using the Hydropunch™ sampling tool for field screening to determine monitoring
well locations at the edge of the plume. Samples were collected from two depths
and sent to a laboratory for rapid analyses. Sample results were used successfully
to determine whether the proposed well locations were at the edge of the
groundwater plume (analytical results showed no detectable levels of
contamination). Alternate well locations were identified when the Hydropunch™
samples showed detectable levels of contaminants.
4.2.1.5 Waterloo Profiler
Tool Description
The Waterloo Profiler (patent pending) is a groundwater sampling tool designed
to collect depth-discrete groundwater samples in a single borehole with one probe
entry. The Profiler consists of a tip containing multiple screened ports located
around it. The Profiler tip is connected to 3-foot lengths of heavy-duty threaded
steel pipe that extends to the ground surface. The Profiler is advanced by pushing,
pounding, or vibrating the steel pipe into the ground using one of Precision
Sampling, Inc.'s custom-made sampling rigs. Groundwater samples are conveyed
to the surface via small-diameter tubing that is attached to a fitting inside the
Profiler tip. The internal tubing, made of stainless steel or Teflon, passes up
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Tools and Techniques For Expediting Site Characterization
through the inside of the pipes to a pump and sample collection station located at
the ground surface (Precision Sampling, 1998). Chemical concentrations in highly
stratified formations can vary by several orders of magnitude over vertical
distances of 1 foot. One significant advantage of the Waterloo Profiler is its ability
to vertically profile contaminants in microstratigraphy without having to
withdraw and reinsert the probe. This minimizes cross-contamination and the
need for frequent tool decontamination between sample collection. The Profiler
can be pushed through clay and silt beds without plugging, which makes vertical
profiling easy.
Operational Considerations
Sampling with the Waterloo Profiler, as with similar tools, is limited by the depth
to which the tool can be driven. Other geologic conditions, such as fine-grained
sediments, also limit the tool's effectiveness and range.
Sample collection with the Waterloo Profiler is the most time-consuming part of
sampling operations. Sample collection can vary from 10 minutes per sample in
coarse-grained sand and gravel to 30 minutes in fine- to medium-grained sand.
Groundwater sampling with the Waterloo Profiler is not recommended for
lithology with sediments finer than fine-grained sands because of the lengthy
sampling time required.
Applications and Cost
The Waterloo Profiler is a useful tool for
rapid vertical profiling of hydrostratigraphy
down to a maximum of 100 feet bgs. (Actual
maximum depth is dependent .on site-
specific conditions and is typically shallower
than 100 feet). The tool allows for
delineation of contaminants in highly
stratified formations where
microstratigraphy plays a significant role in
contaminant migration.
The cost of the Waterloo Profiler plus direct-
push rig adds approximately $1,600 per day
to total sample collection costs. Sampling
depth and frequency, site hydrostratigraphy,
and buried obstructions can have significant _^^_^__^^^^__
impact on the tool's effectiveness. Reference: Precision Sampling, Inc.
Benefits
• Allows multiple depth-discrete groundwater sampling in a single borehole
(i.e., sampler does not have to be withdrawn between samples)
• Less prone to cross-contamination than multiple pushes with conventional
push sampler
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Chapter 4
Tools and Techniques For Expediting Site Characterization
• Can be used with field instruments to screen for volatile organic compounds
while pushing
« Field tested and proven
• Allows for delineation of contaminant pathways in microstratigraphy
Limitations
• Profiler available only through a limited number of vendors
• Limited by depth to which the sampler can be pushed/driven
* Shallow groundwater sampling via peristaltic suction-lift pump may cause
volatilization of some contaminants during sampling
• Groundwater sample collection recommended only for fine-grain sands and
coarser materials
4.2.1.6 Multi-Level Groundwater Samplers
Multi-level groundwater samplers are used to collect groundwater samples at
multiple, discrete levels within a single monitoring well. These types of
groundwater samplers are equivalent to a series of nested monitoring wells but
require only one casing in a single borehole.
"!'" , , ' "It,:'",:, , , ':,
The tools discussed below include several types of multi-level groundwater
samplers:
» Westbay System
• Waterloo System
» Diffusion Multi-Layer Sampler (DMLS)
4.2.1.6.1 Westbay System
Tool Description
The Westbay System is a fixed, multi-level sampler built for installation in a multi-
port monitoring well. It is designed to collect groundwater samples and hydraulic
head measurements at multiple, discrete levels in a single monitoring well. Multi-
port monitoring wells are like a series of nested monitoring wells but require only
one casing in a single borehole. The Westbay System incorporates valved
couplings, casings, and permanently inflated packers into a single instrumentation
string that is installed inside a cased borehole with multiple screened intervals,
allowing multi-level groundwater monitoring for a fraction of the installation cost
of nested monitoring wells.
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Chapter 4
Tools and Techniques For Expediting Site Characterization
The following figure shows the typical design detail for a Westbay System multi-
port monitoring well.
'TKWne BOX rr*-
wrm BOC.T-OOWN C
ROURE NOT TO SCALE
Operational
Considerations
Westbay System multi-port
monitoring systems are
complex and require
trained technicians to
install. Monitoring wells
must be designed
specifically to conform with
the Westbay System
requirements. Field quality
control procedures enable
verification of the quality of
the well installation and
operation of the testing and
sampling equipment.
Groundwater samples from
Westbay monitoring wells
are collected without
repeated purging. In
addition, Westbay is
currently developing
instruments to enable the
use of in situ sensors to monitor various chemical parameters.
Applications and Cost
The Westbay System is useful for MGP sites where multiple groundwater zones
exist and discrete monitoring of multiple screened zones is required.
One of the primary cost savings with the Westbay System is that several discrete
groundwater zones can be sampled by installing only one well. Fewer boreholes
mean lower drilling costs, a shorter project schedule, and less IDW (e.g., drill
cuttings and fluid). This can result in substantial savings in waste management,
site access approval, noise abatement, and project management. In addition, fluid
samples are collected from the Westbay monitoring wells without repeated
purging (the groundwater in each zone is not in contact with the atmosphere),
which can lead to significant cost reductions at sites where purge water must be
stored, transported, and treated before disposal. The cost of installing a Westbay
System is approximately $30,000 for a five-level system that can range from 50 to
200 feet in depth. The price does not include the cost of installing the monitoring
well and does not include sample collection or analysis.
Benefits
• Reduces the amount of drilling
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Chapter 4
Tools and Techniques For Expediting Site Characterization
• Provides reliable data
• Field tested and proven
Limitations
• Mechanically complex
• Requires well construction to specific Westbay specifications
• Not portable between wells
4-2.1.6.2 Waterloo System
Tool Description
The Waterloo System is used to obtain groundwater samples, hydraulic head
measurements, and permeability measurements from multiple isolated zones in a
single monitoring well. The Waterloo System uses modular components held
firmly together to form a sealed casing string composed of casing, packers, ports, a
base plug, and a surface manifold. Monitoring ports are isolated by packers at each
desired monitoring zone and are individually connected to the surface manifold
with narrow-diameter tubing. Formation water enters the port, passes into the
stem, and rises to its static level in the monitoring tube attached to the stem. A
sampling pump or pressure transducer may be dedicated to each monitoring zone
by attachmenfto the port stem, or the monitoring tubes may be left open to allow
sampling and hydraulic head measurements with portable equipment. A section
of the sampler is shown in the following figure.
Operational Considerations
A typical Waterloo System can be
installed in a few hours by one trained
technician and an assistant. Purge
volumes are small, and dedicated
pumps for all zones can be purged
simultaneously. Because the
groundwater in each zone is not in
contact with the atmosphere, formation
water may be sampled without repeated
purging. The Waterloo System may be
used in hollow-stem augers, temporary
casing, or cased and screened wells.
Applications and Cost
The Waterloo System is useful for MGP
sites with multiple groundwater zones
when discrete monitoring of the zones is
required. Project costs may be reduced
by limiting the number of wells
~>—- Bentanrte- Seal
1n-FiJI Packer
Permanent or Removeable Packers
in Casing or Well Screen
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Tools and Techniques For Expediting Site Characterization
installed and maximizing the number of groundwater zones sampled. The purge
volumes necessary for groundwater sampling using the Waterloo System are
likely to be smaller than those from conventional nested monitoring wells.
The cost of installing the Waterloo System is approximately $25,000 for a five-level
system that can range from 50 to 200 feet in depth. This price does not include the
costs of monitoring well installation or sample collection or analysis.
Benefits
• Reduces the number of wells needed for multiple-zone monitoring
• Reduces purge volumes and may reduce time required for purging/sampling
relative to conventional monitoring well requirements
• Provides reliable data
• Removable or permanent systems available
Limitations
• Mechanically complex
• Specially ordered materials necessary
• Removable packer system sometimes difficult to cost-effectively reuse
• Requires trained technician for installation
Contact
Solinst Canada Ltd., (800) 661-2023, www.solinst.com
4.2.1.6.3 Diffusion Multi-Layer Sampler (DMLS™)
Tool Description
DMLS ™ is portable, multi-layer device that can collect groundwater samples at
multiple intervals in the same monitoring well. The DMLS ™ uses dialysis cells
separated by seals that fit the inner diameter of the well. This arrangement allows
natural diffusion of groundwater into the unit at different elevations. Once the
DMLS ™ is lowered into either an open rock borehole or a groundwater
monitoring well with a long screen, the dialysis cells are exposed to water in the
borehole and natural diffusion gradients permit external formation water to reach
equilibrium with the water in the dialysis cells. The water flowing from the
formation into the stratified dialysis cells is separated by seals; therefore, each
dialysis cell contains a groundwater sample from a different layer.
The basic unit of the DMLS ™ is a 5-foot-long polyvinyl chloride (PVC) rod with a
variable number of dialysis cells and nylon membranes separated from each other
by seals. A string of up to five rods can be formed. Vertical layers of groundwater
as narrow as 3 inches can be segregated and sampled. The rods fit into 2-inch-
diameter and larger wells.
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The following figure shows the typical design detail for a DMLS ™ multi-level
groundwater sampler.
Operational Considerations
Once the DMLS™ is lowered into a well, it should remain undisturbed for 7 to 10
days to allow stratification of the water flowing from the formation. Once
stratification of the formation water is complete and
the water in the sampling cells is representative of
ambient conditions, the rods are pulled to the surface
and the sampling cells are removed and sent to a
laboratory for analysis. The sampling cells in the rods
can then be replaced, and the process can be
repeated. The DMLS™ may be left in the water for
periods of time that conform to individual sampling
•schedules. For example.DMLS™ sampling cells may
be collected and replaced every three months.
Because the DMLS™ relies on natural groundwater
diffusion principles, no purging is required. The
DMLS™ does not permit head measurements.
Applications and Cost
The DMLS™ is useful for MGP sites where
monitoring wells have long screens and a vertical
characterization of the screened aquifer is desired.
The DMLS™ reduces costs because several vertical groundwater zones can be
sampled by installing only one well. Having fewer boreholes reduces drilling
costs, shortens project schedules, and produces less secondary waste (e.g., drill
cuttings and fluid). The result is substantial cost savings in waste management,
site access approval, noise abatement, and project management. Groundwater
samples are collected from DMLS™ monitoring wells without repeated purging
(the groundwater in each zone is in direct contact with the formation water),
which can significantly reduce costs at sites where purge water must be stored,
transported, and treated before disposal.
The cost of the DMLS™ is approximately $3,000 for a 10-foot-long unit. The price
does not include labor costs for installing the DMLS™ rods, nor does it include
costs for sample collection or analysis.
Benefits
• Allows vertical characterization of groundwater in a single borehole or well
• Requires minimal training for installation
« Requires no purging
Limitations
• Not widely used
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Does not permit head measurements
May not be appropriate for zones with strong vertical gradients
4.2.1.7 Discrete Point Samplers
Tool Description
Floating product layers (e.g., LNAPL) or sinking product layers (e.g., DNAPL)
may cause stratification of contaminant concentrations in groundwater. Discrete
point samplers are used to represent groundwater at distinct elevations or points
of inflow in either open boreholes or screened wells. Discrete point samplers are
designed to minimize disturbance and/or mixing that would be caused by
pumping and purging water from different zones.
Several tools are available that have been designed to collect groundwater samples
at discrete points in either open boreholes or in screened wells. Solinst Canada,
Ltd., manufactures a number of samplers designed for use in wells screened over
multiple water-bearing zones. Two examples are the Model 429 Point Source
Bailer and the Model 425 Discrete Interval Sampler. The Model 429 Point Source is
a stainless steel bailer with dual ball valves that prevent the mixing of water from
multiple depths during retrieval of a sample from a specific depth. The Solinst
Model 425 Discrete Interval sampler (shown in the figure below) is a stainless steel
sampler connected by tubing that is pressurized before the device is lowered into a
well; pressurization prevents water from
entering the sampler until the sampling zone
is reached. When the desired sampling depth
is reached, pressure is released, and
hydrostatic pressure fills the sampler and
tubing with water directly from the
sampling zone. When the sampler is filled, it
is repressurized and raised to the surface; the
sample is decanted using the sample release
device provided, which avoids degassing of
the sample (Solinst, 1998).
Solinst also manufactures a Triple Tube
Sampler that uses a narrow-diameter pump
and packer assembly to seal off a discrete
interval in groundwater. A nitrogen-inflated packer is placed just above the
desired sampling point within the sampling tube. The packer seals against the
walls of the sampling tube and isolates the formation water standing in the tube. A
second nitrogen line applies pressure down the sampling tube. The water is
pushed to the surface through the coaxial tubing. The cycle is repeated until
purging and sampling are complete.
The Solinst Triple Tube Sampler is similar to the Waterloo Profiler multi-level
groundwater sampler discussed in Section 4.2.1.5 except that the Solinst sampler is
designed to sample from wells whereas the Waterloo Profiler is a direct-push
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sampler designed to collect grab groundwater samples without boreholes or wells
(Solinst, 1998).
: . I
Operational Considerations
The Solinst Model 429 Point Source Bailer and the Solinst Model 425 Discrete
Interval Sampler do not require or allow purging prior to sampling. It is assumed
that a sample collected at a discrete depth is representative of the formation water
flowing through the well at that depth. The Solinst Triple Tube Sampler does
permit purging of the discrete interval being sampled.
Applications and Cost
Discrete point samplers are useful for field scenarios where heterogeneities exist in
the vertical distribution of contaminant concentrations in groundwater in an open
borehole or screened well.
The purchase costs for Solinst Model 429 Point Source Bailer, Solinst Model 425
Discrete Interval Sampler, and the Solinst Triple Tube Sampler are approximately
$150, $675, and $2,000, respectively.
Benefits
• Permits groundwater sampling from a discrete vertical point in a well or
borehole
• Minimizes mixing of water from different levels during sample collection
• Fits in small-diameter wells/boreholes
• Is portable (the Triple Tube Sampler may be dedicated)
! '" !
• Solinst Triple Tube Sampler is usable for purging in addition to sampling
Limitations
• May require limited training to operate equipment (especially the Triple Tube
Sampler)
• May be difficult to obtain a complete seal with the Solinst Triple Tube Sampler
Contact
Solinst Canada Ltd., (800) 661-2023, www.solinst.com
4.2.2 Analytical Field Screening
Field screening tools allow practitioners to detect the presence and determine the
estimated concentrations of chemical constituents in the field. As noted above,
combining these tools with direct-push grab sampling techniques allows rapid and
cost-effective preliminary screening of former MGP sites by pinpointing areas of
contamination that require further, focused field investigations. Once these areas
are identified, field screening tools can be used to gather further data so that
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remediation alternatives can be evaluated. In some cases, the tools can also be used
to gather confirmatory data during remediation.
Tools included in this category are:
• Laser Induced Fluorescence (LIF) (such as ROST™)
• X-ray fluorescence (XRF) (such as the Spectrace 9000, SEFA-P, or X-MET 880)
• Colorimetric testing (such as Hach Kits, Draeger Tubes, Sensidyne, Handby
Kits, PetroSense™, and PetroFLAG™)
• Immunoassay testing (such as Strategic Diagnostics)
• Portable laboratories
4.2.2.1 Rapid Optical Screening Tool (ROST™)
Tool Description
The ROST™ is a sampling and screening technology used to field screen for
petroleum hydrocarbons and other contaminants. Like its military sister, the
SCAPS, ROST™ is designed to offer a suite of CPT tools on a single platform.
Using fiber-optic technology with LIF, ROST™ provides rapid, real-time, in situ
delineation of subsurface petroleum hydrocarbon contamination down to depths
of 150 feet.
The ROST™ consists of a sensor-tipped, hydraulically advanced, penetrometer
probe with a self-contained data collection and analysis system housed within a
CPT truck. Additional probes incorporate video imaging technology and soil
moisture measurements while the latest CPT sampling devices allow for the
collection of soil, water, or gas samples with analytical confirmation or other
measurements. A diagram of ROST™/SCAPS is shown in the figure on the
following page.
Operational Considerations
Operational considerations with ROST™ sampling technology are similar to those
of cone penetrometers. Depths are limited to 100 to 150 feet bgs in normally
consolidated soils, shallower in coarser materials. The ROST™ sampling
technology does not produce soil cuttings and can provide real-time, in situ field
screening for petroleum hydrocarbons. The ROST™ can also detect small
deviations in concentrations, thereby making it useful in mapping areas with
significant subsurface structures/materials. Microwells can also be installed using
this tool.
Applications and Cost
The ROST™ sampling technology is useful for field surveys and initial
characterization of sites, and for post-remediation confirmation for petroleum
hydrocarbons. The system is limited to the depths of the CPT and by the sensors
currently available.
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ROST™ costs approximately $4,000 to $4,500 per day with production up to 300
feet (around 10 pushes) per day.
Benefits
• Provides rapid, real-time geology and hydrocarbon data
• Can be used to converge on an area of interest
• Works for both fuel (aromatic) hydrocarbons and PAHs
• Generates little waste during testing/sampling
• Verified by USEPA and certified by California EPA
Limitations
• Limited availability (only two commercial licenses currently held)
• Limited to unconsolidated geology (same as CPT)
• Only relative concentration data provided
Case Study
North Cavalcade Superfund Site, Houston Texas
The North Cavalcade Street Superfund Site is a former wood treating facility,
located in northeastern Houston, Texas. The site encompasses approximately 21
acres, and was used for treating wood from 1946 to 1964. Initially, creosote was
employed as the primary wood preservative, but later operations also included
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pentachlorophenol. Operations included wood storage and pole peeling, and a
treatment plant with pressure vessels, storage tanks, and drip racks.
The site is relatively flat with elevations ranging from 43.2 feet to 53.8 feet above
mean sea level. The water table occurs at depths ranging from approximately 2 to
5 feet bgs. Surficial soils are part of the Beaumont Formation, which is composed
of clays, silts, and silty sands. The depositional environment was fluvial and
deltaic, and the deposits can be characterized as stream channel, point bar, mud
flat, and coastal marsh. The majority of the soils are composed'bf continuous and
noncontinuous clay to silly clay layers with two principal sand to silty-sand layers
located at average depths of 15 feet and 30 feet bgs. The various clay layers are
known to be fractured to various degrees. The site is intersected by at least three
and possibly four relatively minor surface faults with displacements of 2 to 5 feet.
At least one of these faults is known to be active.
The site was divided into separate soil and groundwater operable units during the
feasibility study. The soil operable unit consists of approximately 10,000 cubic
yards of contaminated soil that was excavated and stockpiled into a
bioremediation cell. The groundwater operable unit was addressed through a
pump-and-treat system consisting of 19 wells, pumps, a treatment plant, and three
groundwater infiltration galleries. The pump--and-treat system operated at an
average flow rate of 12 gallons per minute for 24 months. It removed
approximately 7,000 gallons of DNAPL out of approximately 11,500,000 total
gallons of extracted water. The pump-and-treat system was subsequently
discontinued due to a drastic decline in the amount of DNAPL recovered.
Previous information sources of subsurface data consisted mainly of a limited
number of boring logs and soil samples. In order to gather more information on
the horizontal and vertical extent of DNAPL that exists in the subsurface and to
refine the site conceptual model, the CPT/ROST™ technology was selected as the
most cost effective option for data collection. A total of 101 pushes were completed
at an average depth of approximately 45 feet for data collection. The data from the
cone penetrometer portion of the tool, which is displayed similar to well logs,
were used in the construction of isopach and structure maps and fence diagrams
to aid in the characterization of the subsurface. Based on an extensive correlation
of the pushes, it was determined that the tool's lithologic determinations were
internally consistent and correlated well with the existing data. Also, due to the
greatly increased number of data points, two and possibly three additional faults
were located.
The ROST™ data, like that from the CPT portion of the tool, was provided in a
format similar to a well log with total fluorescence graphed versus depth.
Windows of the "•waveform," which consisted of a graphical presentation of the
breakdown of the total fluorescence into four wavelengths, were also presented on
this log for various peak fluorescence values. This enabled a quick identification of
the type of hydrocarbon contamination present at a given depth. Additionally,
another log was provided which displayed the total fluorescence signature and a
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Toois and Techniques For Expediting Site Characterization
continuous breakdown of this signal into the four component wavelengths, which
allowed more detailed analyses of the different types of hydrocarbons.
The data from the ROST™ portion of the tool was used to gain an understanding of
the vertical and horizontal extent of creosote contamination, and the relative
concentration of the creosote contamination in three dimensions. Due to the tool's
ability to detect a wide range of hydrocarbon contamination, other sources of
hydrocarbon, such as diesel, gasoline, and oil, were also discovered. Interestingly,
four of the pushes, which are located adjacent to a known pipeline easement
exhibit a relatively strong oil-like signature at shallow depths. It is postulated that
this represents leaks in the pipeline. Because the focus of the investigation was
creosote, these signals were filtered out from the total fluorescence signal by
running the data through a FORTRAN program written specifically for that
purpose. Refinement of this filtering methodology, although effective, is currently
somewhat primitive and is undergoing further development.
When creosote was encountered, it was usually found at several depths within a
given push. The tops of the creosote occurrences were tabulated by depth and by
whether they occurred in a sand or a clay. It was determined that almost all of the
creosote hits occurred within the two sands zones, with the lower sand zone
registering the majority of the hits. The deepest creosote contamination that was
observed occurred at a depth of approximately 50 feet bgs. Based on 'these data,
the remediation strategy of the site has re-focused on the lower sand zone.
CPT/ROST™ has proven cost=effective for the determination of lithology and the
delineation of creosote contamination at the North Cavalcade Superfund site. Also,
based on its performance at the site, its effectiveness appears to extend to the
identification of other less dense hydrocarbon signatures. The CPT/ROST™ offers
advantages in both price and the rapidity with which the data can be acquired.
This technology is being evaluated for use at two additional creosote sites.
Contact
Joe Kordzi, USEPA Region VI, 214-665-7186
4.2.2.2 X-Ray Fluorescence (XRF)
Tool Description
Energy dispersive XRF is used to analyze trace metals (e.g., mercury, chromium,
lead, cadmium, copper, nickel, and arsenic) in soils, sludges, and groundwater.
The technique uses x-rays (high-energy electromagnetic radiation) to penetrate the
soil matrix and excite metals. Radiation emitted from fluorescence of the metals is
measured to quantify the concentrations of metals present in the soil.
XRF analyzers yield semiquantitative results with detection from a few to a few
hundred parts per million (ppm) depending on the soil matrix and the metals
being analyzed. XRF is generally considered a screening tool because of its
relatively high reporting limits. The XRF analyzer is easily transported to the field
and very fast (reportedly 5 to 40 samples per hour can be analyzed depending on
sample preparation and measurement times).
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Operational Considerations
Several manufacturers supply XRF analyzers including TN Spectrace (the
Spectrace 9000) and Metorex Inc. (the HAZ-MET 920, HAZ-MET 940, and the X-
MET series). XRF analyzers contain a radioactive source that may require special
handling. Although XRF methods do not require soil samples to be digested (as do
conventional analytical methods), some sample preparation (e.g., drying and
homogenization) may be required. XRF analyzers are susceptible to interference
from water, petroleum, and soil heterogeneity. Nontechnical personnel may
operate XRF analyzers with minimal training.
Applications and Cost
XRF methods are mostly used as screening tools for trace metals. Because of their
relatively high detection limits, these methods are best suited to site
characterizations requiring metal screening at relatively high levels.
The cost to rent an XRF analyzer is approximately $2,000/week. A comparative
conventional analytical method (inductively coupled plasma) is 30 to 40 percent
more expensive and requires that samples be digested.
Benefits
• No IDWs generated
• Easily transportable to the field
• Does not require digestion of soil samples
Limitations
• Sample preparation required (e.g., drying and homogenization)
• Poor detection limits on some metals, especially as a result of matrix
interference
• Limited penetration depth
• Not well suited to measure liquid samples
• Radioactive source in the analyzer
Contacts
Jim Moore, TN Spectrace, (512) 388-9100, x208
James R. Pasmore, Metorex Inc., (541) 385-6748 or (800) 229-9209
4.2.2.3 Colorimetric Field Test Kits
Tool Description
Colorimetric field test kits are used to detect the presence or determine the
concentrations of contaminants in soil and water. Because detection limits are
generally in the low ppm range, field test kits are primarily used as a screening
tool for site characterization. Colorimetric field test kits may be used to screen for a
broad range of inorganic parameters, total hydrocarbons, selected organic
compounds, and selected explosive compounds.
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Colorimetry is generally performed by mixing reagents in specified amounts with
the water or soil sample to be tested and observing the color change in the
solution. The intensity of the color change is an indicator of the concentration of
the chemical of interest. The color change is either observed visually (compared
with color charts) or electronically with a handheld colorimeter.
It is important to understand the limitations of the specific test kit being used,
including the chemicals it can detect. Some kits are susceptible to interference from
both naturally occurring organic matter and other co-contaminants.
Specific vendor technologies discussed below include Handby, PetroFLAG™,
PetroSense™, and Quick Testr field test kits. Handby field test kits are generally
used to screen for petroleum-derived substances in soil and water. Results are
quantified by comparison to substance-specific calibration photographs. Handby
kits are also available to quantify PAHs. The PetroFLAG™ test kit for soil is
primarily used to detect petroleum hydrocarbons with detection limits ranging
from 20 to 2,000 ppm. The PetroFLAG™ test kit can use either a conservative
calibration to estimate total hydrocarbons present or it can be calibrated to specific
hydrocarbons. The Dexsil Corporation, which markets the PetroFLAG™ test kit,
indicates that PAHs can be measured using the technology. The PetroSense™
PHA-100 Petroleum Hydrocarbon Analyzer (PetroSense™), marketed by FCI
Environmental Inc., combines fiber optic chemical sensor technology and digital
electronics to measure the vapor concentration ofTPHs in soil and benzene,
toluene, ethylbenzene, and xylenes (BTEX) in water. Envirol Inc., markets Quick
Testr field test kits, which can estimate total cPAHs in soil. Quantitative results are
obtained by establishing a site-specific correlation between test kit and laboratory
results.
Operational Considerations
The Handby Kit is susceptible to positive interference if extremely large quantities
of organic matter (e.g., peat) are present. The PetroFLAG™ is sensitive to a wide
range of hydrocarbons including natural waxes and oils. For both the Handby Kit
and PetroFLAG™, the user must test background samples and calibrate the
equipment to detect only foreign (i.e., not naturally occurring) substances.
!
The Handby Kit analyzes a sample in less than 10 minutes; detection limits
typically range from 1 to 1,000 ppm for soil and 0.1 to 20 ppm for water.
Approximately 25 samples per hour can analyzed using the PetroFLAG™ field test
kit. The PetroSense™ analyzer is very sensitive to turbidity and temperature in
water samples. Preconditioning and calibration for the PetroSense™ take
approximately 30 minutes; sample analysis takes less than 10 minutes. The
PetroSense™ probe may be lowered directly into a borehole for analyzing in situ
groundwater. The Quick Testr field test kit for cPAHs in soil reportedly takes less
than 20 minutes per sample to analyze. The Quick Testr must be used in
temperatures ranging from 40 to 110 °F.
Applications and Cost
Test kits are most useful as screening tools. Colorimetric test kits are available for
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different media and contaminants. Prices vary with the type of kit. Most test kits
include some of the following equipment: hand-held analyzer, glassware,
reagents, and scales. The more expensive units use electronic colorimeters, and the
less expensive units usually use visual colorimetric matches. Handby kits for soil
or groundwater cost about $1,300 including enough reagent for 30 samples, and
$550 for an additional 30 samples. The PetroFLAG™ kit for soil costs about $800
with enough reagent for 10 samples, and $250 for an additional 10 samples. The
Petrosense™ rents for about $150/weekplus minimal costs for calibration
standards. The Quick Testr analyzer rents for about $275/week plus $40 per
sample for consumables.
Benefits
• Rapid on-site screening tool
• Kits available for petroleum-derived substances and polynuclear aromatic
hydrocarbon (PNAs)
• Useful for remote sampling
" Generally requires minimal training
Limitations
« Relatively high detection limits
• Possible interference by naturally occurring chemicals and other contaminants
• Possible difficulty reading colorimetric matches under low light conditions
Contacts
Dexsil Corporation (PetroFLAG™), (203) 288-3509, www.dexsil.com
Envirol, Inc. (Quick Testr), (801) 753-7946 or (435) 753-7946, www.environl.com
FCI Environmental Inc. (PetroSense™), (702) 361-7921
Handby Environmental Laboratory Procedures, Inc., (Handby Kit), (512) 847-1212
4.2.2.4 Immunoassay Screening
Tool Description
Immunoassay testing can be used in the field to detect target chemicals in soil and
other samples. Most immunoassay-based test kits for analyzing environmental
contaminants are of the competitive enzyme-linked immunosorbent assay (ELISA)
type. In competitive ELISAs, the sample to be tested is combined with a labeled
enzyme and an antibody to which both the contaminant in the sample and the
enzyme will bind. The contaminant and the enzyme compete for the limited
number of antibody binding sites that are available. Each will bind to a number of
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sites that is proportional to its concentration in the mixture, so the relative
concentration of the contaminant can be determined.
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Tools and Techniques For Expediting Site Characterization
• Does not speciate individual PAHs
• Does not work effectively on MGP sites where crude oil was used as fuel
• Does not produce quantified concentrations of target substance being analyzed
• Requires a trial period or test runs to confirm satisfactory performance
Contact
Dwight Denham, Strategic Diagnostics, Inc. ,(714) 644-8650.,,- ,
Case Study
Georgetown Former MGP Site
In 1930, the Georgetown Coal Gas plant was demolished after about 20 years of
operation. The objectives of using immunoassay kits at the Georgetown Former
MGP Site were to evaluate the entire site quickly and to find areas with actionable
levels of PAHs, determine the extent and depth of each contaminated area, and
compare in-laboratory methods with immunoassay results in terms of accuracy,
cost, and time. Of the 36 samples analyzed at the site, the PAH immunoassay test
kits were consistent with in-laboratory results with the exception of five false
positives from the immunoassay test method. By not performing laboratory
analysis of the samples determined to be negative via immunoassay (as defined by
a concentration less than 1 ppm), a savings of approximately $4,000 would have
been realized. Used as a screening tool, the immunoassay results can be very
useful in determining which samples to send to a lab (immunoassay costs were
approximately one tenth of laboratory analysis).
4.2.2.5 Mobile Laboratories
Tool Description
Under the right conditions for field programs in which rapid site assessment is
necessary, mobile laboratories can provide rapid on-site, soil, air, and water
sample analyses.
Field characterization programs are often conducted in phases of field sample
collection and analysis. The results from the first phase are used to plan the
sampling strategy of the second phase. The results from the second phase are used
to plan sampling for a third phase, and so on until delineation of contaminants is
complete. The time spent between phases waiting for analytical results from
standard offsite laboratories translates into additional costs for repeated
mobilization/demobilization of drilling equipment and field personnel. Mobile
laboratories can provide same-day results for field sampling, allowing field
personnel to make quick decisions about the locations of subsequent sampling. It
is not necessary to demobilize then remobilize the sampling effort.
Operational Considerations
The analytical capabilities of mobile laboratories vary considerably among
companies. However, several laboratories are equipped to analyze PAHs in
addition to petroleum hydrocarbons and other common contaminants. Some
mobile laboratories are also equipped to analyze natural attenuation parameters in
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the field. Many natural attenuation parameters (e.g., dissolved oxygen, oxidation-
reduction potential, ferrous iron, hydrogen, methane, ethane, and ethene) require
rapid analysis for accurate reporting, so mobile laboratories can be very effective
for analyzing these parameters.
Several mobile laboratories can identify and quantify PAHs by SW846 Methods
8100,8270, and 8310. Prior to selecting a mobile laboratory, it is important to
determine the quality of data required (e.g., are results from immunoassay methods
acceptable, or are gas chromatography/mass spectrometry procedures warranted).
Similar to offsite laboratories, mobile laboratories require trained chemists to run
analyses and perform QA/QC functions.
Applications and Cost
The decision to use a mobile rather than an offsite laboratory depends on a
number of factors, including quality of data required, number of samples to be
analyzed, types of analyses required, possibility of access to a fixed laboratory, and
cost of onsite versus offsite analysis.
If the mobile laboratory does not require specialized instrumentation, the cost of
sample analysis may be 10 to 15 percent less than the cost of sending samples
offsite and requesting rapid turnaround (Onsite Laboratories, 1998). It is important
to note that the cost of laboratory analyses at both onsite and offsite situations
varies markedly among laboratories and that unit costs depend on the number of
samples to be analyzed. Approximate laboratory rental costs are $2,500 to $3,000
plus $13 to $30 per sample for expenditures.
Benefits
• Extremely rapid turnaround analytical results
• May reduce mobilization/demobilization charges for drilling and field
personnel
• Can rapidly perform time-critical analyses, such as for natural attenuation
parameters
Limitations
• May be more efficient to send samples for rapid turnaround at an offsite
laboratory
• More expensive than standard turnaround analysis
( 'iii'
• Not all mobile laboratories use USEPA analytical methods
4.2.3 Geophysical Surveys
Geophysical surveys encompass a broad group of tools historically used by the
geophysical, mining, and petroleum industries for mapping geological formations.
All of these tools operate from the surface to sense buried obstructions and objects,
changes in geologic formations, and/or the location of groundwater, thus
minimizing uncertainty about what might be unearthed during excavations and
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giving additional information to conceptual and numerical modeling of
groundwater flow. These tools are generally grouped into one of two categories:
surface geophysical and borehole geophysical.
Surface geophysical tools are nonintrusive and include:
• Electromagnetics
• Seismic Refraction
• Ground-Penetrating Radar
• Magnetometry/Metal Detection
Borehole geophysical tools are designed to be put into a well or borehole. They
include:
• Electrical Logging (including single-point and multi-electrodes)
• Mechanical Logging
• Sonic Logging
• Radiometric Logging
• Thermal Logging
• Video Logging
In general, all geophysical tools work on a "preponderance of evidence" basis.
That is, an individual geophysical method does not typically provide definite
results. Rather, several methods are used in conjunction at a site to provide
information concurrently through their results.
4.2.3.1 Electromagnetics
Tool Description
Electromagnetic surveys (EMS) comprise two subclasses of surveys:
magnetometer surveys and terrain conductivity electromagnetic surveys. Both
types of surveys are nonintrusive geophysical surveying techniques that have
traditionally been used to detect geologic features (e.g., formations with magnetic
properties). More recently, EMS has been successfully applied with ground-
penetrating radar (GPR) surveys at former M.GP sites to locate buried obstructions
and objects such as old underground storage tanks, buried sumps and pits, and
current and abandoned utility lines.
Magnetometer surveys are conducted by using an instrument that measures the
varying intensity of magnetic fields produced by natural objects (e.g., rocks) and
man-made objects (e.g., utility lines). Interpreting the magnetic readings produced
by the magnetometer allows conclusions to be drawn about the location of the
buried objects.
Terrain conductivity electromagnetic surveys are conducted by remote seismic
inductive electric measurements made at the surface. The apparent conductivity of
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subsurface formations and objects is measured by a conductivity meter consisting
of a receiver coil and a separate transmitter coil that induces an electric source field
in the ground. Lateral variations in conductivity values generally indicate a
change in subsurface conditions. The figure below is an example of an output from
a terrain conductivity electromagnetic survey.
Operational Considerations
Soil factors that affect the accuracy of EMS include moisture content, iron content,
and dissolved salts and ions. EMS results can also be affected by electromagnetic
interference. Overall, EMS results are best interpreted in parallel with other
geophysical survey techniques, such as ground-penetrating radar surveys, that
provide correlating information.
Applications and Cost
EMS uses a nonintrusive source and detectors and is therefore ideal for screening
sites for buried objects. It is a fast, relatively inexpensive method to obtain
"ballpark" data. Under favorable conditions (low moisture, low iron content, low
electromagnetic interference), EMS's resolution and accuracy improve. EMS is well
understood and provides reliable results.
The cost of an EMS survey varies depending upon access to the site (directly
related to the time required to perform the field work) and detail desired (e.g., the
target depth to which a survey is to be conducted). Typically, an EMS survey on a
1-acre site will take 3 to 4 days to complete, costing around $3,500.
Benefits
« Provides reliable data
• Field tested and proven
Limitations
» Requires expertise to plan, collect, and interpret data
i '
• Data subject to interference from soil moisture ••^^^•^•••••^•••••i
or clay in the subsurface and nearby
electromagnetic sources (e.g., power lines)
• May be problematic in iron-rich, deeply
weathered soils
. : * '. •> v-i ";
Case Studies
Chico Former MGP Site
Available historical information for PG&E's Chico
former MGP site indicated multiple locations for
the historical buried feedstock tank. Terrain
conductivity electromagnetic surveys were
performed in conjunction with GPR to determine
whether the tank still existed and, if so, to better
estimate the tank's location (thereby determining if
soil contamination observed in the general area
TERRAIN CONDUCTIVITY
CONTOUR MAP
3 ... 300
(TO
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Chapter 4
Tools and Techniques For Expediting Site Characterization
might be from the tank or from a different former MGP structure). At the time of
the surveys, the site consisted of the former MGP sheet-metal generating building
and an adjacent substation. There was significant interference in the EMS survey
from the adjacent substation, but the GPR survey was able to place the location of
the former buried feedstock tank farther west than the location estimated from
historical Sanborn Fire Insurance maps.
Stockton Former MGP Site
Terrain conductivity electromagnetic surveys were also used at FG&E's Stockton
former MGP site to delineate debris-filled areas, covered pits and sumps, and
concealed foundations associated with the former MGP. The terrain conductivity
electromagnetic surveys correlated well with the estimated locations of former
MGP structures as determined by a GPR survey.
Contact
Robert Doss, Pacific Gas and Electric Company, (415) 973-7601
4.2.3.2 Seismic Refraction
Tool Description
Seismic refraction is a nonintrusive geophysical surveying technique that can be
used to determine depth to bedrock, thickness of surficial fracture zones in
crystalline rock, extent of potential aquifers, and depth of the water table.
Seismic refraction surveys are conducted by measuring the velocity of elastic
waves in the subsurface. Elastic waves are generated by a source (hammer blow or
small explosion) at the ground surface, and a set of receivers is placed in a line
radiating outward from the energy source to measure the time between the shock
and the arrival. The velocity of the elastic waves in the subsurface increases with
increasing bulk density and water content. The depth of various strata and objects
may be calculated if their wave velocities are sufficiently different. The survey
data are processed and interpreted, typically along with other geologic
information and geophysical surveys, to provide a picture of subsurface
conditions. The following figure exemplifies the output from a seismic refraction
survey.
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. • • , ;;,; '.• ' I ,.. ,• ; ;, •; Chapter 4
Tools and Techniques For Expediting Site Characterization
340 1960 1980
Three-dimensional/three-component (3-D/3-C) seismic imaging can be an
extremely powerful tool for characterizing the hydrogeological framework in
which contaminants are found at MGP sites. 3-D/3-C seismic imaging is a
nonintrusive geophysical surveying technique that can delineate subsurface
geophysical features including: bedrock channels, clay layers, faults, fractures, and
porosity. In addition, 3-D/3-C seismic imaging can identify trench/pit boundaries
and differences in soils and wastes (Hasbrouck et al, 1996).
3-C imaging entails analysis of one-component compression-wave and two-
component shear-wave data. Two-dimensional (2-D) seismic refraction surveys
use only one-component compression-wave data. The 3-D/3-C seismic imaging
uses shear-wave data to map much thinner features than can be detected with 2-D
surveys; 3-D/3-C imaging can determine anisotropy (i.e., preferred grain
orientation, periodic layering, and depositional or erosional lineation), which may
correlate to preferential contaminant transport pathways (Hasbrouck et al., 1996).
Operational Considerations
Interpretations of seismic refraction surveys are most reliable in cases where there
is a simple two- or three-layer subsurface in which the layers exhibit a strong
contrast in seismic velocity. For shallow investigations (i.e., up to approximately
10 feet deep), the energy source for the elastic waves is a hammer blow on a metal
plate set on the ground surface. For a deeper investigation or at sites with noise
interference (heavy machinery or highways), an explosive source is necessary.
High gravel content in the soil matrix may diminish the quality of the data.
3-D/3-C seismic imaging data can be processed so that cross sections are oriented
from any angle and specific zones of interest can be displayed and interpreted.
Specially developed 3-D/3-C software is necessary to process the data, and skilled
data interpretation is required (Hasbrouck et al., 1996).
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Chapter 4
Tools and Techniques For Expediting Site Characterization
Overall, seismic refraction results are best interpreted in parallel with other
geophysical survey techniques (such as magnetometer surveys and
electromagnetic terrain surveys) or well logs, which provide correlating
information.
Applications and Cost
Where deep groundwater, consolidated materials, or both make test drilling
relatively expensive, it may be advantageous to get as much information as
possible by seismic refraction. Seismic refraction is a nonintrusive survey method
that is well understood and provides reliable results.
3-D/3-C seismic imaging can be used for subsurface characterization. The
relatively high cost of 3-D/3-C seismic imaging may be justified in situations
where site entry is restricted because of high levels of subsurface contaminants
and a three-dimensional picture of the sites's subsurface is required without
intrusive sampling.
The cost of a seismic refraction survey varies depending upon access to the site
(directly related to the time required to perform the field work) and the level of
detail desired (e.g., the target depth to which the survey is to be conducted).
Typically, one week of seismic refraction surveys may yield 3 to 5 line miles of
interpreted data for approximately $10,000.
Benefits
• Provides reliable data
• Field tested and proven
• Minimizes the number of times an area must be accessed for subsurface
characterization and maximizes the amount of information gathered
• 3D/3C seismic refraction provides greater level of detail (e.g., thinner features)
than traditional 2-D seismic surveying results
Limitations
• Requires expertise to plan, collect and interpret data
• Data subject to interference from complex geological strata
• 3D-3C seismic refraction relatively expensive
• Needs to be correlated with other site-specific subsurface data such as drilling
logs
• Heavy traffic or numerous surface obstructions can be problematic
Contact
Dennis Olona, U.S. Department of Energy, Albuquerque, NM, (505) 845-4296
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4.2.3.3 Ground-Penetrating Radar (GPR)
Tool Description
GPR is a nonintrusive geophysical surveying technique that has traditionally been
used to detect geologic features (e.g., fractures and faults). More recently, GPR has
been successfully applied with EMSs at former MGP sites to locate buried
obstructions and objects such as old foundations, underground storage tanks,
buried sumps and pits, current and abandoned utility lines, and concrete rubble.
1 l!l11 •'' ..• ,. ; ' • " 'I" :" ..'• : ' '< " ''
GPR surveying emits high-frequency electromagnetic waves into the subsurface.
The electromagnetic energy that is reflected by buried obstructions is received by
an antenna at the surface and recorded as a function of time. The recorded patterns
are interpreted, typically along with other geologic information and geophysical
surveys, to provide a picture of subsurface conditions. The following figure is an
example of an output from a GPR. Results are best interpreted in parallel with
other geophysical survey techniques, such as magnetometer surveys and EMSs,
which provide correlating information.
Applications and Cost
GPR uses a nonintrusive source and detectors and is therefore ideal for screening
sites for buried objects. It is a fast, relatively inexpensive method to obtain
"ballpark" data. Under favorable conditions (low moisture, low iron content, low
electromagnetic interference), GPR's resolution and accuracy is best. GPR is well
understood and provides reliable results.
The cost of a GPR survey varies depending upon access to the site (directly related
to the time required to perform the field work) and the level of detail desired (e.g.,
the target depth to which the survey is to be conducted). Typically, one week of
GPR surveys yields 5 to 7 line miles of interpreted data for around $10,000.
izo
100
— 14O
- 12O
— IOO
SO
EASTING
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Chapter 4
Tools and Techniques For Expediting Site Characterization
Benefits
• Field tested and proven
Limitations
• Requires expertise to plan, collect, and interpret data
• Data subject to interference from soil moisture or clay in the subsurface
• May be problematic in iron-rich, deeply weathered soils
Case Study
Chico Former MGP Site
Historical information for PG&E's Chico former MGP site indicated multiple
locations for the buried former feedstock tank. Ground-penetrating radar was used
in conjunction with EMS to determine whether the tank still existed and to verify
its location (in order to determine whether soil contamination observed in an area
might be from the tank or from a different former MGP structure). Although there
was significant interference in the EMS survey from an adjacent substation, the
GPR survey placed the location of the former buried feedstock tank farther west
than the location estimated from historical Sanborh Fire Insurance maps.
Interpretation of the survey data identified the location of the tank excavation but
was not able to confirm whether or not the tank was still in place.
Contact
Robert Doss, Pacific Gas and Electric Company, (415) 973-7601
4.2.3.4 Magnetometry/Metal Detection
Tool Description
Magnetometry is a nonintrusive electromagnetic geophysical surveying technique
commonly used in the construction industry to detect and map buried drums,
metallic pipes, utilities, cables, and piping before excavation, demolition and/or
construction. This technology has also been applied to former MGP sites to
identify buried utilities before drilling and to survey and map historical MGP
structures such as buried piping, tanks, and other metal structures.
Magnetometer surveys use an instrument that measures the varying intensity of
magnetic fields produced by buried metallic objects. The magnetic readings
produced by the magnetometer can be interpreted so that conclusions can be
drawn about the location of the buried objects. The following figure is an example
output from a magnetometer survey.
Operational Considerations
Soil factors that affect the accuracy of magnetometry include moisture content,
iron content, and dissolved salts and ions. In addition, magnetometry surveys are
typically depth limited and cannot distinguish among types of metallic objects.
Nonferrous objects are invisible to magnetometry survey instruments.
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Chapter 4
Tools and Techniques For Expediting Site Characterization
Applications and Cost
Magnetometry uses a nonintrusive
source and detectors and is
therefore ideal for screening sites
for buried objects. It is a fast,
inexpensive method to obtain
"ballpark" data on the location of
buried metallic objects. Under
favorable conditions (low moisture,
low iron content, low
electromagnetic interference),
magnetometry resolution and
accuracy is best. Magnetometry is
Well understood, well accepted, and
provides reliable results.
The cost of a magnetometry survey _____
varies depending upon access to the site (directly related to the time required to
perform the field work), the size of the area to be surveyed, and the level of detail
desired (e.g., the target depth to which the survey is to be conducted). Typically, a
magnetometry survey on a 1-acre site with 10-foot grid spacing will take 3 to 4
days to complete. Equipment rental may cost approximately $500 per month,
exclusive of labor (for both testing and data interpretation) and other related
expenses.
': . .1 • :
Benefits
• Field tested and proven
• Widely accepted
Limitations
* Details obtainable only at relatively shallow depths
• Cannot distinguish among metallic objects
• May be problematic in iron-rich, deeply weathered soils or where there is a lot
of scattered metal debris
• Nonferrous objects will not be visible to the technology
4.2.3.5 Borehole Geophysical Methods
Borehole geophysical methods are used to physically characterize sediments, rocks,
and fluids in boreholes and wells. Data are acquired by moving a string of
instruments up or down a borehole and measuring the response. Depending on the
specific information required, one or more borehole geophysics techniques may be
used in a single well. The radius of the investigation depends on the particular
instrument used.
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Tools and Techniques For Expediting Site Characterization
The tools discussed below include several categories of borehole survey
techniques:
» Electrical
• Mechanical
• Sonic
• Radiometric
• Thermal
• Video
Borehole geophysical logging is a useful tool for site characterization. Because of
the mobilization effort required and because multiple logging techniques can be
used simultaneously, borehole geophysical surveys are most cost effective when
performed as part of a multiple-log suite.
Geophysical logs provide a continuous profile of response versus depth in a well or
boring. Typically, direct soil sampling is undertaken only at 5-foot intervals. A
substantial amount of information can be obtained from a few logging runs into a
well. In addition, data can be correlated between adjacent wells. Examples of some
of the well logs that may be produced with the techniques discussed herein is
shown below.
In general, borehole logging is relatively expensive (including actual logging and
post processing), and equipment must be transported to the site. In addition, the
radius of the investigation may be small and may not be representative of the bulk
formation.
BesistitilyS
Gamma &
Caliperlogs
SonicLcg
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Tools and Techniques For Expediting Site Characterization
4.2.3.5.1 Electrical Logging
Tool Description
Electrical logging includes electrical resistivity methods, induction logs, self-
potential logs, and fluid conductivity logs. Electrical resistivity relies on different
electrode configurations to give information on different zones around the
borehole. The characteristics (e.g., thickness, permeability, salinity) of a region
energized by particular current electrode ranfiguration can be estimated by
measuring variations in current among electrodes. Many variations of electrical
resistivity logging exist in which different electrode configurations are used
including: normal logs, lateral logs, guard logs, and micrologs. Using empirical
constants specific to the particular rocks in the area and the drilling fluid, electrical
resistivity is also used to estimate porosity, water and hydrocarbon saturation, and
permeability.
An induction log is a profile of resistivity obtained by utilizing electromagnetic
waves. This technique is used in dry holes or boreholes that contain nonconductive
drilling fluid. Lithologic boundaries show up on induction logs as gradual changes
in apparent resistivity.
On self-potential logs, measurements of potential differences between an electrode
on the sonde (probe) and a grounded electrode at the surface are made in
boreholes filled with conductive drilling fluid. The self-potential effect originates
from the movement of ions at different speeds between two fluids of differing
concentration, in this case groundwater and drilling fluid. Self-potential logging
can be used to identify the boundaries between geological beds based on the
differing rates of penetration of drilling mud into the lithology. In hydrocarbon-
bearing zones, self-potential logs show less deflection than normal.
Fluid conductivity logging uses an electrical conductivity probe to profile water
quality by depth. It is used to select sampling depths and also used in conjunction
with a flow-meter log (see Section 4.2.3.5.2, Mechanical Logging) to identify water-
producing zones.
Operational Considerations
The electrical logging techniques described here require an open borehole.
Borehole fluids must be electrically conducting if electrical resistivity and self-
potential logging are to be used. Induction logging, however, requires either a dry
borehole or nonconducting fluids in the borehole. Single-electrode logging yields a
poor response in saltwater aquifers and provides qualitative data elsewhere.
Multi-electrode logging permits quantitative data and estimates of formation
water salinity. Fluid conductivity logging yields less precise information in highly
saline waters.
Applications and Costs
The cost of electrical logging is approximately $ 1,200-$2,500 per day. Five to seven
wells can be logged per day. Fluid conductivity logging is approximately $500-
$600 per well when performed as part of a multiple-log suite and approximately
$1,500-$2,500 per well when done alone.
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Benefits
• Quantitative data may require corrections
Limitations
• The electrical logging techniques described require an uncased borehole
• Electrical resistivity and self-potential techniques require conductive borehole
fluids
• Induction logging requires a dry borehole or borehole with nonconductive
fluids
• Induction logging may be complex and provide poor results in situations of
high-resistance formations, thin beds, and shallow wells
• Poor response in saltwater aquifers
4.2.3.5.2 Mechanical Logging
Tool Description
Flow-meter and caliper logging are two different types of mechanical logging.
Flow-meter or spinner logging incorporates mechanical flow meters to measure
horizontal and vertical groundwater flow rates. These flow rates can be used to
identify permeable zones in a formation. When used in conjunction with'the
caliper log, the flow meter yields semiquantitative measurements of groundwater
into the borehole.
A mechanical flow meter measures the velocity of fluid in a borehole by means of
low-inertia impellers that are turned by the fluid flow. Turning of the impellers
causes a magnet mounted on the impeller shaft to rotate and generate electrical
signals. Mechanical flow meters are capable of measuring flow rates down to
about 2 feet per minute (ft/min). A newer electromagnetic flow meter uses
thermal principles to measure flow rates as low as 0.1 ft/min.
Mechanical flow-meter logging can be done under natural (non-pumping) or
forced-flow (pumping) conditions. Pumping flow-meter logs can be used to
estimate the relative transmissMty of different water-bearing zones; non-pumping
flow-meter logs can be used to identify the direction and magnitude of vertical
well-bore flow caused by vertical gradients.
Another common type of mechanical logging uses the caliper log, which measures
borehole diameter and roughness. The tool itself has a number of feelers (usually
four) attached. The feelers are electromechanical devices, held by springs against
the wall of the hole, that send information to the surface. The information from the
log is used mainly to estimate the volume of cement that might be required to seal
around a collapsed region, to verify well-construction details, and to provide
lithologic information. Information gained from the caliper log is used to estimate
velocity losses in the gap between the borehole wall and the flow-meter impeller,
thereby correcting velocity measured by the flow-meter log. The key use of the
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caliper log data is to correlate vertical velocity data to vertical flow data by
allowing the area of the borehole to be factored into the vertical profile.
Operational Considerations
Flow-meter logging requires a minimum flow of approximately 2 ft/min. Caliper
logging requires an open borehole, which may be difficult to achieve in deep,
unconsolidated deposits. Conductor casing may be necessary to contain
unconsolidated sediments near the top of the well.
Applications and Costs
The cost of flow-meter logging is roughly $500 to $600 per well when performed as
part of a multiple-log suite. The cost of flow-meter logging (with recommended
caliper logging) is $1,500 to $2,500 per well.
Benefits
• Caliper log is widely available, rapid, and inexpensive
• Flow meter logging is relatively simple and inexpensive
Limitations
• Flow-meter logging is relatively insensitive at low velocities
• Most applications of flow-meter logging require a pumping or flowing well
during the survey
• A caliper log is needed for interpretation of flow-meter logs
4.2.3.5.3 Sonic Logging
Tool Description
Sonic logging, also known as continuous velocity or acoustic logging, is used to
determine the relative porosity of different formations. Sonic logging may also be
used to determine the top of the water table, to locate perched water-bearing
zones, and to assess the seal between a casing and formation material.
' " ; • ' J •• ,:; '!
A probe containing one or more transmitters that convert electrical energy to
acoustic energy is lowered into the borehole on a cable. The acoustic energy travels
through the formation and back to one or more receivers also located on the tool.
The acoustic energy is converted back to an electrical signal, which is transmitted
back to the surface by the receivers and recorded.
Sonic logging determines the seismic velocities of the formations traversed. The
average velocity of the acoustic wave passing through the formation depends on
the matrix material and the presence of fluid in the pore space. The speed of the
wave is slowed by the presence of pore fluid; therefore, sonic logging provides a
measure of fluid-filled pore space. The velocity of the solid matrix can be
determined by laboratory analysis of core samples.
Operational Considerations
Sonic logging can be performed in a borehole cased with metal; however, the
results are most representative of formation properties if logging is performed in
an open borehole. The borehole must be fluid-filled for signal transmission to
•: . i • I',;1
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Tools and Techniques For Expediting Site Characterization
occur. Obtaining meaningful results in unconsolidated materials with low
groundwater velocities may be difficult.
Applications and Costs
Sonic logging maybe used for site characterization where information is needed
on the relative porosity of different formations and the location of water-bearing
zones. The cost of sonic logging is approximately $1,500 to $4,500 per well.
Benefits
• Widely available
• Suitable for uncased or cased boreholes although the results are more
representative of the formation if the borehole is uncased
• Useful for characterizing rock aquifers to identify high-porosity zones that may
transmit water
• Allows porosity determination without use of radioactive source
Limitations
• Interpretation of the data may require expertise
• The borehole must be fluid-filled
• Not applicable in shallow wells or in unsaturated conditions
4.2.3.5.4 Radiometric Logging
Tool Description
The radiometric logging techniques discussed here include neutron logging and
natural gamma (or gamma) logging. Neutron logging is used to estimate porosity
and bulk density, and, in the vadose zone, to locate saturated zones outside a
borehole or well casing. Natural gamma logs are used to evaluate downhole
lithology, stratigraphic correlation, and clay content of sedimentary rocks.
Both logging techniques are based on the process by which particles of mass or
energy are spontaneously emitted from an atom. These emissions consist of
protons, neutrons, electrons, and photons of electromagnetic energy that are called
gamma rays. Radiometric logs either make use of the natural radioactivity
produced by the unstable elements U238, Th232, and K40, or radioactivity induced by
the bombardment of stable nuclei with gamma rays or neutrons.
In neutron logging, nonradioactive elements are bombarded with neutrons and
stimulated to emit gamma rays. The sonde (probe) contains a neutron source, and
the neutrons collide with atomic nuclei in the wall rock and emit gamma rays,
which are measured by a gamma-ray detector also on the sonde. The amount of
gamma radiation from neutron logging correlates directly with the proportion of
water-filled pore space in a rock unit.
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Natural gamma radiation logging uses a detector mounted on a sonde to measure
the gamma rays produced by radioactive elements in a formation. Because
different types of formations contain different amounts of radioactive elements,
gamma logging is used primarily to determine lithology, stratigraphy, and the clay
or shale content of a rock.
Operational Considerations
Neutron and gamma logging techniques can be used in cased holes, which means
they offer a distinct advantage under some circumstances. Neutron logging
requires handling of a radioactive source.
•
Applications and Costs
Neutron logging costs approximately $2,500 to $5,000 per well (depending on well
depth and the number of other logs run at the same time). Gamma logging costs
are on the order of $1,200 to $2,500 per well; approximately five to seven 100-foot
wells can be logged per day.
,, " , . ' *
Benefits
• Radiometric logging is suitable for both uncased and cased boreholes
• Specialized training is not required for gamma logging
• Radiometric logging is useful in characterizing rock aquifers to identify high-
porosity zones that may transmit water.
Limitations
i t
» Gamma rays detected using neutron and natural gamma logging come from the
formation only within a few feet from the well
• Lithology must be determined by other logs before porosity estimates can be
made using the neutron logging technique
• Neutron logging requires special training, transportation, and permits to allow
handling of a radioactive source; its availability is also limited
• Neutron logging may only be allowed in cased holes in some states (e.g.,
Oregon)
.
4.2.3.5.5 Thermal Logging
Tool Description
Thermal logging is primarily used to locate water-bearing zones. It can also be
used to estimate seasonal recharge or a source of groundwater. A temperature
sensor, usually a thermistor mounted inside a protective cage, is lowered down a
water-filled borehole. The probe is lowered at a constant rate and transmits data
related to the temperature change with change of depth to surface. The natural
variation of temperature with depth is called the geothermal gradient. Water-
bearing zones intersected by the borehole may cause changes in the geothermal
gradient, which is shown on the temperature log. Seasonal recharge effects may
also be detected because the influx of recharge water changes the natural
temperature regime. It is also possible to assess the source of groundwater if the
regional sources have characteristic temperatures.
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Operational Considerations
Thermal logging may be performed in an open or cased borehole; however, the
borehole must be fluid-filled. Thermal logging should be performed several days
after drilling is complete to ensure that water in the boring is representative of
ambient conditions.
Applications and Costs
Thermal logging is often combined with other borehole geophysical methods. The
cost of thermal logging is approximately $500 to $600 per well (depending on the
total depth logged) as part of a multiple-log suite. The cost of temperature logging
when no other borehole geophysical methods are used is approximately $1,500 to
$2,000 per well.
Benefits
• Thermal logging is widely available, rapid, and inexpensive
• Data are easy to interpret unless internal borehole flow is present
Limitations
• Temperature measured is that of borehole fluid, which may not be
representative of surrounding formation
• This technique requires a fluid-filled borehole
• Interpretation of log is complicated if internal borehole flow is present
4.2.3.5.6 Video Logging
Tool Description
Video logging a borehole can provide visual inspection of the interior of a well,
detecting damaged sections of screen and confirming well construction details. In
uncased boreholes, video logs can detect fractures, solution cracks, and geological
contacts if turbidity in the well is low.
Operational Considerations
Video logging requires very low turbidity in the well for a successful survey. Both
monochrome and color videography are available; however, color is preferred
because interpretation of images is easier.
Applications and Cost
Video logging is primarily used to detect fractured bedrock and the integrity of •
screens and casing. Video logging may cost from $400 to $3,000 per well.
Benefits
• Video logging allows visual inspection of well interior
• Video logging is useful for troubleshooting potentially damaged casings
Limitations
• Video logging requires an open borehole and is therefore not useable with
unconsolidated formations
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The borehole walls must be clean and the groundwater relatively clear
4.2-4 Soil Gas Surveys
•• • i • • • i •
Soil gas measurements can successfully predict actual concentrations of MGP
residues in soil and water. MGP residues are present in the soil as a gas because of
their vapor pressure and solubility. Measuring the amount and composition of
these gases can indicate the extent of source areas' and grouridwater plumes. Soil
gas investigations, used in conjunction with physical soil and groundwater
sampling, can provide a more thorough and cost-effective site investigation than
borings and well samples alone. Soil gas surveys are grouped in two categories:
passive and active. Passive soil gas surveys measure the relative concentration of
contaminants through subsurface detectors sensitive to diffusion. Active soil gas
surveys relatively quickly withdraw soil vapors using a vacuum pump system to
analyze the concentration of contaminants in the vapor phase. The active gas soil
gas technique provides real-time concentration data; the passive soil gas technique
provides a time-integrated relative concentration that may detect less volatile
compounds. Each of these methods of soil gas sampling is discussed in more detail
below.
4.2.4.1 Passive Soil Gas Survey
Tool Description
Passive soil gas surveys use subsurface detectors sensitive to diffusion to measure
the relative concentration of contaminants. Passive methods involve integrated
sampling over time and collection of the sample on an absorbent material. Because
sampling is integrated over time, fluctuations in soil gas availability resulting from
changing ambient and subsurface conditions are minimized. Passive soil gas
sampling does not disrupt the natural equilibrium of vapors in the subsurface as is
the case with active sampling methods. iPassive gas sampling only provides
qualitative results because it does not measure the specific amount of
contamination per unit of contaminated material. Because passive soil gas
sampling occurs over a period of at least a few days, it can detect heavy organic
compounds with lower vapor pressures, such as PAHs.
Gore-Sorbers® and Emflux® are both patented technologies that use passive soil
gas principles. The Gore-Sorbers® Module uses a granular absorbent within an
inert Gore-Tex® membrane that only permits vapor transfer into the module. Each
thin, cord-like, module is placed in the shallow subsurface for a period of 2 to 4
weeks and then removed and shipped to a laboratory for analysis. Emflux®
samples consist of a sampler vial containing an adsorbent cartridge. The samplers
are placed at a depth of approximately 3 inches below grade for 72 hours, after
which they are removed and sent to a laboratory for thermal desorption and
analysis. Results of a passive gas survey is shown below.
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Operational Considerations
As opposed to active gas sampling, passive soil gas sampling can be used in areas
with relatively low soil permeability. Installation and retrieval of samples can be
accomplished with minimal training and equipment. Soil gas samples should be
taken at points deep enough to avoid background contamination from surface
spills or exhaust. Installations directly beneath concrete or paved surfaces should
be to a depth below the zone of lateral migration of soil gas to avoid misleading
results. Depths of at least 2 to 3 feet are typically sufficient to insure good
sampling. It may be difficult to obtain passive soil gas data for vertical
characterization; active soil gas sampling is often used to vertically characterize
contamination. Passive gas sampling may be applied directly in a saturated zone.
Application and Cost
Passive gas testing has been used for many different types of contaminants
(including MGP residues) and is becoming more popular because of its low cost
and flexibility in different types of soil. Using soil gas sampling data in
conjunction with other site-specific data can be a cost-effective method for
delineating MGP residues.
Passive soil gas testing is approximately $250 per sample location (including
analysis and reporting) and $50 to $100 per location for installation and retrieval.
Benefits
• Easy to use
• Can be used in areas of relatively low permeability
• Can be more sensitive than active soil gas, soil, or groundwater sampling
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Limitations
• May not correlate well with active soil sampling results
• Does not measure direct concentration
•i Data at depth for vertical characterization may be difficult to collect
p Gore Sorber® passive detector must remain in situ for 14 days, whereas
Emflux® passive detector must remain in situ for only 3 days
Case Study
McCIellan Air Force Base (AFB)
Past disposal practices at McCIellan AFB, located near Sacramento, California,
from 1936 to the late 1970s, contaminated the soil and groundwater of more than
3,000 acres. Contaminants include caustic cleaners, electroplating chemicals, heavy
metals, industrial solvents, low-level radipactiyq wastes, PCBs, and a variety of
fuel oils and lubricants.
As part of a test location for innovative technologies, McCIellan AFB tested the
Gore-Sorber® Module, primarily to monitor VOCs (perchloroethylene [PCE] ,
trichloroethylene [TCE], andcis-l,2-dichloroethylene [CIS-1, 2-DCE]). A very good
correlation was observed between the relative contamination levels measured by
the survey and actual levels determined using active soil gas sampling (Elsevier
Sciences, 1997).
Contacts
Paul Henning, Quadrel Services (Emflux® Module), (800) 878-5510
Gore Technologies (Gore-Sorber®), Mark Wrigley (410) 392-3406 and Andre Brown
(415) 648-0438
i: ' ,. •• -, ••.,.., . , . . ,
4.2.4.2 Active Soil Gas Survey
Tool Description
Active soil gas surveys use a vacuum pump to induce vapor transport in the
subsurface and to instantaneously collect samples of contaminants in the vapor
phase. Active soil gas surveys provide a snapshot of vapor concentration in the
subsurface, in contrast to passive soil gas surveys, which provide time-integrated
sampling data.
Because active soil gas sampling provides real-time data, a relatively coarse
sampling grid is initially used; this grid can be refined in areas of interest (e.g.,
areas with relatively high contaminant concentrations) for additional sample
collection. The following figure shows a schematic of one type of active soil gas
sampling device. (Adapted from "Handbook of Vadose Zone Characterization and
Monitoring" by L.G. Wilson, et al., 1995.)
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PLOW VALVE
Other active soil gas sampling
methods also use a vacuum
pump; however, a gas sampling
bag, an evacuated canister/vial,
or a solid adsorbent may be
used instead of a gas sampling
syringe. The active soil gas
sampling method that uses a
solid adsorbent is similar to
passive soil gas sampling
techniques except that active
soil gas sampling uses vacuum
pressure instead of diffusion to
pull the vapor sample through
the solid adsorbent.
Operational Considerations
The vacuum used in active soil
gas sampling disrupts the
equilibrium soil gas vapor in the
subsurface by forcibly drawing
the vapor and soil gas from the M^MM^^^^^^HMH^^^^^^^^^HHBMM
soil matrix surrounding the
sampling point. Active soil gas sampling typically must be done at least 10 to 20
feet bgs; passive soil gas sampling, by contrast, typically occurs at 3 feet bgs. It
may be difficult to collect an active soil gas sample in an area of relatively low soil
permeability. Active soil gas surveys may not be used in the saturated zone and
may result in false negative or low soil gas concentration measurements in areas of
elevated soil moisture.
Active soil gas sampling may be adversely affected by transient processes such as
barometric pressure changes, earth tides, and precipitation, as well as by
stationary features such as buried foundations. Active soil gas sampling data
should be interpreted to account for the fluctuations these transient processes may
create in the data.
Laboratory sample holding/extraction times are dependent on the specific active
soil gas sampling method used. The solid adsorbent active gas sampling method
requires relatively long sample holding/extraction times. The gas syringe active
gas sampling method (shown in the figure above) requires relatively short sample
holding/extraction times.
Applications and Cost
Active soil gas sampling is well suited to delineating areas of higher and lower
VOC concentrations. Passive soil gas sampling may be better suited to measuring
lower contaminant concentrations and less volatile compounds such as PAHs
because of the time-integrated nature of the sampling methodology. Active soil
gas sampling costs approximately $3,000 to 4,000 per day.
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Benefits
• Provides real-time data
^ Provides rapid results that allow the user to converge on areas of interest
• Provides a direct measure of vapor concentration
• Can be used to evaluate vertical changes in soil gas concentrations
Limitations
• Requires samples collected at least 10 to 20 feet bgs
• Cannot be effectively used in areas of relatively low permeability
• May not be effective in detecting semivolatiles (e.g., PAHs)
• May be affected by barometric and other transient processes
,j
• Subsurface equilibrium vapor conditions disrupted by vacuum
Contacts
tracer Research, (800) 989-9929
Transglobal Environmental Geosciences, (800) 300-6010
4.2.5 Contaminant Migration Evaluation
Three techniques for evaluating the movement and degradation of contaminants
in aquifers include a Push-Pull Natural Attenuation Test, a Partitioning Interwell
Tracer Test (PITT), and an In Situ Bio/Geochemical Monitor (ISM) test. Each of
these are discussed in more detail below.
4.2.5.1 Push-Pull Natural Attenuation Test
Tool Description
The push-pull natural attenuation test is an infrequently used single-well
injection/extraction test used to obtain quantitative information on in situ
microbial metabolic activity. A push-pull test is conducted in three steps:
1. Inject in an existing monitoring well a pulse of test solution consisting of water,
a conservative tracer, and microbial substrates (electron acceptors and donors).
2. Allow the test solution to interact with indigenous microorganisms and then
extract a slug of water/tracer/microbial substrates from the same well.
3. Measure the tracer, substrate, and product concentrations from the extracted
slug of the test solution/groundwater mixture, and use measurements to
calculate rates of microbial activities.
This method provides direct estimates of rates for microbial activity and mass
balances for reactants.
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The following figure shows an idealized breakthrough curve for a process
generating a single product from a single reactant. The curves show the typical
relationship between contaminant concentration and time, providing information
on the way advection, dispersion, diffusion, and biodegradation affect
contaminant movement within the aquifer.
U
D
Operational Considerations
Push-pull tests require specially trained field personnel although an individual test
typically only requires a few hours, so several tests can be completed by a single
operator in a day. The test solution used during the injection phase of a push-pull
test is composed of various electron acceptors and donors (e.g., sodium bromide)
that depend on the objectives of the sampling. The tracer selected should have a
decay rate similar to or greater than the groundwater flow rate.
Applications and Cost
Push-pull tests are ideal for situations in which quantifiable estimates of microbial
activity are desired for potential natural attenuation scenarios.
The cost of push-pull tests for a site contaminated with BTEX is approximately
$12,000 to $15,000 for two to three wells, including analytical costs. The costs are
very dependent on the specific analyses required.
Benefits
• Can document microbial metabolism, loss of degraded contaminants,
production of degradation products, and estimates of zero- and first-order
decay constants
• Provides in situ data (versus in an artificial laboratory environment)
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111 ' • ii -I ' '"' * -I. -
• Can be used in wells that are already installed
'• ' • ''•' : ':' • !, * • • t- i" ; -.,•..:;
• Can assay a wide variety of processes
• Is field tested
Limitations
• Is a fairly new test; not widely used
• Can be difficult to use when decay rate is slow relative to groundwater flow
- ' " ' ' .,.,..
4.2.5.2 Partitioning Interwell Tracer Test (PITT)
Tool Description
The PITT is an in situ technology that measures the volume and percent
saturation of NAPL contamination trapped in water-saturated and vadose zone
sediments. The PITT technology is primarily used to:
• Quantify and locate NAPL contamination
• Assess the performance of remediation activities
« Quantify water saturation in the vadose zone
The technique is essentially a large-scale application of chromatography. The
migration of a partitioning tracer between an injection well and an extraction well
*?, ret£!rded relative to a nonpartitioning tracer because it spends a portion of its
residence time in the immobile residual NAPL. The chromatographic separation of
the tracers indicates the presence of NAPL in the interwell zone and is used to
determine the volume of NAPL present. The figure below shows a typical
injection-extraction system.
The PITT technique can be used before
ahd after an in situ remedial activity,
such as surfactant flooding, to estimate
the fraction of NAPL removed and the
volume of NAPL remaining.
Operational Considerations
The PITT technique requires wells
situated so that the potential NAPL
source is within the radius of influence
of the wells used to inject/withdraw the
conservative and nonconservative
tracers. It is important for the tracers to
be nontoxic and to have npndetectable
background concentrations and for the
partitioning tracer to have an affinity for
the particular NAPL found at the site.
Vnn
San/uttHk
Uimt
(IMS BBSS)
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Tools and Techniques For; Expediting Site Characterization
Applications and Cost
The PITT technique is ideal for in situ characterization of NAPL and is limited by
the well network available to perform the injection/withdrawal tests and the
project budget.
The cost of PITT technology may range from $100,000 to $400,000 depending on
the scale of the test.
Benefits
• Provides quantitative estimates of NAPL volume
• Can be used to design remediation methods targeting a NAPL source
• Is relatively accurate compared with other in situ tests that utilize point values or
small aquifer volumes
Limitations
• Expensive
• Technology is patented
• Not economical for smaller sites
• Most application experience is with solvents
Case Study
Hill Air Force Base, Utah
The PITT technique was used at Hill AFB in 1996 to demonstrate surfactant
remediation of a DNAPL-contaminated site. Partitioning interwell tracer tests
were used to estimate the volume of DNAPL, in place and to assess the
performance of the surfactant remediation. Three constituents make up more than
95 percent of the DNAPL present at the site: TCE; 1,1,1-trichloroethane (1,1,1-
TCA); and PCE. Approximately 99 percent of the DNAPL source within the test
volume was recovered by the surfactant remediation leaving a residual DNAPL
saturation of only approximately 0.0004. The PITT technique successfully provided
quantitative estimates of DNAPL volume before and after an in situ remedial
activity at this site.
4.2.5.3 In Situ Bio/Geochemical Monitor (ISM)
Tool Description
Chemical and biochemical reactions affect the geochemical composition of
groundwater and the migration and persistence of inorganic and organic
contaminants. The ISM allows in situ measurement of biochemical reaction rates
and retardation factors for both soluble organic and inorganic compounds. The
ISM maintains the geochemical integrity of sediment and groundwater and may
be less expensive than collecting similar data, via conventional tracer tests.
Installed below the water table, the ISM isolates a small section of the aquifer with
minimal disturbance of the geological medium. Groundwater is removed from the
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test chamber, reactants and tracers are added, and it is reinjected into the test
chamber. Samples are then collected for laboratory analysis to monitor the
biological and geochemical reactions occurring within the test chamber (Solinst
1998).
I
Operational Considerations
The ISM requires saturated aquifers with a hydraulic conductivity greater than 10"4
centimeters per second (cm/sec). The monitor is installed through the center of a
hollow-sterri auger with a special "trap door'" cutting head'and"pushed into the soil
using either a hydraulic ram or vibrating hammer. The ISM consists of a stainless
steel test chamber, open at the bottom and bounded at the top by a set of coarse and
fine mesh screens. These screens are used to draw groundwater into the test
Chamber. A depth-adjustable central spike with a fine mesh screen extends into the
test chamber. In biodegradation studies, groundwater samples are collected via the
spike. To create a one-dimensional flow system in retardation studies, water is
injected through the spike and collected from the outer screens (Nielsen 1996'
Solinst, 1998).
The ISM has a relatively complex design and requires knowledgeable personnel to
design, implement, and interpret tests. A numerical model may be necessary to
estimate degradation rate constants from test data (Neilsen, 1996).
Applications and Cost
The ISM can be used in aquifers with a hydraulic conductivity greater than 10~4
cm/s where in situ biochemical reactiqn rates and, retardation factors must be
determined. The cost of ISM is approximately $3,000 for equipment purchase only,
not including installation, analyses, and trained personnel (Solinst, 1998).
Benefits
• Reduces the time and cost of obtaining site-specific biological and geochemical
data (as compared with injection-withdrawal and field tracer tests)
• Provides in situ measurement of biochemical reaction rates
'> , • " , n '!i '. ' i1 ' M| • •" , ,|n:ijl|." ! ':•" ' , i, '''ill, . •, • :"" ,.,'... ,;
• Provides estimated rates of denitrification during biodegradation
* Provides estimated retardation factors for organic and inorganic compounds
•' '•• ' ' ' ' ' '- ': ••',,• "f11 v • "!" i ,-• • ••: '••',- -.' .{•
Limitations
• Design, implementation, and interpretation of ISM tests are complex and
require knowledgeable personnel
• A numerical rgodel may be necessary to help estimate the degradation rate
-'" constant i ' t ," ' '
• Typically applicable only with permeability greater than 10 ^ cm/sec
• Small aquifer volume tested means results may be affected by small-scale
variations in aquifer properties
Contact
Solinst Canada Ltd., (800) 661-2023, www.solinst.cpm
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4.2.6 Other Tools
Listed below are other tools and techniques that offer a range of advantages for
expediting site characterization but do not fit in one of the categories previously
described. These tools include:
» Microscale solvent extraction
• PAH sample filtration
• Inverse specific capacity method
• Hand-augering/trenching/pot holing
• Noise and fugitive emission controls
• Information management
4.2.6.1 Microscale Solvent Extraction
Tool Description
Conventional laboratory analysis of PAHs in soil and water matrices may take 2
weeks from the time samples are received to the time the results are released.
Current EPA-approved Methods 8240,8270, and 8310 require a 24-hour extraction
period before analysis can be run. EPRI has developed a technique for analysis
that requires smaller sample volumes and shorter laboratory turnaround times
than conventional techniques. Because microscale solvent extraction (MSB)
methods require smaller sample volumes, MSB analytical methods are ideal for
alternative collection methods that yield smaller sample volumes (e.g., Geoprobe™
and Hydropunch™) (EPRI, undated).
MSB methods are microextraction techniques used by a lab to prepare samples for
analysis by gas chromatography. Microextraction is defined as a single-step
extraction process with a high liquid-sample-to-solvent ratio. Historically,
microextraction techniques have been limited by extraction inefficiencies, in
precision, and elevated detection limits. However, recent MSB methods involve
multiple microextraction steps as needed to improve analyte recovery and reduce
detection limits. EPRI reports that the comparison of MSB results to standard
USEPA methods ranges from good to excellent.
As a screening tool, MSB methods provide quantitative results for individual PAH
components at the site characterization or remediation stages of a project. Several
states have approved MSB methods for specific projects either in lieu of certified
laboratory analysis or as a percentage of samples being submitted to a certified
laboratory for confirmation analysis.
Operational Considerations
MSB methods were originally developed for use at an on-site laboratory; therefore,
these methods can easily be used in an on-site laboratory to perform expedited
characterization of PAHs.
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Soil sample volumes required for MSE analytical methods can be up to six times
smaller than those for conventional laboratory analysis. Turnaround times for
MSE methods range from 12 hours to 2 weeks; in contrast, laboratories following
conventional EPA protocol may have turnaround times ranging from 24 hours to 4
weeks.
Many conventional laboratories may not have instrumentation and protocol
readily available for MSE methods. Analytical laboratories chosen to use MSE
methods should be interviewed and audited prior to contracting and use.
Applications and Cost
MSE methods are applicable during the site characterization or remediation stages
of a project where quantified concentrations of PAHs are needed.
The cost of MSE depends on the laboratory (prices vary widely) and the types and
numbers of samples to be analyzed. Analytical costs can be as much as 50 percent
lower than costs for conventional analyses. In addition, using MSE methods may
significantly reduce overall project costs because of rapid turnaround times on lab
results (which could translate into fewer mobilizations/demobilizations of field
crews) and lower sample volumes (which permit alternative drilling/sampling
techniques to be implemented).
Benefits
* Small sample volumes
• Fast laboratory turnaround times
" Minimal laboratory waste
• Quantitative results for individual components
«,,' '<' , '!' , '.' ..',;,.• t , ij ; ; '" '.j ,; '• '' • ' ,
Limitations
• Relatively new procedure
Contact
Electric Power Research Institute, (800) 313-3774
4.2.6.2 PAH Sample Filtration
Tool Description
When monitoring wells are constructed or aquifers are disturbed (e.g., pumped at
rates higher than natural groundwater flow), small particles called colloids are
mobilized in the groundwater. Although it is common practice to require turbidity
during sampling to be less than 5 nephelometric turbidity units (NTUs), in practice
it may be difficult to acheive (unless low-flow sampling techniques are employed).
Artificially suspended particles become entrained in groundwater at flow rates
higher than the natural groundwater flow rate and these suspended particles may
bias concentration data higher than true concentration levels. PAHs are relatively
immobile, hydrophobic compounds that tend to sorb onto soil particles. Because
PAHs have low aqueous solubility values and a high affinity to sorb onto
artificially mobilized suspended particles, it may be more representative to filter
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PAH samples that are collected under high turbidity conditions (Backus, 1993; and
Saar, 1997).
A standard environmental filter has a pore diameter of 0.45 micrometers (mm).
Research has shown that naturally transported colloids may have diameters up to
2 mm. Therefore, a drawback to sample filtering is that naturally transported
colloids may be filtered, in addition to the artificially mobilized colloids, and
contaminant concentrations may be understated depending on the importance of
natural colloid transport at a particular site (Backus, 1993).
In deciding whether to filter groundwater samples or not, the potential for natural
and artificial colloid transport should be considered. Because sampling turbid
groundwater often necessitates the use of field filters, it is recommended that all
attempts be made to lower the turbidity (e.g., low-flow sampling) and thereby
avoid filtering altogether. Analysis of both filtered and unfiltered samples from
the same location may provide an indication of the relative impact of colloidal
transport; however, it cannot distinguish between natural and artificial colloidal
transport.
Operational Considerations
Turbidity is often highest in formations characterized by reducing conditions and
fine-grained or poorly sorted lithologies. Typically, filtering is not an issue with
samples collected from higher permeability (and presumably lower turbidity)
formations. For groundwater samples collected in a temporary monitoring well or
borehole, turbidity will most likely be relatively high, so it may be justifiable to
field filter because of the large amount of artificially entrained colloids (Backus,
1993).
The ultimate use of the sampling data should also be considered when deciding
whether or not to filter a groundwater sample. In general, the following guidelines
may be used in making this decision:
• Filtered samples should be used whenever groundwater samples are collected
to determine whether water quality has been affected by a hazardous
substances release that includes metals or' chemicals susceptible to colloidal
transport.
• Samples should not be filtered when a water supply well is sampled.
• For data to be used in risk assessment, unfiltered samples should also be
considered if the hydrogeologist suspects that colloidal transport could be
significant.
• It is generally recommended that both filtered and unfiltered samples be
collected at the same time for comparison.
Several different filter types are available at equipment supply stores. Filtration
may occur in an open filter funnel with filter discs (the sample is pulled through
the filter with a vacuum system) or by using an in-line filter where the sample is
pushed through a self-contained, enclosed filter. Many different filter sizes are
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available. A 0.45-mm filter should be used unless some information is known
regarding the distribution of natural and artificial colloids at a particular site.
Applications and Cost
Field filtering of PAH samples is applicable to groundwater samples that have
relatively high turbidity levels (e.g., greater than 5 NTUs). One key drawback,
however, is that filtering also removes naturally transported colloids. The presence
of naturally transported colloids should be taken into consideration when
Analyzing the results.
The cost of field filtering equipment is nominal compared with the cost of sample
analysis and may add a small labor cost to complete the field filtering. Analyzing
both filtered and unfiltered samples doubles analytical costs and raises the labor
costs associated with groundwater sampling.
•I ' . ; • •'.•; : - '/-' .."J .. • .. ., .
Benefits
• Eliminates the high bias in PAH concentration measurements introduced by
artificial colloidal entrainment
• ,, - • • '..''' f ;•••*••'•'••• ! '
" A simple technology requiring minimal training
Limitations
• PAH concentrations determined from filtered samples may not include naturally
transported colloids and create a low bias
» Dissolved or colloidal contaminants may adsorb onto the filter or apparatus
4.2.6.3 Inverse Specific Capacity Method
Tool Description
The hydraulic conductivity of the interval yielding water to permanent monitoring
Wells is routinely estimated by pumping tests or slug tests conducted in a well.
The inverse specific capacity method estimates the hydraulic conductivity of the
depth interval that provides the water sample in a temporary monitoring well.
Specific capacity refers to the flow ofwater yielded by a well at a drawdown or
drop in the water surface. The specific capacity test is usually estimated by
pumping a well at a fixed rate and monitoring the drop in the level of water in the
well over time. The inverse specific capacity method sets the drawdown at a
predetermined level and then measures the yield required to maintain this
predetermined drawdown (Wilson, 1997).
Operational Considerations
The inverse specific capacity test is conducted using the GeoProbe™ as a
temporary monitoring well. Once the GeoProbe™ (or similar technology) rods are
pushed to the desired depth, %" plastic tubing, a peristaltic pump, and a
measuring cup collect the inverse specific capacity data. Typically, a peristaltic
pump can lift up to 40 feet of head; therefore, when groundwater is more than
approximately 40 feet bgs, the inverse specific capacity method is not feasible.
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Site-specific permeability data from conventional means (pumping or slug tests)
are needed to calibrate the inverse specific capacity data if quantitative data are
desired. In addition, the inverse specific capacity method is only appropriate for
zones with hydraulic conductivities ranging from 10 ~l to 10 "5 cm/sec (Wilson,
1997).
Applications and Cost
The inverse specific capacity method can be used with any direct-push drilling
technique where groundwater can be sampled via suction lift using a pump on the
surface. The cost is negligible assuming that a peristaltic pump and push sampler
are already in use at the site. The typical time for a test ranges from 5 to 10
minutes.
Benefits
• Provides quantitative estimates of hydraulic conductivity in a temporary
monitoring well
• Allows variation in horizontal hydraulic conductivity to be assessed in the
vertical direction for preferential pathway identification
Limitations
• Provides hydraulic conductivity estimates for a small volume of aquifer
• Requires hydraulic conductivity values from conventional monitoring wells on
site for calibration
• Only approved for zones having permeability ranging from 10 "J to 10 "5 cm/sec
4.2.6.4 Hand Augering/Trenching/Pot Holing
Tool Description
Hand augering, trenching, and pot holing are well-accepted, simple techniques for
gathering shallow geologic information and for surveying and delineating wastes
from former MGP sites. All three methods require minimum equipment and result
in the gross collection of geologic and analytical information.
Hand augers are thin-tube cylinders that are driven by hand into the ground.
Typically 18 inches in length, hand augers split lengthwise to allow insertion of
three stainless steel or brass rings. When driven into the ground, soil is pushed
into the rings, which are then removed and used for sample analysis.
Trenching and pot holing both use equipment such as shovels or backhoes to
excavate soil. Trenching is basically excavation along a single axis, often designed
to create vertical walls that can then be mapped for geologic strata. Pot holing
incorporates the random or sequential digging of pits and is typically used to
grossly delineate the extent of MGP residues. A photograph of a typical trench is
shown below.
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Operational Considerations
Trenching and pot holing are easy exploratory techniques that often do not require
regulatory (e.g., boring) permits. They are especially effective at large sites with
few above- or underground obstructions and where labor is inexpensive. Both
techniques will, however, create significant quantities of waste, which can be
costly to handle and dispose of if found to be hazardous.
Similar to trenching and pot holing, hand augering is effective at sites where labor
is inexpensive. In contrast to trenching and pot holing, hand augering is effective
for sites where there are significant above- or underground obstructions and/or at
sites where generation of wastes is a significant concern. In contrast to trenching
and pot holing, hand augering is limited to the depth to which the sampler can be
driyen, often a maximum of 3 to 5 feet bgs.
! '"
Applications and Cost
As noted above, trenching, pot holing, and hand augering are inexpensive if labor
is inexpensive. The costs for the techniques vary directly with local labor costs.
Benefits
• I ' •
• Can be used to expose buried objects
1 'I ! ' . • ' ' " '
• Discrete and can get into tight locations (hand augering)
Limitations
• Hand augering and pot holing are depth limited
• Trenching and pot holing are visible to the public
, „".;! ; •
• Borehole and slope stability may be a problem
« Waste management may be a problem with trenching and pot holing
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Case Study
Marysville-1 Former MGP Site
The MGP formerly operating at PG&E's Marysville Service Center was originally
located in what is now an operating substation. Because of clearance restrictions
and operating limitations, standard drilling methods (e.g., hollow-stem auger
drilling) could not be conducted within the substation. Hand auger sampling was
initially performed within the substation in areas historically thought to contain
some former MGP structures (e.g., the generating and scrubbing building,
lampblack dump, and gas holder). Soil samples collected via hand augering
indicated that MGP residues did exist in soil within the substation. Partial
substation de-energizing was subsequently arranged, and limited access drilling
(via Precision Sampling's limited-access direct-push drilling rig) was conducted to
approximately 28 feet bgs within the substation.
Contact
Robert Doss, Pacific Gas and Electric Company, (415) 973-7601
4.2.6.5 Noise and Fugitive Emission Controls
Tool Description
During site characterization and remediation, noise and/or emission controls may
be required for regulatory, political, and safety reasons. Sound barriers, such as
curtains or berming, may be necessary to minimize noise in residential areas
during 24-hour drilling or near school/community centers during the day. One
primary disadvantage of sound barriers and tenting to control noise is that
decreased air flow may result in the work area, so emission controls (such as
ventilation blowers) may have to be increased.
Construction activities such as grading, excavation, material handling, and travel
on unpaved surfaces can generate substantial amounts of dust. Water sweeping or
soil stabilization may be necessary at sites where airborne dust could pose a health
and safety risk. Foam suppressants and chemical applicants such as magnesium
chloride are also used to control dust. A site can be completely enclosed (tented) to
prevent dust migration off-site; however, ventilation of work areas may be
required.
Operational Considerations
All alternatives to control noise and fugitive emissions should be considered. If, for
example, several days of 24-hour construction in a, residential area are required, it
may be more cost effective to forgo noise control and place nearby residents in
hotels during the noisiest construction. Seasonal and diurnal constraints such as
cooler weather or the calmest periods of the day should be factored into the
remediation schedule. To control noise from generators and other construction
equipment, one alternative is to use an electrical power source or advanced muffler
systems. Monitoring the effectiveness of the controls is critical. Noise monitors are
readily available from field equipment catalogs and provide constant-readout,
time-averaged, or peak sound levels. Airborne emission levels are often monitored
visually or with the use of a hand-held meter that gives real-time measurements of
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dust, aerosols, fumes, and mists. Monitoring of noise or dust levels may occur at the
project site perimeter if off-site migration is the primary concern; monitoring may
take place close to sources if worker safety is the primary concern.
i ' , |
Applications and Cost
Noise and/or fugitive emission controls should be used at any site where
Regulatory, health, or community concerns dictate action. The cost and level of
effort to implement noise and/or emission controls vary widely. Water sweeping at
a smaller construction site may cost from $200 to $500 per day; renting and
installing a sound barrier around a drilling operation may cost $5,000; and
complete enclosure of a site could easily add tens of thousand of dollars to project
costs.
. • * , :,
Benefits
• Protects community and workers
V ' • |i ,| vr , ' •
• May satisfy regulatory requirements
• Limits noise and air pollution
,11 . ;, • . i. ' I I- ",'•! •' i '
• Minimizes migration/transport of contaminants during remediation
Limitations
• Noise emission control on a large scale may involve prohibitive cost and effort
• Controls may make investigations/remediations logistically more complex
and/or may limit the rate of completion
'"..., " ,! .'.':. :
4.2.6.6 Information Management
Tpol Description
There is a growing awareness of the importance of information management in
expediting and streamlining remedial action planning, coordination, and
execution. In particular, information management tools can:
• Ensure that the quality and integrity of environmental data are maintained
throughout the site investigation process.
P Facilitate data interpretation and remedial selection.
At the project level, information management tools allow geologists, engineers and
project managers to plot and view site characterization data quickly and efficiently.
At a management level, a database management system may provide a "big
picture" of critical issues, significantly improving an environmental manager's
communications with decision makers both withiri their organizations and with
regulatory agencies. The efficiencies gained through the effective use of database
and information management systems allows resources to be shifted from labor-
intensive data manipulation to analyzing data through efficient management and
focusing on solutions and project closure.
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Chapter 4
Tools and Techniques For Expediting Site Characterization
A variety of commercial software packages are available to support this type of
initiative. The most common characteristic of these systems is that the system
architecture is designed around a common premise that all project information can
be assigned a spatial address, converted to electronic formats, and entered into a
geographic information system (GIS) project database.
The architecture of a GIS-based information management system must allow for
multi-level participation in information use since all information is derived from a
common database. Once construction of the database architecture is complete, any
portion of the database can be accessed depending on user needs but not changed.
This approach allows all information to be available in one location significantly
reducing time spent searching for information — a common challenge without •
effective data management tools. The features and benefits of using a GIS-based
information management system are as follows:
Feature
Data associated with unique spatial address
Information available electronically in one location
Elimination of manual data handling
Benefit
High quality data integrity
Time accessing information reduced
Reduction in data transcription errors and
compounding of errors over the remainder of the
project
If correctly utilized, GIS-based information management systems can reduce cycle
times for completing site characterization and remediation activities.
Operational Considerations
Prior to the purchase and/or development of an information or database
management system, specific project needs must be evaluated. Questions to be
answered include the following:
• What kind of data may be expected?
• How much data may be expected?
• Who will be the direct users of the package (e.g., one computer operator,
multiple personnel)?
• How would prospective system users interact with the system (e.g., read-
only access)?
» What is the level of 'the users' computer literacy?
• How would the data be manipulated (e.g., tables, boring logs, cross-sections,
figures, interaction with groundwater flow models)?
• How much would the client need to spend?
• What are the software's system requirements (e.g., memory, coprocessor
speed)?
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The answers to these questions will aid the manager in selecting the right package
for the project. Options will range from sophisticated GIS packages such as
Arclnfo, to less sophisticated software packages built on common computer
software such as ACCESS and AutoCAD.
Applications and Cost
Data and information management packages are applicable to all projects that
generate data. The level of sophistication required will vary, however, from site to
site. Smaller sites, may be able to use common software packages such as ACCESS,
DBASE, LOTUS, and EXCESS to easily tabulate and sort data. Larger projects may
look towards more sophisticated, expensive software such as Arclnfo or BOSS
CMS. Costs, too, will vary considerably depending on the management system
purchase, associated hardware costs, and labor costs for data entry and system
maintenance.
•i •'-. • * " „ " * • •, '=' ' '• • ',, • i '" ;>' •• t; "•;•••..' , • . • ,.
Benefits
» Helps ensures data quality and integrity
i '
• Facilitates data use and interpretation
• Combined with electronic deliverables from analytical laboratories, may
reduce data entry costs
• May reduce labor costs associated with report preparation
Limitations
• System may act only as data repository
• No single system may be able to fulfill all project requirements
Case Study
t i • . " •! , c.. . . , ,•
Bordentown Gas Works, Bordentown, New Jersey
The Public Service Electric and Gas Company (PSE&G) former Bordentown Gas
Works site is located in a mixed commercial and residential area in Bordentown,
New Jersey. The site was used as an MGP from approximately 1853 to 1900 and as
a gas distribution regulating station until 1960. Since the demolition and clearing
of structures, the site has remained vacant and remains the property of PSE&G.
A pilot project was initiated by PSE&G as part of an ongoing joint effort between
PSE&G and the New Jersey Department of Environmental Protection (NJDEP) to
continue to streamline remedial processes associated with MGP cleanups. A
remedial investigation was previously conducted at the site, indicating that
remedial actions were required:
• • i 1
• Collect additional site characterization data to support PSE&G's remedial
objective
• .Conduct a remedial alternative analysis
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Chapter 4
Tools and Techniques For Expediting Site Characterization
• Prepare and submit a remedial action selection report to NJDEP. The report
included a comprehensive evaluation of environmental conditions at the site
using a GIS-based data management system developed and applied by
Woodard & Curran, Inc.
The Woodard & Curran environmental data management system was selected to
aid in data evaluation to understand the site's environmental conditions; facilitate
real-time interpretation of subsequent field work activities to complete.site
characterization; streamline mapping and mtefptetatib'n of geologic and
contaminant profiles; and assist in the evaluation of viable remedial options. The
system consisted of a customized software platform based on ESRI's Arc View® as
the overall platform and GISXSolutions' GISXKey™ as the application software for
environmental data. The key benefit of utilizing ArcView® is that the software has
the ability to import information from a variety of software packages (including
those specifically designed for environmental data management) increasing the
robust performance of this system.
The data management work performed by Woodard & Curran, Inc., on this project
consisted of the following tasks:
• Electronic loading of environmental data (approximately 10,000 records) into
the system
• Querying of data to understand site conditions and identify data gaps in
concert with the NJDEP
• Development of a supplemental investigation work plan to address data gaps
• Input of supplemental data (approximately 4,000 records) for use in mapping,
assessment of environmental conditions at the site, and identification of areas
of concern for evaluation of remedial alternatives
• Review of findings in a series of workshops with the NJDEP prior to
preparation of the remedial action selection report
This project resulted in improvements in the overall site investigation process,
including reductions in cycle time for data collection, compilation and
interpretation. Supplemental field work activities filled in the data gaps and
allowed the project team to focus on remedial alternatives. Field and laboratory
data were in the system within one week of completion and were available to the
project team for interpretation and analysis immediately thereafter. The project
team conducted technical workshops to keep NJDEP apprised of results
throughout the process. The data management system was used at project
meetings to conduct "what if" scenarios, creating contaminant isopleths and
assisting in understanding hydrogeologic features at the site. The final report
included a summary of findings and conclusions that were developed in concert
with NJDEP throughout the project. In summary, the application of the
information management system assisted the project team and resulted in the
following:
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Chapter 4
Tools and Techniques For Expediting Site Characterization
Reductions in time and cost required to complete the site investigation
Increased reliability of data interpretation
A simplified way of presenting site environmental data
permitted them to be part of the project team evaluating
remedial alternatives in real time
Contacts
Woerner Max, Public Service Electric and Gas '
Matt Turner,:
, New Jersey Department of Environmental Protection
to NJDEP and
irig site conditions and
Company, (973) 430-6413
, (609) 984-1742
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Chapter 5
Technologies for Source Material
Treatment
5.1 Introduction
This chapter describes technologies for treating former MGP residues. These
technologies have either been proven successful and.costeffective or are new
and promising for use at former MGP sites. The technologies described
below destroy or encapsulate MGP residuals in the vadose zone, reducing or
eliminating the threat that chemicals from these materials will reach groundwater
or human populations and thus limiting or reducing the responsible party's
liability. (This is in contrast to past methods of disposal that often involved
sending wastes to landfills where the responsible parties continue to bear long-
term responsibility for the waste's environmental and health effects.)
The technologies discussed in this chapter are summarized in the following table.
Although each technology is discussed independently, multiple treatment
technologies may be applied at a site to address the various chemical components.
For example, soil vapor extraction (SVE) may be applied at a former MGP site to
remediate the volatile components of the MGP residues concurrent with or prior to
in situ stabilization (which will treat the heavier, less mobile chemical
compounds). Multiple technologies applied concurrently or sequentially are often
referred to as treatment trains, and are often formed to address an overall site
remediation.
The costs provided in this section are based on limited data and are dynamic.
Many variables will affect the cost of a remediation technology as applied to a
specific site or set of sites. The cost information provided herein reflects an order-
of-magnitude guide to cost, and is provided on an informational basis.
This document does not address the treatment of NAPLs or MGP contaminants in
groundwater. These issues may be addressed in a future volume of this document.
However, remediation at a site should address all the site's contaminants,
including those present in both soil and groundwater.
5.2 Technologies for Source Material Treatment
The following sections contain specific information pertaining to each of the
technologies for treating residuals and contaminated soil from former MGP sites.
5-1
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r
Name
Co-Burning
Thermal Treatment Processes
Ex Situ Thermal Desorption
In Situ Thermal Processes
Dynamic Underground Stripping
(DUS)
In Situ Thermal Desorption (ISTD)
Contained Recovery of Oily
Wastes (CROW)
Source Material Treatment Technologies
Description
Combustion of MGP residues with
coal in utility boilers and cement
kilns.
Benefits
• Recycles wastes
• Destroys organic contaminants
• Cost effective
Limitations
• Long-term impacts on boiler efficiency,
maintenance, and operation is unknown
Desorption and/or destruction of
organic contaminants in excavated
soil by heating.
• Demonstrated PAH and organic
contaminant reduction
• Moveable units available for onsite
treatment
• Hazardous levels of contaminants may not
be accepted at offsite facilities
• Wet or saturated media requires dewatering
prior to treatment
• Soil with high organic content is unsuitable
for treatment
• Air emissions control may be required
"*
Injection of steam into subsurface
contaminants to volatilize and
mobilize contaminants.
Soil heating via in-well heater or
electrodes to vaporize/volatilize
fluids and contaminants.
Hot water flushing/displacement
and extraction of subsurface
contaminants.
• Minimal disruption to site operations
• Removes contaminants under existing
structures
• Works well under wide range of soil
types
• Minimal disruption to site operations
• Removes contaminants under existing
structures
• Works well under wide range of soil
types
• Minimal disruption to site operations
• Removes contaminants under existing
structures
• Works well under wide range of soil
types
• Utility costs may be high
• Sufficient contaminant mass may not be
removed during treatment
• Utility costs may be high
• Works best in unsaturated conditions
• Utility costs may be high
• Sufficient contaminant mass may not be
removed during treatment
Approximate
Cost*
$44-$309/ton
$100-$200/lon
$110/cy
$120-$300/cy
N/A
5-2
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Name
Asphalt Batching
Cold-Mix Asphalt Batching
Hot-Mix Asphalt Batching
Source Material Treatment Technologies, continued
Description
Benefits
Limitations
Encapsulation of contaminant by
blending residues, wet aggregate
and asphalt emulsion at ambient
temperature.
Encapsulation of contaminant by
blending residues, wet aggregate
and asphalt emulsion at high
temperature.
• Reuses materials
• Immobilizes PAHs
• Viable treatment technology for coal tars
• Reuses materials
• Immobilizes PAHs
• Viable treatment technology for coal tars
• Curing times can be affected by temperature
• Not viable for fine-grained materials (e.g., clays)
• Physical properties of final product not always
appropriate for traffic reuse
• Curing times can be affected by temperature
• Not viable for fine-grained materials (e.g., clays)
• Physical properties of final product not always
appropriate for traffic reuse
Approximate
Cost*
$40-$70/ton
$40-$70/ton
Bioremediation/ Chemically Enhanced Bioremediation
Ex Situ Bioremediation
Landfarming
Biopiles
Bioreactor
In Situ Bioremediation/
Bioventing
Destruction of organic compounds
in contaminated soil by
microorganisms. Treatment occurs
on lined beds during contaminated
soil tilling and irrigation.
Destruction of organic compounds
in contaminated soil by
microorganisms. Treatment occurs
through soil amendment and
stockpiling.
Destruction of organic compounds
in contaminated soil by
microorganisms. Treatment occurs
in an enclosed reactor vessel.
Destruction of organic compounds
in subsurface contaminated soil by
microorganisms.
• Shorter treatment periods than in situ
bioremediation alternatives
• Reduces contaminant concentrations
• Shorter treatment periods than in situ
bioremediation alternatives
• Reduces contaminant concentrations
• Shorter treatment periods than in situ
bioremedialion alternatives
• Reduces contaminant concentrations
• Generally inexpensive
• Minimal disruption of existing operations
• Removes contaminants from under
existing structures
• Not effective for higher molecular-weight
hydrocarbons
• May be slower than alternative treatment
technologies
• Not effective for higher molecular-weight
hydrocarbons
• May be slower than alternative treatment
technologies
• Not effective for higher molecular-weight
hydrocarbons
• May be slower than alternative treatment
technologies
• Verification of destruction is sometimes difficult
• Not effective for higher molecular-weight
hydrocarbons
• Treatment uniformity uncertain because of
subsurface variables
$75/cy exclusive of
lab and pilot studies
$1uO-$200/cy
exclusive of lab and
pilot studies
$216/cy exclusive of
lab and pilot studies
$10-$70/cy exclusive
of lab and pilot
studies
5-3
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Source Material Treatment Technologies, continued
Name
Containment
Description
Containment or capping of
contaminated soil to prevent or
significantly reduce contaminant
migration and to prevent human and
animal exposure.
Benefits
• Quick installation
• Does not require soil excavation
• Prevents vertical infiltration of water
• Prevents human and animal exposure
Limitations
• Contains wastes; does not reduce contaminant
concentration
• Requires operation and maintenance program
• Typically requires institutional controls (e.g.,
deed restriction)
Approximate
Cost'
$45,000-
$170,000/ac
Stabilization/Solidification
In Situ S/S
Ex Situ S/S
Soil Washing
Soil Vapor Extraction
Encapsulation of contaminant by in
situ blending with chemical binders
to immobilize contaminant of
concern.
Encapsulation of contaminants in
excavated soil by blending with
chemical binders to immobilize
contaminant of concern.
Physical/chemical process for
scrubbing soils ex situ to remove
contaminants.
Extraction of air from subsurface to
remove volatile compounds from
vadose zone soils.
• Immobilizes contaminants
• Neutralizes soil
• Improves bearing capacity or shear
strength of treated area
• Immobilizes contaminants
• High degree of certainly regarding
treatment performance
• Removes contaminant from under
existing structures
• Promotes in situ biodegradation
• Well established treatment technology
• minimal disruption to site operations
• Possible leaching of volatile or mobile
contaminants
• Creation of concrete-like material in subsurface
• Effective in situ mixing may be difficult
• Performance dependent upon chemical
composition of wastes
• Long-term immobilization of contaminant may
be affected by environmental conditions
• Material handling possibly expensive
• Effectiveness limited by complex waste
mixtures and high humic content
• Not effective for low-volatility compounds
• May not be effective in areas with water tables
shallower than 5 to 10 feet bgs or in fine-grain
soils
• Limited effectiveness on pools of contaminants
$40-$60/cyin
shallow applications,
exclusive of lab and
pilot studies
$100/ton exclusive
of lab and pilot
studies
$170/ton
$24450/cy
* Approximate costs do not include cost of excavation, transportation, material handling, etc.
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Chapter 5
Technologies for Source Material Treatment
5.2.1 Co-Burning
Technology Description
Co-burning is the process by which MGP residues such as coal tar and tar-
contaminated soils are combusted along with coal in utility boilers. Developed by
the Edison Electric Institute's (EEI) subcommittee for MGP sites with technical
support from the Electric Power Research Institute (EPRI), this technology blends
remediation waste recovered during site excavation with coal so as to render it
nonhazardous for co-burning in utility boilers. EPRI also developed a sampling
approach that is consistent with EPA test methods for characterizing soils and
wastes and for developing blending ratios for treating soils. This strategy is
intended to ensure that only nonhazardous MGP wastes are co-burned in utility
boilers, and allows utilities to burn this waste without entering the RCRA
hazardous waste permit program or paying the high cost of commercial
incineration (EPRI, 1995).
Operational Considerations
Utilities have co-burned MGP site wastes in a variety of utility boilers, including
stokers, cyclones, and those fired by pulverized coal. Preparation consists of
screening waste to remove oversized material and rendering the material
nonhazardous under RCRA if necessary (GRI, 1996). MGP materials are typically
blended with coal feedstock in the range of 5 to 10 percent coal or wastes. Co-
burning increases the amount of ash requiring management. For example, a 10
percent co-burning mixture doubles the amount of ash generated by a boiler (GRI
1996). y
Applications and Cost
As of 1996, co-burning was used as part of full-scale remediation at five MGP sites;
four other demonstration tests have been completed (GRI, 1996). Media that have
been treated include coal tars, purifier box wastes, and contaminated soils. Co-
burning is currently offered as a commercial service by one utility in the northeast
United States. The cost of co-burning in a case study in Rochester, New York,
ranged from $44 to $142 per ton for soil and from $134 to $309 per ton for tars.
The utility company currently offering co-burning charges a tipping fee of
approximately $90 per ton to incorporate the MGP site residuals into its boiler
feed, but this cost does not include any preprocessing, transportation, or analytical
work necessary for disposal (GRI, 1996).
Benefits
• Reuses/recycles waste into a usable product
• Has demonstrated technical feasibility to destroy organic contaminants
• Allows utilities to expedite flexible, cost-effective remediation at MGP sites
Limitations
• Long-term impact of co-burning on boiler efficiency, maintenance, and
operation is unknown
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•;..••• i", T, '..I,
; > • . !' :: •;;.' | j; • ' •! " ' .| : Chapter 5
Technologies for Source Material Treatment
'" ' ,11 ; in ,, ,, r, ,,, ^ ., ,|: , ^ * • ,, , , ,,1 , i| .. M, i| ly
Case Studies
Rochester, New York
Rochester Gas and Electric (RG&E) with the assistance of EPRI, the Gas Research
Institute (GRI) and the New York Gas Group evaluated co-burning for use at their
plant. RG&E operates an 80-megawatt, tangentially fired, pulverized coal unit
built in 1959 by Combustion Engineering. It is located on the same site as the
former West Station MGP. Residues in the form of "neat" coal tar and soil with
rnajor amounts of rock, brick, coke, concrete, and other demolition debris remain
at the West Station site. The soil contains from 40,000'to 70;000'ppm of PAHs.
Although preprocessing was needed to remove large rocks and other debris, the
tar and soil were easily blended with coal to make two distinct fuel products. One
fuel product contained 4 percent tar, and the other contained 5 percent soil, with
the balance in both cases made up of coal.
The test burn program contained a series of inspection and evaluation protocols
directed at monitoring the effects of these mixed fuels on the boiler and ancillary
systems. In a program that lasted approximately 12 weeks (4 weeks of which were
dedicated to actual co-burning), the boiler performed without significant
performance losses, PAH removal efficiency exceeded 99 percent, electrostatic
precipitator performance was unchanged, and emissions appeared unaffected (air
emissions were actually significantly reduced for certain parameters).
Two factors that arose in this demonstration could greatly affect the feasibility and
cost of co-burning. The first factor is that the state environmental agency required
ash leachate to meet drinking water standards before it would grant RG&E
permission to reuse the ash. Because drinking water standards are set below the
method detection limit for many parameters, the ash could not meet these
standards, and the state denied permission to reuse it. If not resolved, this
prohibition on reuse will add more than $50 per ton to the cost of the residues to
be treated. (One bottom ash sample also showed PAH concentrations of 800 ppb,
attributed to spillover from the mill reject system.) The second factor that affects
co-burning is the potential physical damage to a boiler using this technology. Mill
abrasion was measured during the test and one measurement indicated a rate of
wear about eight times that from processing ordinary coal. If this measurement
and test are representative, maintenance costs of co-burning could increase
proportionally.
" • | • :•• ...... »
Contact
ICevin L. Hylton, Rochester Gas and Electric Corporation, (fa6) 546-2700
Greenville, South Carolina
Co-burning of MGP residues was demonstrated in a pulverized-coal, tangentially
fired utility boiler at the Duke Power Company in South Carolina. The
remediation site was the Broad Street MGP in Greenville, where a 1.2-acre,
carbureted water gas plant operated from 1875 until 1951. The co-burn facility was
Duke Power Company's Lee Steam Station, located in Pelzer, South Carolina. The
MGP residues were co-burned in unit No. 3, which has a capacity of 175 MW and
was constructed in 1956.
"'5-6
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Chapter 5
Technologies for Source Material Treatment
The project's remediation goals were to prepare the site for future sale as an
industrial/commercial property. A cleanup level of 200 ppm total PAHs was
required. The matrix treated consisted of soil impacted with MGP residues. Prior
to co-burning, soil was screened to Vz inch arid then blended with coal at a
maximum rate of 5 percent. Plant operations preferred a 2 percent blend.
This was a full-scale operation. The plant had a permit for 19,000 tons of soil per
year, but the actual amount treated was estimated at 3,000 tons per year. Before
treatment, total PAH concentrations in site soils ranged up to 1,600 ppm. After
treatment, BTEX and PAH concentrations were below the detection limit in all
bottom ash and fly ash samples. Stack gas concentrations were the same as when
co-burning was not taking place. The project is now complete, with 3,000 tons of
material treated and managed; a destruction and removal efficiency (DRE) of 100
percent was obtained. No additional co-burns of MGP residues are planned at this
time.
Contacts
Ralph Roberts, Duke Power Company, (704) 875-5536, rcrobert@duke-energy.com
Lori Murtaugh, South Carolina Department of Health and Environmental Control,
(803) 734-4668
Illinois Power Companyllllinova Resource Recovery
Illinois Power and Illinova Resource Recovery, Inc. operate a commercial waste
management facility at Illinois Power's Baldwin Power Station. The program is
designed to co-burn MGP remediation wastes from the utility industry. These
wastes are blended with coal and burned in the Baldwin Power Station's two
cyclone boilers.
Power Station Description
The Baldwin Power Station is located outside the village of Baldwin, Illinois,
approximately one hour southeast of St. Louis, Missouri. The area is primarily
rural agricultural property.
Two 600-megawatt cyclone boilers are utilized to co-burn remediation wastes. The
cyclone units are especially suited to burning these wastes due to the fact that
materials can be fed at up to a one-inch size, without the need of pulverization to '
200 mesh as is required in some coal-fired power plants. In addition, 90 percent of
the ash generated from cyclone boilers is in the form of a vitrified, inert slag
material. All this slag is sold commercially as sandblast grit and roofing shingle
aggregate. Both power station boilers are base-load units, meaning that they
operate 24 hours per day, 7 days per week at full-load. This allows co-burning to
be conducted on a steady basis and maximizes the capacity of the program. The
Baldwin units are equipped with electrostatic precipitators and continuous
emission monitors. The units are fueled with Illinois Basin coal.
Waste Management Facility
A dedicated waste management facility has been constructed at the Baldwin
Power Station specifically designed to receive, store, and process remediation
wastes. All waste storage and processing activities are conducted in a 30,000
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"" ;''" "f '' •• ' '• ! • ': ' '': " Chapters"
Technologies for Source Material Treatment
square foot water-tight concrete and steel containment pad. The containment pad
can store 8,000 cubic yards of contaminated soil. Baldwin is allowed to load waste
at a rate of 5 percent of the coal loaded daily. This corresponds to approximately
450 tons per day capacity. Baldwin has demonstrated a 300-ton-per-day sustained
rate capacity. The practical annual capacity is currently about 100,000 tons per
year. The waste materials are delivered by dump trailer and off-loaded directly
into the containment pad. The materials are then crushed, screened, and blended
with coal to produce a final product that is homogenous, less than two inches in
size, and free of metal, plastic and other unprocessable debris. Rock, gravel, and
nilsonry are accepted an3 crushed with trie other materials and burned in the
boilers. The processed material is delivered to the power plant coal conveyors
i|smg an enclosed conveyor systeml
.)";'( '•• "" . "';•'_..:; ;i •:„!', '!• * : „'• - i -• ..• ' • , • -
Environmental Permits
The Baldwin facility is fully permitted by the Illinois Environmental Protection
Agency as a commercial waste treatment and storage facility. Solid waste permits
limit types and quantities of acceptable waste, and define the management
practices, documentation and inspection requirements, and quality control
procedures. Water discharge permits require collection, treatment, and analysis of
runoff water prior to discharge to the environment. Air permits limit the amount
of dust generated and the emissions from the boiler stacks. The Illinois
Environmental Protection Agency has been very supportive of the program as a
safe and effective means of permanently eliminating the hazards and liabilities
associated with these wastes, which previously were disposed of in landfills
almost exclusively. Three USEPA Regions have approved the operation for receipt
of coal tar and petroleum contaminated soil and debris for federal Superfund sites.
Operating History
A test burn in March of 1994 convinced Illinois Power that the power plant
systems could handle the contaminated soils effectively witn acceptable impacts to
bfliler operations and efficiencies. The costs, however, indicated that the process
wc|uld not be cost effective for only Illinois Power's quantities of waste. It was
determined that a commercial operation could be supported by the quantities of
waste market, thereby providing the economies of scale required to make the
project feasible.
Since the initiation of operations in June of 1996, over 135,000 tons of waste have
been accepted and treated at Baldwin. Materials have been received from as far as
1,200 miles away. Baldwin has been an integral contributor to the remediation of
over 40 contaminated sites for more than 20 customers.
5.2.2 Thermal Treatment Processes
Thermal desprption is a treatment technology in which organic chemical
constituents contained within a contaminated soil matrix volatilize as a result of
heating. The volatilized constituents are then extracted from nonvolatile materials,
such as soil, and treated prior to release. Thermal desorption can be grouped into
in situ and ex situ practices. Both technologies are described below.
• • 'i , ' - • •
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Chapter 5
Technologies for Source Material Treatment
5.2.2.1 Ex Situ Thermal Desorption
Technological Description
Full-scale thermal desorption has been successfully used to remediate soils
containing MGP wastes (e.g., lampblack, coal tar) since the early 1980s, achieving
concentration reductions of more than 98 percent for TPHs, BTEX compounds,
PAHs, and cyanide. Thermal desorption has been used in many non-MGP
applications, and is a common remediation technology for MGP sites. The
technology can be applied on site with a mobile unit or at an off-site facility. Below
is a photograph of a thermal desorption unit.
Thermal desorption uses temperatures ranging from 400°F to 1,200°F to desorb
chemicals from the soil. Soil is fed into a material dryer where heated air causes
chemicals to volatilize. In general, temperatures between 200° F and 900°F are
required to desorb VOCs and many PAH compounds. Higher temperatures (up to
1,200°F) are required to desorb high-molecular-weight PAHs (Barr, 1996). After
chemicals in the offgas are treated, the cleaned air is vented to the atmosphere.
The dry, hot soil is then discharged to a pug mixer where water is introduced to
reduce dust and lower the soil temperature. The quenched soil is discharged and
transported to a stockpile. Each day's production volume of soil is held separately
while residual concentrations are determined. The treated soil is then returned to
the excavation, transported to an off-site facility for disposal, or reused at a
different location. A typical thermal desorption unit can treat approximately 8 to
45 tons per hour, depending on soil conditions (e.g., water content, waste
concentrations, etc.) and the size of the dryer unit used.
Operational Considerations
The thermal desorber's operational characteristics depend on soil type and
properties, contaminant type and concentrations, moisture content, organic
material content, pH, compound volatility, and temperature and residence time
during drying. This technology may require a pilot test demonstration. Blending is
recommended to reduce variations in organic concentrations.
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Application and Cost
Full-scale systems have achieved a DRE of 99 percent when treating contaminated
soils frorri MGP sites at temperatures of 750°F to 850°F with residence times of
approximately 10 minutes (GRI, 1996). A summary of costs from six remediation
efforts conducted to date in California (see the table below) shows on-site
treatment costs ranging from approximately $110 to $130 per ton for 16,000 and
9,000 tons of soil, respectively, and offsite treatment costs ranging from
approximately $100 to $200 per ton for 11,000 and 1,000 tons of soil, respectively.
All estimates include costs for general contracting, confirmation sampling,
construction management, permits, and transportation for offsite treatment (GRI,
1996). Recent projects suggest the potential for even more favorable pricing.
Summary of Total Project Costs for Thermal Desorption
at six California Former MGP Sites
(CostHon ($))
Thermal Treatment
Transportation
General Contractor
Confirmation Sampling
Construction
Management
Miscellaneous Costs
(Agency oversight, air
permitting)
Adjusted Total Cost
Total Cost
Total Project Costs
Tons Soil Excavated
Santa
Barbara
$52
--
$42
$10
$30
$14
$131
$178
$1,556,974
8,745
Dinuba
$49
-
$25
$4
$21
$4
$106
$140
$2,257,630
16,120
Covina
$45
$18
$31
$7
$17
$8
$120
$130
$906,735
7,000
Inglewood
$38
$19
$35
$5
$11
$8
$115
$133
$666,416
5,024
Orange
$44
$20
$62
$19
$45
$13
$202
$202
$212,384
1,050
Visalia
$32
$30
$24
$2
$7
$3
$96
$96
$1,055,950
10,775
Source: Southern California Gas Company
Benefits
• Demonstrated PAH reduction to less than 1 mg/kg under optimal conditions
80 to 99 percent removal of carcinogenic PAHs
90 to 99.7 percent removal of total PAHs (Barr Engineering, 1996)
Production rates of 8 to 15 tons per hour for small units and 25 to 45 tons per
hour for large units
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Limitations
• Very wet or saturated media must be dewatered prior to treatment
• Soil with high organic content (peat) is unsuitable
• Air emissions of chlorinated compounds, sulfur, etc. may need to be abated
Case Studies
Huron, South Dakota, Former MGP Site
The Huron MGP site is a 3-acre parcel that once housed«a process plant for the
production of carburetor water gas. Site geology consists of a surficial fill unit
underlain by a clayey lacustrine deposit and a glacial till unit. Depth to bedrock
beneath the site is approximately 100 feet. The glacial till unit acts as a barrier to
the vertical migration of MGP residuals.
The requirements under which the ex situ thermal desorption project was
conducted were negotiated with the state regulatory agency. These included
excavation criteria, a treatment performance criterion, and an operating permit for
thermal treatment. Field demonstration activities consisted of excavating and
staging soils containing MGP residuals, preparing the staged soils, treating the
prepared soils, backfilling and compacting the treated soils, and managing
wastewater.
The Huron MGP site used a low-temperature thermal desorption (LTTD) system, a
two-stage counter-flow direct-fired rotary desorber capable of heating
contaminated soils to 1,200 °F. The system is equipped with an oxidizer that can
operate at 1,800 °F. Field demonstration costs included mobilization/.
demobilization, material excavation and handling, thermal treatment, soil and
water analyses, utilities, backfilling and compaction, dewatering and wastewater
management, and project oversight. The total cost of the project was $3,819,000.
Approximately 47,000 tons of soil containing total PAH concentrations ranging
from 84 to 3,733 mg/kg were treated to below the treatment performance criterion
of 43 mg/kg for the sum of cPAHs, at a cost of $82 per ton.
Conclusions from the Huron MGP site field project are summarized as follows:
• The thermal desorption system achieved removal/destruction rates of greater
than 79 percent to greater than 99 percent for cPAH compounds, and greater
than 89 percent to 99.7 percent for total PAH compounds.
• The system showed good operating stability; critical operating parameters,
shown below, were relatively constant:
- Feed rate of 20 to 31 tons per hour with an average rate of 26 tons per hour
- Desorber temperature of 1,050 °F to 1,200 °F with a residence time of 18
minutes
- Oxidizer temperature of 1,741 °F to 1,773 °F with a residence time of 2 to 2.5
seconds
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Stack emissions, which were in compliance with the operating permit
requirements, were as follows:
Opacity
Sulfur Dioxide
Oxides of Nitrogen
Total Hydrocarbons
Naphthalene
<20 percent
2.4 pounds per million Btu of heat input
, ': I' < V 1.'" r . ,.
10.7 pounds per hour
0.07 pounds carbon per hour
<926 micrograms per second
Soil type and moisture content affected total cost. Had the clay and moisture
content of the site soils been lower, Sp}l preparation time would have been
shorter, and unit treatment costs would have been lower.
Inclement weather significantly affected project costs. Approximately 20 days
out of a 6-month period were lost to rain delays. The rain delays increased soil
preparation time and costs associated with dewatering, wastewater
management, and project oversight.
Contact
Ed Highland, Northwest Public Service Co., (605) 353-7510
Waterloo, Iowa, Former MGP Site
A two-stage thermal desorption unit was installed on the Waterloo, Iowa, former
MGP site. The treatment used natural gas as a fuel. In the first stage of the two-
stage desorber, the soil was mixed in a rotating drum and heated to approximately
300 °F to 500 °F by a 40-million-Btu-per-hour burner. In the second stage, the soil
was further heated to between l.lpO °F and 1,200 °F by three additional 6-million-
Btu-per-hour burners. The first stage was used to drive off moisture and the more
3/platile hydrocarbons; the second stage desorbed the contaminants from the soil.
All heating conducted by the two-stage desorber was direct fired and oriented
counter to soil flow. The vapors from the desorption stage were passed through an
oxidizer (secondary burner) and heated to between 1,750 °F and 1,800 °F to destroy
hydrocarbon contaminants. The desorber unit used at the Waterloo site was
specifically modified for treatment of coal tar compounds and operated at a higher
temperature in the high-temperature stage of the two-stage desorber than some
thermal desorption units. This was necessary to desorb higher-molecular-weight
coal tar compounds. The desorber used at the Waterloo site was capable of
thermally treating soil at a rate of 25 to 40 tons per hour, depending upon the
concentration of contaminants, and soil type and moisture content. During the
lljial burn conducted at the site, soil was treated at a rate of 31.6 tons per hour.
The minimum space required for setup and operation of the Waterloo desorber
unit was approximately 140 feet by 120 feet, not including space for storage of soils
prior to and after treatment. The thermal desorption unit and all auxiliary
equipment were transported to and from the temporary locations with 14 tractor
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trailers. It took approximately 7 days to complete setup of the equipment and an
additional 5 days for startup and fine tuning of the equipment in preparation for
trial bum or routine treatment of soils. Natural gas (or propane), electricity, and
water were required to operate the system. In addition, water was required for
rehydration of the treated soil and other cooling operations.
The remediation goal for the project was to treat the soil to less than 5 mg/kg total
PAHs. Routine sampling of treated soil showed concentrations well below 5
mg/kg. A total of 83 samples of treated soil (one sample for every 300 tons of soil)
had an average concentration of 0.59 mg/kg total PAHs. The media treated
included clay, sand, and silt.
A trial burn of coal tar materials was conducted to determine the DRE for the
organic contaminants in the excavated coal tar materials. A grab sample of soil
was collected for every 100 tons of treated soil, composited with two other 100-ton
representative samples, and analyzed for PAHs. Routine thermal treatment of soil
began as soon as the Iowa DNR and USEPA approved the results of the DRE
testing. The treated soil could not be backfilled, however, until laboratory analysis
was received and the results were shown to be below the treatment criterion of
less than 5 mg/kg total PAHs.
The specific operating conditions observed during the trial burn were used as the
operating criteria for the remainder of the soil to be treated. Continuous
monitoring included waste feed rate, system treatment temperatures, carbon
monoxide concentration in stack gas, and other parameters. Of the 83 samples of
treated soil that were collected and analyzed throughout the project, three lots of
300 tons each did not pass. These values were not included in the average above
because the soil was blended with other soil and retreated.
The following table shows the amount of soil excavated and treated for each of the
four sites:
Site
Hampton
Charles City
Independence
Waterloo
Total
Tons of Soil Treated
3,651
2,138
4,734
14,167
24,690
Treated soils from all sites were used to backfill an earlier excavation on the
Waterloo site. All contaminated oversized debris was crushed and thermally
treated. Some exceptionally large debris, such as foundations, was decontaminated
in place and left in the excavation. All scrap steel was cleaned and sent to a
recycler. As a result, nearly all of the materials removed were thermally desorbed
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or recycled. Very little material, primarily wood debris and tree roots, was taken to
the local landfill. The total cost of the project was $2 million. This cost includes
preparing the thermal desorption site and installing utilities, excavating all the
sites, hauling excavated material from Hampton, Charles City, and Independence
to Waterloo, backfilling, and labor to place the fill; it also includes the thermal
desorption services, with the cost of fuel. The average cost per ton of soil treated
was calculated for the project and is shown in the table below.
Item
Excavation
Thermal Treatment
Transportation
Backfill
Miscellaneous*
Total
Average Cost per Ton* ($)
4.83
47.87
12.53
4.83
8.62
78.62
'This includes the cost of analytical and engineering services, air monitoring, etc.
- " ' ii,',, ' :
Contacts
Sam Nelson, MidAmerican Energy Company, (712) 277-7851
Dan Klimek, MidAmerican Energy Company, (712) 277-7930
Johanshir Golchin , Iowa Department of Natural Resources, (515) 281-8925
Jim Colbert, USEPA Region VII, (913) 551-7489
Mason City, Iowa, Former MGP Site
Thermal desorption was used at a site in Mason City, Iowa, owned by Interstate
Pqwer Company. The property had been used for production of natural gas from
coal in the late 1900s and had become contaminated with a variety of heavily
weathered PAHs and cPAHs. From April to October 1996, approximately 22,000
tons of soil were thermally treated at temperatures of up to 1,200 °F. A process rate
of 32 tons per hour was achieved.
The soil that was treated contained concentrations of PAHs in excess of 3,000
mg/kg, and in many areas, soft, agglomerated, heavy oil was present.
Pretreatment of excavated soils included shredding, crushing, screening, and
blending to avoid exceeding the process capacity of the thermal desorption
system. Also, a significant amount of brick, concrete, wood, and steel pipe
repjuired specialized material handling and processing. The brick and concrete
were crushed and blended with more heavily contaminated soil before thermal
treatment; the steel and wood were separated and sent off for recycling.
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Six test runs were performed during a comprehensive demonstration testing
program. The average results of these test runs showed that concentrations of total
and cPAHs in the treated soil were reduced from 804 mg/kg and 95 mg/kg,
respectively, to less than 3.3 mg/kg and less than 1.22 mg/kg, respectively. A DRE
of greater than 9,9.99 percent was demonstrated for all combined PAH compounds.
Stack gas was sampled and analyzed for all combined PAH compounds. Sulfur
dioxide, nitrogen oxide, carbon monoxide, and PAH emissions were in accordance
with the USEPA and Iowa DNR protocol.
Contacts
Bruce Greer, Alliant Energy, (608) 252-3948
Johanshir Golchin, Iowa Department of Natural Resources, (515) 281-8925
Diane Engeman, USEPA Region VII, (913) 551-7746
5.2.2.2 In Situ Thermal Processes
In situ thermal processes are treatment processes designed to increase the
mobilization of contaminants via volatilization and viscosity reduction. The
addition of heat to the subsurface by radio frequency, electrical resistance, or
steam increases the removal of organic compounds particularly in low
permeability formations. Heat also increases volatility (and hence removal) of
compounds that are not readily extractable using conventional SVE (e.g., heavy
oils). Three in situ thermal processes are reviewed in this section: Dynamic
Underground Stripping (DUS), In Situ Thermal Desorption (ISTD), and Contained
Recovery of Oily Waste (CROW™).
5.2.2.2.1 Dynamic Underground Stripping (DUS)
Technology Description
Lawrence Livermore National Laboratory and the School of Engineering at the
University of California, Berkeley (UC Berkeley), developed DUS in the early
1990s. The area to be cleaned using DUS is ringed with wells for injecting steam.
Extraction wells in the central area are used to vacuum out vaporized
contaminants. To ensure that thick layers of less permeable soils are heated
sufficiently, electrode assemblies may be sunk into the ground and heated, which
forces trapped liquids to vaporize and move to the steam zone for removal by
vacuum extraction. These combined processes achieve a hot, dry, treatment zone
surrounded by cool, damp, untreated areas. Steam injection and heating cycles are
repeated as long as underground imaging shows that cool (untreated) areas
remain (Newmark, 1998).
Operational Considerations
The capacity of DUS treatment systems is limited only by the size of the
installation. DUS generally does not require material handling or pretreatment
prior to application at a site. Electrical heating may be applied to less-permeable
contaminated clay layers in situ to help release contaminants prior to steam
injection. DUS requires both subsurface and aboveground equipment.
Aboveground equipment includes a steam generation plant, electrical heating
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equipment, and treatment systems for recovering free product and contaminants
from the separate liquid and vapor streams collected from the extraction wells.
Because the aqueous and gaseous streams are in intimate contact with the free
product, they will typically be saturated with dissolved or vaporized free product
components following their passage through the oil/gas/water separators.
The DUS treatment system consumes significant quantities of electricity, water,
and, for some applications, natural gas. Operation difficulties that may be
encountered during DUS include biofouling (especially from microorganisms
(destroyed by steaming), scaling and deposits on sensors, clogging from fines
brought to the surface, and difficulties in maintaining the cycling, pressure-
yarying, and high-temperature technology. Further refinement is also required for
system design and operating and monitoring techniques.
The DUS technology is labor intensive, requiring significant field expertise to
implement. If is best applied to sites with contaminants above and below the water
table and complex sites that are difficult to clean up.
Applications and Cost
Although the initial capital outlay for DUS is higher than for pump-and-treat
systems, DUS could save money in the long run because it is completed much
more quickly. Most of the equipment, such as boilers for generating steam, can be
rented. Initial expenditures include installing the heating wells and operating the
system intensively for a short period of time. Because the technology is short term,
long-term operation and maintenance costs are reduced or eliminated. In a 1993
field trial of DUS at Lawrence Livermore National Laboratqry, the technology cost
about $110 per cubic yard of soil treated (Newmark, 1998).
Benefits "" ' "" '' ! i ' " '
* Will work in a wide range of soil types
• Works in both saturated and unsaturated conditions
:.':; ' • : • , ;. 1,' •'«' : "'„'""' f;;!.•'',";: ':: '!' " ' : ..
• Treatment possible in areas where traditional excavation and removal are
impossible
• Minimal disruption to nearby industrial operations or surrounding
neighborhoods; no digging and hauling of contaminated materials eliminates
exposure to toxic fumes and dust
• Will work close to or under existing structures, including buildings and
roadways
Limitations
« Although DUS removes considerable mass and may improve groundwater
quality, there is currently limited experience regarding the ability of DUS to
achieve maximum contaminant levels (MCLs) and thus alleviate the need for
purrip-ahd-treat.
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Case Study
Visalia Poleyard, California
The Southern California Edison Visalia Poleyard site was used for 80 years to treat
utility poles with both creosote and pentachlorophenol (PCP). Creosote contains
PAHs similar to those found in MGP wastes. This 4-acre site was one of the first to
be listed on the National'Priorities List. The sediments underlying the poleyard are
alluvial fan deposits, and the site currently contains DNAPL contamination in
three distinct water-bearing zones. There are several shallow aquifers from about
35 to 75 feet bgs, and an intermediate aquifer from about 75 to 100 feet bgs. The
most sensitive groundwater resource is found in the deep aquifer below about 120
feet. The thermal remediation system was designed to remove contaminants from
the intermediate and shallow aquifers without disturbing the deep aquifer.
DUS was selected for the Visalia poleyard. An array of 11 injection wells was
installed encircling the contaminant source area. Although each injection point
had two injection pipes, screened in either the shallow or the intermediate aquifer,
only the 11 pipes completed in the lower unit were used for injection from 80 to
100 feet bgs. Three additional extraction wells were placed in the central area to
supplement existing extraction wells. No supplemental electrical heating was
performed; the entire site was heated using steam alone. Steam was generated
utilizing commercially available oil field steam generators (Struthers type). Steam
was injected at pressures up to 150 psi, routinely at pressures less than 100 psi.
Vacuum pressures of approximately 0.5 atmospheres (atm) were applied in a
steady mode.
Ancillary equipment included cooling equipment for the extracted water and
vapor, two stages of free product separation (including dissolved air flotation),
and final filtration of the pumped water by activated carbon. Approximately 16
percent of the contaminant was destroyed in place, yielding carbon dioxide. Both
vapor and water streams were continuously monitored for hydrocarbon and
carbon dioxide content.
In addition to thermocouples, an innovative geophysical technique was employed
to monitor movement of steam and progress of heating. Electrical resistance
tomography is an imaging method like CAT scanning that provides near-real-time
images of underground processes between pairs of monitoring wells. Baseline
measurements are used to characterize a site and predict steam pathways. Soil
electric properties vary with temperature, soil type, and fluid saturation. During
treatment at Visalia, daily resistivity readings provided a picture of the progress of
the steam front and heated zones. Monitoring the progress of the heating fronts
ensured that all soil was treated. Temperature measurements made in monitoring
wells revealed details of the complex heating phenomena in individual soil layers.
As of August 1998, the DUS process recovered approximately 110,000 gallons of
free product a rate of about 46,000 pounds per week. In addition, approximately
29,400 pounds of hydrocarbon were burned in the boilers; 17,500 pounds of
dissolved hydrocarbon were collected in the activated carbon filtrator; and, based
on removed carbon dioxide, an estimated 45,500 pounds were destroyed in situ.
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Contaminant concentrations iri recovered groundwater continue to decline.
Southern California Edison will treat the liquid free product onsite and may use it
aS a lubricant. Current estimates are that the project will be completed in 1 to 2
years, with an additional 4 years of monitoring. This is in contrast to the 20 or
itibre years expected for pump-and-treat remediation.
With DUS, contaminants are vaporized and recovered at the surface.
Approximately 50 percent of the cost of cleanups is associated with treating
recovered groundwater and disposing of contaminants. The addition of hydrous
pyrolysis oxidation (HPO) to the basic DUS technology could save additional
costs. HPO involves injection of steam and air to aerate a heated oxygenated zone.
When injection is halted, the steam condenses and contaminated groundwater
returns to the heated zone. The groundwater mixes with the condensed steam and
oxygen, destroying dissolved contaminants^ As noted above, HPO is estimated to
|e responsible for a portion of the contaminant treatment at the Visalia site. To
evaluate the progress of in situ chemical destruction, field methods were
developed to sample and analyze hot water for contaminants, oxygen,
intermediate products^ and reaction products.
i • .
Laboratory testing on the Visalia suite of contaminants showed that both PCP and
the range of PAH compounds present are readily destroyed by HPO's in situ
oxidation process. Isotopic testing during remediation showed that the carbon
dioxide being recovered in the vapor stream was coming from oxidation of
creosote. This process is expected to aid in bringing groundwater concentrations to
regulatory standards.
Contacts
'•--"'I I ' . . ' . »!' ..' I ' "| I , I • ' • • ."• I
Roger D. Aines, Lawrence Livermore National Laboratory, (925) 423-7184
Robin Newmark, Lawrence Livermore National Laboratory, (925) 423-7184
Kent Udell, UC Berkeley, (510) 642-2928
Craig Eaker, Southern California Edison, (626) 302-8531
5.2.2.2.2 In Situ Thermal Desprption (ISTD)
Technology Description
ISTD consists of a system or array of surface and/or in-well heaters or electrodes
Combined with vacuum wells to heat contaminated soils and extract the resulting
vaporized/volatilized fluids and contaminants. Vapors produced through the soil
heating process are treated in surface facilities to remove residual contaminants.
According to the ISTD vendor, up to 99 percent of contaminants are destroyed.
ISTD involves the placement of Thermal Blankets (over areas of surface
contamination to a depth of approximately 18 inches) or Thermal Wells (which can
be drilled in areas of deep contamination) in the area to be treated. Both the
blankets and the wells use electricity to heat soil to the boiling temperatures of
contaminants. The contaminant vapors are then extracted and further processed
through a flameless thermal oxidizer and activated charcoal filter. Water and
carbon dioxide are released to the atmosphere during treatment.
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Operational Considerations
A staging area near the contaminated site and accessibility to a local power grid
are required for the placement of ISTD process and control trailers. Limitations of
the ISTD process are primarily related to the amount of moisture in the soil. Too
much water (e.g., groundwater recharge) requires either dewatering or installing
of a barrier to halt groundwater recharge as the soil is heated. There is minimal
impact to surrounding neighborhoods during ISTD treatment because the process
is confined to the site, and there is no direct handling of contaminated soils.
Minimal dust and noise are gerterated'-duping'treatinenfc-A schematic ISTD setup is
shown below.
A limited number of applications have been conducted to date; therefore, other
operational considerations that may affect the application of this technology at
former MGP sites are not known. Additional unknown factors include how the
technology will handle tarry waste material and underground subsurface
structures (e.g., former gas holders) at former MGP sites, and the depth of soil to
which this technology can practicably be applied.
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I ' , _ ^ , Chapters
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Applications and Cost
ISTD can be applied to shallow contamination (to a depth of 18 inches below
grade) through the use of Thermal Blankets and to deeper contamination through
the use of Thermal Wells. The technology is capable of treating a wide variety of
volatile and semivolatile organic contaminants including PCBs, chlorinated
solvents, pesticides, and petroleum wastes. The system is designed to control
emissions through use of a flameless oxidizer and activated carbon absorber.
Soil treatment by TerraTherm Company's ISTD at the Missouri Electric Works
(MEW) Superfund site in Cape Girardeau, Missouri, cost $120 to $200 per cubic
yard of soil. Sites with special water-handling requirements, custom well or
blanket configurations, or other size restrictions may cost up to $300 per cubic
yard.
Benefits , , ...'..
• Will work in a wide range of soil types
• Treatment possible in areas where traditional excavation and removal are
impossible
• Minimal disruption to nearby industrial operations or surrounding
neighborhoods; no digging and hauling of contaminated materials eliminates
exposure to toxic fumes and dust
• n ;••• •" (v " " _,,"' ip ;;<; _ • ••; JT";;:"„';;; - ] ;;•;/ ;;;" • '
• Will work close to or under existing structures, including buildings and
roadways
• Demonstrated ability to recover PCBs with residual soil concentrations well
below 2 ppm
Limitations
• ISTD has not been applied in full-scale at an MGP site to date, nor has it been
applied to MGP wastes (e.g., PAHs, tars)
1 '" i i , •' i .
" Unclear whether sufficient contaminant mass can be recovered to alter
groundwater quality
• Utility costs associated with heating may be high
Case Studies
Mare Island Naval Shipyard, California
A demonstration of ISTD was performed at the Mare Island Naval Shipyard in
California from October through November 1997. Soil samples at Mare Island's
former electrical shop site were contaminated with PCB Aroclors 1254 and 1260,
with average pretreatment concentrations of 54 ppm and maximum concentrations
of 2,300 ppm. The most stringent USEPA requirement for residual PCB
concentrations is 2 ppm following treatment.
The Mare Island demonstration was conducted as a collaboration between the U.S.
Navy, the Bay Area Defense Conversion Action Team, TerraTherm (a subsidiary
of Shell Technology Ventures, Inc.), and RT Environmental Services, who acted as
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general contractor. Agencies participating included the USEPA, California EPA,
and the Bay Area Air Quality Management District. A draft Toxic Substance
Control Act (TSCA) permit was issued by USEPA. California EPA worked closely
with TerraTherm to streamline the permit process and expedite approvals with the
California DTSC and the Bay Area Air Quality Management District while still
providing strong regulatory oversight.
The test site was chosen to demonstrate the effectiveness of ISTD near an existing
large structure without damaging it. Both Thermal Blankets (two 8-foot by 20-foot
units) and Thermal'Wells (12 wells containing heating elements drilled to a depth
of 14 feet) were used during the demonstration. The soil was heated to the boiling
point of the PCBs (approximately 600 °F); heated vapors were extracted through a
vacuum collection system utilizing a flameless ceramic oxidizer and an activated
charcoal filter. Resulting vapor releases to the atmosphere contained primarily
carbon dioxide and water. Both aspects of the demonstration were completed in a
total of 44 days. All post-treatment samples exhibited nondetectable PCB
concentrations (less than 0.033 ppm).
Contact
Rich G. Hansen, TerraTherm, (281) 544-2020 '•
Cape Girardeau, Missouri
A field demonstration of ISTD was completed at the Missouri Electric Works
Superfund site in Cape Girardeau, Missouri, from April 21 to June 1, 1997. This
demonstration removed high-concentration PCB contamination from clay soils
using 12 heater/vacuum wells installed in multiple triangular arrays with 5-foot
well spacing to a depth of 12 feet. Surface heating pads were placed at the center of
each triangle to assist in heating near-surface soils between the wells. A vacuum
frame structure was constructed around the well area to insulate the surface and
provide a seal. Steel sheets were fitted together and welded to the heater wells. A
16-inch-thick layer of vermiculite insulation was placed over the steel plates to
reduce heat losses and insulate the surface-piping manifold embedded in the
vermiculite (TerraTherm, 1997).
During remediation, electric resistance heating and vacuum were applied to the
wells for 42 days. Approximately 500 watts per foot were initially injected into the
clay soil at heater temperatures of 1,600 °F. Later in the process as the soil dried,
about 350 watts per foot could be injected. The thermal wells were connected to a
single manifold, which delivered the desorbed and partially treated vapors to a
thermal oxidizer unit. Stack sampling was performed to monitor for by-products
(e.g., hydrogen chloride) and to measure DRE of PCBs.
Soil temperatures were monitored throughout the experiment, and soil samples
were taken with a split-spoon sampler fitted with 6-inch brass coring sleeves to
verify the removal of contaminants. Temperatures above 1,000 °F were achieved in
the interwell regions, and PCB concentrations in the treated area were reduced
from a maximum of approximately 20,000 pp>m to nondetect (< 33 ppb) after
treatment by EPA Method 8080. The system DRE for PCBs was 99.98 percent
(TerraTherm, 1997).
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'"Contacts ,
Ms. Paulette France-Isetts, USEPA Region VII, 726 Minnesota Avenue, Kansas
City, KS 66101, (913) 551-7701
Mr. Donald Van Dyke, Missouri Department of Natural Resources, P.O. Box 176,
Jefferson City, MO 65102, (573) 751-3176
. Rich G. Hansen, TerraTherm, (281) 544-2020
,„!,„,!'! i,,, »: ......... '!' „ i ;) ' i'," i,," -li-i lint!1. .I1, '.; ...... i , 'i ........ ' i1;, "" „ , i ' ...... ';,' i,11'. n11 ..... \ ,, ' t, .1, ' » r " • >
5.2.2.2.3 Contained Recovery of Oily Waste (CROW™) *
Technology Description
The CROVV™ process was developed by the Western Research Institute (WRI) in
tfre 1 970s as^ a' hot-water flushing technology to aid in extraction of oil from sands
ai^d deep shale deposits. During the 1980s, the concept of hot water flushing was
revisited as a remedial technology. Hot- water displacement is used to move
accumulated oily wastes and water to production wells for aboveground
treatment. Hot water is injected through wells and in groundwater to dislodge
contaminants from the soil matrix. The mobilized wastes are then displaced
toward pumping wells by the hot water.
, ", ' "jis, • '• , ,'::- r <• ^ ' • •.' .............. ; • '- ' ".' " ..... i- ' -'" 1 ...... 'i- :;:i '•'"'. i ...... '
With the CROW process, subsurface accumulations of oily wastes are reduced by
reducing NAPL concentrations to residual saturation. Controlled heating of the
subsurface reverses the downward penetration of NAPL. The buoyant oily wastes
afe displaced to production wells by sweeping the subsurface with hot water.
NAPL flotation and vapor emissions are controlled by maintaining both
temperature and concentration gradients in the injection water near the ground
surface.
Operational Considerations
QROW"* requires both subsurface injection and extraction wells and an
aboveground treatment train. No pretreatment of soils is required for CROW™
......... ,,;,, ^operation.
Si; i ' | ' '
Applications and Cost
The CROW™ process has been demonstrated to treat PAHs, coal tars,
pentachlorophenol, creosote, and petroleum by-products.
„; •:, :;,;;" ignefits, ....... , , „ '„ , ',., „ " ....... " . ' , . '.
I Will work in a wide range of soil types
1! I' ill'"! i '„ '"I ...... |,| , ,,"',' ,» f, , ." ,, I '|!'l., . J. ' I . . ", "» I",, , i ' ........ • ., ! ...........
• Applicable in both saturated and unsaturated conditions
• Treatment possible in areas where traditional excavation and removal are
impossible
ii ' ' . -' , . ' ' . • • . I ' ' ' ,;
• Minimal disruption to nearby industrial operations or surrounding
neighborhoods; no digging and hauling of contaminated materials eliminates
exposure to toxic fumes and dust
• Will work close to or under existing structures, including buildings and
roadways
, ; ..... !! • I'iil.is „ ' " r . , ... ,. , ... , ............... .......
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Limitations
• Ability to control injected steam in the subsurface has been questioned
• Unclear whether sufficient contaminant mass can be recovered to alter
groundwater quality
Case Study
Stroudsburg, Pennsylvania
The Brodhead Creek MGP Site is an NPL site located in Stroudsburg,
Pennsylvania. The site occupies "a" flood''plain area orapproximately 12 acres at the
confluence of Brodhead Creek and McMichael Creek. The enhanced recovery
technology CROW™ was utilized to mobilize and extract free coal tar from the
subsurface at the site. The ROD specified that 60 percent of the free coal tar be
removed from the subsurface at the site. Because of sampling difficulties and the
heterogeneity of the subsurface, the tar volume was not quantified although it was
estimated to be several thousand gallons. Without a reliable starting figure,
removal of 60 percent was impossible to document.
However, based on treatability results, the enhanced recovery process was
expected to recover more than 80 percent of the free tar present. For this reason,
EPA allowed a performance standard to be written that the enhanced recovery
process would operated until the increase in cumulative recovery of coal tar
dropped to 0.5 percent or less per pore volume of water flushed through the
formation.
The affected soils at the site were 30 feet bgs, below the water table. The soils were
a sand/gravel mixture residing above a silty sand confining layer. The sand and
gravel soils did not allow for representative sampling of the subsurface to
determine chemical characterization although free DNAPL was observed in wells
in this portion of the site at depths from inches to several feet.
At the Brodhead Creek site, six injection wells were installed near the edges of the
tar deposit. Two production wells were installed near the center of the tar deposit.
Water and tar were pumped from the production wells at approximately 40
gallons per minute (gpm), which produced a drawdown within the wells and
induced a gradient from the injection points to the production points. The induced
gradient contained the heat within the target zone and prevented mobilized
contaminants from being released into the surrounding aquifer. Once the
tar/water mixture was pumped to the surface, tar and water were separated. The
tar was then stored in the gravity settling tanks and an oil storage tank until being
trucked off site for disposal. Approximately 33 gpm of separated water was
recycled through the water heater and injected into the six injection wells. The
remaining 7 gpm was pumped to a granular activated carbon fluidized bed reactor
where the organic constituents were biologically degraded. The treated water was
then pumped through four carbon adsorption units prior to discharge to Brodhead
Creek.
Because of sampling difficulties in the gravelly matrix and because of
heterogeneity of the subsurface soils, no pre- and post-remediation samples were
obtained that were representative of the subsurface. CROW™ was operated at the
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ill" -II ':,"
Chapter 5
Technologies for Source Material Treatment
Mte for one year. During that time, the CROW™ process swept approximately
5,000 to 6,000 cubic yards of soil in the subsurface to recover more than 1,500
gallons of DNAPL. Remediation at the site has been completed, and the
Equipment has been dismantled and removed. The final Remedial Action Report
has been accepted by USEPA Region III.
.Contacts
Mr. James F. Villaume, Pennsylvania Power & Light Company, (610) 774-5094
l5r. T.homas D. Hayes, Gas Research Institute^ (773) 399-8325
!"'[ ; MUSI : " . '!!! •',i, ;fiill,'•' !"" I"1 . : • , m>m.<» "" v'lt i',.'In .•> "'-."a f »f.' •'•'•' I',"1"! »'t " : '•' ' •'*: • '•:••
Mr. John Banks, USEPA Region III, (215) 566-3214
5.2.3 Asphalt Batching
wCzMi— - •, ". ,-'•'.•( t< .*. .n. ;.; • (i'..v ,:, (,• *y i; \ . .:;VH ••'<•;•• •••-.. • •
Asphalt batching is a widely demonstrated technology for reuse of
petroleum-contaminated soils. During asphalt batching, contaminated soils are
hlixed with asphalt, aggregate^ and other emulsions to create a product for use in
paving and backfilling. Asphalt batching can be a cold-mix or hot-mix process;
both are described below.
5.2.3.1 Cold-Mix Asphalt Batching
Technology Description
Cold-mix asphalt batching has been successfully used to immobilize and reuse
MGP-contaminated soils andjesidues. Asphalt batching is essentially an ex situ
stabilization process that binds contaminated soil and tarry residues into the
matrix of an asphalt product. Residues are mixed with wet aggregate and asphalt
emulsion at ambient temperature. The product is used as paving.
In the cold-mix asphalt batch process, wet aggregate material and an asphalt
emulsion are mixed and left at ambient temperature. The cold-mix batch product
is then cured or allowed to set undisturbed for a specific period that depends on
its ingredients. This curing process can begin either before or after the pavement
has been placed and compacted.
"the asphalt batching process is generally performed in several steps:
• Excavation and stockpiling of materials
• Material preprocessing (typically screening and/or crushing material to the
desired size)
• Stabilization with asphalt emulsion reagent
• Curing in a stockpile
• Using material for paving
Tl]ie final product is a material that can be used as a sub-base for paving in areas of
heavy vehicular traffic or possibly as surface paving in areas of light traffic.
jfGditional grading and paving or excavation are often required around the
treated material to accommodate its height.
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'Jllir li 'i :.
.If r
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Chapter 5
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Cold-mix asphalt batch products are typically produced either at a central plant
location or are mixed in place. The choice between producing them at a central
plant pavement or mixing in place must consider the intended use of the product
and the logistics and economics of staging an onsite treatment versus transporting
to an offsite facility (EPRI, 1997). A photograph of asphalt plant operations is
shown below.
Operational Considerations
This technology requires a treatability study to test leachability and engineering
properties of the treated material. The mix design is dependent on the
performance requirements of the finished product and the nature of the soil being
treated. Clayey soils are generally not appropriate for cold-mix asphalt batching
because a high clay content will reduce the strength of asphalt concrete. However,
soils with high clay or loam content can be mixed with high-grade aggregate to
produce a material used in lower-performance applications such as parking lots or
driveways. Similarly, the percentage of fine grains in contaminated soil should be
less than 20 percent passing the No. 200 sieve because excessively fine-grained
particles could lead to both an increase in the required asphalt content and
performance problems such as cracking and instability.
Applications and Cost
Before processing soil for cold-mix asphalt batching, an asphalt batching
contractor typically examines the physical and chemical characteristics of the soil
to determine whether it can be incorporated into a usable-quality pavement. For
offsite asphalt batching, the preacceptance criteria for using soil that contains tar
are plant specific and designed to meet certain chemical and physical thresholds.
None of the preacceptance criteria require that the chemistry of the MGP tar be
examined to see how closely it resembles that of asphalt (EPRI, 1997). The
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Technologies for Source Material Treatment
analytical requirements of the batch plant may include EPA-certified analyses for
VOCs and SVOCs, petroleum hydrocarbons, pesticides, herbicides, and metals.
.|| " ,!.. in i... . , „ mil , , . ., r ' **.i ''. . I ll III
Because there have been few fjuLL-scale applications of cold-mix asphalt batching,
cost information is limited. In California, vendor quotations range from $40 to $50
• . • ,, .• • ' . ii' ','IN:I , iNinfi •„ ,' " ' f'li'11, |L"' *,,,,,,,, , ,, C? in ,
per ton for onsite cold asphalt batching and $60 to $70 per ton for offsite batching
(transportation included).
Benefits
(: <"! Ill; i
ii !L "•
• Materialreused rather than; disposed of'offsite *"-•'
• Effective in immobilizing PAHs
Limitations
• Curing times can be long, particularly in cold weather
• Limits on acceptable percentage of fine-grained material
• Few examples of long-term durability of" the product
Case Studies '., ' ,_ "n| ,'"",', , " ', ^..' ^M.'' [ .]..'.".. ] '., . '„ .,
Monterey Former MCP Site
From 1900 to 1947, an MGP in Monterey, California^ provided gas to canneries in
the immediate area. This former MGP site was subsequently sold to the City of
Monterey, which planned construction of a gymnasium and pool complex. Site
investigations indicated that KlGP wastes were present in the form of an oxidized
ijlllliiii'i i' ' 'I, ;;i"i|i',i, O | Jp
ipixture of crude oil and bunker fuel to depths of 20 feet below grade. Soil at the
site consisted of sandy silt to clay material with a moisture content ranging from 6
to 22 percent.
Y . -i! • "j, i,,,f; j, , • . ;; • I. ,|i ., • ;.;; •i.)i. , i '.••.yk • ,i • j", .<•.. •:• •: • ; • , • .• tvt ... ill
Contaminated soil excavated from the former MGP site was Wended into an
asphalt product at a rate of 300 tons per hour using onsite portable mixing
equipment. The treated material was then trucked to a second location, also
owned by the city of Monterey. The treated material was used in place of %-inch
Class II aggregate base in a new construction project A 2-inch lift of dense hot mix
was applied as a wearing surface over the treated material.
Contact
Robert Doss, Pacific Gas and Electric Company, (415) 973-7601
Salt Lake City Former MGP Site
From 1872 to 1908, the American Barrel NPL site in Salt Lake City, Utah, was used
as a coal gas manufacturing plant with an oil gas plant for meeting peak demands.
The plant had one holder, one tar well pump, six tar wells, and two coal tar stills.
From approximately 1920 to 1950, creosote operations were conducted at the site.
From 1955 to 1987, the site was leased to a barrel refurbisher, American Barrel,
•who stored approximately 50,000 barrels on the property. The surface soils
contained high levels of PAHs, phenolic compounds, heavy metals and other
organic residues associated with the barrel storage activities. Subsurface soils had
high levels of PAHs and phenolic compounds.
!' ,„,,;'! , I
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Chapter 5
Technologies for Source Material Treatment
USEPA and state agency regulatory managers felt that recycling the material was
superior to landfilling or thermal desorption. Salt Lake City is a Clean Air Act
nonattainment area; therefore at the time of the remediation, the air quality
division of the state would not allow thermal desorption in the valley. Cold-mix
asphalt batching was selected over hot-mix asphalt batching for the proposed
remedial technology because the regulators felt that the hot mix was simply
another form of thermal desorption. USEPA and the state required that the asphalt
produced be used for roads and not for parks and schools.
Approximately 20,700 tons of soil and debris were removed from the site. About
12 tons of this material were determined to be hazardous (e.g., wood from the tar
wells) and shipped to an incinerator. About 1,300 tons of the material were
nonhazardous but were not acceptable for asphalt batching (e.g., contained metal
and other debris). These were shipped to a landfill. The remaining 19,400 tons of
material were incorporated into cold-mix asphalt, including bricks and concrete
from the gas holder, tars from the holder and tar wells, and contaminated surface
and subsurface soils. This produced 194,966 tons of cold-mix asphalt. The gravel
pits in the Salt Lake City area are very low in fines, and the contaminated soil had
a high percentage of fine-grained material, so the asphalt with the contaminated
soil was of higher quality than could be produced with local gravel. The original
estimates for blending the contaminated soil into asphalt were 10 percent
contaminated soil, 7 percent oil, and 83 percent aggregate. The contaminated soil
had enough tar and oils in it to replace 40 percent of the oil needed to produce the
cold-mix product.
The first batch of asphalt produced with 7 percent oil was not of good quality and
had to be removed and mixed with additional aggregate. The final batches of
asphalt contained 4 percent oil, 10 percent contaminated soil, and 86 percent
aggregate and were of very high quality. All the resulting asphalt product was
donated to counties and cities. The county and city that ultimately used the
product asked the contractor if the mix could be made as a regular product
because of its superior performance in Utah's cycles of cold and hot weather.
Contact
Jeff Tucker, Pacific Corp, (801) 220-2989
1993 Harbor Point Study, Utica, New York
In August 1993, Niagara Mohawk Power Corporation (NMPC) and United Retek
Corporation jointly performed a field demonstration of cold-mix asphalt batching
of soils at the Harbor Point site located in Utica, New York. Four 100-ton pilot
batches of soil were processed into pavements; three of the batches included MGP
soils containing tar; the fourth was a control sample of aggregate that met the
grading requirements of cold-batch pavements. The following evaluations were
then conducted:
• Leachabiliry and permeability testing to determine how well hazardous
constituents were immobilized
• Marshall stability tests to determine the structural applicability of the finished
product
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: .: Chapter 5
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* Road tests to evaluate how the fines content and constituents of the MGP soils
affected the product's environmental acceptability
,, ,n ,,,1, i .ii' ,, ,„ , , .i, ,, , ,„ '.I ,, ,,, , „ ,,,,, i , .. ...... », i n.i, i,,, ,,, , , • :,, , , „:, , ,, , ,
• Evaluation of the extent of contaminant migration from the installed product
as measured by a stormwater runoff test
KviL iLi!'1),1"1! "(I,
* Additional nondestructive deflection road tests to further evaluate structural
1 :! ' ' """ 1 ' " ": """ "!" ••"' ' !
performance
General conclusions of the testing indicated that the incorporation of MGP tar-
containing soils in cold-batch asphalt pavements reduced the leachability of the tar
constituents associated with these soils (EPRI, 1997). The data showed that the
more water-soluble compounds, such as benzene and naphthalene, would
continue to leach from these pavements after 21 days of curing. Further research to
establish the curing time to decrease leaching needs to be conducted. During the
study, unconsolidated material curing durations of the pavements was 2 weeks;
however, depending on the site-specific tar composition, curing durations may
need to be extended to ensure benzene and naphthalene concentrations in leachate
are minimized.
1 ' ' ',:
MGP asphalt products appear to be slightly lower in strength than PCS asphalt
while still meeting the minimum requirements specified by the Asphalt Institute.
The durability of MGP asphalt was inferior to the control asphalt in the Harbor
Point study, as evidenced by the development of some potholes in the test road
sections (EPRI, 1997)^
~ California Former MGP Site
A cold-mix asphalt batching study was performed for a California utility to assess
the potential for treating tar-containing soils from MGPs in standard cold-batch
pavements. Chemical data consisting of total and extractable PAHs were
e^alu^tedtp 'determine how successful the batching was in immobilizing
Contaminants. Several structural parameters were also evaluated to determine the
• ,, ,' , , " ,:, ' ' li' * , , , , ,
engineering properties of the pavement created by the batching process.
The results of the study indicated that some lighter-weight PAH compounds
leached from the pavement. However, the study also concluded that, had
additional leaching tests been conducted on the asphalt products after longer
curing periods, improvement in chemical immobilization might have been
observed. Further investigation into the relationship between curing times and
chemical immobilization was recommended {EPRI,1997). Engineering data also
indicated that as the MGP soil percentage was increased, engineering properties
deteriorated, most notably for durability parameters such as moisture loss.
Nonetheless, the pavements generated through the cold-mix asphalt batching
process were strong enough for general use (all batches exceeded the minimum
Marshall stability value of 2,200 Newtons) even though their moisture content was
higher than is generally accepted for cold-batch pavements (EPRI, 1997).
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Chapter 5
Technologies for Source Material Treatment
1995 to 1996 Harbor Point Study, Utica, New York
Niagara Mohawk Power Company conducted a joint hot- and cold-mix asphalt
batching study in 1995 and 1996 at its Harbor Point facility. As part of this study,
tar-containing soils from MGP sites were thermally desorbed before cold-mix
batching. The desorption step was necessary because of acceptance criteria
established by New York State Department of Environmental Conservation
(NYSDEC). Approximately 100 tons of previously excavated MGP soils were
mixed and designated for use in the project; these consisted of 30 percent coal tar
soils, 30 percent water gas tar soils, 30 percent processed construction spoils, and
10 percent tar emulsion soils (EPRI, 1997).
Following thermal desorption, two cold-mix designs were used. The first cold-mix
design was for a bituminous stabilized base course; the second was a dense graded
mix. Desorbed material was supplemented with clean aggregate: 56 percent
desorbed soil for cold-mix No. 1 and 40 percent desorbed soil for cold-mix No. 2.
The cold-mix products were prepared offsite by combining the desorbed material
and clean aggregate in a pugmill with a predetermined addition of asphalt
emulsion.
Two areas were selected for test panels using the cold-mix asphalt. Panel A
consisted of a composite design of a 3-inch-thick layer of bituminous stabilized
base course overlain with a 3-inch-thick layer of hot-mix top course. Panel B
consisted of adjoining 3-inch-thick sections of the two cold-mix products. After the
panels were placed, they were subjected to qualitative and quantitative
evaluations. Visual inspections were made over six months. The cold-mix products
improved over that period, consistent with previous observations that cold-mix
asphalt batch products require longer curing times. A quantitative analysis which
consisted of in-place density and deflection testing was also conducted. Based on
the results of these tests, the study concluded that the test panels performed
satisfactorily for a variety of applications, especially for roads subjected to light
and moderate traffic.
5.2.3.2 Hot-Mix Asphalt Batching
Technology Description
Pilot projects have used hot-mix asphalt batching to immobilize and reuse MGP-
contaminated soils and residues. Hot-mix asphalt batching is an ex situ
stabilization process that blends contaminated soil and tarry residues with
aggregate and asphalt emulsion to create a hot asphalt product. The high
processing temperatures of hot asphalt batching volatilize lighter weight
compounds found in MGP wastes (e.g., benzene) and promote formation of a
homogenous blend of aggregate and asphalt cement. Materials treated via hot-mix
asphalt batch are used in paving surfaces.
The hot-mix asphalt batching process is generally performed onsite or offsite in
several steps:
• Excavation and stockpiling of materials
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Chapters
Technologies for Source Material Treatment
• Material preprocessing (typically screening and/or crushing material to the
desired size)
• Heating and drying aggregate material prior to mixing
••••; • ' | ,|, • •' '"'
• Stabilization of dried material with asphalt emulsion reagents
* Compacting the finished product at temperatures well above ambient
• Using treated material for paving
The final product is a material that can be used as a sub-base for paving in areas of
heavy vehicular traffic.
Stack Emissions
Aggiegaic Screening
Aggreguc Bras
'PugtnUi/Mifter
„, . Asphalt Cement
Aggregate Dryer Cyclone
Operational Considerations
Hot-mix asphalt batching requires a treatability study to test leachability and
engineering properties of the treated materials. The mix design is dependent on
Marshall and Hveem testing of the performance requirements of the finished
product and on the nature of the material being treated. Clayey soils are generally
not appropriate because a high clay content will reduce the strength of asphalt
concrete. However, soils with high clay or loam content can be mixed with high-
grade aggregate to produce a material used in lower-performance applications
such as parking lots or driveways. Similarly, the percentage of fine grains in the
contaminated soil should be less than 20 percent passing the No. 200 sieve because
excessively fine-grained particles could lead to both an increase in the required
asphalt content and performance problems such as cracking and instability.
Applications and Cost
Prior to processing soil for hot-mix asphalt batching, an asphalt batching
contractor typically examines the soil's physical and chemical characteristics to
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Chapter 5
Technologies for Source Material Treatment
determine whether it can be incorporated into a pavement of usable quality. For
offsite asphalt batching, different plants have different preacceptance criteria
regarding use of soil that contains tar; these criteria establish certain chemical and
physical thresholds. None of the preacceptance criteria require that the chemistry
of the MGP tar be examined to see how closely it resembles that of asphalt (EPRI,
1997). The analytical requirements of a plant may include EPA-certified analyses
for VOCs, SVOCs, petroleum hydrocarbons, pesticides, herbicides, and metals.
Because there have been few full-scale applications of this technology, cost
information is limited. In California, vendor quotations have ranged from $60 to
$70 per ton for offsite asphalt batching (transportation included).
Benefits
• Material reused rather than disposed of offsite
» Effective in immobilizing PAHs and volatilizing VOCs
• One of the few viable technologies available for MGP tars
Limitations
• Potential for leaching of contaminant from the asphalt product
• Potential for release of volatile contaminants
• Potential for objectionable odors
• Excavation treatment primarily limited to gravelly soils and sands
• For offsite asphalt batching, possible difficulty in identifying a local facility
technically prepared and permitted to process MGP waste
• Few examples of long-term durability of the product
Case Studies
Wisconsin Power & Light
EPRI, in cooperation with Wisconsin Power & Light, performed a limited study on
the chemical and physical properties of hot-batched asphalt pavements that
incorporate tar-containing soils from MGPs. The aggregate blend produced for hot
batching consisted of 25 percent tar-containing soils, 20 percent clean sand, 40
percent bottom ash with 9/ie-inch diameter, and 15 percent bottom ash with 3/sz-
inch diameter. The tar-containing soils used in this study had total PAH
concentrations as high as 690 mg/kg. The only TCLP metal detected in a
pretreatment extract was barium. This constituent actually increased in extract
concentration after treatment. The average reduction in contaminants was 88
percent. TCLP extract concentrations were reduced to below the practical
quantitation limit (PQL) for all of the metals and all VOCs except benzene,
toluene, and naphthalene, which were reduced but still detected in the low parts
per billion range (EPRI, 1997).
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Chapter 5
Technologies for Source Material Treatment
Harbor Point Study, Utica, New York
Niagara Mohawk Power Company conducted a joint hot- and cold-mix asphalt
batching study in 1995 and 19§6 at its Harbor Point facility'. In this study, tar-
cphtaining soils from an MGP were thermally desorbed prior to hot-mix batching.
The desorption step was necessary because of the acceptance criteria set by the
state regulatory agency. Approximately 100 tons of previously excavated MGP
spils were mixed and designated for use in the project; these consisted of 30
percent coal tar soils, 30 percent water gas tar soils, 30 percent processed
construction spoils, and 10 percent tar emulsion soils (EPRl, 1997).
Following thermal desorption, two hot-mix designs were used. The first hot-mix
design was for a top course, and the second hot-mix design was for a modified
bituminous plant mix. Desorbed material wasi supplemented with clean aggregate:
30 percent desorbed soil for hot-mix No. 1, and 40 percent desorbed soil for hot-
mix No. 2. The hot-mix products were prepared at an offsite batch mix plant, with
hot asphalt and the desorbed material-aggregate blended in a pugmill. These,
products were then conveyed to the site in trucks. Temperature loss during
transport of the hot mix was approximately 25 °F, which was within acceptable
.limits., , r , ; '" .. „
Three areas were selected for test panels using the hot-mix asphalt. Panel A
consisted of a composite design of a 3-inch layer of bituminous stabilized base
course overlain with a 3-inch thick layer of hot-mix top course (hot-mix design No.
1). Panel C consisted of adjoining 3-inch sections of the two hot-mix products.
After the panels were placed, they were subjected to qualitative and quantitative
evaluations. Visual inspections were made over 6 months. A quantitative analysis
was also conducted which consisted of in-place density and deflection testing.
Based on the results of these tests, the study concluded that the test panels
performed satisfactorily for a variety of applications, especially for roads subjected
to light and moderate traffic!
I|;,,M i11.'
it '', «'
5.2.4 Bioremediation/Chemically Enhanced Bioremediation
, .! - ' • . f !' , . ' ' • | :'• . . i is. ; - i . • i
5j,2.4.1*Ex S»itu Bioremediation^ ' '.'.."'',',, 1"', ', i ",„', ',, ,
Bioremediation generally refers to the breakdown of organic compounds
(contaminants) by microorganisms. This degradation can occur in the presence of
Oxygen (aerobic) or in the absence of oxygen (anaerobic). Bioremediation
techniques create a favorable environment for microorganisms to use
contaminants as a food and energy source. Ex situ bioremediation processes treat
soil above grade using conventional soil management practices to enhance
degradation of contaminant. Generally, some combination of oxygen, nutrients,
and moisture are provided and pH is controlled. Bioaugmentation may be used, in
which microorganisms adapted for degradation of specific contaminants are
applied (USEPA, 1998).
Although not all organic compounds are amenable to biodegradation,
bipremediation techniques have been successfully used to remediate soils and
sludges contaminated by petroleum hydrocarbons, solvents, pesticides, wood
""-'" 5-32
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Chapter 5
Technologies for Source Material Treatment
preservatives, and other organic chemicals. The rate and extent to which
microorganisms degrade these contaminants is influenced by the specific
contaminants present, soil type, oxygen supply, moisture content, nutrient supply,
pH, and temperature. Other factors that influence the rate and extent of
degradation include the availability of contaminants) to the microorganisms, the
concentration of the contaminants (e.g., high concentrations may be toxic to the
microorganisms), and the presence of other substances toxic to the
microorganisms, (e.g., mercury), or inhibitors to the metabolism of the
contaminant (USEPA, 1998).
For MGP applications, biological treatment is generally most effective on BTEX
and 2- and 3-ring PAH compounds, with treatment efficiency declining for 4-, 5-,
and 6-ring PAH compounds because of their reduced solubility and availability to
microorganisms.
A common observation with bioremediation is that eventually the degradation
rate reaches a plateau and it is difficult to reduce concentrations further in a
practical manner. Residual PAHs after bioremediation, though detectable and
often above regulatory standards, may have little or no significant effect on the
environment. The leaching potential from residual PAHs in soils and direct
contact toxicity from these residuals are the subject of ongoing research.
The most commonly used ex situ biological technologies include landfarming,
biopiles (composting), and slurry phase biological treatment. Each of these is
described below.
5.2.4.1.1 Landfarming
Technology Description
Landfarming (also called land treatment) involves placing contaminated soil in
lined beds and periodically turning it over or tilling it to aerate the waste. The soil
is irrigated, and nutrients are added as needed to optimize growing conditions.
Land farming requires excavation and placement of contaminated soils onto
prepared beds or liners to control leaching of contaminants. Contaminated soil is
then treated in lifts that are up to 18 inches thick. After the desired treatment is
achieved, the lift is removed and a new lift is constructed. It is advantageous to
remove only the top of the remediated lift and then to construct the new lift by
adding more contaminated media to the remaining material and mixing. This
strategy inoculates the freshly added material with an actively degrading
microbial culture and can reduce treatment times (USEPA, 1998).
Operational Considerations
Soil conditions are controlled for ex situ bioremediation to optimize the rate of
contaminant degradation. Conditions normally controlled include:
• Moisture content (for biopiles and landfarming; solids content for slurry
treatment)
• Aeration
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I'll
:: • >• I ! ' Chapter 5
Technologies for Source Material Treatment
• pH
,':i!|,| , "' 'i , • ' • •„ " ,' ! "!•"!,„ •;•,;! „
• Nutrients
• Other amendments (e.g., bulking agents)
I'-!1'.. ,>,".• „ ';'•., ij; kll>. 4j,, i. i;.i" h >'" '"" •."••;. Vi'•'^"iijfte •:.', ..^': I:.v.-'i'.'•."• •'
Although a contaminant might have been shown to be biodegradable in the
laboratory or at another site, its rate and extent of degradation in each particular
location and specific soil condition depend on many factors. To determine whether
bioremediatipn is an appropriate and effective remedial treatment for the
contaminated soil at a particular site, it is necessary to characterize the
contamination, soil, and site, and to evaluate the biodegradation potential of the
contaminants. A preliminary treatability study for all ex situ bioremediation
methods should identify:
• Amendment mixtures that best promote microbial activity
• Percent reduction and lowest achievable concentration limit of contaminant
• Potential degradation rate
Landfarrning requires a large amount of space and is dependent on environmental
conditions affecting biological degradation of contaminants (e.g., temperature and
rainfall). VOC emissions and dust control are also important considerations,
especially during tilling and other material handling operations. Waste
constituents may be subject to "land-ban" regulation and thus may not be eligible
for treatment by landfarming.
Applications and Cost
Ex situ bioremediation methods have been used to treat petroleum hydrocarbons,
VOCs, and PAHs. As a rule of thumb, the higher the molecular weight (and the
more rings a PAH has), the slower the degradation rate. Landfarming is very
simple from a technology point of view.
•••-•' • • • •':•• '• " ''"••!• .:'•". •' •• '"' '."I •• A ' • •)•••' ' ''....'
Costs for treatment include approximately $75 per cubic yard for the prepared
bed. Studies conducted prior to treatment can range from $25,000 to $50,000 for
laboratory studies, and $100,000 to $500,000 for pilot tests or field demonstrations.'
Benefits
• Ex situ's main advantage is that it generally requires shorter time periods than
in situ treatment, and there is more certainly about the uniformity of treatment
because soil can be homogenized, screened, and continuously mixed
• Ex situ treatment is favored over in situ biological techniques for
heterogeneous soils, low-permeability soilsi areas where underlying
groundwater would be difficult to capture, or when faster treatment times are
required
• Bioremediation reduces the source of contamination
ii'tii- ,v i, .••• :, •'. • •', ,, ' • •• • ,: 'it: !•:,; ;;, 1 '>•['-, ' ,. , ,: •
Limitations
« None of the ex situ biological treatment options can completely remove organic
contaminants
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Chapter 5
Technologies for Source Material Treatment
• All ex situ treatment requires excavation of soils, with associated costs and
engineering for equipment, permits, and material handling/worker exposure
considerations
Case Study
Vandalia Road MGP Site
MidAmerican Energy has used the Institute of Gas Technologies (IGT) MGP-REM,
a chemically enhanced bioremediation process, for a full-scale remediation of its
• MGP site near Des Moines, Iowa. This was the first full-scale-use of-the MGP-REM
chemical/biological treatment process for coal-tar contaminated soils in a solid-
phase application (landfarming). The process combines the two complementary
remedial techniques of chemical oxidation and biological treatment. The MGP-
REM process uses the addition of Fenton's reagent (H2O2 plus Fe2+) to produce
hydroxyl radicals that start a chain reaction with the organic contaminants. These
contaminants, specifically PAHs, are transformed into products that are more
readily degraded by microorganisms; the ultimate products of the process are
carbon dioxide, water, and biomass (Srivastava, 1996).
The Vandalia Road site is a former landfill that contains residues from a former
MGP related to the Capital Gas Light Company site located in Des Moines. This
site operated from 1876 to 1957. The Vandalia Road MGP site was selected for a
full-scale test of the MGP-REM technology because of a number of site attributes:
• The site is located on property that is currently owned by MidAmerican.
• The site is located in a rural area, even though it is within the city limits of the
City of Pleasant Hill.
• The site is surrounded by company-owned farmland that could be used to
construct an adjacent treatment facility (Kelley, 1997).
After laboratory treatability studies were completed at the IGT laboratory facilities
in Des Plaines, Illinois, and the data indicated that the contaminated media at the
Vandalia Road MGP site were amenable to the MGP-REM process, the full-scale
treatment facility was constructed in the fall of 1996 and the spring of 1997. The
soil treatment portion of the facility was 100 feet by 300 feet, bermed and lined
with high-density polyethylene (HOPE). The two 12-inch lifts each had a capacity
of 1,000 cubic yards. Overall capacity for a given treatment phase was 2,000 cubic
yards. At the end of the first treatment phase, treated soil was removed from the
facility and used for backfill in the former excavation. Adjacent facility structures
included a water retention basin for runon and runoff control, an automatic
sprinkler system, a decontamination/soil processing pad and a field laboratory.
The total cost of the treatment facility and associated structures was approximately
$360,000 (Kelley, 1997). Additional phases of treatment may be required to
complete the site remediation.
In 1997, contaminated soil was excavated from the former landfill and placed in
the treatment facility. All of the soil that was excavated from the former landfill
was located below the groundwater level, so ,a dewatering area was constructed
adjacent to the excavation to assist in reducing the water content of the excavated
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[, , ; -" ' Chapter 5
Technologies for Source Material Treatment
rriedia prior to loading into the land treatment unit (LTU). Once sufficiently
dewatered to allow handling, the material was hauled to the adjacent treatment
facility and placed in the LTU (Kelley, 1997). A small bulldozer was used to spread
the materials across the facility to a consistent depth of 12 inches. Originally,
excavated material was to be processed through a screening plant to remove
oVersize debris; however, the material, even after dewatering, was too wet to pass
through the screening plant. Because the landfill appeared to consist of coal tar
materials placed there in liquid form, the debris typically found at an MGP site
(brick, concrete, timbers, etc.) was not-present, which reduced the need for
screening.
'HI tJ ! •," „;', ' .i',!1 " '" „ ; 1' I'1,,, if, !' ,li",, " ' , ,r?" "!l\ ii r 111!' 'I;'/,, I il'ljl , ,j, ",",; ., : ,| " , ,. : , , , ; ;' "
The routine operations for the biological portion of the process consisted of
aeration of the soil, addition of nutrients, and maintenance of the proper moisture
content. All of the equipment used for operation of the treatment facility was
standard agricultural equipment, such as field cultivators, rototillers, subsoilers,
and a two-bottom plow. The two-bottom plow was necessary to turn over the
entire lift of soil placed in the facility, for proper aeration. The plow was necessary
because the lower 4 to 6 inches of soil were so compacted by loading in the LTU
that the soil could not be turned over using a tiller or field cultivator. A critical
parameter for biological degradation is the moisture content of the media treated;
moisture content needs to be between 40 and 80 percent of field-holding capacity.
An irrigation system was installed to automate the soil moisture adjustments.
During the first year of operation, too much water, in the form of heavy rain,
Effected the facility's operations. This made aeration difficult and may have caused
a lack of oxygen, which may have inhibited biological degradation.
Chemical enhancement was also used in this bioremediation treatment process.
IGT's MGP-REM chemical treatment process consisted of three steps. First, the soil
pH was adjusted to approximately 5.0. Next, ferrous sulfate was added to the soil
and mixed by rototilling. Third, hydrogen peroxide was added to the process
resulting in a combination of direct oxidation and hydroxylation of the 4-, 5-, and
6-ring PAH compounds. Both of these chemical reactions (oxidation and
hydroxylation) generally increase the solubility of the PAH compounds and, as a
result, improve their biological availability to the bacteria (Kelley, 1997). The
Chemicals were added to the plot using commercially available agricultural
equipment modified for this project
i: 'irlliI I , ,; , , . " i , ,: ' . ,1', !i:!l!i' ' l,, 'VL ' ijliijli,'' 4| ''"'' i , > i:
During the first year of operation of the biological treatment phase, total PAH
reduction was 51 percent. Chemical treatment reduced total PAHs by an
Additional 20 percent. In addition, the reduction "of "4- to 6-ring compounds was
increased twofold. Overall, the MGiP-REM process used at the Vandalia Road
IAGP site reduced total PAHs by 70 percent. Based upon current cost estimates for
continued operation of the facility, MidAmerican expects to save approximately
- $1.2 million using this technology as compared to co-burning the soil in its power
plant facility near Sioux City, Iowa (Kelley, 1997).
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,:':;;;;: ,,; ..ij...!.!;.;,;
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Chapter 5
Technologies for Source Material Treatment
5.2.4.1.2 Bippiles
Technology Description
Biopile treatment is a variation of composting in which excavated soils are usually
mixed with soil amendments and placed in piles on a treatment area. Biopiles
often include leachate collection systems and some form of aeration. In most cases,
indigenous microorganisms are used. Soil amendments may include nutrients,
moisture, or bulking agents such as wood chips.
Moisture, heat, nutrients, oxygen, and pH can be controlled to/enhance
biodegradation. The treatment area will generally be contained with an
impermeable liner to minimize the risk of contaminants leaching into
uncontaminated soil. Biopiles often have a buried distribution system that passes
air through the soil either by vacuum or by positive pressure. As an alternative to
forced aeration, biopiles may also be turned regularly. Biopiles can be covered
with plastic to control runoff, evaporation, and volatilization (USEPA, 1998). Heat
can be generated in the piles, potentially providing for higher degradation rates
and winter operation.
Operational Considerations
Soil conditions are controlled for ex situ bioremediation to optimize the rate of
contaminant degradation. Conditions normally controlled include:
• Moisture content (for biopiles and landfarming; solids content for slurry
treatment)
• Aeration
• pH
• Nutrients
• Other amendments (e.g., bulking agents)
Although a contaminant might have been shown to be biodegradable in the
laboratory or at another site, its rate and extent of degradation in each particular
location and under specific soil conditions depend on many factors. To determine
whether bioremediation via biopiles is an appropriate and effective remedial
treatment for contaminated soil at a particular site, it is necessary to characterize
the contamination, soil, and site, and to evaluate the biodegradation potential of
the contaminants. A preliminary treatability study for all ex situ bioremediation
methods should identify:
• Amendment mixtures that best promote microbial activity
• Percent reduction and lowest achievable concentration limit of contaminant
• Potential degradation rate
For biopiles, batches of the same size may require longer retention times than in
slurry-phase processes. Static treatment processes may result in less uniform
treatment than processes that involve periodic mixing, which is difficult for
biopiles. Windrow composting is an alternative that overcomes that problem.
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Chapter 5
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Applications and Cost
Ex situ bioremediation methods have been used to treat petroleum hydrocarbons,
VOCs, and PAHsi As a rule of thumb, the higher the molecular weight (and the
more rings a PAH has), the slower the degradation rate. Biopiles are a little more
complex technologically than landfarming. The associated costs of this method
reflect the increased complexity. Costs for biopiles may run $100 to $200 per cubic
yard, exclusive of laboratory and pilot studies. Laboratory studies may cost
Between $25,000 and $50,000. Pilot tests or field demonstrations may cost $100,000
to $500,000.
Benefits
• Ex situ treatment's main advantage is that it generally requires shorter time
periods than in situ treatment, and there is more certainty about the uniformity
of treatment because soil can be homogenized, screened, and continuously
';;;;";_; mixed ' . ,
» Ex situ treatment is favored over in situ biological techniques for
heterogeneous soils, low-permeability soils, areas where underlying
groundwater would be difficult to capture, or when faster treatment times are
required
• •• " •" ' '"•" '" :" ''• • • "": '• .••'•'•: ;:f | '":"'" •• " I- •• •'" ;! ' ' ' ' '
• Bioremediatiqn reduces the source of contamination
Limitations .
• None of the ex situ biological treatment options can completely remove organic
contaminants
• '"! "l ' • j :: ' I . - :••.: -:• • : :
• All ex situ treatment requires excavation of soils, with associated costs and
engineering for equipment, permits, and material handling/worker exposure
considerations
Case Study ' ^ '
Navy National Test Site
A demonstration of biopile technology was performed to investigate and optimize
methods of pretreatment, construction, operation, and performance monitoring.
Soil contaminated'with petroleum hydrocarbons was 'treated in 500-cubic-yard
biopiles at Port Hueneme, California, following a treatability study that was
conducted to predict biopile performance and to identify optimum nutrient rates.
Two biopiles with the appropriate dimensions of 52 feet by 52 feet by 8 feet were
constructed on a liner, with an aeration system consisting of slotted PVC piping
and a positive displacement blower. An irrigation system vras also included. The
piles were covered with polyethylene, and a carbon emission control system was
installed (Chaconas, 1997). The demonstration was conducted in two phases from
1994 to 1996. In the first phase, soils consisted of brown silty sand with a trace of
clay (35 percent passing a No. 200 sieve), contaminated primarily with diesel fuel.
The second phase of the test used soils that consisted of brown clayey silt (52
percent passing a No. 200 sieve), contaminated wlth"a combination of diesel fuel
and heavier fuel oils. In both phases, the petroleum hydrocarbons were found to
be significantly weathered (degraded), as evidenced by the absence of normal
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Chapter 5
Technologies for Source Material Treatment
alkanes. In the second phase of the test, contaminated soils were pulverized with
the hammer mill prior to placement in the biopile; in the first phase soils were
directly placed in the pile.
Moisture and temperature probes, field respirometry testing, and innovative
laboratory techniques to track degradation of various hydrocarbon classes were
employed to monitor performance. Nondestructive field measurements of
biological respirometry (oxygen uptake), moisture content, and temperature
proved successful in monitoring the operation of the biopiles (Chaconas, 1997).
During the first phase, the technology removed 88 percent (reduction from an
average of 1,990 mg/kg to 232 mg/kg) of petroleum hydrocarbons in the diesel
range during 51 weeks. During 47 weeks of operation, the second phase achieved
an 88 percent reduction in the diesel range, from an average of 4,769 mg/kg to 592
mg/kg, and a 71 percent reduction in the motor oil range, from an average
concentration of 5,638 mg/kg to 1,617 mg/kg (Chaconas, 1997). In each phase, the
largest reductions occurred during the first 4 weeks of biopile operations, and
TEPH degradation rates slowed dramatically after 6 to 8 weeks of operation. This
"plateauing" of concentrations is consistent with result of other studies in the
literature for this technology. The hammer mill step in the second phase appears to
have been successful because comparable results were obtained although the
pulverized soil contained more clay. Degradation rates calculated from
respirometry testing data correlated well with TEPH degradation observed in
laboratory analyses.
5.2.4.1.3 Bioreactors
Technology Description
Slurry-phase biological treatment involves controlled treatment of excavated soil
in a bioreactor. Excavated soil is first physically processed to separate gravel, sand,
and debris, and the soil is then mixed with water to a predetermined concentration
dependent upon the concentration of the contaminants, the rate of biodegradation,
and the physical nature of the soils. Typically, a slurry contains from 10 to 50
percent solids by weight.
The solids are maintained in suspension in a reactor vessel and mixed with
nutrients and oxygen. Microorganisms may be added if a suitable population is
not present. When biodegradation is complete, the soil slurry is dewatered using
clarifiers, pressure filters, vacuum filters, sand drying beds, centrifuges or other
dewatering devices.
Operational Considerations
Soil conditions are controlled for ex situ bioremediation to optimize the rate of
contaminant degradation. Conditions normally controlled include:
• Solids content (for slurry treatment, moisture content for biopiles and
landfarming) •
• Aeration
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32;
•ISM' <;
:: :" ' ": '['•. •: • Chapters
Technologies for Source Material Treatment
i;.; 0
• pH
• Nutrients
• Other amendments (e.g., bulking agents)
Although a contaminant might have been shown to be biodegradable in the
laboratory or at another site, its rate and extent of degradation in each particular
location and under specific soil conditions depend on many factors. To determine
whether bioremediation is an appropriate and effective remedial treatment for the
contaminated soil at a particular site, it is necessary to characterize the
iSi ; j icr . ;• , , , ' s, i .,f. ' / , ,
contamination, soil, and site, and to evaluate the biqdegradation potential of the
contaminants. A preliminary treatability study for all ex situ bioremediation
methods should identify:
• Amendment mixtures that best promote microbial activity
• Percent reduction and lowest achievable concentration limit of contaminant
» Potential degradation rate
,;;.;. ;. / . . -V;, , ; , _;,;; .. . . . • , ; .. .. ' ;[- ;.';.» :•• [ ;•;',•, . .- ." . " .,
For bioreactors, sizing of materials prior to putting them into the reactor can be
difficult and expensive. Nonhomogeneous and clayey soils can create serious
materials handling problems. Dewatering of treated soil fines can be expensive,
and finding an acceptable method for disposing of nonrecycled wastewaters is
required.
I '
Applications and Cost
Ex situ bioremediation methods have been used to treat petroleum hydrocarbons,
VOCs, and PAHs. As a rule pf thumb, the higher the molecular weight (and the
more rings a PAH has), the slower the degradation rate. Bioreactors are the most
complex of the ex situ processes. The associated costs of this method reflect its
complexity. However, bioreactors provide the highest level of treatment attainable
for ex situ bioremediation of soils because they provide optimal conditions (e.g.,
mixing, temperature, pH). Costs for bioreactors run approximately $216 per cubic
yard, exclusive of laboratory and pilot studies. Laboratory studies may cost
between $25,000 and $50,000. Pilot studies or field demonstrations may run
between $100,000 and $500,000.
Benefits ^ ' ' ,
• Ex situ treatment's mairj.advantage is that it generally requires shorter time
periods than in situ treatment, and there is more certainty about the uniformity
of treatment because soil can be homogenized, screened, and continuously
mixed
• Ex situ treatment is favored over in situ biological techniques for
heterogeneous soils, low-permeability soils, areas where underlying
gfoundwater would be difficult to capture, or when faster treatment times are
required
• Bioremediation reduces the source of contamination
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Chapter 5
Technologies for Source Material Treatment
Limitations
• None of the ex situ biological treatment options can completely remove organic
contaminants
• All ex situ treatment requires excavation of soils, with associated costs and
engineering for equipment, permits, and material handling/worker exposure
considerations
Case Study
Niagara Mohawk Research
A field-scale pilot test of bioslurry treatment was performed in 1995 at the Niagara
Mohawk Power Corporation (NMPC) Remediation Research Facility in Utica,
New York. Sediment was dredged from Utica Harbor and placed in two 10,000-
gallon capacity slurry bioreactors where it was mixed by single top-mounted
mixers, aerated by blowers, and treated for 68 days.
Grain size analysis of the sediments dredged from the harbor indicated that the
material was approximately 34 percent sand, 52 percent silt, and 14 percent clay.
The target slurry density for the pilot test was 20 percent by weight, and a working
slurry volume of 7,300 gallons was used in each tank. Prior to treatment, the
sediments exhibited a hydrocarbon odor and sheen. Initial concentrations of BTEX
and PAHs were 86 and 651 mg/kg, respectively. Oil and grease analysis showed a
concentration of 1.4 percent (dry weight), and total organic carbon was measured
at 5.8 percent (dry weight).
Following bioslurry treatment, the sediments did not exhibit the hydrocarbon odor
or sheen that had been observed when the material was dredged. No detectable
BTEX was present in the sediments, and the total PAH concentration was
measured at 203 mg/kg. The overall DRE for PAHs was 69 percent, ranging from
a DRE of 89 percent for 3-ring PAHs to a DRE of 0 percent for 6-ring PAHs. The
majority of PAH degradation was achieved within the first 21 to 35 days of
treatment. The oil and grease concentration was measured following treatment at
0.31 percent, a reduction of 78 percent.
The sediments were tested before and after treatment using a 14-day earthworm
test. Prior to treatment, only 24 percent of the test organisms survived using
undiluted dewatered sediment; after treatment, 94 percent of the organisms
survived. Decanted wastewater post treatment was found to be toxic to fish, in
part because of residual nutrient concentrations from the treatment process. These
results indicate that management of residual nutrients in the wastewater effluent
will be required as part of full-scale bioslurry treatment.
The potential for leaching BTEX and PAHs before and after bioslurry treatment
was measured using the EPA synthetic precipitation leaching procedure test
(SPLP). Following treatment, no BTEX or PAHs were found in the SPLP extract
above the detection limit.
This remedial technology demonstration confirmed that bioslurry treatment of
aquatic sediments can be performed at a field scale. Although bioreactor treatment
of the sediments did not achieve the removal efficiency typical of more aggressive
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, i.,t ! * "i
',!>!' 1,1' • ' I , "
. ,.i:«".- ,:,„ •,. Chapters
Technologies for Source Material Treatment
iyiethods such as incmeration or thermal desorptioh, this demonstration suggests
that, after bioslurry treatment, sediments may be placed in aquatic or terrestrial
.. environments. Using risk-based treatment criteria for such placement may be an
environmentally acceptable option for biologically treated sediments.
Contacts
jean-Pierre Moreau, Niagara Mohawk Power Corporation, 300 Erie Boulevard,
^(Vest, Syracuse, NY 13322, (315) 428-6808
Dr. Thomas D. Hayes, Gas Research.Institute, ,8600, West,Bryn;Mawr, Avenue,
Chicago, IL 60631, (312) 399-8325
James B. Harrington, P.E., New York State Department of Environmental
Conservation, 50 Wolf Road, Albany, NY, (518) 457-0337
1 'fl1*,! 'Hi'' "" r i,' ' • ". *, " " L':'' Si' '• a ' i,"'"! -','!, •' ,?»! ' ..i" ' Ji ;'' : j; I' , "i i 'i r.i''!': ,' ii" !'• , , "• ;„, : hi, 'Jh, n . • .1 »i;; •; ij;, • f it < |.,, • ;, ;• i , h ;.',',• .' ,;
i'"1:!!: :" ' i«, "'' ,;» "• "I?1 ... * ' ' i, '•• " ' ... 'lhi"' n lh+" " s!1' :j in1' "«, •: " , - ! „ •- • |u >' „ •" ',
5.2.4.2 In Situ Bioremediation/Bioventing
Technology Description
Bioremediatiori generally refers to the breakdown of organic compounds
(contaminants) by microorganisms. This degradation can occur in the presence of
oxygen (aerobic) or in the absence of oxygen (anaerobic). Bioremediation
technologies stimulate the growth of microorganisms and their use of
contaminants as a food and energy source. Biodegradation processes are enhanced
by creating a favorable environment for microorganisms through the introduction
of some combination of oxygen (aerobic), nutrients and moisture, and by
controlling the temperature and pH of the soil or groundvrater environment.
Bioaugmentation is another bioremediation technology in which microorganisms
adapted for the degradation of specific contaminants are added to enhance the
biodegradation process (USEPA, 1998). Bioventing is a third bioremediation
technology. It uses conventional soil vapor extraction (SVE) equipment to
introduce oxygen to indigenous soil microorganisms.
Although riot all organic compounds are amenable to biodegradation,
bioremediation has been successfully used to clean up soils and sludges
contairiinated by petroleum hydrocarbons, solvents, pesticides, wood
preservatives, and other organic chemicals. Aerobic biodegradation is the primary
mechanism for in situ biotreatment of petroleum hydrocarbons and PAHs in soil.
The rate at which microorganisms degrade contaminants is influenced by the
Concentrations of contaminants present, the degree of contact between the •
microorganisms and the contaminants, the oxygen supply, moisture, temperature,
pH, and nutrient supply in the soil or water to be treated (USEPA, 1998). In situ
biological treatment technologies are sensitive to certain soil parameters. For
example, the presence of clay or humic materials in soil can cause variations in
biological treatment process performance. For MGP sites, biological treatment of
PAHs is generally most effective on BTEX and 2- and 3-ring PAH compounds;
treatment efficiency declines for 4-, 5-, and 6-ring PAH compounds because of
their reduced solubility and availability to microorganisms.
i"" » A • i i , ,•> ' ' ;•» li •„ : t IL ,'*lr s ,4,' , •• . .• •. «- i ;
Of the available in situ biological treatment technologies, bioventing has been the
most frequently demonstrated. As previously mentioned, this technology
stimulates the in situ biodegradatidn of aerobically degradable compounds in soil
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Chapter 5
Technologies for Source Material Treatment
by providing oxygen to existing indigenous soil microorganisms. Bioventing uses
conventional SVE equipment to stimulate biodegradation by providing oxygen to
indigenous soil microorganisms. However, bioventing uses low air-flow rates to
provide just enough oxygen to sustain microbial activity while minimizing
contaminant volatilization (GRI, 1996), which is the opposite of the high air-flow
rates used in treatment by SVE. Bioventing systems may either use a vacuum
approach to draw air and oxygen into the contaminated subsurface area or a
positive pressure system to inject air into the contaminated subsurface through
wells. Extraction wells may be used at the perimetepof th&treatment zone to
control vapors. Bioventing is a medium- to long-term technology applicable only
to soils in the vadose zone, and cleanup times range from a few months to several
years (USEPA, 1998).
Operational Considerations
Soil characteristics that affect microbial activity (and therefore biodegradation
rates) include pH, moisture, presence of nutrients, (e.g., nitrogen and phosphorus),
and temperature. The optimal pH range is 6 to 8 for microbial activity although
microbial respiration has been observed at sites that have soils outside this range.
Optimum soil moisture is very soil-specific. For bioventing, too much moisture can
reduce the air permeability of the soil and decrease its oxygen transfer capability.
Too little moisture inhibits microbial activity. A sufficient population of
microorganisms needs to be present to attain reasonable degradation rates.
Applications and Cost
In situ bioremediation is typically useful for treating the portion of MGP residues
containing lower molecular-weight hydrocarbons (e.g., volatile and semi-volatile
portions of coal tar.) Bioventing and in situ bioremediation techniques have been
successfully used to treat soils contaminated by petroleum hydrocarbons,
nonchldrinated solvents, pesticides, wood preservatives, and other organic
chemicals. For example, the U.S. Air Force Bioventing Initiative is demonstrating
that this technology is effective under widely varying site conditions. As of 1996,
data have been collected from 125 sites (Leesch and Hinchee, 1996). Regulatory '
acceptance of bioventing has been obtained in 35 states and in all 10 USEPA
Regions (Leesch and Hinchee, 1996).
The time required to remediate a site using bioventing or in situ bioremediation is
highly dependent upon the specific soil and chemical properties of the
contaminated media. Costs for operating a bioventing system typically are $10 to
$70 per cubic meter of soil ($10 to $60 per cubic yard; AFCEE, 1994). Factors that
affect the cost of bioventing include contaminant type and concentration, soil
permeability, injection well spacing and number, pumping rate, and off-gas
treatment. Bioremediation costs vary considerably depending on the volume of
soil to be treated, specific soil and chemical properties of the contaminated media,
and site-specific requirements for bioremediation enhancements or nutrients. The
technology does not have high capital or operation and maintenance costs because
it does not require expensive equipment and relatively few personnel are involved
in the operation and periodic maintenance of the bioventing system.
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!' • •'•'•' :', I :i ' , \,, Chapters
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•••/'. /Benefits '
• Cost savings achieved by avoiding excavation and transportation of soil
I 'i t ' ,
• Generally inexpensive
" Contaminants partially destroyed
• "Low tech" and relatively easy to implement.
• Minimal disruption of current operations at sites
• Bioventing demonstrated highly effective for treating lighter-weight petroleum
hydrocarbons (e.g., gasoline)
""" Limitations p ' ' ': ' [
"I Generally more time required than for ex situ processes
i Verification that contaminants have been destroyed sometimes difficult
* Treatment uniformity uncertain because of variability in soil characteristics
and contaminant distribution
« Not demonstrated effective for higher-molecular-weight petroleum
hydrocarbons or PAHs
» Bioventing performance reduced by shallow groundwater table, saturated soil
lenses, or low-permeability soils; low soil moisture content may limit
bioventing effectiveness.
• Monitoring of offgases at soil surface possibly required for bioventing; possible
vapors buildup in basements within the radius of influence of air injection
wells can be alleviated by extracting air near any facility of concern
;* Case Studies ^ ' f ^ ^ ^ „
Tar Site, St. Louis Park, Minnesota
A demonstration of bioventing was conducted at the Reilly Tar and Chemical
Corporation site in St. Louis Park, Minnesota. This site formerly housed a coal tar
refinery and wood-preserving facility at which creosote in mineral oil served as
the primary preservative. The facility operated from 1917 until 1979. A pilot-scale
biqyenting demonstration began in November 1992 to determine whether the
technology was effective for PAHs.
The pilot-scale bioventing system consisted of a single-vent well with 12 tri-level
soil-gas monitoring points. The vent well was screened from 5 to 15 feet below
grade and was placed in the center of a 50-foot by 50-foot treatment area that was
selected based on depressed oxygen concentrations measured during an initial soil
gas survey(Alleman, 1995) .The soil-gas monitoring points were placed radially
pufward at 10,20, and 30 feet from the vent well in four directions towards the
corners of the plot. The probes were set at 4,6, and 8 feet below grade. A control
area was established approximately 150 feet to the northwest of the treatment area.
Soil samples were collected from both the treatment and control areas to quantify
PAH concentrations prior to bioventing. Respiration measurements were made to
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estimate PAH biodegradation as a means of monitoring the progress of the
bioventing. In situ respiration tests were conducted every 3 months to measure
oxygen utilization rates and calculate biodegradation rates (Alleman, 1995).
Bioventing at the tar site achieved a greater than 10 percent reduction per year in
total PAHs during the first two years of the study. Respiration measurements
indicated that 13.4 percent and 17.3 percent degradation of total PAH content was
possible during the first and second year, respectively. Although not all of the
respiration can be attributed conclusively to PAH metabolism, strong correlations
were found between the PAH concentration and biodegradation rates (Alleman,
Loring Air Force Base, Maine
Bioventing was selected to treat petroleum-contaminated soils at Loring AFB in
Maine. Sixteen bioventing systems were installed and all continue to operate.
These systems cover approximately 17.6 acres and are treating a combined total of
more than 500,000 cubic yards of fuel-contaminated soil. The major contaminants
being treated by bioventing are TPHs, benzene, toluene, and xylene. The cleanup
goal for TPHs is 870 mg/kg, based on risk to human health. Cleanup criteria for
benzene, toluene, and xylene are based on soil leaching potential.
Operational difficulties have been encountered because of soil heterogeneity, high
or perched groundwater, and inability to collect soil-gas samples. Oxygen
utilization rates from more than 40 respiration tests range from 0.01 to 7.5 percent
per hour, with the site median being 0.63 percent per hour (Underbill, 1997).
5.2.5 Containment
Technology Descriptioin
Containment methods are used to prevent or significantly reduce migration of
contaminants in soils or groundwater and to prevent human and animal exposure
to contaminants. Containment is generally necessary whenever contaminated
materials are to be buried or left in place at a site. In general, containment is
chosen when extensive subsurface contamination at a site precludes excavation
and removal of wastes because of potential health hazards, prohibitive costs, or
lack of adequate treatment technologies (USEPA, 1998).
Containment or site capping can be implemented in various forms. The technology
can be as simple as an asphalt or concrete cap or as elaborate as RCRA Subtitle C
or Subtitle D engineered landfill cap. The goals of cap design are to prevent
rainwater infiltration through impacted soils, prevent soil vapors from rising to
the surface, and provide a barrier between animal and plant life and the
underlying contaminated media. The final design of a cap depends on the
structural and performance requirements of the particular area. The cap should be
designed to facilitate water collection into drains and to minimize ponding. Cap
maintenance consists of inspection for and repair of cracks.
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Cap design is site-specific and depends on the intended or existing use of the
former MGP site. The most effective single-layer caps are composed of concrete or
bituminous asphalt. These materials are used to form a barrier between the waste
and the surface environment. All covers should be designed to prevent the
^tuB'' effect, which occurs when a more permeable cover is placed over a less
plrrneaBIe bottom liner of natural subsoil. When this occurs rainfall infiltrates the
cover and ponds on the less permeable underlying material, thereby "filling up"
the bathtub (USEPA, 1998).
:t
jCandfilJ caps are generally complex and can range from a one-layer system of
Vegetated soil to a complex multi-layer system of soils and gebsynthetics. The
most critical components of a landfill cap are the barrier layer and the drainage
layer. The barrier layer can be low-permeability soil (clay) and/or geosynthetic
clay liners (GCLs). The low-permeability material diverts water and prevents its
passage into the underlying waste. The higher permeability materials placed atop
the barrier layer carry away water to prevent percolation through the cap. Soils
used as barrier materials are generally clays compacted to a hydraulic conductivity
no greater than 1 x 10"6 cm/sec. Compacted soil barriers are generally installed in
6-inch minimum lifts to achieve a thickness of 2 feet or more (USEPA, 1998).
Operational Considerations
Aspects to be considered in cap design include the existing and future uses of the
facility, the leaching potential of the waste materials, and the location of the waste
relative to the groundwater table. Other considerations include the ease of
relocating existing facility operations during construction activities.
,• , •, ;','"' , ; • • ; i1"1 :] iv ;, ' '!"
Site capping mitigates migration, but does not lessen toxicity, mobility, or volume
of hazardous wastes. Caps are .most effective where most of the underlying waste
js.above the water table. A cap, by itself, can prevent only the vertical entry and
migration of precipitation into and through waste, not the horizontal flow of
groundwater through the waste. In many cases, caps are used in conjunction with
vertical cutoff walls to minimize horizontal flow and migration. The effective life
of the cap can be extended by long-term inspection and maintenance. Vegetation
must be eliminated, from the cap area because roots may penetrate deeply.
Precautions must be taken to assure that the integrity of the cap is not
compromised by surface activities.
Laboratory tests are needed to ensure that the materials being considered for cap
components are suitable. Testing includes grain size analysis, Atterberg limits, and
compaction characteristics (USEPA, 1998). The key engineering soil properties that
ifijUst be defined are shear strength and hydraulic conductivity. Shear strength
may be determined with the unconfined compression test, direct shear test, or
uiaxial compression test. Hydraulic conductivityof soils may be measured in the
laboratory by the constant or falling head permeability test. Laboratory tests are
also needed to ensure that geosynthetic materials will meet cap requirements
(USEPA, 1998).
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Quality assurance for cap construction is the most critical factor in containment;
USEPA has generated a technical guidance document on this subject; this technical
guidance should be consulted during design and construction.
Applications and Cost
Containment approaches vary from repaying existing blacktop to installing a
single- or double-layer concrete cap to installing a full-blown RCRA landfill cap.
In between these extremes are double-layer concrete caps and non-RCRA Subtitle
D landfill caps.
A RCRA Subtitle C multi-layered landfill cap is a baseline design that is suggested
for RCRA hazardous waste applications. This cap generally consists of an upper
vegetative (topsoil) layer, a drainage layer, and a low-permeability layer made of a
synthetic liner over 2 feet of compacted clay. Compacted clay liners are effective if
they retain a certain moisture content and are susceptible to cracking if the clay
material dries out. Therefore, other cap designs are usually considered for arid
environments.
RCRA Subtitle D requirements are for nonhazardous municipal solid waste
landfills. The design of a landfill cover for a RCRA Subtitle D facility is generally a
function of the bottom liner system or natural subsoils present. The cover must
meet the following specifications (USEPA, 1998):
» The material must have a permeability no greater than 1 x 10 "5 cm/s or
equivalent permeability of any bottom liner or natural subsoils present,
whichever is less.
• Generally the infiltration layer must contain at least 45 cm of earthen material.
• The erosion control layer must be at least 15 cm of earthen material capable of
sustaining native plant growth.
• Concrete is somewhat less susceptible to cracking and is more durable than
asphalt (engineered or standard) as a capping material.
The costs of single-layer concrete and asphalt caps are dependent upon the cost of
the material and local labor costs. Approximate per-acre construction costs for
concrete caps are $140,000; for asphalt caps and multi-layer, $170,000; for soil caps,
$45,000. Each type of cap involves some operations and maintenance costs. Costs
per acre per year are estimated as follows: concrete caps, $2,000; asphalt caps,
$4,000; multi-layer and soil caps, $20. Additional cost information can be found in
the Hazardous, Toxic, and Radioactive Wastes Historical Cost Analysis System
developed by Environmental Historical Cost Committee of Interagency Cost
Estimation Group.
Benefits
• Requires only short installation times ;
• Unlike ex situ soil treatment, does not require excavation of soils and thus
avoids some of the associated disadvantages (increased costs from engineering
design of equipment, permits, waste handling)
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Generally less expensive than other technologies
, : i • "i ; • ."' -i -; . ; (.-I : •;
Minimizes potential worker exposure onsite at an operating facility
• Prevents vertical infiltration of water into wastes and subsequent vertical
migration of contaminants
• Creates a land surface that can support vegetation and/or be used for other
purposes
Limitations
• Generally contains wastes, does not address future liability at site
1 . n , i , ," ™ ' i S| ', ' h
• Requires periodic inspections for settlement, ponding of liquids, erosion, and
naturally occurring invasion by deep-rootecl vegetation
• Usually requires groundwater monitoring for verification of containment
i ' , , ,;•,,..,;, Ji i,,!, ,! „, ,." ';-;,,'„'':",is : '. '1. •'.. „ i I; "i : , ,. I ,; ", ',
•'" Typically requires deed restrictions or other institutional controls
« Typically requires long-term operation and maintenance programs
Case Study ' | | "
Jackson MGP Site, Jackson, Michigan
|lie Jackson, Michigan, site housed an MGP that operated from 1887 until 1947
and was demolished during the 1950s. The current land uses at the site include a
residential apartment complex, city park, and elementary school playground. The
remedy selected for a portion of the site was a cap consisting of an impermeable
HDPE membrane,covfrep1l.vvitjbi,3.feet qf spil for frost protection. The cap was
designed and constructed according to Michigan's requirements for an
impermeable cap at a hazardous waste landfill.
".>', "" ' ' '•••:•- • : "'. '".I i i;" ":'; .-' :•'• '••••"•- • ;;jvif "'" •'•}•'•'• '.:•.'; "••-• "• *>•
The remedial goals for the cap were to: eliminate a potential direct human contact
hazard posed by PAHs present in subsurface soils and fill materials at
Concentrations in excess of Michigan's residential criteria; and limit the leaching of
PAHs to groundwater to less than Michigan's health-based drinking water criteria.
Tjae matrix covered by the cap is a mixture of topsoil, sandy subsurface soils, and
fill materials consisting of slag, wood, coal, and "brick." A concrete slab foundation
for a former gas holder is also present below ground! The area covered by the cap
is approximately 2 acres. A cap was chosen because removal of the wastes would
have resulted in greater human exposure.
" :' ' ".'. ;'• ,|" "I ••• I " '
T%ptal PAH concentrations in the subsurface soils and fill materials range up to
9,000 mg/kg. The cap is not expected to affect the concentration of PAHs.
However, the cap will control exposure by eliminating a direct human contact
pathway at the site. The cap is also expected to serve as a source control by
eliminating potential source of PAH loading to groundwater.
The volume ofsubsurface soilsland fill ^rnaterialstap'actecl'fcy'P'AHsancl covered
by the cap is estimated to be approximately 10,000 cubic yards. The Michigan
Department of Environmental Quality approved the cap as an interim remedial
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action (pending completion of the remedial investigation on other portions of the
site) in May 1995. Construction of the cap was completed in August 1995.
Contact
G.L. Kelterborn, (517) 788-2484, fax (517) 788-1064
5.2.6 Stabilization/Solidification (SIS)
5.2.6.1 In Situ Stabilization/Solidification
Technology Description
In situ solidification/stabilization (S/S) is a remediation technology that can be
used for MGP-related soil contamination. In-place cutoff walls are constructed,
and soils and residues are treated in situ to depths of 30 feet or more. In situ S/S
involves mixing soil with chemical binders such as cement, bentonite, additives,
and proprietary chemicals that immobilize contaminants of concern (e.g., PAHs).
One method of in situ S/S uses a series of overlapping, large-diameter stabilized
soil columns. A crane-mounted drill attachment turns a single-shaft, large-
diameter auger head consisting of two or more cutting edges and mixing blades.
As the auger head is advanced into the soil, grout is pumped through a hollow
drill shaft and injected into the soil at the pilot bit. Cement, bentonite, additives,
and proprietary chemicals may also be mixed into the grout. The cutting edges
and mixing blades blend the soil and grout with a shearing motion. When the
design depth is reached, the auger head is raised to expose the mixing blade at the
surface and then advanced again to the bottom. Once the shaft is completed,
another column is drilled using a specified pattern of overlapping columns; what
is left behind is a series of interlinked columns. '
The following is a schematic diagram showing the mixing augers.
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A second method of in situ S/S requires the MGP wastes to be stabilized in
shallow soil (approximately the upper 2 feet). In this scenario, admixtures
containing Portland cement, bentonite, and other chemicals are placed directly on
the ground surface. Tillers and sheepsfoot rollers are used to mix and compact the
§oil. ' ' [
Operational Considerations
The success of S/S methods depends on soil type and properties, contaminant
type and concentrations, moisture content,.organic content, density t permeability,
unconfined cpmpressive strength, teachability, pH, and particle size. A treatability
study is recommended for this technology to create a mix that minimizes leaching
and has appropriate strength characteristics. The creation of concrete-like material
in the subsurface may severely limit access to utilities, which may need to be
permanently rerouted. The machinery used for in situ S/S via mixing augers is
approximately the same size as a large drilling rig; low overhead lines may limit
the use of this technology.
Applications and Cost
Inorganic constituents have traditionally been the target contaminant group for in
situ S/S. The technology has limited effectiveness against SVOCs and no expected
effectiveness against yOCs. It has been applied to MGP sites for PAH treatment.
Costs for cement-based S/S techniques vary widely according to materials or
reagents used and their availability, project size, and the chemical nature of the
Contaminants. In situ mixing/auger techniques average $40 to $60 per cubic yard
in shallow applications.
'.Benefits, ' , , .. '.",,,,,'..'!
I Immobilizes contaminants
• Neutralizes soil
• Improves bearing capacity or shear strength of treated area
• Leaves treated area, if reinforced, able to withstand differential soil and
hydrostatic loading
Limitations
• Possible leaching of volatile or mobile constituents
• Creation of concrete-like material in the subsurface (may severely limit access
to utilities, which may need to be permanently rerouted)
• Possible significant increase in volume of mixture (up to double the original
volume)
• Reagent delivery and effective mixing more difficult than in ex situ
applications
Case Studies _'_' i: { i
Columbus, Georgia, Former MGP Site
A full-scale demonstration of in situ S/S for MGP contamination was performed in
Columbus, Georgia, where an estimated 94,000 cubic yards of soil at a town gas
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site were stabilized (Geo-Con, 1993). The 4-acre site is located in the central
business district of Columbus and is bounded to-the west by the Chattahoochee
River. Contaminated soils extended over a 15-foot interval beneath 10 to 20 feet of
miscellaneous fill. Depth to groundwater was approximately 20 feet bgs, and the
10-foot saturated zone was underlain by bedrock.
In situ treatment was accomplished by mixing/drilling a Type I Portland Cement
slurry with the soil to an approximate depth of 35 feet using an 8-foot-diameter
auger. A containment wall was installed adjacent to the river; the remainder of the
site was stabilized by advancing augers at approximately 1,800 overlapping
locations.
Prior to treatment, contamination of the MGP-affected soils was as high as 300
mg/kg of VOCs, 2,400 mg/kg of PAHs, and 5,500 mg/kg of petroleum
hydrocarbons. The performance criteria for the concrete mixtures were:
• Ultimate Compressive Strength (UCS) of 6.0 psi within 28 days
• Permeability of no more than 1x10 '6 cm/s for the containment wall and no
more than 1x10 "5cm/s for the remainder of the site
• PAH concentration in TCLP leachate not to exceed 10 mg/L
UCS testing was conducted on all samples, and permeability and leach testing was
performed on 10 percent of the samples obtained from approximately 300
randomly selected shafts of freshly stabilized soils. Any shafts that did not comply
with the performance criteria had to be reprocessed. After the soils were stabilized,
the area was covered with an HDPE liner and backfilled soil and then converted
into a park and walkway.
Contacts
Darahyl Dennis, Georgia Power Company, Atlanta, GA 30302, (404) 526-7064
Harold F. Reheis, Georgia Department of Natural Resources, Atlanta, GA 30334,
(404)656-4713
Manitowoc, Wisconsin, Former MGP Sitti
The Wisconsin Fuel & Light site is a former MGP facility located along the
Manitowoc River in Manitowoc, Wisconsin. The site had been filled with
uncontrolled material, including debris and other material typically used behind
sea walls. Portions of the foundations from trie previous coal gasification
structures also remained. The underlying soils at this site were contaminated with
coal tars; these were stabilized using a reagent mixture of activated carbon,
cement, fly ash, and organophilic clays.
The S/S treatment of impacted soil was accomplished by simultaneous injection
and mixing of cement-based grout using 4- and 7-foot-diameter tools. This created
a series of overlapping, vertically oriented columns of stabilized soil. The rotary
and vertical movement of the boring/mixing tool was designed to assure effective
mixing. In 1994 alone, a total volume of 6,859 cubic yards of soil was stabilized
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with 209 soil columns. Overall, approximately 15,000 cubic yards of soil were
treated during a 2-year period to an average depth of 32 feet.
A minimum UCS of 120 psi and a permeability of 1.8 x 10 "7 cm/s were achieved
through the stabilization process, and the stabilized material also passed ASTM
D559 and D560 durability tests. Verification soil samples were extracted using a
modified Static Leaching Method. Of 16 extracts, only one contained a PAH
, (naphthalene at a concentration of 16 ug/L), and no other SVOCs were detected
above the Minimum Detection Limit. Four extracts cpntain£d.a YP9< ^JW6116
chloride, but because this compound also snowed up in an apparatus blank arid is
not a normal constituent of coal tar, it is thought that this was a laboratory
contaminant. ^ ^ ' , '"_] \ •_
, • if,., , , .' .. ,,ii ... ,,• j, i ' l-iv • • .T , '..,, :." • > • •. ,.
Contact
Ted Vallis, Wisconsin Fuel & Light, Manitowoc, Wisconsin, (414) 683-2538
;li •>.. • , «. I1,!, . :.:" , ,. if ', H •••.• ,, , 'I . . ,. ',j ; ..;• •'.,,..' ,ir,,,'
" ' ' ' I .i1 | Ill'l-
5.2.6.2 Ex Situ Stabilization/Solidification (S/S)
Technology Description
Stabilization/solidification (S/S) uses physical and chemical means to reduce the
rnobility of hazardous substances and contaminants. Unlike other remedial
technologies, S/S seeks to trap or immobilize contaminants, instead of removing
them. The term S/S has been vised synonymously with other terms, including
immobilization, encapsulation, and fixation (GRl^ 19%). Specific definitions have
been assigned to each of these terms by USEPA and others to differentiate among
them. For the purposes of this document, all of these technologies will be referred
to as S/S. , ' ' ' ' ' '_'" " ' "'"_ " ' -' ' I".."...,,"' " ',.
Ex situ S/S was originally developed for inorganic wastes. Although this
technology has limited applicability to organics and cyanides, it may be useful at
MGP sites for management of purifier box wastes, gas-holder tank sludge, and
soils contaminated with organic compounds (GRl, 1996). Contaminants are
physically bound or enclosed within a stabilized mass (solidification), or-chemical
reactions are Introduced between the stabilizing agent and contaminants to reduce
their mobility (stabilization).
fix situ S/S is one method by which" soil containing MGP wastes "can be stabilized
and replaced. The technology typically involves mixing the soil with chemical
Einders that solidify and/of immobilize the chemicals of concern. Pugmills are
often used to perform mixing, although stockpiles may be mixed by mechanical
means. Following S/S, treated materialsi'rhay be replaced in their excavation,
recompacted, and allowed to cure. Leachability testing is typically performed to
verify contaminant immobilization.
There are many variations of the S/S technology using different processes and/or
stabilizing agents such as Pozzolan/Portland cement, bitumen, and emulsified
asphalt. The technology has been applied to soils, sludges, lagoons, and
radioactive waste. The use of MGP soils in the production of asphalt is discussed
t!>! 5:52
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in Section 5.2.3. The discussion in this section will focus on the use of
Pozzolan/Portland Cement with MGP soils.
Pozzolan/Portland cement consists primarily of silicates from Pozzolanic-based
materials like fly ash, kiln dust, pumice, or blast furnace slag as well as cement-
based materials. These materials react chemically with water to form a solid matrix
that improves the strength of the matrix in which waste is found and minimizes
the likelihood of contaminant leaching. They also raise the pH of the water, which
may help precipitate and immobilize some heavy metals. Ppzzolanic and cement-
based binding agents are typically appropriate for"inorganic contaminants. The
effectiveness of this binding agent with organic contaminants varies (USEPA
1998).
Operational Considerations
A key design consideration is the identification of a stabilizing agent that is
compatible with the waste at a site and that yields a treated product that contains
no free liquids, meets a minimum compressive strength, and does not leach
contaminants (GRI, 1996). Lab- and pilot-scale studies are required to identify the
type and quantity of agent for each application. Physical and chemical
characterization of the soil are also required to select suitable mixing materials.
The effectiveness of ex situ S/S depends primarily on effective mixing. If large
materials (greater than 3/8 inch) are present, they must be excluded by screening.
These materials can be used in the S/S process if they are crushed and screened.
Mixing time should be sufficient to produce a homogeneous mix. This parameter
has a great impact on project duration and treatment cost (GRI, 1996).
Soil parameters that must be determined for ex situ S/S include particle size,
Atterberg limits, moisture content, metal concentrations, sulfate content, organic
content, and density. Post-treatment parameters that require monitoring and
testing include permeability, unconfined compressive strength, leachability,
microstructure analysis, and physical and chemical durability (USEPA, 1998). Soil
particle size is an important factor as fine particles may delay setting and curing
times and can surround larger particles, causing weakened bonds in S/S processes
(USEPA, 1998). Soil homogeneity and isotropy also affect S/S. Larger particles,
such as coarse gravel or cobbles, may not be suitable for the S/S technology.
A consideration in the use of the technology at MGP sites is the presence of oil and
grease. Oil and grease coat soil particles, which tends to weaken the bond between
soil and cement in cement-based solidification (USEPA, 1998).
Applications and Cost
Ex situ S/S may be used to treat soils from MGP sites. It is a viable option when
soil contaminants are primarily metals (as with purifier box wastes). Full-scale S/S
of free-phase hydrocarbons and contaminated soils from MGP sites has been
performed, but there is little documentation of the result of these demonstrations
(GRI, 1996).
Cost of ex situ S/S depends on the costs of mobilization/demobilization of
personnel and equipment, excavation, equipment, startup, supplies and
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''I',:!'1 '' J! " I'T'I 1' J i . i' I ', Mi» ,r ,' i. •'«, . " ' ',: ,
!,,,,! I
consumables, labor, utilities, and analytical requirements. Ex situ S/S processes
are among the most accepted remediation technologies. Comparing representative
overall costs from more than a dozen vendors gives an approximate cost of under
$110 per metric ton ($100 per ton), including excavation (USEPA, 1998).
Benefits ' ' ." ^ '
I Has been widely used to immobilize inorganic chemicals; several vendors
claim that their proprietary additives can make organics amenable to
stabilization
•TV.I - • , .in, : •' M; ••,!•>,. i.1 i":: : • " • r • • . .. i i it '.' ... | ' •'..* i '•• • *!••'-.• • ;.;!
• • • •• - "' , ' • " 'i -ii •. i in j i ii •• • •
Limitations
"" Performance of S/S process is dependent upon the chemical composition of the
wastes
I Long-term immobilization of contaminants possibly affected by environmental
,WI"'il : ', J'.",. , '
conditions
• Certain wastes incompatible with certain S/S processes; treatability studies
generally required
• VOCs are generally not immobilized by the stabilization process
• Long-term effectiveness not demonstrated for many contaminant/process
combinations
• Volumetric increase in amount of material
Case Study
DuQuoin Former MGP Site , , |
Remedial activities were conducted under the Illinois Site Remediation Program at
an 8-acre former MGP site owned by Ameren CIPS in DuQuoin, Illinois. The
remedial work, funded jointly by Ameren CIPS, Commonwealth Edison, and
Nicor Gas, was cpnducted during the first half of 1997.
Tar and purifier waste was excavated from a lagoon approximately 59,650 square
feet in area. A total of 4,290 tons of tar and tar-c6ntaminated soil was generated
during the excavation of impacted material at the site. This material was
manifested as a hazardous waste and transported to a RCRA Subtitle C landfill.
!", , , ..,,' '"; '„,',!;, ; •;. ' , ' ' ; "*" ;;, , ' ;[•„;, ;;;,;. • ; l •.; ; ; • , ;„
The area identified as the lagoon excavation was stabilized by incorporating
calciment bottom ash at a ratio of 7 parts ash to 10 parts soil into the bottom two
feet of impacted clay subgrade. The stabilized clay was then placed back in 6-inch
.lifts and compacted with a D-6 bulldozer and sheepsfoot roller.
ii'W if ' •''' ",'« i '.- v ' ii'1' I1",!'1'1-" ••. , "'vi, "K" . In i "Hi*1! .i.vi' ,' iiil'-iiii . . •:, » ' . . • i".
i i'lii"" ' ,;: . • .!!„: ,:,, ,,'„ n ,'v > .It1 'A* •>..!'. * fa '
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Chapter 5
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performed in the area of excavation and stabilization activities indicated that the
remediation activities were successful.
Backfill obtained from an offsite commercial source was used to cover the
stabilized material in the lagoon area. The backfill was compacted in place, graded
to promote drainage of precipitation, and seeded with prairie grass.
The site is zoned commercial/industrial and will be used for these purposes in the
future. Because stabilized impacted soils are present beneath the 1-foot surface
cover, certain procedures and precautions will be followed to maintain this layer.
Contacts
Don Richardson, Ameren CIPS, (314) 554-4867
Peter McCauley, Com Ed, (312) 394-4470
Stan Komperta, Illinois Environmental Protection Agency, (217) 782-5504
5.2.7 Soil Washing
Technology Description
Soil washing is a physical/chemical process for scrubbing soils ex situ to remove
contaminants.
The process removes contaminants from soils in one of two ways (USEPA, 1998):
by dissolving or suspending them in the wash solution (which can be sustained by
chemical manipulation of pH for a period of time); or by concentrating them into a
smaller volume of soil through particle size separation, gravity separation, and
attrition scrubbing (similar to techniques used in sand and gravel operations).
Soil washing is considered a media transfer technology because contamination is
not destroyed but merely transferred from solid- to liquid-phase media. The
contaminated water generated from soil washing is treated with the technologies
suitable for the contaminants. Soil washing is potentially applicable to soils
contaminated with a wide variety of heavy metals, radionuclides, and organic
contaminants. Application of the process is not widespread in the United States.
This technology has been more widely applied in Europe.
The concept of reducing soil contamination through the use of particle size
separation is based on the finding that most organic and inorganic contaminants
tend to bind, either chemically or physically, to clay, silt, and organic soil particles
(USEPA, 1998). Silt and clay attach to sand and gravel particles by physical
processes, primarily compaction and adhesion. Washing separates the fine (small)
clay and silt particles from coarser sand and gravel soil particles thus
concentrating contaminants into a smaller volume of soil that can then be
managed (treated further or disposed of at a landfill). Gravity separation is
effective for removing high- or low-specific-gravity particles such as heavy-metal-
containing compounds. Attrition scrubbing removes adherent contaminant films
from coarser particles. It can also increase the fines in soils. The clean soil can be
returned to the site for reuse.
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Complex mixtures of contaminants in soil (such as a mixture of metals, nonvolatile
organics, and semivolatile organic compounds) and heterogeneous contaminant
compositions throughout a soil mixture make it difficult to formulate a single
Cashing solution that will consistently and reliably remove the different types of
contaminants. Soil washing is typically not recommended for these types of sites.
' '! I I, "' , '' '
Operational Considerations
Soil type is an important factor for soil washing, m general^ coarse, uhcbhsolidated
materials, such as sands and fine gravels, are easiest to treat. Soil washing may not
be effective where the soil is composed of large percentages of silt and clay
because of the difficulty of separating the adsorbed contaminants from fine
particles and from wash fluids (USEPA, 1998).
High soil moisture content may cause excavation, material handling, and material
"transport problems (USEPA, 1998).
The pH of the waste being treated may affect soil washing; high pH in soil
normally lowers the mobility of inorganics in soil (USEPA, 1998).
High humic content will bind the soil, decreasing the mobility of organics and
thus the threat to groundwater; however, high humic content can inhibit soil
Washing as a result of strong adsorption of the contaminant by the organic
material (USEPA, 1998).
A complete bench-scale treatability study is typically required before using soil
Cashing as a remedial solution. Like any ex situ soil treatment, this technology
requires space for soil processing and materials handling.
Applications and Cost
This technology is suitable for treating soils anct sediment contaminated with
dVganics such as PCBs, creosote, fuel residues, and heavy petroleum; heavy metals
sucah as cadmium, chromium, lead, arsenic, copper, cyanides, mercury, nickel,
and zinc; and radionuclides. The technology can recover metals and can clean a
wide range of organic and inorganic contaminants from coarse-grained soils.
At the present time, soil washing is used extensively in Europe but has had limited
use in the United States. Between 1986 and 1989, the technology was one of the
! |'|,,i . u | *-'*'
selected source control remedies at eight Superfund sites. The average cost for use
of this technology, including excavation, is approximately $170 per ton, depending
on site-specific conditions and the target waste quantity and concentration.
Benefits
•"" Offered by multiple vendors
• High degree of certainty regarding treatment performance
Limitations
• Material handling possibly expensive and time consuming, especially for large
amounts
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• Applicability and effectiveness of the process limited by:
- Complex waste mixtures (e.g., metals with organics) which make
formulating washing fluid difficult
- High humic content in soil, which may require pretreatment
• Washwater requiring treatment at demobilization
• Additional treatment steps that may be required to address hazardous levels of
washing solvent remaining in the treated, residuals
• Difficultly removing organics adsorbed onto clay-size particles
Case Studies
Former Basford Gasworks, Nottingham, UK
A large-scale UK soil washing project is being conducted at the former Basford
gasworks site in Nottingham. The 7.8-hectare (ha) site is owned by BG pic, the UK
gas supply infrastructure group. The cleanup is valued at $7.5 million (Haznews,
1998).
Soil washing commenced in August 1997, and was scheduled to be completed in
July 1998 after processing approximately 72,000 cubic meters of contaminated
material. The soil washing was performed by Linatex/Heijmans, a joint-venture
between UK and Dutch firms, using a plant with a nominal process rate of 50
tonnes per hour.
The Basford site is underlain by a drinking water aquifer, with no subsurface
geological barrier to prevent off-site migration of contaminants. The soil
conditions at the site made it a suitable candidate for evaluating the cost-
effectiveness of soil washing; information which would be useful in evaluating
this technology for other contaminated MGP sites. Basford began operating in
1854 and was the principal gas supply for the City of Nottingham. The site also
provided by-products such as coke, sulphuric acid, and ammonium sulphate
fertilizer until gas production stopped in 1972 (Haznews, 1998).
During the site characterization, 350 test pits were dug on a 10 meter grid,
producing 2,500 samples for analytical testing. This detailed investigation allowed
a more accurate identification of waste types, volume, and location. A model was
subsequently developed to optimize the treatment, technology and estimate the
amount of materials that could be recycled. For example, 26,000 cubic meters of
clean ash and clinker are being recovered for use in steel and building block
production (Haznews, 1998).
Approximately 91,000 cubic meters of contaminated material was identified. Of
this, about 15,000 cubic meters has been classified as unbeatable (along with tar
and asbestos wastes) and was sent to an off-site disposal location. The remainder
of the wastes are being processed through the soil washing plant.
In the soil washing process, excavated material is crushed and screened to 100 mm
and magnetically separated. The remaining material is wetted and then passed to
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,1
a 2-mm vibrating screen where it is disaggregated with high-pressure water. The >
2 mm gravel fraction goes to a counter-current washer and is eventually drained
and discharged for reuse as onsite fill. The gravel washwater and a smaller slurry
fraction is split between two hydrbcyclohes which separates the material into a 63
um to 2 mm sand fraction and a < 63 um slurry (Haznews, 1998). The sand is
processed in a dense medium separator from which clean sand is dewatered and
tfeen discharged to a collection bay. The fines fraction slurry is treated in a
thickener tank where flocculants may be added tp improve the treatment process.
This tank produces sludge with 20 to 40 percent dry matter which is pumped to a
continuous filter press. The resulting contaminated filter cake is sent to a landfill
for disposal.
Light materials, such as coke, wood fragments, and plastics, are separated out
during the washing process and also sent to the landfill with the contaminated
fines (Haznews, 1998).
According to BG's property division, the use of soil washing has resulted in a
remediation period that is 60 to 70 percent longer than the conventional clean-up
approach of excavation of contaminated material and landfill disposal. However
the advantages of soil washing include the reduced need for imported clean fill,
and a large reduction in transportation during the site work. Overall, the cost of
the project is comparable to a "dig and haul" approach (Haznews, 1998).
SITE Program Demonstration, Toronto, Ontario
Soil washing was accepted into the Superfund Innovative Technology Evaluation
(SITE) Demonstration Program in the winter of 1991. It was demonstrated in
Toronto, Ontario, Canada, in April 1992 as part of the Toronto Harbour
Commission soil recycling process.
r'l*!;11 !, , '!!„ I,! u i ij i L ;,;„
1 '' 'I ,/ " : ' '
The soil washing process begins when an attrition soil wash plant removes
relatively uncontaminated coarse soil fractions using mineral processing
equipment; contaminants are concentrated in a fine slurry that is routed for further
treatment The wash process includes a trommel washer to remove clean gravel,
hydrocyclones to separate the contaminated fines, an attrition scrubber to free
fines from sand particles, and a density separator to remove coal and peat from the
sand fraction. If only inorganic contaminants are present, the slurry is treated in an
inorganic chelator unit. This process uses an acid leach to free inorganic
contaminant from the fine slurry and then removes the metal using solid
chelating-agent pellets in a patented countercurrent contactor. The metals are
recovered by electrowinning from the chelation agent regenerating liquid. Organic
removal is accomplished by first chemically pretreatirig the slurry from the wash
plant or metal removal process. Next, biological treatment is applied in upflow
slurry reactors using bacteria that have developed naturalty in tne soils. The
treated soil is dewatered using hydrocyclones and returned to the site from which
it was excavated.
The technology is designed to reduce organic and inorganic contaminants in soils.
The process train approach is most useful when sites have been contaminated as a
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result of multiple uses over a period of time. Typical sites where the process train
might be used include refinery and petroleum storage facilities, former metal
processing and metal recycling sites, and manufactured gas and coal or coke
processing and storage sites. The process is less suited to soils with high inorganic
constituents that are inherent to the mineralogy.
Results of the demonstration described above have been published in the
Demonstration Bulletin (EPA/520/MR-92/015), the Applications Analysis Report
(EPA/540/AR-93/517), the Technology Evaluation Report (EPA/540/R-93/517),
and the Technology Demonstration Summaiy (EPA/540/SR-93/517). These
reports are available from USEPA.
The demonstration results showed that soil washing produced clean coarse soil
fractions and concentrated the contaminants in the fine slurry. The chemical
treatment process and biological slurry reactors, when operated on a batch basis
with a nominal 35-day retention time, achieved at least a 90 percent reduction in
simple PAH compounds such as naphthalene, but did not meet the approximately
75 percent reduction in benzo(a)pyrene required to achieve the cleanup criteria.
The biological process discharge did not meet the cleanup criteria for oil and
grease; the washing process removed almost no oil and grease. The hydrocyclone
dewatering device did not achieve significant dewatering. Final process slurries
were returned to the excavation site in liquid form.
The metals removal process achieved a removal efficiency of approximately 70
percent for toxic heavy metals such as copper, lead, mercury, and nickel.
The metals removal process equipment and chelating agent were fouled by free oil
and grease, forcing sampling to end prematurely. Biological treatment or physical
separation of oil and grease will be required to avoid such fouling.
Contact
Teri Richardson, USEPA Project Manager, National Risk Management Research
Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, (513) 569-
7949, fax (513) 569-7105
SITE Program Demonstration, Saginaw, Michigan
A field demonstration of Bergmann, Inc.'s soil washing technology was conducted
in May 1992 at the Saginaw Bay Confined Disposal Facility in Saginaw, Michigan.
The Applications Analysis Report (EPA/540/AR-92/075) and the Demonstration
Bulletin (EPA/540/MR-92/075) are available from USEPA.
Demonstration results indicate that the soil- and sediment-washing system can
effectively isolate and concentrate PCB contamination into organic fractions and
fines. Levels of metals contamination were also beneficially altered. The
effectiveness of soil and sediment washing on inorganic compounds equaled or
exceeded its performance for PCB contamination.
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Technologies for Source
;..;.;.• ; ;i ;;}, :,..'.;,. : • : ' -,.'. •,
During a 5-day test in May 1992, the Bergmann soil and sediment washing system
experienced no downtime, operating for 8 hours per day to treat dredged
sediments from the Saginaw River.
The demonstration provided the following results:
• Approximately 71 percent of the particles smaller than 45 pm in the input
sediment were apportioned to the enriched fines stream.
» Fewer than 20 percent of the par.ticles,smallen,than.45 um,in the,input sediment
were apportioned to the coarse clean fraction of soil.
The distributions of the concentrations of PCBs in'the input and output streams
were as follows:
• Input sediment =1.6 mg/kg
• Output coarse clean fraction = 0.20 mg/kg
1 Output humic materials =11 mg/kg
» Output enriched fines = 4.4 mg/kg
Heavy metals were concentrated in the same manner as the PCBs. The coarse clean
sand consisted of approximately 82 percent of the input sediment.
The core of the process is a multistage, countercurrent, intensive scrubbing circuit
with interstagei classification. The scrubbing action."disintegrates soil aggregates,
freeing contaminated fine particles from coarser material. In addition, surficial
contamination is removed from the coarse fraction by the abrasive scouring action
cjf the particles themselves. Contaminants may also be solubilized as dictated by
solubility characteristics or partition coefficients.
5-60
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Contacts , , K , _ h , ; ^ B_
Mr. Jack Hubbard, USEPA Project Manager, National Risk Management Research
Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, (513) 569-
7507, fax (513) 569-7620
i,':..„! .a,1.;!'! s A.; ; •i-'l/tit.. '.• ' "!' •« '• ill :. > M t" ; v. ':> I!'1':;'" 'Mi, "i a *:-• :l<".iv -, .». •'«'..> '• i-j-t,-
Mr. George Jones, Bergmann, A Division of Linatex, Inc., 1550 Airport Road,
Gallatini TN; 37066-3739, (615) 230-2217, fax (615) 452-5525
:$JTE Program Demonstration, New Brighton, Minnesota
The BioTrol Soil Washing System is a patented, water-baseci volume reduction
process used to treat excavated soil. The system may be applied to contaminants
concentrated in the fine:sized soil fraction (silt, clay, and soil organic matter) or in
the coarse soil fraction (sand and gravel).
' • i '-.-'• . - " :: • ;;•••• : • ••• -iv '• • f .-
In the first part of the process, debris is removed from the soil. The soil is then
mixed with water and subjected to various unit operations common to the mineral
processing industry. The equipment used in these operations can include mixing
trommels, pugmills, vibrating screens, froth flotation cells, attrition scrubbing
machines, hydrocyclones, screw classifiers, and various dewatering apparatus.
iiiii ....... a, ............ i ...... '%&&& ......... , .......... i ...... ..... .i
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Chapter 5
Technologies for Source Material Treatment
Contaminated residual products can be treated by other methods. Process water is
normally recycled after biological or physical treatment. Contaminated fines may
be disposed of offsite, incinerated, stabilized, or biologically treated.
This system was developed initially to clean soils contaminated with wood
preservative wastes, such as PAHs and PCP. The system may also apply to soils
contaminated with petroleum hydrocarbons, pesticides, PCBs, various industrial
chemicals, and metals.
The BioTrol Soil Washing System was accepted into the SITE'Demonstration
Program in 1989 and demonstrated between September and October 1989 at the
MacGillis and Gibbs Superfund site in New Brighton, Minnesota. A pilot unit with
a treatment capacity of 500 pounds per hour operated 24 hours per day during the
demonstration. Feed for the first phase of the demonstration (2 days) consisted of
soil contaminated with 130 ppm PCP and 247 ppm total PAHs; feed for the second
. phase (7 days) consisted of soil containing 680 ppm PCP and 404 ppm total PAHs.
Contaminated process water was treated biologically in a fixed-film reactor and
then recycled. A portion of the contaminated soil fines was treated biologically in a
three-stage, pilot-scale EIMCO Biolift reactor system supplied by the EIMCO
Process Equipment Company. The Applications Analysis Report (EPA/540/AR-
91/003) and the Technology Evaluation Report Volume I (EPA/540/5-9 l/003a)
and Volume II (EPA/540/5-9 l/003b and EPA/540/5-9 l/003c) are available from
EPA.
Key findings from the BioTrol demonstration are summarized below:
• Feed soil (dry weight basis) was successfully separated into 83 percent washed
soil, 10 percent woody residues, and 7 percent fines. The washed soil retained
about 10 percent of the feed soil contamination; 90 percent of this
contamination was contained in the woody residues, fines, and process wastes.
" The multistage scrubbing circuit removed up to 89 percent PCP and 88 percent
total PAHs, based on the difference between concentration levels in the
contaminated (wet) feed soil and the washed soil.
• The scrubbing circuit degraded up to 94 percent PCP in process water. PAH
removal could not be determined because of low influent concentrations.
Contact
Dennis Chilcote, BioTrol, 10300 Valley View Road, Suite 107, Eden Prairie, MN
55344-3456, (612) 942-8032, fax (612) 942-8526
5.2.8 Soil Vapor Extraction (SVE)
SVE is mechanically similar to bioventing (Section 5.2.4.2), but is operated at a
higher flow rate to achieve volatile compound removal in addition to oxygen
replenishment. SVE uses an electric- or gasoline-powered blower system
connected to wells via manifolds. Air treatment, whether through a separate
system (such as activated carbon or catalytic oxidation) or as part of a gasoline-
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Chapter 5
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powered system, is usually the most expensive single component of an SVE project
and may represent as much as 50 percent of the overall cost.
Performance of an SVE system is monitored using measurements at the blower
" "'system and at piezometers (small-diameter wells or soil gas sample points)
installed in the zone being treated. Flow measurements at the blower or at
individual wells can be used to help calculate removal rates. Vapor samples from
giezometers, wells, or at the blower discharge can be analyzed in the field or by a
laboratory, and the results can be used to estimate £Ee rate of subsurface
decontamination and the rate of volatile compound removal. Vapor samples from
(he discharge of the air treatment system are usually required to test system
performance and to verify permit requirements. Final evaluation of SVE
performance can be assessed ty collecting soil vapor samples .from piezometers
and/or soil samples from the treated zone.
i,;,:', in! .'si i:, .si I ! >(•!, '• '^!|iL!l'»i>'1 !••;,'! l;{ .'.•«i|11i, .I,-,,,; T,, ii ;"f" i1 •.•' • - •
Operational Considerations
The suitability of SVE for MGP sites will depend on the site-specific requirements
for volatile compound removal or prevention of volatile compound migration as a
remediation objective. The site also needs to have a water table depth at least 10
feet and a subsurface profile that allows air to flow through the zone to be treated.
This profile criterion is met if the soil is coarse-or fine-grained but not saturated
H " and if the organic compound mass is infiltrated into the soil, rather than collected
in a subsurface pool (which would be impermeable to air flow).
fii,,!!' \Sf> -, '"V •'/?'•"[.'-• ' . (""f"; •>'.' '.' !tl ' ,;"':':'! ' •'•';:( *;'!(•'.;.','.; '.i ';V..: iW^""'i }:^ft '.JJ/"'1.1.',.'.';.*.p^j .'T,11;;".^1:;. ..!•; •!,•>. '*'? .''•".. ..'
TJie design feasibility of SVE.is typically proven through a field pilot test. The test
typically consists of pumping a single well that is screened in the center of the
zone to be treated. Piezometers are
zone to be treated. The purposes of this test are to:
I | I • ,;„''", ,':;, ,;
• Size the blower by assessing how much air can be pumped from a well.
• Size the air treatment system by determining what initial concentrations might
be expected.
* Observe the subsurface flow pattern throughout the zone of treatment.
lf&
$|ibsurfaceflow pattern, the full-scale design could call for additional wells, a new
Vgell wi1|i a deeper screened interval, or sealing to eliminate surface leakage.
Shallow sites may be more effectively treated using horizontal wells in trenches.
; i " '" ,, i; v ", .„ ,- ;_: ; i ;„":?". | : , •• ;; . r " , '
Most SVE systems operate for 1 to 3 years. During this time, the air treatment
system requires periodic; maintenance or charigebut, a conciensate tank requires
empiying (especially in cold weather), and samples and measurements need to be
collected and reported. At the site, the aboveground portion of the system usually
takes up one or two parking spaces and almost always requires 115V or 220V
electrical power. Natural gas is sometimes required (if catalytic oxidation is
selected as the air treatment option). The blower itself may be a source of excessive
noise if silencers (upstream and downstream) or soundproof containment are not
provided or if the blower is undersized and working near its maximum output.
The underground portion of the system is typically accessed through well vaults,
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Chapters
Technologies for Source Material Treatment
and the manifold lines connecting the wells to the blower system are often buried
in frequently accessed areas.
Sites with relatively shallow water tables or with wells screened near the water
table can experience excessive water accumulation and blockage of air flow if too
much vacuum is applied to the system. Most systems can be operated safely under
these conditions by managing the applied vacuum (in feet of water column) to be
less than one half the distance from the water table to the top of the well screen.
Granular activated carbon is often selected as the air treatment alternative because
of its minimal power requirements, its availability, and its acceptability to
regulators. It is often the least expensive, on a unit basis, for sites with relatively
low vapor concentrations. Carbon operates at highest efficiency when
temperatures are lower than 120°F; however, most SVE design manuals fail to
provide guidance on temperature management of the blower discharge to the
carbon vessels. Excessive heat may be a concern at sites with high ambient
temperature, such as in the south or southwestern United States, and/or where
relatively high vacuums are required because of fine-grained soil conditions. In
these situations, carbon may still be cost effective if used in conjunction with a
condenser or a heat exchanger.
Applications and Cost
SVE has been used as a remediation process of choice at thousands of
underground storage tank leak sites. Applications at MGP sites are not as
widespread; however, SVE can be used to treat soils at sites contaminated with
some SVOCs (such as naphthalene).
SVE can be applied with little disturbance to existing facilities and operations. The
technology can be used at sites where areas of contamination are large and deep or
when the contamination is present beneath a building. The system may be
modified depending on additional analytical and subsurface characterization data
and/or changing site conditions (RIMS, 1998).
The components of SVE systems are commonly available off the shelf, and the
necessary wells can be installed by any qualified local engineering firm.
Aboveground installations typically include:
• Vacuum pumps and/or blowers and associated controls
• Pressure gauges and flow meters at wellheads and pumps
• Control valves to adjust air flow
• An air-liquid separator (for removing moisture from the extracted gases)
• Vapor treatment unit(s)
More complex SVE systems may incorporate trenches, horizontal wells, forced air
injection wells, passive air inlet wells, low permeability or impermeable surface
seals, or multiple level vapor extraction wells in single boreholes. In addition,
sophisticated systems are available to monitor moisture, contaminant levels, and
temperature (RIMS, 1998).
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11 if , , t ' :i
"III"1 ! • i.' Ill'
I Chapter 5
Technologies for Source Material Treatment
The efficiency of SVE can be enhanced through the use of formation fracturing,
pulsed pumping, or horizontal extraction wells, these enhancements can increase
the soil permeability or the efficiency of mass removal or allow access to
previously inaccessible areas of contaminated soil (e.g., below the water table, in
less permeable formations) (RIMS, 1998).
, ' ' ;;: '"'f ' ' '• : " '"I1: ll i: j •' l.1'11"1 " •'.' ' ' ''"
Treatment costs for sites using SVE depend on various conditions such as site size,
Hi i i [.• , .1 -,i. ,:• ' H \ , ,
extent of contamination, regulatory requirements for permits, other site-specific
and chemical-specific conditions, and site cleanup criteria. Therefore, cost can only
be estimated on a case-by-case basis, to provide an indication of the range in SVE
project costs, the treatment of 185,000 cubic yards of soil at one site cost $2 per
cubic yard while, at another site where 650 cubic yards required treatment, the
cp'st was $450 per cubic yard. These values represent treating the soil rather than
dost per pound of contaminant treated, the major part of the total process cost
associated with SVE is usually the operating expenses for labor, maintenance, and
monitoring (RIMS, 1998).
Benefits : ^ ,
• treats in situ, volatile compounds in soil, including areas beneath structures, at
lower cost than excavation
I Accomplishes both volatile compound removal and oxygen replenishment,
and promotes in situ biodegradation for compounds that may not be removed
• Can be implemented with relatively little disruption to ongoing operations
» Focuses on volatile compounds, including benzene and naphthalene; therefore
treats the most mobile pf the organic compounds beneath an MGP site, which
makes it an effective risk-reduction approach
• Has well-established design and feasibility evaluations
Limitations , ( IF<<< : '
• Not effective at sites where remediation goals include concentration reduction
of low-volatility compounds (which are frequently important for MGP site
restoration)
"* Difficult to successfully implement where the water table is shallower than 5 to
10 feet below grade, or where the soil is fine-grained (clayey) and nearly
saturated \
• Limited effectiveness on volatile compounds trapped in a liquid mass or pool
of subsurface organic compounds (air will not flow through liquids; volatile
compounds trapped in liquids will only be removed through diffusion, which
is too slow to be cost effective)
L: :•.-:.'
Case Study
Beale AFB, Marysville California
Numerous SVE systems were installed using granular activated carbon with no air
temperature management. Upon start up, breakthrough of the carbon occurred
within three days. Systems were retrofitted with a converted truck radiator
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Chapter 5
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installed downstream of the blower. Air was produced at ten degrees above
ambient for carbon treatment; and carbon efficiency increased three-fold
(CH2M HILL, 1998; Nelline Scheuer).
Contacts
Ms. Carol Goudette, 9 CES/CEVR, 6601 "B" Street, Beale AFB, CA 95903
Ms. Cori Condon, RWGCB, Assistant Engineering Geologist, 3443 Routies Road,
Sacramento, CA 95827
5-65
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Chapter 5
Technologies for Source Material Treatment
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Chapter 6
References
AFCEE, 1994. Bioventing Performance and Cost Summary, Draft. Brooks AFB, TX.
ASTM, 1995. Standard Guide for Risk-Based Corrective Action Applied at
Petroleum Release Sites. Designation E-1739-95.
ASTM, 1996. Provisional Standard Guide for Accelerated Site Characterization for
Confirmed or Suspected Petroleum Releases. Designation PS 3-95.
Alleman et al., 1995. "Bioventing PAH Contamination at the Reilly Tar Site." In
Situ Aeration: Air Sparging, Bioventing and Related Remediation Processes.
Battelle Conference Proceeding.
Backhus, Debra A., Joseph N. Ryan, Daniel M. Groher, John K. MacFarlane, and
Philip M. Gschwerd, 1993. "Sampling Colloids and Colloid-Associated
Contaminants in Ground Water." Ground Water, May-June, Vol. 31, No. 3 pp 466-
479.
Barnett Alexander, Catherine, 1977. MGP Site Planning: New Community
Development Opportunities. American Gas, November.
Barr Engineering Company, 1996. "Field Demonstrations of Thermal Desorption
of Manufactured Gas Plant Soils." EPRITR-105927. Electric Power Research
Institute. Minneapolis, Minnesota. September.
Bay Area Air Quality Management District, 1996. BAAQMD CEQA Guidelines,
Assessing the Air Quality Impacts of Projects and Plans, p. 66. April.
BiotreatmentNews, 1996. "BAG Meets." p. 10. November.
Bradley, L.J.N., B.H. Magee, and S.L. Allen, 1994. "Background Levels of
Polycyclic Aromatic Hydrocarbons (PAH) and Selected Metals in New England
Urban Soils." Journal of Soil Contamination. CRC Press, Inc.
Bevolo, A.J., B.H. Kjartanson, and J.P. Wonder, 1996. "Ames Expedited Site
Characterization Demonstration at the Former Manufactured Gas Plant Site,
Marshalltown, Iowa." Ames Laboratory. March.
Brown, S.M., D.R. Lincoln, and W.A. Wallace, 1988. "Application of Observational
Method to Hazardous Waste Engineering." ASCE. Journal of Management
Engineering, Vol. 6, No. 4, pp. 479-500.
Burton, Jacqueline C., 1994. "Expedited Site Characterization for Remedial
Investigations at Federal Facilities." Argonne National Laboratory, PER III and
WMII Conference & Exhibition. April 27-29.
6-1
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, : is;-, ; - fffi'- ,, •, ••;* ',ryi ,n ..... -f.fflftoJl
Chapter 6
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I ;
6-4
[i:.:' :::;„.]
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Chapter 7
Additional Sources of Information
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Protection Agency, Department of Toxic Substances Control, Site Mitigation
Branch. August. 1991.
7-1
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