United States
Environmental
Protection Agency
Office of Solid Waste and
Emergency Response
Washington. DC 20460
Technology Innovation Office
and Office of Underground
Storage Tanks
Technologies and
Options for UST
Corrective Actions
EPA/542/R-92/010
August 1992
Overview of Current Practice
-------
EPA/542/R-92/010
August 1992
TECHNOLOGIES AND OPTIONS FOR
UST CORRECTIVE ACTIONS:
OVERVIEW OF CURRENT PRACTICE
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Technology Innovation Office and
Office of Underground Storage Tanks
Washington, DC 20460
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NOTICE
This material has been funded wholly or in part by the United States Environmental
Protection Agency under Contract Number 68-WO-0015. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
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TABLE OF CONTENTS
CHAPTER PAGE
1.0 INTRODUCTION 1-1
1.1 Objectives 1-1
1.2 Information Sources 1-1
1.3 Information Analysis 1-2
2.0 CURRENT PRACTICES FOR MANAGING CONTAMINATED MEDIA AND
DEBRIS FROM UST CORRECTIVE ACTION SITES 2-1
2.1 Introduction 2-1
2.2 Summary of Current Management Practices for Petroleum Contaminated Soil
and Debris from UST Corrective Action Sites 2-2
2.3 Summary of Current Treatment Practices for Petroleum Contaminated
Groundwater at UST Corrective Action Sites 2-5
2.4 Summary and Conclusions 2-9
2.5 References 2-9
3.0. OVERVIEW OF TECHNOLOGIES CURRENTLY EMPLOYED FOR MANAGING
PETROLEUM CONTAMINATED MEDIA AND DEBRIS FROM UST
CORRECTIVE ACTION SITES 3-1
3.1 Introduction ' 3-1
3.2 Technologies for the Ex-situ Management of Petroleum Contaminated Soils
3.2.1 Low Temperature Thermal Strippers 3-2
3.2.1.1 Process Description 3-2
3.2.1.2 Treatment Efficiency 3-6
3.2.1.3 Operating Parameters that Affect Treatment
Performance 3-8
3.2.1.4 Conditions that Affect Treatment Costs ...3-10
3.2.2 Hot Mix Asphalt Plants 3-11
3.2.2.1 Process Description 3-11
3.2.2.2 Treatment Efficiency 3-13
3.2.2.3 Operating Parameters that Affect Treatment
Performance 3-15
3.2.2.4 Conditions that Affect Treatment Costs . . . 3-15
3.2.3 Land Treatment 3-17
3.2.3.1 Process Description 3-17
3.2.3.2 Treatment Efficiency 3-18
3.2.3.3 Operating Parameters that Affect Treatment
Performance 3-19
3.2.3.4 Conditions that Affect Treatment Costs . . . 3-23
3.2.4 Landfilling 3-23
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3.2.4.1 Process Description 3-23
3.2.4.2 Treatment Efficiency 3-24
3.2.5 Other Ex-situ Corrective Action Technologies 3-24
3.2.5.1 Cold Mix Asphalt Plants 3-25
3.2.5.2 Stabilization and Solidification 3-26
3.2.5.3 Cement Kilns 3-26
3.2.5.4 Biological Processes 3-27
3.3 Technologies for the In-situ Management of Petroleum Contaminated Soils 3-29
3.3.1 Soil Vapor Extraction 3-29
3.3.1.1 Process Description 3-32
3.3.1.2 Treatment Efficiency 3-33
3.3.1.3 Operating Parameters that Affect Treatment
Performance „ 3-35
3.3.1.4 Conditions that Affect Treatment Costs ... 3-36
3.3.2 Bioremediation 3-37
3.3.2.1 Process Description 3-37
3.3.2.2 Treatment Efficiency 3-40
3.3.2.3 Operating Parameters that Affect Treatment
Performance 3-40
3.4 Technologies for the Treatment of Petroleum Contaminated Ground water 3-41
3.4.1 Free Product Recovery 3-41
3.4.1.1 Process Description 3-41
3.4.1.2 Treatment Efficiency 3-46
3.4.1.3 Conditions that Affect Treatment Costs ... 3-46
3.4.2 Pump and Treat 3-47
3.4.2.1 Process Description 3-47
3.4.2.2 Treatment Efficiency 3-48
3.4.2.3 Operating Parameters that Affect Treatment
Performance 3-50
3.5 Summary and Conclusions 3-50
3.6 References 3-52
APPENDIX A SUMMARY OF STATE REQUIREMENTS OF PETROLEUM
CONTAMINATED SOIL GENERATED AT UST CORRECTIVE
ACTION SITES A-l
A.I Summary of State Requirements A-l
A.2 Corrective Action Technologies Used in Each State A-l
n
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TABLES
2-1 States Included in this Review 2-1
3-1 Corrective Action Technologies for the Ex-situ Treatment of PCS Generated at
Petroleum UST Sites 3-4
3-2 PCS Treatment Efficiency Using LTTS 3-8
3-3 PCS Treatment Efficiency at Mobile Low Temperature Thermal Strippers in
Minnesota 3-9
3-4 Costs Reported for Treatment of PCS by Low Temperature Thermal Strippers . 3-11
3-5 PCS Treatment Efficiency at an Asphalt Plant 3-14
3-6 PCS Treatment Efficiencies and Associated Conditions in Asphalt Plants 3-16
3-7 Costs Associated with Treatment of PCS in Asphalt Plants 3-16
3-8 PCS Treatment Efficiencies at Landfarming Facilities in Minnesota 3-20
3-9 PCS Treatment Efficiency at a Landfarming Facility in Vermont 3-21
3-10 Oil Contaminated Soil Treatment Efficiency at a Landfarming Facility in Vermont3-21
3-11 Costs Associated with Treatment of PCS at Land Treatment Facilities 3-23
3-12 PCS Treatment Efficiency at Three Iowa Landfills 3-25
3-13 Corrective Action Technologies for the In-Situ Remediation of PCS at Petroleum
UST Sites 3-30
3-14 SVE Technology Pre-Treatment Effluent Vapor Concentrations 3-34
3-15 Treatment Effectiveness of VOC Emissions Control Technologies 3-35
3-16 Conditions Which Generally Limit the Effectiveness of SVE 3-36
3-17 Key Emissions Stream Characteristics Important to Performance of VOC Treatment
Systems 3-37
3-18 Costs Associated with Treatment of PCS with an In-situ Soil Vapor Extraction
System 3-38
3-19 Residual Concentrations and Remediation Times for Some In-situ Bioremediation
Projects 3-40
3-20 Corrective Action Technologies for the Treatment of Petroleum Contaminated
Groundwater 3-42
3-21 Site Specific Conditions Which Favor Either a Trench or Extraction Well for the
Removal of Free Product 3-44
3-22 Free Product Groundwater Separation Techniques 3-45
3-23 Costs Associated with Free Product Recovery 3-47
3-24 Groundwater Pump Effluent Monitoring Data 3-49
A-l Summary of State Requirements for Management of Petroleum Contaminated
Soils A-2
A-2 Corrective Action Technologies Used in States Contacted During this Study . . . A-12
in
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FIGURES
2-1 Distribution of PCS Treatment/Disposal Methods 2-4
2-2 Predominant PCS Remediation/Disposal Practices 2-6
2-3 Distribution of PCS Treatment/Disposal Methods by Major Category 2-7
2-4 Distribution of PCS Treatment/Disposal Methods by Specific Technology 2-8
2-5 Groundwater Remediation Practices 2-10
3-1 Costs of Low Temperature Thermal Stripping Pilot Plant Units 3-12
3-2 Generalized Schematic of Soil Vapor Extraction System 3-33
3-3 Basic Components of an In-situ Bioremediation System 3-39
IV
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ACRONYMS
B
BTEX
C
cm/s
DOT
E
EPA
F
P.O.
FP
GAC
IR/F
LTTS
LUST
mg/1
MPCA
N.D.
OUST
OVA
PAH
PCS
POTW
ppb
ppm
ppmv
RCRA
S/S
SVE
T
TC
TCLP
TPH
TRPH
USATHAMA
UST
voc
X
Benzene
Benzene, Toluene, Ethylbenzene, Xylene
Celsius
Centimeters per Second
Department of Transportation
Ethylbenzene
Environmental Protection Agency
Fahrenheit
Fuel Oil
Free product
Granulated Activated Carbon
Infrared and Fluorescence
Low Temperature Thermal Strippers
Leaking Underground Storage Tanks
Milligrams per liter (equivalent to ppm for water)
Minnesota Pollution Control Agency
Not Detected
Office of Underground Storage Tanks
Organic Vapor Analyzer
Polynuclear Aromatic Hydrocarbons
Petroleum Contaminated Soil
Publicly Owned Treatment Works
Parts per billion (equivalent to /*g/kg for soils)
Parts per million (equivalent to mg/kg for soils)
Parts per million volume
Resource Conservation Recovery Act
Stabilization/Solidification
Soil Vapor Extraction
Toluene
Toxicity Characteristic
Toxicity Characteristic Leaching Procedure
Total Petroleum Hydrocarbons
Total Recoverable Petroleum Hydrocarbons
U.S. Army Toxic and Hazardous Materials Agency
Underground Storage Tank
Volatile Organic Compound
Total Xylenes (meta-, para-, ortho-)
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CHAPTER 1
INTRODUCTION
1.1 OBJECTIVES
A number of ex-situ and in-situ technologies are currently being used across the U.S. to
treat petroleum contaminated media and debris generated at leaking underground storage tank
(UST) corrective action sites. The objectives of this study are:
• To examine the current level of use of corrective action treatment technologies at leaking
underground storage tank sites;
• To summarize experience with these technologies as documented in the literature in terms
of treatment efficiency, relationship of performance to key operating parameters, and
costs; and
• To summarize current state requirements that may affect the selection of technologies.
1.2 INFORMATION SOURCES
This study was based on information collected by the Environmental Protection Agency's
(EPA) Office of Underground Storage Tanks (OUST) from the following sources:
• State regulatory agencies;
• EPA dockets for various rulemaking packages;
• Published literature;
• EPA data bases; and
• Discussions with technical experts.
This information was collected during the period of August 1990 through June 1991.
State Regulatory Agencies. Underground storage tank officials in 26 states were
contacted to request data on UST corrective actions and state standards governing the
management of petroleum contaminated media and debris. Initial contacts in each state were
identified by EPA UST Regional Program Managers. Subsequent contacts were identified
through state agency referrals. Each contact was asked to characterize the types and accessibility
of data that the state maintains for UST sites and to explain how their particular state manages
petroleum contaminated media and debris, from initiation of UST corrective actions to the final
disposal or treatment and closure. Officials were also asked to provide copies of any regulations
and/or guidance documents that would outline their requirements and policies.
1-1
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State officials were contacted by telephone from October, 1990 through February, 1991.
The majority of the written comments were received in February, 1991 with the last received
in May 1991.
EPA Dockets. Information from the dockets for a number of EPA rulemaking packages
was reviewed in early 1991. The most important docket sources for purposes of this study
included the Technical Standards for Corrective Action Requirements for Owners and Operators
of Underground Storage Tanks (UST) (April 17, 1987), the final Toxicity Characteristic rule
(March 29, 1990) and the "Third Third" Land Disposal Restrictions rule (June 1, 1990).
Scientific Publications: A computer-assisted literature search (Dialog) was performed to
identify relevant information in published literature. Search criteria included references to
USTs, various petroleum classifications, petroleum storage facilities, remedial technologies,
analytical procedures, and contamination studies. The search included literature published
through June 1991.
EPA Computerized Data Bases. Two EPA-managed data bases were accessed as part
of this study effort. The Revelation Data Base, managed by OUST, contains descriptive and
numerical information on USTs submitted to EPA by the states on a state, regional and national
basis. Of particular interest was information on the ages, sizes and contents of all registered
USTs. Information related to this data base was also obtained from OUST on the status of
corrective actions and closures in each state, region and nationally as of March 1991.
Additionally, the EPA's Technical Information Exchange - Computerized On-Line Information
System (TIX-COLIS) was accessed to obtain information on well-documented UST corrective
action sites.
Discussions With Technology Vendors. Throughout early 1991 EPA contacted selected
corrective action technology vendors to obtain information on technology performance.
1.3 INFORMATION ANALYSIS
Almost all states that were contacted provided some form of written documentation (e.g.,
guidance, regulations etc.) that allowed for a reliable presentation of their UST program
requirements (See Appendix A). However, officials in only 4 of the 26 states contacted were
able to readily provide precise statistics on the numbers of sites where each corrective action
technology alternative was used. While the other states had the information requested in their
files, they generally did not maintain readily accessible centralized records that would facilitate
a rapid analysis of trends in technology use and performance. Therefore, in these states, best
estimates of the percentage utilization of each technology per state were provided by agency
officials. These estimates were applied to information provided quarterly by states to the Office
of Underground Storage Tanks indicating the number and status of their corrective actions. This
analysis was used to generate information on trends in technology utilization, as discussed in
Chapter 2.
1-2
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The information obtained from the sources listed in Section 1.2 was also reviewed to
characterize the performance of each technology alternative in terms of treatment efficiency,
operating parameters that affect treatment performance, and conditions that affect treatment
costs. The results of this review are summarized in Chapter 3.
1-3
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CHAPTER 2
CURRENT PRACTICES FOR MANAGING CONTAMINATED MEDIA
AND DEBRIS FROM UST CORRECTIVE ACTION SITES
2.1 INTRODUCTION
One objective of this study was to examine the current level of use of each technology
alternative under the RCRA Subtitle I program for managing contaminated media and debris
generated at UST corrective action sites. The review was performed by contacting 26 state UST
agencies (See Table 2-1) to request information on their regulations, policies, and guidance
relevant to management of media and debris, and to obtain data on management technologies
currently in use. Because of resource limitations EPA was not able to contact every state.
Therefore, a subset of states was selected to provide a broad geographic and demographic
distribution from each of the EPA Regions.
Table 2-1
States Included in this Review
EPA Region
I
II
III
IV
V
VI
VII
VIII
IX
X
State(s)
Connecticut, Maine, Massachusetts
New Jersey, New York
Delaware, Maryland, Virginia
Florida, Kentucky, Tennessee
Indiana, Minnesota
Louisiana, New Mexico, Texas
Iowa, Missouri
Colorado, Montana, Utah, Wyoming
Arizona, California
Oregon, Washington
2 - 1
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Initial contacts in each state were identified by EPA UST Regional Program Managers.
Subsequent contacts were identified through state agency referrals. State officials were contacted
by telephone from October, 1990 through February, 1991. Information obtained by initial
telephone contacts and available guidance was compiled and sent to each state for review and
comment. While the 26 states provided substantial information on their requirements,
information on current management practices sufficient for this review was not provided by all
states, and the level of detail provided for each technology alternative varied considerably. The
majority of the written comments were received in February, 1991 with the last received in
May, 1991.
This chapter summarizes the information provided by the states on corrective action
technologies used at UST corrective action sites. Section 2.2 summarizes the current
management practices for petroleum contaminated soil (PCS) and debris. Section 2.3
summarizes the current practices for treating petroleum contaminated groundwater at UST
corrective action sites. Section 2.4 provides a summary of the significant findings and
conclusions of the state review as they relate to current treatment/disposal practices. See
Appendix A for a summary of state requirements for management of petroleum contaminated
soils and debris.
2.2 SUMMARY OF CURRENT MANAGEMENT PRACTICES FOR PETROLEUM
CONTAMINATED SOIL AND DEBRIS FROM UST CORRECTIVE ACTION
SITES
The states contacted during this study were requested to provide information regarding
the practices they currently employ for managing soils and debris at UST sites. The responses
indicate that a broad range of approaches are used, varying both in the type of remediation
method employed and in the extent of their application.
Studies in the published literature on treatment/disposal methods for petroleum
contaminated soil have used different interpretations and nomenclature to describe these methods.
For example, the term "landfarming" includes aeration and bioremediation in some studies, but
not in others. To reduce the potential for confusion, EPA classified the technologies addressed
in this study into the five categories outlined below. For consistency, these definitions are
maintained throughout this report.
• In-situ Treatment (PCS excavation is not a prerequisite for treatment):
vapor extraction, volatilization, air/vacuum extraction, and in-situ soil venting.
in-situ bioremediation, including bioreclamation.
isolation/containment, passive remediation, and groundwater pump and treat.
• Landfilling:
includes all landfill disposal options.
2-2
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• Land Treatment:
landfarming, including ex-situ bioremediation.
land application, including land spreading and passive aeration.
aeration, including ex-situ soil venting, and air stripping.
• Thermal Treatment:
treatment in asphalt plants.
incineration.
low temperature thermal stripping (LTTS).
• Other:
All other categories reported by the states, including soil fixation and soil
washing, and categories reported as "undefined."
State agency officials were asked to supply information regarding the relative use of these
technologies at UST sites. Many of the states contacted during this study did not track
information of this type and, consequently, the information provided was often based on best
estimates provided by state personnel. Because much of the information provided only the
percentages of sites employing each type of technology, EPA developed statistics for all of the
states contacted by apportioning the percentages reported by states to the number of corrective
action sites in these states using the following formula:
Frequency (%) = Technology utilization per state (%) x number of corrective actions per state x 100
Total number of corrective actions in all states
The number of corrective actions per state is based on information reported by the states
to the Office of Underground Storage Tanks1. Reports submitted to OUST as of the first quarter
1991 were used in this study. A total of 25 states supplied information on the major categories
of treatment/disposal practices currently in use (Figures 2-1 and 2-2). Of these, 22 states
provided sufficient information to quantify the use of specific technologies within each category
(Figures 2-3 and 2-4). As of the second quarter of 1991, nearly 34,000 corrective actions had
been initiated in these 22 states.
The results of the analysis of petroleum contaminated soil and debris treatment/disposal
practices data are presented in a Figures 2-1 through 2-4.
Figure 2-1: Figure 2-1 illustrates the number of states reporting use of treatment/disposal
methods for each of the four major categories. The figure includes states that did
not provide detailed information on the degree of utilization, but simply indicated
the usage of the technology for management of contaminated soils and debris at
UST sites.
2-3
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Figure 2-2: Figure 2-2 is a geographical representation indicating the most commonly
practiced treatment/disposal method reported by these states. The indicated
methods are not necessarily used in a majority of the corrective actions initiated;
rather, they are the methods which are the most widely practiced (e.g., in
Oregon, only 49 percent of the cleanups initiated involve landfilling, yet it is the
most predominant practice).
Figure 2-3: Figure 2-3 summarizes the frequency with which the technologies in each of the
four major treatment/disposal categories are currently used in 22 states (In-situ
Treatment, Landfilling, Land Treatment, and Thermal Treatment). The "Other"
category in Figure 2-3 consists of information from six states where reported
corrective action technology utilization was too small to be apportioned, or where
states simply reported "Other Technologies."
Figure 2-4: Figure 2-4 presents a more detailed breakdown of the In-situ Treatment, Land
Treatment, and Thermal Treatment categories shown in Figure 2-1 (landfilling is
completely represented in Figure 2-1). Each of the pie charts provides the
percentage of utilization of specific technology options within each of these
categories. In regard to in-situ technologies, 14 states reported using vapor
extraction and six reported using bioremediation. However, only a few states
provided the degree of utilization of these technologies. Therefore, the majority
of technologies are identified as "Undefined/Other" in the figure. The
"Undefined/Other" pie slice includes corrective action using "pump and treat"
methods, as well as the other technologies discussed above.
2.3 SUMMARY OF CURRENT TREATMENT PRACTICES FOR PETROLEUM
CONTAMINATED GROUNDWATER AT UST CORRECTIVE ACTION SITES
To supplement the information on current treatment and disposal practices, EPA also
collected information on the percentages of sites requiring cleanup of groundwater and the types
of groundwater remediation technologies employed. Data of sufficient detail for analysis were
provided by 14 states. Approximately 37 percent of the UST corrective action sites in these
states maintain active groundwater remediation systems (i.e., the employment of remedial
technologies exclusive of monitoring and assessment, and other passive remediation).
2-5
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Figure 2-5: This figure illustrates the types of groundwater remediation technologies reported
for these sites. Approximately 96 percent of the total groundwater remediation
activities reported are based on "pump-and-treat" methods, involving the pumping
of contaminated groundwater by wells to the surface for treatment. Groundwater
treatment methods under this category typically include oil/water separation
followed by air stripping and/or carbon adsorption. As shown in Figure 2-5, air
stripping and carbon adsorption account for at least 59 percent of the total
groundwater remediation reported in these states (for an additional 37% of sites,
"pump-and-treat" methods were reported as being used, but no information
regarding groundwater treatment technologies was provided).
2.4 SUMMARY AND CONCLUSIONS
Following are the significant findings regarding current management practices in the
states that provided sufficient information for this analysis:
1. The current level of use of the major treatment/disposal options for media and debris
generated at UST sites in 22 states are: Landfilling - 55% of corrective action sites; In-
situ treatment - 19%; Thermal Treatment - 13%; Land Treatment - 11%; and Other -
2%.
2. Of the thermal options for treating petroleum contaminated soils in the 22 states,
treatment in asphalt plants is the most common (61% of sites), followed by low-
temperature thermal stripping (39%), and incineration (less than 1%).
3. Of the land treatment in these states, aeration predominates (50% of sites), followed by
landfarming (36%) and land application (13%).
4. Within 14 states that provided information sufficient for analysis of groundwater
remediation practices, approximately 37% of the UST corrective action sites have
groundwater contamination requiring remediation. Pump and treat methods predominate,
accounting for about 96% of the sites in these states. Surface treatment of contaminated
groundwater is performed by air stripping at about 33 % of these sites and by carbon
adsorption at about 26%, with the treatment method for the remaining sites using pump
and treat methods not specified.
2.5 REFERENCES
1. Information provided by Mr. Greg Waldrip, U.S. Environmental Protection Agency,
Office of Underground Storage Tanks.
2-9
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CHAPTER 3
OVERVIEW OF TECHNOLOGIES CURRENTLY EMPLOYED FOR
MANAGING PETROLEUM CONTAMINATED MEDIA AND
DEBRIS FROM UST CORRECTIVE ACTION SITES
3.1 INTRODUCTION
EPA's review of state programs, summarized in Chapter 2, illustrates the types of
technologies currently employed in the Subtitle I corrective action program for management of
media and debris and the level of utilization of each of these technologies. To better evaluate
the Subtitle I program, EPA reviewed information available as of June 1991 documenting the
performance of these technologies at UST sites.
This evaluation was limited to a review of information from readily available sources.
The primary sources were published literature, as supplemented by information obtained from
state UST agencies and selected technology vendors. Priority was placed on collecting the
following data for each type of technology:
• Contaminant removal efficiency;
• Operating parameters of equipment or techniques that affect the contaminant removal
efficiency; and
• Costs.
This chapter is divided into the following sections. Section 3.2 provides information in
each of the categories discussed above for ex-situ technologies for the treatment of petroleum
contaminated soils (PCS). Section 3.3 addresses in-situ treatment of these soils. Section 3.4
addresses groundwater remediation technologies. A table is provided at the beginning of each
section to summarize information for each technology alternative that has been documented
regarding the mode of treatment, costs, residuals generated by the process, emissions equipment,
treatment effectiveness, and significant limitations on applicability of the technology at UST
sites. This information is then discussed in the text. Finally, Section 3.5 summarizes significant
findings and conclusions.
3.2 TECHNOLOGIES FOR THE EX-SITU MANAGEMENT OF PETROLEUM
CONTAMINATED SOILS
EPA's review of selected state UST programs (see Chapter 2) indicated that the
technologies currently used most extensively for ex-situ management of PCS under the current
Subtitle I program (i.e., soil that is excavated prior to treatment) include the following:
• Low Temperature Thermal Strippers (LTTS);
• Asphalt Plants;
3- 1
-------
• Landfilling; and
• Land Treatment.
Since these technologies are predominant in the current Subtitle I program, priority in this
review was placed on collecting performance information on them. This information is
summarized in Table 3-1 and discussed in Sections 3.2.1 through 3.2.4. In addition to the
above technologies, other alternatives are available and are currently used to a limited extent for
the treatment of petroleum contaminated soils. Brief overviews of these technologies are
provided in Section 3.2.5. Note that high temperature incineration is not discussed since the
performance of incineration for treating contaminated soils has been extensively documented in
other studies.
3.2.1 Low Temperature Thermal Strippers
3.2.1.1 Process Description
The treatment of PCS by low temperature thermal strippers (LTTS) consists of the PCS
excavation, PCS processing, PCS feed into the LTTS system, thermal treatment of PCS,
treatment of volatilized petroleum gases, and discharge of treated solids. The mode of treatment
is thermal desorption of contaminants and subsequent treatment of desorbed volatiles. The
treatment steps are as follows:
PCS processing. PCS processing prior to thermal treatment may be necessary if the aggregate
size of the PCS is large or the PCS contains excessive debris (e.g., asphalt chunks). Processing
can include screening, crushing, or grinding1.
PCS feed into the LTTS system. The feed of PCS is managed by the feed hopper and PCS
conveyor. Feed rates are controlled by the system operator to maintain optimum temperatures
and PCS residence times in the combustion chamber. PCS process rates of 5 yd3 to 25 yd3 per
hour are common. The largest commercial units are reportedly capable of processing 40 to 50
tons per hour2'3'4'5.
Thermal treatment of PCS. LTTS are available in a variety of configurations: hot oil, steam,
or electrically heated thermal screws, directly or indirectly fired rotary kilns or infrared/flame
radiation heaters (IR/F radiation heaters)2 are the most common. Although design considerations
may vary among units, the basic treatment process is the same. In the combustion chamber,
soils are gravimetrically (rotary kiln) or mechanically (thermal screw or IR/F radiation heater)
agitated and moved through the combustion chamber as they are heated to a temperature
sufficient to volatilize, not combust, the petroleum hydrocarbons. Soil temperatures during
treatment average 250° to 450° Celsius (482°F to 842°F)50.
3-2
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(THIS PAGE INTENTIONALLY LEFT BLANK)
3-3
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Table 3-1
Corrective Action Technologies for the Ex-situ Treatment of PCS
Generated at Petroleum UST Sites
Corrective Action
Technology
Mode of Treatment
Cost1
Residual/Process Wastes
Low Temperature Thermal
Strippers
Thermal desorption and low
temperature destruction (250° to
450° celsius, 482°F to 842°F)
with process gas; incineration,
dilution or carbon adsorption
with/without reclamation of the
desorbed volatiles6.
Treatment costs range from
$74 to $184 per ton of
PCS1'2'13'14.
Volatile hydrocarbons (if
emissions control devices
are not used).
Process waters.
Combustion products.
Particulate matter.
Processed soils2'8'13.
Hot Mix Asphalt Plant
Hot Mix Asphalt Plant
Converted to LTTS
Thermal desorption and low
temperature destruction (260° to
427° celsius, 50(f°F to 800°F)
with encapsulation , or thermal
desorption and low temperature
destruction without
encapsulation8'17.
Thermal desorption and low
temperature destruction with
process gas; incineration,
carbon adsorption, dilution or
reclamation of desorbed
volatiles.
Treatment costs range from
$50 to $100 per ton of
PCS1'8'14'17'22
(The sources of cost
information were not specific
in associating their costs with
a specific type of asphalt
plant).
Volatile hydrocarbons.
Combustion products.
Scrubber process water (if
used).
Unencapsulated soils.
Combustion products.
Scrubber process water.
Unencapsulated soils.
Land Treatment
Microbial degradation,
photolysis, leaching,
adsorption/immobilization,
volatilization and aeration8'22.
Treatment costs range from
$5 to $70 per ton
1,2,8
Potential residuals include
surface run-off, vapor
emissions, leachates and
contaminated soils17.
Landfilling
Disposal process; no active
treatment process. In some
instances state regulations or
landfill operating procedures
may dictate the use of PCS
solely as cover material, where
a limited amount of
volatilization, photolysis, and
biodegradation may occur34.
For all solid wastes, median
of national annual operating
expenditures is $11 per ton,
with expenditures ranging
from > $20 per ton for small
landfills (1 TPD) to < $5 per
ton for large landfills (1,000
TPD)54. Tipping fees in
1988 ranged from $4.07 per
ton to $132 per ton, with a
national average of $26.93
per ton54.
PCS contaminant levels
may persist, and leachate
and vapors may be
generated.
Citations quoting costs of disposal/remediation using a particular treatment technology were not specific in identifying
what percentage of the costs was attributable to the actual treatment and what percentage, if any, was due to PCS
transport and storage, treated soil disposal, or emissions control costs. See text for additional information on factors
affecting costs.
3-4
-------
Table 3-1 (continued)
Corrective Action Technologies for the Ex-situ Treatment of PCS
Generated at Petroleum UST Sites
Corrective Action
Technology
Low Temperature Thermal
Stripper
Hot Mix Asphalt Plant
Hot Mix Asphalt Plant
Converted to LTTS
Land Treatment
Landfilling
Emissions Control
Equipment
Baghouses.
Venturi scrubbers.
Cyclones.
Carbon adsorption
units.
Afterburners (secondary
combustion units).
Condensers/demisters.
Cyclones.
Wet scrubbers.
Demisters.
After burners
(secondary combustion
chamber).
Baghouses.
Venturi scrubbers.
Quencher/demisters .
Caternary grid
scrubbers.
Proper management is
needed to reduce the
generation of vapors.
No technologies exist
for the treatment of
vapor emissions from
uncapped landfills.
Treatment
Effectiveness
Numerous case studies
demonstrate LTTS
achieving >95%
removal efficiencies
with removal
efficiencies >99%
reported in some
cases8'10'13; however
removal efficiencies as
low as 27% have been
reported9'10.
93.2-99% for X21
50-70% for PCS as
diesel fuel21
84-95% for PCS as
gasoline21
94.5-99% removal for
B20
97-99% removal for
TPH20
>99% removal for!20
> 99.99% for
hazardous organic
constituents in a drum
mix plant6.
99.25% removal of
X&T from contaminated
soil18.
Cited sources and
monitoring data
collected from state files
indicate that land
treatment can reduce the
concentration of
petroleum products in
soil by 70% to
>99%2,23,36_
No treatment performed
Limitations
Excessive soil moisture limits treatment
effectiveness and may require
preprocessing. Large concentrations of
fines (silts and clays) can limit treatment
effectiveness. Debris (e.g., asphalt
chunks) reduce effectiveness and may
result in unacceptable emissions. Initial
PCS concentrations > 10,000 ppm TPH
may need to be processed more than once
to achieve acceptable concentrations. Less
effective on heavy end petroleum products
(e.g., No. 6 fuel oil). Process waste
streams (gas, water, and treated soil) may
require proper storage, treatment and
disposal1'3.
Material <200 mesh screen limited to
10% of total weight.
High organic content or high fractured
rock content in soil is not conducive to
treatment.
Seasonal operations.
Some states limit acceptable PCS to virgin
product contaminated14.
Off-site transport of the PCS may be
necessary13.
Retrofit may be expensive.
Additional manpower may be needed to
monitor process13.
Seasonal operations. Requires a great deal
of land (usually agricultural land) relative
to other treatment options. May be
unreclaimable following PCS treatment.
Treatment is slow (requiring years in some
instances to achieve remediation goals)2'8'24.
Future liability remains.
3 -5
-------
Treatment of the volatilized petroleum gases. Volatilized petroleum hydrocarbons, water vapor,
and participates become part of the process gas stream, then exit the primary combustion
chamber, and enter the emissions control system. The first step in gas treatment is typically a
baghouse or cyclone where entrained particulate matter is removed and collected. Depending
upon system design, the volatilized hydrocarbons can be recycled for reuse, immobilized, or
destroyed.
Petroleum vapor collection for reuse. If the volatilized hydrocarbons are to be recycled, the
process gas is sent to a condenser or demister. Through cooling, the water and volatiles are
removed from the gas stream, creating a new waste stream of water and liquid hydrocarbons.
The remaining gases are vented to an afterburner or carbon adsorption system where they are
treated and finally vented to the atmosphere. The hydrocarbon water mixture is pumped to a
oil/water separator where the hydrocarbons are recovered and subsequently transferred to a
storage tank for eventual reprocessing. The waste water is treated as necessary.
Petroleum vapor destruction or immobilization. If contaminant levels in the soil and/or soil
volumes are too low to warrant recycling, the hydrocarbons can be destroyed through thermal
oxidation or immobilized through carbon adsorption. The system design in these instances is
much simpler than the design required for petroleum collection for reuse17.
Discharge of the treated solids. Treated soils are discharged, via a conveyor system, directly
from the primary combustion chamber. Unlike incineration units, the discharged soils do not
need to be cooled prior to discharge and handling.
3.2.1.2 Treatment Efficiency
Low temperature thermal strippers are cited in the literature as having the capacity to
reduce the levels of volatile organic compounds, including petroleum hydrocarbons, in soil by
more than 99 percent. However, sources available to the EPA indicate that a wide variation in
performance has been experienced. This is summarized in the following case studies:
Case Study Example 1: A feasibility study was performed for the USATHAMA to evaluate
the effectiveness of LTTS technology (hot oil heated thermal screw unit) for the removal of
volatile and semi-volatile organics from soil. The system was operated under a variety of test
conditions: heating oil temperature (100° to 300° Celsius, 212°F to 572°F); soil residence times
(30 to 90 minutes); and soil discharge temperatures (50° to 150° Celsius, 122°F to 302°F).
About 165 yd3 of soil was treated during the test, with VOC levels in the soil initially as high
as 20,000 ppm1. Pre- and post- treatment sampling and analysis of soil samples indicated that
more than 99.99 percent of the VOCs had been removed from the soil. The process gas was
sent to an afterburning unit operating at 1,000° Celsius (1,832°F), where it resided for longer
than 2 seconds. No VOCs were found in the stack emission gases, indicating a destruction and
3-6
-------
removal efficiency for the overall system of more than 99.99 percent8. (For more information
refer to Noland, McDevitt, and Koltuniak (1986) for a description of this demonstration project
conducted by Roy F. Weston for USATHAMA.)
Case Study Example 2: About 700 yd3 of diesel contaminated soil was treated as part of a
demonstration project. Pre-burn contaminant levels as high as 67,000 ppm TPH were reduced
on average greater than 98.5 percent. Approximately 4.5 yd3 of soil were treated per hour1.
(This demonstration cleanup was performed in October 1986 for San Diego Gas and Electric
by Earth Purification Engineering of Fremont, California.)
Case Study Example 3: A private vendor remediated 1,200 tons of leaded gasoline, unleaded
gasoline, kerosene, diesel fuel, and No. 4 fuel oil contaminated soil. Pre-treatment TPH levels
in the excavated soil ranged from 1,200 ppm to 5,000 ppm. The rotary drier LTTS unit reduced
the TPH concentrations in the clayey soil by greater than 99.5 percent, at a soil treatment rate
of approximately 11 to 15 tons per hour6.
Case Study Example 4: About 11,500 yd3 of contaminated soil at the McKin Superfund Site,
Gray, Maine, was treated using LTTS technology. The LTTS system included a thermal dryer,
baghouse, scrubber, and carbon treatment system. The system was operated at 121° to 204°
Celsius (250°F to 400°F). Periodic testing of pre- and post-treatment soil samples indicated that
the system consistently removed greater than 90 percent, but ranged as low as 33 percent, of the
aromatic compounds from the contaminated soil (selected results are presented in Table 3-2).
The lower removal efficiencies were attributed to the low initial contamination levels. This
source postulated that removal efficiencies were directly proportional to the initial concentration
levels9.
In addition to the literature sources, EPA obtained LTTS treatment efficiency data from
the Minnesota UST program which tracks the disposition of PCS at its thermal treatment units.
Analytical results from pre- and post-burn sampling of PCS from 20 sites are listed in Table 3-3.
These are sites where soils were treated with mobile LTTS units10. The analytical results were
used to calculate removal efficiencies (percent reduction = 100% - ((postburn data/preburn data)
x 100)) of benzene, total BTEX, TPH as gasoline, and TPH as fuel oil when applicable.
The results indicate that in the majority of cases removal efficiencies were greater than
99 percent. In several cases however, the data indicate low removal efficiencies. A number of
factors may contribute to the low removal efficiencies observed. Low pre-treatment contaminant
concentrations may contribute to reduced removal efficiencies. The available data, however,
did not provide a description of operating conditions or waste stream characteristics sufficient
to determine factors may have contributed to the observed results. A review of the data in Table
3-3 shows that, in those cases where contaminant reduction was low, pre-burn concentrations
of contaminants were relatively low with respect to the other cases. The data suggest that as the
3-7
-------
PCS pretreatment VOC content decrease, the LTTS systems were unable to appreciably decrease
the contaminant concentrations.
Table 3-2
PCS Treatment Efficiency Using LTTS7
Contaminant Name
xylenes (total)
xylenes (total)
ethylbenzene
ethylbenzene
xylenes (total)
xylenes (total)
xylenes (total)
ethylbenzene
xylenes (total)
ethylbenzene
ethylbenzene
toluene
benzene
ethylbenzene
toluene
Untreated Concentration
(ppm)
840
160
130
72
62
44
4.9
20
3.3
1.5
1.3
4
2.7
1.8
0.3
Treated Concentration
(ppm)
1
1
1
1
1
1
0.2
1
0.2
.2
0.2
1
1
1
0.2
Removal Efficiency
(%)
99.88
99.37
99.23
98.60
98.38
97.72
95.91
95.00
93.93
86.66
84.61
75.00
62.96
44.44
33.33
3.2.1.3
Operating Parameters that Affect Treatment Performance
There are a number of variable operating parameters that affect the PCS treatment
effectiveness of LTTS units. The three operating parameters that with the largest influences on
LTTS units ability to remove petroleum hydrocarbons from soils are: 1) temperature; 2)
residence time; and 3) agitation/exposure15. These, and other operational parameters typical of
LTTS systems used in the Subtitle I program are:
• Soil characteristics: Excessive soil moisture can decrease removal efficiencies. The
higher the percentage of fines (clay and silt), the lower the expected treatment
efficiency1. Preprocessing of soils may be necessary if aggregate size is too large or
excessive debris exists in the waste stream.
3-8
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Soil contamination: Soil with contaminant concentrations above 10,000 ppm TPH may
not be able to be treated so that post treatment contaminant levels are below state
required clean-up levels2. Treatment is most effective when treating light end
hydrocarbons (gasoline) and less effective as the mean boiling temperature of the
contaminant increases (i.e., No. 6 fuel oil)3.
Temperatures: Temperatures at LTTS units typically range from 250° to 450° Celsius
(482°F to 842°F)6. (Data sufficient to characterize the relationship between temperature
and removal efficiency were not found during this study.)
Emissions control equipment for the removal of particulate matter and volatilized organic
compounds: VOC emission control equipment can be designed to destroy the volatilized
hydrocarbons (afterburner), immobilize them, (carbon adsorption), or capture them for
recycling (carbon adsorption, condenser and oil/water separator)2. Afterburner
temperatures of approximately 650° Celsius (1,202°F) are typical14. Temperatures of
500° to 650° celsius (932°F to 1,202°F) are needed to oxidize hydrocarbons, and
temperatures of 650° to 800° (1,202°F to 1,472°F) are needed to oxidize carbon
monoxide6.
3.2.1.4 Conditions that Affect Treatment Costs
A wide range of treatment costs using LTTS have been reported in the literature ($74 to
$184 per ton)1'2'13'14. The sources used in this review are not specific in identifying what amount
of the costs was attributable to the actual capital and operating costs, and what percentage, if
any, was due to PCS transport and storage, treated soil disposal, emissions control costs, or
other factors. Further, since the cost estimates were presented simply as ranges, with no
information regarding the numbers of units involved or the distribution of costs within the cited
ranges, it is not possible to prepare a statistical analysis of the data. Table 3-4 lists the cost
estimates as cited in the literature and the conditions under which these costs were experienced.
Figure 3-1 shows the results of an economic evaluation performed for USATHAMA to
examine the costs of LTTS for treating soils contaminated with volatile organics in the following
categories: 1,000 tons, 10,000 tons, and 100,000 tons. Based upon this evaluation, it was
concluded that System B was the most cost-effective approach for sites with 15,000 to 80,000
tons of soil to be treated (far in excess of volumes found at typical UST sites). The unit costs
for this system ranged from $160 to $174 per ton without flue gas scrubbing and from $87 to
$184 per ton with scrubbing. Operating costs for stripping 1,000 tons of soil ranged from $89
to $142 per ton for the four systems. Capital costs were a significant portion of the total costs
for processing4.
3 - 10
-------
Table 3-4
Costs Reported for Treatment of PCS by Low Temperature Thermal Strippers
Treatment Costs
$100 per ton2
$100 to $165 per ton'
$80 to $150 per ton13
$100 to $120 per ton13
$74 to $160 per ton14
$87 to $184 per ton14
Applicable Conditions
Based on operation of commercial LTTS units in Holland.
Costs are based on a production rate of 2 to 6yd3 per hour and
may vary depending on VOC concentration, soil moisture
content and grain size of the PCS. Costs are expected to
decrease as capacity increases.
Based on a capacity of 30 to 50 tons per hour and is dependent
on soil characterization and treatment criteria.
Based on a 20% moisture content, and a contaminant
concentration of 10,000 ppm.
System does not include a flue gas treatment system. PCS
volume to be treated is 15,000 to 80,000 yd3-
Capital costs are a significant portion of the total costs for
processing, and increase as the volume of PCS to be treated
decreases. Operating costs for processing less than 10,000 tons
would be expected to be in excess of $200 per ton.
System includes flue gas treatment system. PCS volume to be
treated is 15,000 to 80,000 yd3.
3.2.2 Hot Mix Asphalt Plants
3.2.2.1
Process Description
Two basic types of asphalt plants are currently in use, batch mix and drum mix, with
approximately an equal number of each of these types of plants in operation. Batch mix plants,
which separate the heating, screening, blending, and production steps, mix one batch of product
at a time. In this process, the drier is stopped and started numerous times during a day. Drum
mix plants first size the aggregate and then heat and blend it in one combined production step.
Drum mix plants usually run continuously for long periods of time13. Most new plants are of
the drum mix type15.
3 - 11
-------
Figure 3-1
Costs of Low Temperature Thermal Stripping Pilot Plant Units4
03 06
11
Sfc 05
04 -
03 -
02-
01 -
0
SYSTEM A -ONE THERMAL PROCESSOR WITH
TWO 24 INCH DIAMETER AND TWO
24 FOOT LONG HOLO-FLUTE® SCREWS
SYSTEM B - ONE THERMAL PROCESSOR WITH FOUR
24 INCH DIAMETER AND FOUR 24 FOOT
LONG HOLO-FLUTE® SCREWS
SYSTEM C -TWO SYSTEM B UNITS ARRANGED
IN SERIES
SYSTEM D -FOUR PROCESSORS CONSISTING OF
TWO PARALLEL SYSTEM C UNITS
ALL WITH FLUE GAS SCRUBBING
System B
20
T
40
T~
60
T-
80
100
Quantity of Soil Processed (Tons)
(Thousands)
Source: Economic Evaluation of Low Temperature Thermal Stripping of Volatile Organic Compounds from Soil. U.S.
Army Toxic and Hazardous Materials Agency Report No. AMXTHOTE-CR 8CO85 (Roy F. Weston, 1986)
The manufacture of asphalt, which uses PCS as an aggregate supplement, can either be
a cold or hot process. The cold mix process blends untreated PCS directly with the liquid
asphalt16. This process is discussed in Section 3.2.5.1 of this report. The hot mix process is
the most common process under the Subtitle I program and is discussed in this section.
Hot mix asphalt plants are typically used as fixed regional treatment centers for PCS12.
The treatment entails either desorption, oxidation and encapsulation, or desorption and oxidation
without encapsulation. It is not known, however, to what degree each treatment mechanism
contributes to the overall removal/destruction of the petroleum compounds in the soil. The
hydrocarbons not volatilized in rotary driers at asphalt plants are expected to be incorporated
3 - 12
-------
into the asphalt mix. None of the literature reviewed'in this study, however, addressed with any
certainty the fate of these compounds following encapsulation, (e.g., leaching potential).
Asphalt plants process from 20 to 180 tons of gravel, sand, and mineral filler per hour.
When PCS is being treated, the standard industry practice is to mix less than 5 percent by weight
PCS with clean aggregate to achieve an average treatment capacity of 1 to 9 tons PCS per
hour6'17. The asphalt plant rotary driers, in which PCS thermal treatment occurs, are usually
maintained at temperatures of approximately 260° to 427° Celsius (500°F to 800°F)8>17. The
PCS processing capacities of these facilities are limited by air quality concerns and the need to
ensure and maintain the quality of the asphalt mix. An improper PCS/aggregate feed may result
in a low quality mix, which would not meet Department of Transportation (DOT) road use
specifications. Typical aggregate feed into the asphalt mix is 60 percent coarse material and 40
percent fines. To this, 5.5 percent liquid asphalt by weight is added. As the amount of fines
less than 200 mesh (very fine sand and silt) becomes greater than 10 percent, the mix quality
deteriorates18. In addition, too high an organic content or fractured rock content in the aggregate
feed also will deteriorate the asphalt mix.
A number of asphalt plants have been converted into operational units designed
specifically for soil treatment. Modifications are usually made in response to air quality
concerns and entail the addition of more efficient and modern emissions control devices,
including secondary burners, baghouses, venturi scrubbers, quenchers, and catenary grid
scrubbers12. Minnesota now requires that all asphalt plants that are going to treat PCS within
the state be equipped with high efficiency wet scrubbers and afterburner units19. Other
modifications made when PCS are to be handled at a modified asphalt plant may include more
and larger aggregate feed bins, cold storage facilities, and the addition of larger staging areas
designed specifically for soils management.
Converted asphalt plants can process a much more diversified waste stream in terms of
aggregate feed size. Since the PCS treated at these facilities is not incorporated in the asphalt
mix, product quality is not an issue17.
3.2.2.2 Treatment Efficiency
Three sources of information on PCS treatment efficiency were reviewed during this
study: 1) pre- and post-burn analytical data from PCS treatment at an asphalt plant in
Anchorage, Alaska, 2) the results of a test burn of simulated petroleum contaminated soil at an
asphalt plant in Massachusetts, and 3) a study performed for the Minnesota Pollution Control
Agency (MFCA) on petroleum contaminated soil treatment test burn results.
Table 3-5 summarizes treatment data for one asphalt plant in Alaska. The pre-burn
concentrations of organic constituents are based on analysis of samples from stockpiled soils at
3- 13
-------
six UST corrective action sites. The post-burn concentrations are based on analysis of samples
taken after the soils were transported from the sites and treated at an asphalt plant. Removal
efficiencies ranging from 94.5 percent to more than 99 percent were found20.
Table 3-5
PCS Treatment Efficiency at an Asphalt Plant20
Volume
(tons)
1374
2016
141
257
1398
1844
Preburn Analytical Results (ppm)
Benzene
6.9
0.126
-
-
0.973
0.179
Toluene
15
4.13
-
-
-
-
Total
BTEX
74
46
-
-
25 5
83 2
TPH
7200
1100
319
479
-
Postburn Analytical Results (ppm)
Benzene
ND
0.00571
ND
ND
ND
001
Toluene
ND
0.00908
ND
ND
ND
ND
Total
BTEX
0.007
0.0229
ND
0.019
0.0087
0.04
TPH
14
20
ND
14.4
ND
ND
Percent Reduction
Benzene
99
95.5
-
-
99
94.5
Toluene
99
99.7
-
-
-
Total
BTEX
99
99
-
-
99
99
TPH
99
98
99
97
-
-
The results of a test burn at a Massachusetts asphalt plant indicate that volatilization of
organic compounds during pretreatment can be substantial18. During the test burn, a significant
amount of the petroleum compounds' initial mass was lost through volatilization as a result of
the material handling and processing (i.e., excavation, crushing, screening, and debris removal)
performed prior to treatment. At the initiation of the study, 9 tons of sand were spiked with a
50:50 xylene/toluene mix to 30,000 ppmv. A sample collected from the PCS storage hopper
prior to treatment in the asphalt plant showed that the level of the xylene/toluene mix in the sand
was 4,000 ppmv. On the aggregate conveyor, the level was 1,500 ppmv; a 95 percent decrease
in the concentration of the two compounds prior to the treatment process. This reduction was
presumed to be due to volatilization to the atmosphere during processing.
Minnesota performed a test burn evaluating the treatment of PCS at a traditional asphalt
plant during routine operations. The asphalt plant chosen for the test represented what the
consulting contractor thought were worst-case scenarios for several variables: 1) maximum soil
feed rate during test, 2) the asphalt plant operated co-currently, 3) the treated soils had high silt
contents, and 4) the wet scrubber used in emissions control was simple and inefficient in
comparison to more modern devices. The asphalt plant test burn results indicate that a 99.9
percent soil treatment efficiency for benzene was achieved. Similar results were obtained for
xylene, with lower efficiencies reported for total hydrocarbons21.
3- 14
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3.2.2.3 Operating Parameters that Affect Treatment Performance
No data were identified during this study to conclusively indicate the relationship between
treatment effectiveness of asphalt plants and plant operating parameters. Operation of the dryer,
including dryer temperature, residence time, and agitation/exposure, are likely to be among the
most important parameters, but other factors (including soil moisture and soil and contamination
characteristics) may be equally important. Relevant to these factors, asphalt plants that treat
PCS typically operate under the following conditions:
• Dryer temperature: Dryer temperature is normally between 260° and 427° celsius
(500°F to 800°F)5>9;
• Mesh size: Aggregate content below 200 mesh size normally does not exceed 10 per
cent of the total; and
• Feed rate: On average, the feed rate of PCS in plants that mix PCS with product is one
to nine tons per hour.
Table 3-6 lists the PCS treatment efficiencies and applicable conditions, if available, that
were identified in this study.
3.2.2.4 Conditions that Affect Treatment Costs
As shown in Table 3-1, a wide range of treatment costs using asphalt plants have been
reported in the literature, from $50 to $100 per ton. The sources used in this review are not
specific in identifying what percentage of the costs was attributable to the actual treatment and
capital costs, and what percentage, if any, was due to PCS transport and storage, treated soil
disposal, emissions control costs, or other factors. Further, since the cost estimates are
presented simply as ranges, with no information regarding the numbers of units involved or the
distribution of costs within the cited ranges, it is not possible to prepare a statistical analysis of
the data. Table 3-7 lists the treatment costs cited and the conditions that apply to the cost
estimates. One source cited the cost to retrofit an asphalt plant in the range of $10,000 to
$100,0008.
3- 15
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Table 3-6
PCS Treatment Efficiencies and Associated Conditions in Asphalt Plants
PCS Treatment Efficiency
Treatment Conditions
50.5% when calculated as Fuel Oil No. 221
70.2% when calculated as Fuel Oil No. I21
Diesel fuel contaminated soil. The soil was classified as a
mixture of sand fill with native silty sand and silty clay. Plant
operating conditions were: soil throughput of 280 tons per hour,
mix temperature 295° F, and soil moisture content of 11.5%.
Pretreatment contaminant concentrations averaged 308 ppm
(identified as No. 2 fuel oil).
84. % when calculated as Gasoline21
94.1% when calculated as Fuel Oil No. I21
Gasoline contaminated soil. Soil was classified as a fine to
medium sand with silt and a little gravel. Plant operating
conditions were: soil throughput of 255 tons per hour, mix
temperature of 300° F, and soil moisture content of 5.9%.
Sample results indicate that the PCS contaminant was identified
as gasoline prior to screening, and that post screening, pre-
treatment it was identified as No. 2 fuel oil. It is likely that this
is a result of the lighter VOC having volatilized during the
screening process. Pretreatment contaminant concentrations
averaged 862 ppm (identified as No. 2 fuel oil).
99.25 %18
Contaminated aggregate was: 3% organics, 50/50 blend of
xylene and toluene in a natural sand, with a moisture content of
3.3%. Total run time was one hour. Pre-screening contaminant
concentration was 30,000 ppm with a post-treatment
concentration of <0.200 ppm.
Table 3-7
Costs Associated with Treatment of PCS in Asphalt Plants
Treatment Costs
$80 per ton1
$50 to $75 per ton8
$50 to $100 per yd3(17)
Applicable Conditions
Excavation, transportation and
storage of the PCS would add to
the costs. Capital costs vary in
proportion to size of the plant.
Does not include excavation costs.
Assumes off-site operation of the
unit with transportation costs
additional. 3,700 yd3 (4,000 tons)
of PCS were treated.
3- 16
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3.2.3 Land Treatment
3.2.3.1 Process Description
Land treatment of PCS can be done passively through land application or through active
management, which incorporates the PCS in landfarming units.
Land Application: Land application, also referred to as land spreading, is the least labor
intensive approach to the land treatment of PCS. In this process, soils are spread uniformly over
the land to a relatively shallow depth typically not exceeding four inches. The applied PCS is
not incorporated into the soil and is not actively managed. Naturally occurring processes (e.g.,
microbial degradation, photolysis, leaching, adsorption/ immobilization, volatilization and
aeration) decrease the concentration of the petroleum compounds in the soil23.
Landfarming: Landfarming involves controlled application, incorporation (into the top 4 to 8
inches), and active management (e.g., addition of nutrients, irrigation, tilling) of PCS at
prepared sites23. There are generally two categories of landfarming facilities for the treatment
of PCS: single and multiple application24. A single application site is returned to its original
function following the application and treatment of PCS generated from one UST release site.
Reclamation is typically performed 1 to 3 years following closure of the site as an active
treatment facility2. A multiple application site is designed to accept and treat PCS generated at
more than one UST release site.
The landfarming process consists of six distinct steps: 1) site selection, 2) site
preparation, 3) PCS application/incorporation, 4) management, 5) monitoring, and 6) site
closure. The initial, most difficult, and potentially most costly step in this process is the
selection, permitting, and preparation of a landfarming facility. Numerous factors that need to
be considered in site selection have been discussed in the literature, including6'8'13'24'25:
• Location of facility with respect to aquifer recharge zones;
• Topography. The surface should be relatively flat to minimize run-off and erosion
problems. In general, recommended slopes are between 2 and 5 percent;
• Climate (precipitation, temperature, and wind speed);
• Distance to surface water;
• Depth to ground water;
3 - 17
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• Soil physics and chemistry, including soil depth, texture, drainage (unsaturated and
saturated hydraulic conductivities), Ph, organic matter, soluble salts, cation exchange
capacity, moisture holding capacity, and microbial counts; and
• Soil types. In general, facilities should not be established on deep sandy soils or on soils
with the tendency to form crusts. Desirable soils include loam, sandy clay loam, silty
clay loam, clayey loam, and silty clay.
Specific requirements dictating siting (e.g., depth to ground water, distance from surface
water, emissions controls, etc.) and management (e.g., application rates and times, nutrient
application rates, sampling and reporting requirements, etc.) of these facilities depends largely
on the regulatory requirements of the governing state agencies. These requirements vary from
state to state, depending upon variations in geology, hydrogeology, soil chemistry, climate, and
land use that characterize the different regions of the United States.
In general, PCS is applied (spread) and incorporated (mixed) into the top eight inches of
the top soil13. PCS landfarming management should maintain soil moisture, nutrient, and Ph
levels at optimum conditions for microbial growth. Proper management also should guide the
frequency of tilling to ensure optimum aeration/oxygenation. Tilling/aeration of the soil is
typically performed more frequently at early stages of the treatment process, with a diminishing
need as treatment progresses. Monitoring is needed to ensure that conditions optimal for
microbial growth are maintained, that treatment is effective, that contaminants are maintained
within the treatment zone, and to indicate when conditions are appropriate for reapplication of
PCS.
3.2.3.2 Treatment Efficiency
Few studies were identified during this review that presented quantitative data to
demonstrate the effectiveness of treating PCS using land treatment technologies. The available
data is insufficient to characterize the reductions in soil contaminant processes that can be
attributed to physical, chemical, and biological processes taking place in the soil or that which
can be attributed to volatilization to the atmosphere.
One report indicates that removal efficiencies of 70 percent to 90 percent can be achieved
with loadings of 1 to 5 percent by weight2. Unfortunately, the time required to achieve these
reductions was not specified. Another source indicates that relatively rapid rates of degradation
can be expected in the first 60 to 90 days following application, with increasingly diminishing
rates. This report states that up to two years may be needed for completion of treatment,
depending on the initial concentration levels1. It, however, did not specify what levels were
treated or the treatment effectiveness.
3 - 18
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Table 3-8 presents analytical data from the pre- and post- application of PCS at several
landfarming facilities in Minnesota. As shown, reductions of more than 99 percent in the TPH,
total BTEX or benzene concentrations were achieved for sites where PCS were treated for at
least five months23.
Table 3-9 presents analytical results from pre- and post-application of PCS sampling at
a Vermont landfarming facility. In this example, approximately 200 cubic yards of soil
contaminated with kerosene and No. 2 fuel oil were treated. The monitoring results indicate that
the concentration of total petroleum hydrocarbons decreased from 75 to 89 percent over one
year, with a higher rate of reduction found in samples taken at 6 inches than those taken at 12
inches26.
Table 3-10 provides data from a site in Vermont where oil contaminated soil was spread
on a concrete pad in October 1986. Cow manure was incorporated into the PCS as a source of
nutrients, and the treatment site was tilled regularly through the growing season. Within one
year, the concentration of oil and grease in the soil was reduced by 87 percent. In October
1987, a second application of PCS was applied. Within 6 months the PCS contamination levels
were reduced by 99 percent. However, the data do not indicate the extent to which the observed
reductions could be attributed to volatilization26.
3.2.3.3 Operating Parameters that Affect Treatment Performance
A wide range of highly site-specific factors affect performance of land treatment
facilities. The following variables have been cited in the literature as important considerations
in the management of land treatment facilities:
• PCS loading: PCS loading should not degrade the infiltration, percolation and aeration
potential of the land treatment soil25. Loading is generally limited to 5 percent waste by
weight of the soil into which it will be incorporated13.
• The presence of toxic or leachable constituents: Heavy metals, inorganic salts, heavy
halogenated organics, some pesticides, some herbicides, and nitrates diminish the
effectiveness of PCS treatment (concentration reduction). Toxics can eliminate the
microbial populations, and leachables can potentially impact ground water1.
3 - 19
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Table 3-9
PCS Treatment Efficiency at a Landfarming Faculty in Vermont26
Monitoring Date
8/87
9/87
10/87
5/88
6/88
7/88
6" Sampling Depth
TPH Concentration
(mg/kg)
3,271
1,379
946
1010
450
370
Percent Reduction
From First Data
Point
0
58
71
69
86
89
12" Sampling Depth
TPH Concentration
(mg/kg)
233
1,622
1,250
1,220
700
410
Percent Reduction
From First Data
Point
0
-
23"
251
57a
75"
As compared to 9/87 sample.
Table 3-10
Oil Contaminated Soil Treatment Efficiency at a Landfarming Facility in Vermont26
Oil and Grease Concentration (mg/kg)
Monitoring Date
10/7/86
6/26/87
10/2/87
10/22/87a
4/26/88
7/12/88
10/7/88
Average Concentration from
Composite Samples
7,280
1,128
944
4,000
3,727
800
23.3
Percent Reduction from First
Data Point
84
87
—
7
80
99
More contaminated soil added.
3-21
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Nutrient additives: Addition of nutrients is often required to maintain and promote
biological activity. Recommendations cited in the literature include:
Nitrogen: Levels should be maintained in excess of 5 ppm1. Added
nitrogen is in the form of NIL/ or NO3" (ammonium chloride is a
common additive)2. Application rates quoted in the literature range from
50 Ibs to 500 Ibs per acre2'24;
Phosphorous: Levels should be maintained in excess of 1 ppm2. Added
phosphorous is in the form of PO43" (sodium phosphate is a common
additive)2. Application rates quoted in the literature range from 5 Ibs to
120 Ibs per acre2'24;
Potassium2'6;
Iron Fe~24; and
Sulfur.
Soil Ph: A neutral (Ph = 7) or slightly alkaline Ph (Ph > 7) is optimum for microbial
activity and for minimizing the mobility of heavy metals1'6'27. An acceptable range is
between Ph of 6 and a Ph of 82'6. Lime can be added to the field to adjust the Ph;
Soil moisture: Soil moisture should be maintained between 30 percent and 80 percent.
Optimum conditions for microbial activity are soil moisture contents of between 40
percent and 55 percent1'27. Excessive moisture limits the available oxygen and its
capacity for exchange6;
Soil temperature: Temperature directly affects microbial activity rates. Microbial
activity has been shown to slow at 10° Celsius (50°F) and effectively cease at 5° Celsius
(41°F)6. On average, degradation rates of petroleum products can be expected to be 15
percent less in cold climates as opposed to those more southerly6'27;
Aeration: Aeration (tilling, disking, etc.) promotes oxygen exchange and the
maintenance of aerobic conditions. The literature suggests that aeration should be
performed every 2 to 4 weeks2; and
Reapplication: Reapplication of PCS or petroleum products must not occur too soon so
as not to overwhelm the load-bearing capacity of the soil, or too late so as not to
maintain elevated levels of microbial activity13.
3-22
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3.2.3.4
Conditions that Affect Treatment Costs
A wide range of treatment costs using land treatment have been reported in the literature
($5 to $70 per ton)8. The sources used in this review are generally not specific in identifying
what percentage of the costs was attributable to the actual treatment and capital costs, and what
percentage, if any, was due to PCS transport and storage or other factors. Further, since the
cost estimates were presented simply as ranges, with no information regarding the numbers of
units involved or the distribution of costs within the cited ranges, it is not possible to prepare
a statistical analysis of the data. Table 3-11 lists the specific references and the conditions that
apply to the cost estimates.
Table 3-11
Costs Associated with Treatment of PCS at Land Treatment Facilities
Treatment Costs
$5 to $50 per yd3(2)
$10 to $40 per yd3(1)
Approximately $17 per metric ton (1986
dollars)8
Applicable Conditions
Costs are a function of the extent of contamination, waste
type and biodegradation rates. Depending on location, the
need for surface runoff/run-on controls will increase costs.
Includes sampling and analysis costs.
Total costs break down as follows: cultivation and site
operation $1.65 to $2.20 per metric ton; materials
transportation and handling $9.35 per metric ton; and soil
analysis $5.50 per metric ton.
3.2.4 Landfilling
3.2.4.1
Process Description
Under current practices, PCS from UST corrective action sites is excavated, stored, and
transported to a commercial or industrial landfill, where it is placed in disposal cells or spread
as daily cover. If PCS is used as daily cover, it is typically spread and compacted to a depth
of 6 to 18 inches. Deeper covers may be required by state regulatory officials in response to
odor or vector complaints. Whether PCS is disposed of in cells or as daily cover is dependent
largely on state or local regulations34.
If the PCS is used as daily cover, partial reduction of contaminant concentrations occurs
because volatile compounds are emitted during the spreading and compacting process. If,
however, PCS is placed in a cell and covered, microbial degradation of the organic compounds
is the major treatment mechanism. Petroleum range hydrocarbons biodegrade under aerobic
conditions (oxygen is consumed and CO2, H2O, organic acids, and intermediate degradation
3-23
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compounds are generated) and are fairly resistant to degradation under anaerobic or
methanogenic conditions (sulfates, nitrates, carbon dioxide and other fixed oxygen compounds
are consumed to produce methane and other products of incomplete metabolism)14'30. Section
3.3.2 of this report gives a more complete discussion of the biological degradation of petroleum
range hydrocarbons.
3.2.4.2 Treatment Efficiency
Although landfilling is not a treatment process, natural degradation of contaminants in
landfilled PCS can occur over time. However, the EPA could find no data regarding the fate
of soils that have been disposed of and covered in landfills. In regard to PCS used as landfill
covers, one study sponsored by the Iowa Department of Natural Resources Solid Waste Section
examined the concentration of organic contaminants remaining in PCS spread and aerated prior
to disposal at three solid waste landfills. A total of 18 PCS samples (six from each landfill)
were collected and analyzed for dissolved hydrocarbons (gasoline, benzene, toluene, and xylene),
extractable hydrocarbons (diesel, motor oil), EP Toxicity for lead, and TCLP for organics
(Toxicity Characteristic Leaching Procedure for 35 organic substances). The results of the
analysis are summarized in Table 3-1235.
No data regarding containment levels in the PCS prior to treatment were provided in the
report. However, since Iowa's clean-up level for soil is 100 ppm TPH, the initial concentrations
in at least some of the soils may have been above this level. If so, this would indicate that
spreading and aerating the soil prior to actual disposal was effective in reducing the level of
contamination.
3.2.5 Other Ex-situ Corrective Action Technologies
The technologies discussed above account for the vast majority of UST sites using ex-situ
management of petroleum contaminated soils. Other technologies are emerging or under
consideration by state agencies. These are discussed in this section.
3 -24
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Table 3-12
PCS Treatment Efficiency at Three Iowa Landfills
Analytical Procedure
Extractable Hydrocarbons
(detection limit of 3 ppm)
Dissolved Hydrocarbons
(detection limit of 100 ppb)
Benzene
(detection limit of 1 ppb to
5 ppb)
Toluene
(detection limit of 2 ppb to
10 ppm)
Xylene
(detection limit of 2 ppb to
10 ppb)
EP Toxicity-lead
(detection limit of 0.50
mg/1)
TCLP organics
Landfill One
6 to 47 ppm
< 100 to 150 ppb
< 1 to < 5 ppb
< 2 to 10 ppb
< 2 to 8 ppb
all < 0.50 mg/1
all < detection limits
Landfill Two
5 to 11 ppm
all < 100 ppb
all < 1 ppb
< 2 to 3 ppb
2 to 6 ppb
all < 0.50 mg/1
all < detection limits
Landfill Three
2 to 81 ppm
all < 100 ppb
< 1 to 10 ppb
all < 2 ppb
all 5 ppb or less
all < 0.50 mg/1
all < detection limits
3.2.5.1
Cold Mix Asphalt Plants
In cold mix treatment of PCS, the soils are screened and used, without thermal
pretreatment, as an aggregate in the asphalt mix. The number of asphalt plants practicing this
approach or that have the capacity to treat PCS in such a fashion is not known. The PCS
treatment mode is encapsulation/inclusion in the asphalt. Soils contaminated with Nos. 2, 4, and
6 fuel oil are the most frequently cold mixed petroleum contaminated soils. Gasoline
contaminated soils can be used at low contaminant levels and small volumes, but are less
commonly treated in cold mix plants, because the light fraction hydrocarbons in gasoline soften
the asphalt mix, resulting in a low quality asphalt product. A regulatory official contacted
during this study said that the petroleum content of the soil allows the asphalt plant operators
to reduce the volume of asphalt emulsion added to the mix. The reduction in the volume of
emulsion required is small. The final product usually does not meet DOT standards; however,
as non-specification product, it can be used in road foundations for fill material or for paving
parking lots or farm roads16.
3-25
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3.2.5.2 Stabilization and Solidification
The objectives of stabilization and solidification (S/S) treatment may involve: 1)
improving the physical handling characteristics of the waste, 2) decreasing the surface area of
the waste and thus its susceptibility to leaching, or 3) limiting the solubility through chemical
binding or detoxification of the hazardous constituents in the waste8'17'36.
Stabilization also may include solidification. The process goal is to limit the solubility
or mobility and to maintain the hazardous constituent in a chemically stable form, irrespective
of changes in the physical characteristic of the hazardous waste6'37. The addition of a chemical
agent to transform the hazardous constituents into a new less toxic form also can be considered
stabilization. The process goal of solidification is to produce a solidified block exhibiting high
structural integrity. The hazardous contaminants, which may or may not be chemically bonded
to the additive, are physically sealed within the solid block or monolith6'36'37'38.
Contaminated soils can be stabilized and solidified through the addition and mixing of
a variety of standard and proprietary chemical agents. These agents can be grouped into several
general categories: 1) cements, 2) limes plus pozzalans (fly ash, cement kiln dust, hydrated silic
acid, etc.), 3) thermoplastics (asphalt, bitumen, polyethylene, etc.), 4) thermosetting organic
polymers (ureas, phenolics, epoxides, etc.), and 5) miscellaneous others. In addition, organic
contaminants may require pretreatment to improve the binding properties of the additives. Waste
organic chemicals and compounds (such as oil and grease, sugars, formaldehyde, xylene,
benzene, methanol, and others) with concentrations above 10 percent by weight have been
demonstrated to interfere with S/S processes. Some additives that improve the binding
properties of the additives are: selected clays, emulsifiers, surfactants, and proprietary
adsorbents including activated carbon, zeolite minerals, and cellulose materials 6>36'38.
In-situ S/S treatment uses modified auguring drill rigs or earth-moving equipment; on-site
ex-situ treatment uses transportable trailer mounted tanks, earth moving equipment and mixing
drums1'6'36'38. In-situ S/S is not as common as bulk mixing in surface impoundments or
excavation and treatment in tanks36'38.
3.2.5.3 Cement Kilns
Cement kilns are another potential option for treating petroleum contaminated soils. The
two basic cement production processes are: 1) the wet-process, where the feed materials (sand,
clay and limestone) are hydrated from 30 to 35 percent and then interground, forming a uniform
mix, and 2) the dry-process, where the feed stock is dried to less than 1 percent moisture, then
ground, and mixed6. A 1986 EPA report stated that there were 147 commercial cement kilns
in the United States at that time, of which 65 units used the more energy-intensive wet process.
3-26
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According to the report, most new units under construction or planned at that time would use
the dry process, and many of the older facilities were converting to the dry process 28.
The treatment of solid wastes in cement kilns has been limited to the extent that it can
be suspended or dispersed into the flame zone of the kilns. Recent developments, such as a new
method for introducing solid waste-derived fuel into the middle of the kiln, are likely to increase
the capacity of cement kilns for treating solid materials29. In spite of these new developments,
the potential capacity for cement kiln treatment of PCS over the next several years appears to
be very low. Concerns for product quality, combined with the low heating value of these soils,
are major impediments to the use of cement kilns for soil treatment. The cement manufacturing
industry is currently placing emphasis on treating hazardous pumpable sludges. It is therefore
unlikely that cement kiln treatment will be a significant option for PCS treatment under the
Subtitle I program for at least the next two to three years.
3.2.5.4 Biological Processes
There are a number of ex-situ technologies that take advantage of biological processes
to decompose contaminants in soils. Although they are not currently used to any significant
degree for treating PCS from UST sites, they may be viable options for certain sites. These
include:
• Composting;
• Prepared bed bioremediation; and
• Bioreactors.
Composting is a system of waste treatment involving the engineered biological
decomposition of solid or solidified biodegradable residues under controlled conditions
independent of the soil medium6. In 1985, 115 facilities composted sludge in the United States8.
However, no data were found in the literature to indicate the current usage of this technology
for the treatment of PCS.
Results from controlled experiments show that the more recalcitrant compounds can be
treated using this technology. The applicability of the treatment technology is, however,
inherently limited by the biodegradability of the compounds. In addition, composting in itself
is not typically the final stage of the PCS treatment process. During EPA's review, no data
were found to indicate the treatment effectiveness of this technology, although one published
source indicated that additional treatment of the residual soils is usually needed to reduce
contaminant concentrations to acceptable levels8.
Three general processes can be defined as composting: windrowing (turned), static piles
(forced aeration: mechanical pulling, negative pressure or pushing, positive pressure), and in-
3 -27
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vessel. In the windrowing process, PCS is mixed with a bulking agent (wood chips, cow
manure, straw, etc.). The bulking agent is a source of carbon and microbes, and a means of
increasing the porosity and permeability of the soil piles. The PCS bulking agent mixture is
aligned in rows on ideally an impermeable surface (e.g., a plastic liner or asphalt), because
potentially noxious run-off and leachate can be generated when PCS is treated in windrows. The
shape and dimensions of the windrow is partially dependent on the meteorological conditions of
the site, the physical characteristics of the PCS and bulking agent, and the mechanical limitations
of the equipment used for turning. The piles are periodically turned, approximately two times
a week, with more frequent turning occurring early in the treatment. Turning the pile aerates
the soil and promotes the exchange of gases. If necessary, nutrients and Ph control additives
are added periodically. After a given period, approximately three to four weeks, the piles are
flattened and left alone to cool, dry, and off gas. If recovery of the bulking agent is desired,
the piles can be screened and then the residual PCS may be landfarmed if additional treatment
is required.
With the static pile process, a system of perforated pipes and bulking agent is constructed
on an impermeable layer. PCS is added to this system in roughly one to two foot lifts until the
desired height is achieved. Nutrients and Ph adjusters are added as deemed necessary at this
point in the soil pile construction1. The soil pile is covered, and a berm is constructed to control
run-off22. Air or oxygen is then pulled or pushed through the soil pile, promoting and enhancing
the volatilization and microbial metabolism of the PCS. The flux of air through the pile is
adjusted to optimize the moisture content and temperature of the pile and to satiate the biological
oxygen demand6. This process is typically conducted for two to three months22.
In-vessel composting is performed in closed vessels where conditions can be closely
monitored and controlled22. The numerous variations to the basic technology are based in part
on the capacity, orientation, configuration, and means of agitation of the system. In general,
all in-vessel composting technologies use a means of agitation or aeration of the composted mass
or a combination of the two6. Because the use of this technology is presently limited, there is
little related information available. Moreover, this technology is more expensive compared to
windrow or static pile composting technologies.
Prepared bed bioremediation is comparable to land treatment and composting
technologies, but requires a much more involved design and management of the treatment
facility. The treatment site is first prepared by the addition of an impermeable layer (e.g.,
asphalt, clay, or synthetic liners) to limit the leaching and migration potential of the
contamination1'34. Perforated piping may be lain across the impermeable layer prior to the
loading of the excavated PCS on the impermeable layer or may be placed across one to three
foot lifts of PCS. The piping is connected to a blower or vacuum pump31. Some designs
incorporate a separate series of perforated pipes along the top of the soil pile for the
introduction, as needed, of nutrients, moisture, Ph control, and so forth. Others use only the
pre-existing perforated pipe network1'31.
3-28
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Once the soil pile has been completed, typically to a height not exceeding 10 feet, an
impermeable synthetic cover is installed, as well as a containment dike for run-off and run-on
control1. To maintain optimum levels to support aerobic microbial activity, oxygen is drawn or
pushed through the soil pile via the perforated pipes. Nutrients, moisture and other essential
requirements are added as needed to the soil pile until remediation is complete 30'31.
Bioreactors also use biodegradation processes. With bioreactor units, soils are batch,
sequencing batch, or continuously fed into a mixing vat2. Soil introduced into the vat is
hydrated sufficiently to create a slurry. The slurry is continuously mechanically agitated to
ensure adequate exposure of the PCS to the microbial organisms. The physical and chemical
properties of the soil slurry are monitored and adjusted to ensure optimum microbial growth
conditions. Nutrients, trace elements, and all additional requirements are added on an as-needed
basis. Oxygen is typically introduced into the reactor vessel via air sparging technologies.
Microbes acclimated to the metabolism of petroleum range hydrocarbons may be added as
desired.
Once acceptable reductions in the contaminant concentration levels or the technological
limits of the system have been achieved, the slurry is dewatered. The dewatered soils can be
returned to the excavation or disposed of as required. The process/residual water may require
additional treatment prior to discharge. Information in the literature indicates that removal
efficiencies exceeding 90 percent are achievable, with slightly higher efficiencies expected when
ambient temperatures are greater that 24° celsius1'2'32'33.
3.3 TECHNOLOGIES FOR THE IN-SITU MANAGEMENT OF PETROLEUM
CONTAMINATED SOILS
This section presents descriptions of soil vapor extraction and bioremediation technologies
used for the in-situ treatment of PCS. Unlike the ex-situ technologies discussed in Section 3.2,
PCS does not need to be excavated with these technologies. Table 3-13 summarizes information
regarding treatment effectiveness, costs, and residuals generated by these technologies.
3.3.1 Soil Vapor Extraction
Soil vapor extraction (SVE) (also referred to as in-situ soil venting, in-situ volatilization,
enhanced volatilization, and vacuum extraction) is an in-situ corrective action technology for the
treatment of PCS. Given proper site and environmental conditions, this technology can
effectively remove gasoline and some diesel range petroleum compounds from soil. It is an
attractive alternative to other remedial technologies when contamination is extensive (i.e., when
more than 500 cubic yards of soil is contaminated), deep, or unreachable by other alternatives
(e.g., under a building)1'2'7.
3 -29
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Table 3-13
Corrective Action Technologies for the In-situ Remediation
of PCS at Petroleum UST Sites
Corrective Action
Technology
Mode of Treatment
Cost
Residual/Process
Wastes
Soil Vapor Extraction,
also known as:
In-situ Soil Venting,
In-situ Volatilization,
Enhanced
Volatilization, or
Vacuum Extraction
Volatilization/evaporation
of the volatile organics with
enhanced biodegradation of
the heavier petroleum
compounds55.
Considered cost effective
when the volume of soil to
be treated is > 500
yd3(13,i4) The major
capital costs involve vent
well installation, pump
purchase and emissions
controls'. Emissions
controls can be as much as
50% of total costs7.
Quoted estimates are $20
to 25 per yd3 ($22 to $28
per ton)13'14 and $10 to 50
per yd3 ($11 to $75 per
ton)1.
SVE removes petroleum
laden air from the soil
which is vented or
treated2. If an air/liquid
separator is used,
petroleum contaminated
water may be generated7.
If carbon adsorption
units are used, the spent
carbon may be more cost
effectively disposed of
rather than recycled8.
Bioremediation
Microbial populations
metabolize/consume
the petroleum range
hydrocarbons as an
energy source.
Oxygen is consumed
and CO2, H2O,
organic acids and
intermediate
degradation products
are produced14'30*44.
In-situ: Cited costs
from case studies
and literature sources
range from $6 to
$125 per yd3 ($7 to
$138 per ton)1-44.
No waste streams
are expected in
normal operations8
3-30
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Table 3-13 (continued)
Corrective Action Technologies for the In-situ Remediation
of PCS at Petroleum UST Sites
Corrective Action
Technology
Emissions Control
Equipment
Effectiveness
Limitations
Soil Vapor Extraction,
also known as:
In-situ Soil Venting,
In-situ Volatilization, or
Enhanced Volatilization
Liquid vapor
separators may be
used to preserve the
VOC extraction and
control equipment7.
Carbon adsorption
units are useful for
product recovery or
for dilute air
streams.
Diffuser stacks are
useful for dilute air
streams.
Vapor incineration.
Catalytic oxidation.
Condensers.
Experimental results
indicate that >99% of
the gasoline present as
residual saturation in sand
can be removed14.
Recovery rates diminish
with time typically 6 to
12 months8'13. SVE has
removed free product and
reduced groundwater
concentrations to 0.5 to
1.0 mg/114. Emissions
control devices can
reduce petroleum vapor
emissions by > 99%'.
Limited by the physical properties of
the petroleum compound and soil
matrix (4). Effectiveness is reduced
when: Pv > 0.001 atm2, Henry's low
coefficient> 0.011'7'13, contaminant is
low volatility (e.g., crude oil or jet
fuel)2, contaminant is highly soluble ',
soil permeability < 1 darcy2, or soil
has high adsorptive capacity (e.g.,
clay or organic rich)39,
Bioremediation
Generally there are
no emission control
units associated with
the operation of in-
situ bioremediation
processes.
Removal efficiencies are
site specific, with
remediation typically
requiring 6 months to
years to complete.
Degradation rates
diminish with time1'8.
Achievable reductions are
typically > 80% in the
low ppm range8'44.
For aerobic biodegradation to be
effective some critical environmental
factors must be exist or be achieved in
order to maintain optimum growth
conditions for the microbial
populations.
Soil water content: 25% to 85% of
holding capacity,
Oxygen: > 0.2 mg/1 dissolved O2,
minimum air filled porosity of
10 %2'30,
Ph: slightly acidic to slightly basic,
5.5 to 8.58-30,.
Nutrients: sufficient nitrogen,
phosphorous, trace metal and other
available to support microbial
growth2'30,.
Temperature: 15° to 45° Celsius30,
Redox potential: > 50 millivolts for
aerobic microbial degradation8'30.,
In addition, high contaminant
concentrations can be lethal to the
microbial populations2. The
permeability of the soil must be
sufficient to allow the introduction of
nutrients and oxygen and the
circulation of water.
3-31
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3.3.1.1 Process Description
SVE achieves its remedial goals by artificially increasing the natural processes of
volatilization and biodegradation. Vapor laden air is drawn from the soil and replaced with
clean air drawn or forced into the soil via passive or active injection wells. This mechanically
induced circulation of air also serves to remove oxygen depleted air from and reintroduce
oxygen rich air into the zone of contamination. The continual presence of oxygen is essential
to the promotion and maintenance of aerobic microbial activity8.
The SVE system and operation are fairly simple. To be effective and efficient, however,
the system must be designed and constructed properly. Primary design considerations are flow
rate and flow pattern. The more vents (e.g., wells or trenches), the higher the rate at which
volatile contaminants can be removed and the higher the capital and operating costs7'39.
Extraction vents are typically placed in the area of highest contamination, whereas
injection or passive vents are typically placed along the edges of the contamination. Some
primitive systems do not incorporate passive or injection wells into their design; rather, they rely
on air drawn from the surrounding medium. Actual vertical and aerial placement of the vents
is partially a function of the distribution of contamination and site geology (including
stratification, soil porosity, and soil permeability).
Field results indicate that a SVE system is most effective when the extraction wells are
screened only near or through the zone of contamination. Vents typically do not circulate air
effectively below their installation depth, limiting their ability to draw in petroleum vapors 1'8'7'39.
Figure 3-2 is a generalized schematic drawing of the SVE system. Piping (most
commonly PVC), originating at the extraction vents, is attached to a pump. The pump creates
a negative pressure in the extraction well, drawing vapors from the soil pores. If the soils are
highly saturated, the air flow from the vents may be routed through a liquid vapor separator to
preserve the extraction and control equipment. In addition, the extraction system design must
incorporate safe equipment and be operated so that explosive vapor concentrations are not
generated or exposed to potential ignition sources8'14. The petroleum contaminated vapors are
then treated, if needed, to reduce the levels of contamination to applicable emissions standards.
Four basic technologies can be used to treat petroleum contaminated vapors: 1) carbon
absorbers, 2) thermal incineration, 3) catalytic incineration, and 4) condensers40. In addition,
diffuser stacks may be useful to dilute air streams2. Monitoring is required to ensure that the
treatment objectives are achieved.
3-32
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Figure 3-2
Generalized Schematic of Soil Vapor Extraction System4
ELECTRIC
AIR FLOW
HEATER
VERTICAL EXTRACTION
VENT PIPE (TYP)
SOIL CONTAMINATION
SLOTTED
VERTICAL INJECTION
VENT PIPE (TYP)
3.3.1.2
Treatment Efficiency
SVE has successfully removed gasoline, benzene, toluene, ethylbenzene, and xylene from
soil1. Estimates in the literature state that treatment can take from one month to one year or
more to complete39. However, the determination of whether a site is clean or when a SVE
system is not effective in reducing the additional contaminant levels and should be turned off are
dependent upon individual state guidelines.
Concentration data for one extraction well in each of two case studies are presented
below. The data were collected as part of the data collection efforts for another study being
conducted by the EPA:
Case Study Example 1: Approximately 1,600 gallons of gasoline were released from an UST,
contaminating a municipal ground water source. The aerial extent of contamination was
3-33
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approximately 7,432 square meters. The subsurface media was a clean sandy soil. Corrective
action was initiated in May 1986, and is currently ongoing. Table 3-14 presents corrective
action monitoring data and calculated values for the removal efficiency (percent reduction in
contaminant concentrations)41.
Case Study Example 2 More than 3,500 gallons of gasoline were released from an UST system
contaminating a municipal water supply. The subsurface media was an integrated mixture of
sand, silt, and clay. Corrective action was initiated in April 1990, and is ongoing41.
Table 3-14
SVE Technology Pre-Treatment Effluent Vapor Concentrations41
Site Location (Number)
California 1
California 2
Sampling Date
(Cumulative count)
11/2/88 (0)
8/7/89 (278)
1/10/90 (434)
12/20/90 (778)
5/15/90 (0)
8/14/90 (91)
9/19/90 (127)
10/10/90 (148)
11/16/90 (185)
Concentration (ppmv
Benzene)
1720
240
54
2.5
24
1.6
1.9
0.38
0.46
Percent Reduction
-
86
97
>99
-
93
92
98
98
For these two case studies, the data indicate that the contaminant concentrations in the
soil vapor extracted from the soil was diminished by well over 99 percent and 98 percent,
respectively, during the remediation efforts. Other studies show that as remediation time
increases, the composition of the SVE system vapor effluent changes, becoming richer in the
less volatile compounds13. However, soil sample analysis results giving the reduction in soil
contaminant levels with time or confirmatory sampling data that could be used to calculate
approximate values for overall removal efficiency were not available to EPA at the time of
preparation of this report. Since the SVE systems in the two case studies presented were still
in operation, it was not possible at the time of preparation of this report to draw conclusions as
to the actual effectiveness of this technology in remediating the contaminated soil.
3-34
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In some instances, SVE remediation can be enhanced by depressing the groundwater
table. This practice exposes more of the residual contamination to the induced vapor flow.
Contaminant removal then becomes independent of the rate limiting diffusion of the product
through and from the groundwater to the soil vapor. In one example in the literature, free
product was removed and groundwater concentrations were reduced to 0.5 to 1.0 ppm with the
assistance of SVE. In addition, theoretical studies indicate that in sandy soils SVE would be
able to remove 99 percent of the gasoline present as residual saturation. However, no data from
field sites were included14.
SVE technology produces an effluent stream of contaminated vapor. This waste stream
can be treated using any of the technologies summarized in Table 3-15. Table 3-15 also lists
the effectiveness of these technologies in removing or destroying the contaminants in the effluent
stream.
Table 3-15
Treatment Effectiveness of VOC Emissions Control Technologies7
Vapor Treatment System
Removal/Destruction Efficiency
Conditions
Carbon Adsorption
Can be designed to achieve 99 %,
although actual efficiencies may be
as low as 60%.
Efficiency is dependent upon: inlet
concentration, stream temperature,
moisture content, and
maintenance. Well suited for
variable inlet flow rates.
Thermal Incineration
Achieves > 99 % destruction when
inlet concentrations above 200
ppmv; >95% destruction when
concentrations are as low as 50
ppmv.
Not well suited to variable inlet
flow rates. Supplemental fuel
usually required.
Catalytic Incineration
Although 99 % efficiencies have
been reported, 95% destruction
efficiency is typical.
Sensitive to pollutant
characteristics, process conditions,
and inlet stream flowrates.
Condensation
Removal efficiencies range from
50% to 80% using chilled water;
can be increased to 90 % when
using subzero refrigerants (e.g.,
ethylene glycol, freon).
Primarily used as raw material
and/or preliminary air pollution
control devices for removing
VOCs prior to other control
devices.
3.3.1.3
Operating Parameters that Affect Treatment Performance
SVE removes volatile organics from the soil by increasing and directing the flow of air
through the porous medium. To be effective, the physical properties of the porous medium
3-35
-------
(e.g., porosity, moisture content, permeability, organic content) and chemical properties of the
contaminant (e.g., vapor pressure, solubility) must be conducive to the application of SVE
technology. SVE system designs are site specific, dependent upon the site and contaminant
properties for determination of the most effective and efficient design. Design variables include:
number of pumps, size of pumps, induced flow rate, induced vacuum pressure, location, depth
and screen placement of extraction wells/trenches, location, depth and screen placement of
induction wells/trenches, and choice of emissions control equipment. Table 3-16 summarizes
some of the major site-specific factors that limit the effectiveness of SVE systems. Table 3-17
provides a summary of the characteristics of vapor streams that affect the performance of
systems for treating the extracted vapors.
Table 3-16
Conditions Which Generally Limit the Effectiveness of SVE
Conditions
Vapor pressure of the petroleum compound < 0.001
atmospheres2.
Henry's law coefficient of the petroleum compound <
0.01 (dimensionless)1'13'7.
Soils have high adsorptive capacities (high organic or
clay contents)39.
Petroleum contaminant is crude oil or jet fuels2.
Soil has high clay or silt contents, permeability < 1
Darcy2.
Soils have high moisture contents, low air-filled
porosity14'39.
Depth to groundwater is < approximately 5 feet.
Method of Changing Conditions
None
None
None
None
One company claims that it has remediated soils with
high clay contents and permeabilities < 1 Darcy42.
One company claims that it has dewatered a soil prior
to remediation using the SVE system42.
Pumping wells can be installed to lower the water
table, exposing more of the contamination to the
influence of the system.
3.3.1.4
Conditions that Affect Treatment Costs
A wide range of treatment costs using soil vapor extraction systems have been reported
in the literature ($11 to $75 per ton)2>3>4'46. Table 3-18 lists the factors cited in these sources that
affect costs. Since the cost estimates were presented simply as ranges, with no information
regarding the numbers of units involved or the distribution of costs within the cited ranges, it
is not possible to prepare a statistical analysis of the data.
3-36
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Table 3-17
Key Emissions Stream Characteristics Important to
Performance of VOC Treatment Systems7
Vapor Treatment
System
Carbon Adsorption
Thermal
Incineration
Catalytic
Incineration
Condensation
Emissions Stream Characteristics
Concentration"
>700 ppmv
> 100 ppmv
> 100 pprnv
> 5, 000 ppmv
Flowrate
Moisture
<50%
-
Temperature
Variation
Insensitive <65°
celsius
Sensitive ~
Sensitive —
Sensitive <93°
celsius
VOC Characteristics
Molecular weight of VOC
should range from 50 - 150
grams per mole for best
performance.
Can control most VOCs
without operational
difficulty.
Phosphorous, bismuth, lead,
mercury, arsenic, iron oxide,
tin, zinc and halogenated
compounds may foul
catalyst.
Removal efficiency limited
by vapor pressure,
temperature, and
characteristics of VOCs
present.
For optimum efficiency. These techniques will control emissions at lower concentrations than those
given, although usually at reduced efficiencies.
3.3.2 Bioremediation
3.3.2.1
Process Description
Bioremediation is the controlled used of microbial biodegradation for the reduction of
petroleum hydrocarbon concentrations in soil or water. Microorganisms essentially metabolize
(consume) the hydrocarbons as a source of energy (to support growth) using a terminal electron
acceptor (e.g., oxygen), and in the process generate water, carbon dioxide, organic acids and
a range of intermediary degradation compounds43. In some instances, the enzymes produced for
a specific purpose by one organism may unintentionally degrade (co-metabolize) a nontarget
compound, providing no benefit to the original organism44. It has been postulated that this form
of biodegradation is the mechanism by which low contaminant concentrations are achieved.
3-37
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Table 3-18
Costs Associated with Treatment of PCS with an In-situ Soil Vapor Extraction System
Treatment Costs
$11 to $75 per ton1
$300 per ton if steam used to
enhance volatilization.
$11 per ton1
$20 to $25 per yd3<13)
$15 to $20 per yd3(14)
Total annualized costs of $108,360
per year7
Total annualized costs of $203,380
per year7
Total annualized costs of $18,820
per year7
Applicable Conditions
No information provided on conditions affecting operating costs.
Systems not including wells can be purchased for $30,000 to
$60,000 or leased for about $5,000 to $10,000 per month.
Approximately 50,000 yd3 of gasoline contaminated soil remediated.
Catalytic oxidizer used for vapor treatment. Total remediation time
estimated to be four months.
Cost effective when more than 500 yd3 of PCS is to be treated.
Costs excludes treatment of vapor emissions. Operating costs vary
depending on utility costs and time of operation.
Some of the capital costs include: $40 per foot for a 20 foot, 2-inch
diameter slotted Schedule 4O PVC pipe; $500 to $2,000 for
vacuum pump capable of moving 40 to 60ft3 per minute at 1.5 in
H2O; or $4,000 for a vacuum pump capable of moving 1000
standard ft3 per minute at 25 inches Hg (costs are in 1986 dollars).
Costs are for a 4,000 Ibs of activated carbon capacity system, 3.05
foot diameter, 27.3 foot in length regenerative carbon adsorption
system for vapor treatment. Includes operating costs associated
with maintenance, utilities, and operation.
Costs are for a 5,000 scfm system with no heat exchanger unit.
Costs include the price of operation, maintenance and utilities.
Replacement catalyst costs are not included.
Costs are for a 2,000 Ibs canister system, replaced 14 times and
disposed of at a cost of $72 per canister. Costs include the price of
operation, maintenance and utilities.
The microbial populations capable of metabolizing hydrocarbons can be roughly
categorized by the terminal electron acceptor used in the metabolic oxidation of the hydrocarbon
compound. Microbial degradation can be aerobic (O2 is the terminal electron acceptor),
anaerobic (fixed oxygen compounds, nitrate (NO3~), sulfate (SO42~) or iron (Fe3+), manganese
(Mn2+), as well as other ions acting as the terminal electron acceptor), or methanogenic. Of
these, the alkane and aromatic compounds in gasoline degrade much more readily under aerobic
conditions8'14. For aerobic bioremediation technologies to be successful, the oxygen and
nutrients required to support microbial activity must be in contact with the carbon source
(petroleum contamination) and the indigenous or cultured (artificially introduced) microbial
populations43. In addition, environmental conditions (e.g., Ph, moisture, temperature, redox
3-38
-------
potential, etc.) conducive to microbial life must be attained and maintained throughout the
duration of the corrective action.
The addition of nutrients and oxygen into the ground to control environmental conditions
typically involves the installation of downgradient groundwater extraction wells or trenches in
such a configuration and pumped at rates sufficient to create a barrier to contaminant migration
(see Figure 3-3). The collected water is cycled through a mixing vat where nutrients and in
some instances oxygen are added8. The mixture is reintroduced above or upgradient of the
contaminated soil zone via injection wells, trenches or infiltration galleries. If oxygen is not
added to the water in the mixing vat, it may be introduced into the soil in the form of hydrogen
peroxide via injection wells or infiltration galleries, or it may be introduced using air sparging
technology8'45. Microbes acclimated to the metabolism of petroleum hydrocarbons also may be
added to the mixing vat and introduced to the soil system if desired2'32'46. Most soil systems,
however, already support microbe species capable of metabolizing petroleum range
hydrocarbons. This operation is continued until satisfactory contaminant levels or the
technological limitations of the system have been achieved.
Figure 3-3
Basic Components of an In-situ Bioremediation System52
RECOVERY
WELL
NUTRIENTS OXYGENATION
INJECTION
WELL
MIXING TANK
WATER
TABLE
....V...--J
GROUNDWATER
FLOW DIRECTION
ZONE OF PETROLEUM LADEN SOILS
•* ^-i
3 -39
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3.3.2.2
Treatment Efficiency
Removal efficiencies of in-situ bioremediation technologies are site specific, with
remediations typically requiring six months to years to complete. The hydrocarbon degradation
rates observed using this technology decline with time1-8. This decline is partially due to the
competitive advantage of using more common organic molecules as a carbon source while the
concentration of available hydrocarbons decreases14. Some examples of achievable reduction
levels and remediation times using in-situ bioremediation are presented in Table 3-191'8'14'44.
Table 3-19
Residual Concentrations and Remediation Times
for Some In-situ Bioremediation Projects44
Contaminant
BTX
diesel oil
diesel oil
fuel oil
diesel/aromatics
gasoline
Residual Concentrations
< 5 mg/kg (ppm)
150 mg/kg (ppm)
4,600 mg/kg (ppm)
< 100 mg/kg (ppm)
30 mg/kg (ppm)
< 10 mg/kg (ppm)
Remediation Time (months)
12
18
12
9
3
48
3.3.2.3
Operating Parameters that Affect Treatment Performance
The effectiveness of all aerobic bioremediation systems is dependent upon the
maintenance of optimal microbial growth conditions including:
• Soil moisture: Soil moisture should generally be maintained at 25 percent to 85 percent
of soil moisture capacity2'8'30;
• Oxygen: Oxygen levels optimum for maintenance of aerobic microbial activity are >
2 mg/1 dissolved30'47;
• Redox potential: Redox potential for aerobic microbial activity should be > 50
millivolts30;
• Soil Ph: The Ph should be in the range of 5.5 to 8.52'53;
3-40
-------
Nutrients: Major nutrients important to the bioremediation process are nitrogen,
phosphorous, and hydrogen. Suggested carbon: nitrogen: phosphorous ratio is 120:10:1
(A ratio of 250:10:3 has also been proposed as ideal). Actual quantities will be
dependent on the contaminant concentration levels30'44'47;
Minor nutrients (1 to 100 mg/1) include sodium, potassium, ammonium, calcium,
magnesium, iron, chloride, and sulfur47;
Trace nutrients (less than 1 mg/1) include manganese, cobalt, nickel, vanadium,
boron, copper, zinc, various organics (vitamins), and molybdenum (Concentration
requirements for many of these have not been established47; and
Temperature: The temperature range is recommended at between 15° and 45°
Celsius1'2-8'30'47.
3.4 TECHNOLOGIES FOR THE TREATMENT OF PETROLEUM CONTAMINATED
GROUNDWATER
This section presents corrective action technologies for the remediation of petroleum
contaminated groundwater and for the removal of free product. The technologies presented, free
product recovery and pump and treat, are those identified during this study as most commonly
employed in ongoing corrective action projects. Table 3-20 lists these technologies and presents
a summary of the information contained in the following sections.
3.4.1 Free Product Recovery
3.4.1.1 Process Description
Two approaches for the recovery of free product from an UST release are: trenches
(passive trenches/drains and active trench systems/sumps) and extraction wells. The choice of
approach is dependent upon a variety of site specific conditions outlined in Table 3-2114. For
both approaches, the recovery process is similar. A trench or well(s) is installed downgradient
of the migrating contamination plume. Under the influence of gravity (e.g., mechanically
induced hydraulic head differences), the groundwater and free product flow into the well or
trench. Once there, the free product is either separated from groundwater and removed, or the
groundwater and free product are pumped to the surface where the mixture is treated and the
free product collected for disposal or recycling14-48. The waste water, which can still contain
unacceptable levels of dissolved petroleum compounds, can be reinjected in an attempt to wash
residual contaminants from the unsaturated zone, treated (e.g., carbon adsorption, air stripping
3 -41
-------
Table 3-20
Corrective Action Technologies for the Treatment
of Petroleum Contaminated Groundwater
Corrective Action
Technology
Mode of Treatment
Cost
Residual/Process Wastes
Free Product
Recovery
FP is isolated directly through
product sensitive sensors and
floating filters, submerged pumps
or surface pumps.
Alternatively, the FP and water
mixture is pumped to the surface
where oil/water separators
remove the product for storage,
treatment (e.g., blending,
reprocessing) or disposal14'48.
Recovery costs that include the
recovery trench/well installation,
product recovery, separation,
labor, monitoring etc. for four
case studies range from $2.07 to
$93.00 per gallon of product
recovered14.
Recovered product may not
be suitable for direct
consumption as fuel and
may require reprocessing.
The water generated during
the recovery of FP is
contaminated with dissolved
petroleum compounds14.
Pump and Treat
One of the most common
groundwater remediation options
is the pumping of contaminated
groundwater to the surface for
treatment51. The three most
common technologies for the ex-
situ treatment of contaminated
groundwater are: airstripping,
carbon adsorption, and
bioremediation.
Airstripping: Volatile
hydrocarbons exposed to air in
packed towers, diffuser trays or
spray basins partition from the
contaminated groundwater8'14.
Carbon adsorption:
Hydrocarbons in contact with
activated carbon partition from
the contaminated groundwater8.
Bioremediation: Hydrocarbons
are metabolized by microbial
organisms43.
Air stripping: One literature
source cited an average cost of
remediation to be $0.05/1,000
gallons to $0.25/1,000 gallons
of influent14.
Carbon adsorption: One
literature source cited costs for
the treatment of influent
concentrations > 1 mg/1 to
range from $0.45/1,000 gallons
to $2.52/1,000 gallons of
influent; and for influent
concentrations < 1 mg/1 range
from $0.22/1,000 gallons to
$0.54/1,000 gallons of
influent14.
No cost data for the bioremedial
treatment of petroleum
contaminated groundwater was
identified in the literature.
Costs for each system can be
expected to increase as the
residual concentration acceptable
in the groundwater approaches
the low ppb range14.
Potential residuals include
the treated waste water if the
remedial technology did not
achieve acceptable
contaminant concentration
levels. Biosludges may be
generated during the
bioremediation of petroleum
contaminated groundwater.
3-42
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Table 3-20 (continued)
Corrective Action Technologies for the Treatment
of Petroleum Contaminated Ground water
Corrective Action
Technology
Emissions Control
Equipment
Effectiveness
Limitations
Free Product
Recovery
No emissions control
technologies were
identified.
No FP recovery system can
recover 100% of the release
once it is in the soil system.
In 4 case studies examined,
an average recovery of 25 %
of the initial spill volume
was observed. For the
separation techniques, filters
and product pumps are
capable of reducing product
thickness to a sheen, and
above ground oil/water
separators are capable of
reducing petroleum
concentrations to
approximately 15 ppm14.
Different recovery systems
are applicable to a variety
of hydrogeologic and
geologic conditions.
Systems can not recover
entire volume of released
product. Due to the high
concentration of petroleum
compounds processed, all
equipment must be
explosion proof and
resistant to dissolution.
Large volumes of waste
water may be generated by
the process, requiring
secondary treatment12-14'48.
Pump and Treat
Emissions control
equipment may be
associated with the air
stripping treatment
process. If contaminant
emission levels exceed
regulatory guidelines the
exhaust from these
systems can be channeled
through a vapor
emissions control device
(e.g., carbon adsorption
canisters, incinerator,
catalytic oxidizer). If
carbon adsorption
technology is used, the
vapor laden air must be
dehumidified in order to
preserve and extend the
life of the adsorption
units14.
Both carbon adsorption and
air stripping systems are
capable of achieving > 90%
VOC removal efficiencies.
Carbon adsorption
technology can reduce
gasoline range hydrocarbon
concentrations to the low
ppm levels. In addition,
bioremediation systems are
cited as being able to reduce
contaminant levels to the 100
to 1,000 ppb range8-14.
The effectiveness of pump
and treat technology in
removing contamination
from the ground is not
certain. A recent
publication indicated that no
contaminated aquifers have
been remediated to date to
acceptable EPA or State
standards using pump and
treat technology49.
Air stripping: Limited by
the volatility of the
contaminant (BTEX)
compounds are sufficiently
volatile to be removed),
iron and manganese content
of the water, and the
suspended solids content of
the effluent water14.
Carbon adsorption: Limited
by the absorbability of the
target compounds, the iron
and manganese content of
the effluent, as well as the
cost and availability of
carbon adsorption unit
recycling or disposal14.
3-43
-------
Table 3-21
Site Specific Conditions Which Favor Either a
Trench or Extraction Well for the Removal of Free Product 14
Trench
Extraction Well
Simple strategy is sufficient.
Rapid installation is necessary due to product
migration concern.
Intercept of entire plume is possible.
Groundwater is shallow (<4.6 meters).
Soil above groundwater table is firm and well
aggregated so that the trench is self supporting.
Permeable formations exist.
Minimal product thickness exists.
Time is available for hydrogeologic investigations
necessary to optimize the placement of extraction
wells.
Water table is too deep for trenches to be effective.
Entire plume can not be intercepted by trenching
(multiple wells may needed).
towers), or discharged into the municipal sewer system for treatment at the local publicly owned
treatment works (POTW). For UST sites, reinjection of groundwater is not a common practice.
There are a variety of in-situ and ex-situ techniques used to separate free product from
groundwater. The selection of a particular technique is dependent on site specific conditions,
applicable state and/or local regulations, and costs. Table 3-22 presents these techniques, their
operating principles, applications, advantages, and disadvantages14. It is important to understand
that the devices listed in Table 3-22 are only able to remove free product from groundwater that
has been drawn from the formation to a collection area such as a recovery well, trench or
separation tank.
Free product removal technologies are traditionally limited by the physical impossibility
of drawing 100 percent of the petroleum released from an UST system from the saturated and
unsaturated soil zones. Petroleum released into the soil system will form a residual saturation
between and in the micro- and macropores of the soil which is extremely difficult to remove due
to the complex physics of the soil system. Corrective action techniques commonly used to
reduce the level of residual contamination in the soil matrix include: excavating the contaminated
soil above and below the groundwater table, applying in-situ soil washing technology, relying
on natural processes (e.g., biodegradation, oxidation, volatilization), or enhancing the flow of
product toward the recovery well(s) and conducting product recovery operations (e.g., vacuum-
enhanced-free product recovery).
3 -44
-------
Disadvantages
Advantages
e
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Operating Principles
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Since the pump is located at
ground surface, skimmers an
physically restricted to operal
at depths less than
approximately 7.6 meters.
Recovery is limited to reduci
the product thickness to a
sheen.
Easily deployed, and may be
set permanently or
temporarily, or operated
manually. Skimmers are
relatively insensitive to small
suspended particulates (e.g.,
<0.64 cm).
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Skimmers float and respond when electronic sensors
detect the presence of gasoline(pumping gasoline to the
surface for storage or treatment).
£
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Since the pump is located at
ground surface, skimmers ar<
physically restricted to opera
at depths less than
approximately 7.6 meters.
Recovery is limited to reduci
the product thickness to a
sheen.
Easily deployed. Separation
energy requirements are
limited.
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An oleophilic-hydrophobic filter floats at the water
surface, allowing petroleum products to pass through inl
a collection compartment, but preventing water. A
surface pump acting upon an electronic signal pumps th<
accumulated gasoline once a set volume has been
collected.
£
£
m
3
ex
Large volumes of water musi
treated or stored, and during
pumping gasoline is mixed.
No information provided
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A submersible or surface pump is used to pump both
gasoline and water to storage tanks or an oil/water
separator
a.
a
£.
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"ob •£»
.9 £,
00 00
No information provided
V
a o
Two pumps reduce the volui
of water that needs to be
stored or treated. Electroni
sensors allow the system to
function automatically.
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Groundwater and gasoline mixture is pumped into a
series of tanks where its velocity and turbulence are
reduced, allowing gravity to separate the petroleum
emulsion from the water. A variety of internal baffles
can be used to enhance the separation.
•§
5 "
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to ffl rt
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3 - 45
-------
The latter option involves the application of SVE technology in conjunction with
extraction wells. The groundwater extraction pumps lower the groundwater elevation and expose
areas of residual contamination. The well system is sealed, and a vacuum is applied to the
extraction well that pulls air through these exposed areas into the extraction well, expediting the
volatilization of the petroleum compounds41. Refer to Section 3.3.1 for a more detailed
description of SVE technology.
3.4.1.2 Treatment Efficiency
No free product recovery system can recover 100 percent of the released product. The
best these systems can achieve is the removal of a majority of the mobile product, because there
is a limit to the effectiveness of the collection systems to separate free product from water. A
number of case studies support this statement.
Case Study Example 1: Approximately 83,000 gallons of JP-4 jet fuel were released. The
groundwater elevation was 5.2 meters below the surface, and the soil type was sand. A series
of extraction well points were installed downgradient of the plume and attached to a surface-
mounted centrifugal pump. Five weeks after the initiation of recovery operations, the system
was shut down when no additional product was being recovered. A total of 20,800 gallons of
fuel were finally collected, with only 25 percent of the original spill volume. The remedial
engineers concluded that the unrecovered 62,200 gallons of fuel remained as residual saturation
in the pore spaces of the soil14.
Case Study Example 2: Approximately 100,000 gallons of gasoline were released from service
station UST. Product recovery was initiated using the monitoring wells as extraction points.
An automated system of three 0.66 meter recovery wells, submersible groundwater extraction
pumps, and surface mounted product recovery pumps was eventually installed down gradient of
the advancing plume. After 7 months of operation, 28,500 gallons of gasoline were recovered.
The recovered product was recycled for re-use14.
3.4.1.3 Conditions that Affect Treatment Costs
The Office of Underground Storage Tanks has identified treatment costs for free product
recovery at four UST sites. Table 3-23 summarizes this information and the conditions that
apply to the cost estimates. As shown, costs range from $2.07 to $93 per gallon of product
recovered.
3-46
-------
Table 3-23
Costs Associated with Free Product Recovery14
Treatment for Costs for Individual Sites
Applicable Conditions
$2.07 per gallon recovered
Oil/water separator used to treat well point effluent. 25 % of
the 83,000 gallons spilled recovered prior to termination of
recovery project. Installation and equipment rental for five
weeks totalled $21,500.
$70.31 per gallon recovered
Costs include the price of free product recovery, well drilling
costs, oil/water separator, pumps, and construction and
engineering services. 700 of the 3,000 gallons released have
been recovered.
$93 per gallon recovered
Costs include the purchase and installation price of a 6 inch
recovery well, 75 gallon per minute submersible recovery
pump, and a 3 foot diameter packed air stripping tower.
1,200 of the 2,000 to 4,000 gallons spilled were recovered.
$7.89 per gallon recovered
Costs include the price of three 26 inch recovery wells, three
15 horsepower submersible pumps, three surface mounted
recovery pumps, and air stripping towers. 28,500 of the
100,000 gallons released were recovered.
3.4.2 Pump and Treat
3.4.2.1
Process Description
"Pump and treat" systems involve the extraction and ex-situ treatment of contaminated
groundwater. To be effective, the groundwater extraction system (i.e.j wells/trenches and
associated pumps and piping) must be installed and operated so that the contaminant plume is
contained and removed. A thorough site characterization must be performed prior to extraction
well/trench installation in order to determine their optimum location. Once the system is
installed and operational, contaminated groundwater is pumped to the surface where it is treated
or stored for future on-site or off-site treatment. Storage and off-site treatment may be more
economically advantageous when the volume of water to be treated is small or permitting
requirements inhibit the rapid installation of an on-site treatment system.
For small sites (typically service station locations) well placement can be determined after
the collection and analysis of the characterization data, but larger and more complex sites may
need to be modelled (e.g., analytical, numerical) to determine the appropriate well-installation
approach. Groundwater extraction wells or trenches/ditches need to be installed so that the
contaminant plume is contained when contaminant groundwater extraction/pumping is initiated.
3-47
-------
A variety of options exist for the ex-situ treatment of petroleum contaminated water: air
stripping, activated carbon adsorption, biorestoration, resin adsorption, reverse osmosis,
ozonation, oxidation with hydrogen peroxide, ultraviolet irradiation, and land treatment. Of
these, air stripping and activated carbon adsorption are the most commonly employed
technologies14. Airstripping and carbon adsorption are frequently used in series to enhance the
removal efficiencies and to prolong the life of the carbon adsorption units.
Air stripping technologies employ four alternative types of aeration methods: diffused
aeration, tray aeration, spray aeration, and packed towers. Of these, packed towers are the most
commonly used to treat petroleum contaminated water. All of the systems, however, treat
contaminated groundwater by enhancing the ability of the dissolved volatile hydrocarbons to
partition from the groundwater to the air. This is accomplished by greatly increasing the surface
area of the contaminated water exposed to the air51.
Diffused aeration systems sparge air from a diffuser grid upward through the contaminated
water. The volatile hydrocarbons partition from the water into the rising bubbles until they exit
the system saturated with organic vapors. Spray aeration systems pump contaminated water
through nozzles generating a fine mist. The volatile organics partition from the mist into the
air. The treated water is collected in prepared ponds or basins. Treatment can be enhanced by
recirculating the collected water through the nozzles. Tray aeration systems are designed so that
contaminated groundwater fed through the systems top, cascades (under the influence of gravity)
through a series of slat trays. The water is aerated as it descends, allowing the volatile
hydrocarbons to partition into the air. Packed towers are similar to tray aeration systems.
Contaminated groundwater is fed through the top of a tower, packed with inert packing material,
where it cascades through the packing material. Concurrently, air is forced up the column14.
Carbon adsorption units used for the treatment of petroleum contaminated water are
very similar to those used for the treatment of petroleum laden vapors. Groundwater is pumped
through a series of canisters (typically 2 to 4) filled with activated carbon. The dissolved
organic compounds adhere to the carbon. Eventually the carbon in the first canister in the series
will become saturated and will no longer be able to remove dissolved hydrocarbons. The system
is temporarily shut down as a new canister is added to the end of the series and the first canister
is removed and either regenerated on site (steam cleaned), or transported off-site for regeneration
or disposal, dependent on site-specific costs.
3.4.2.2 Treatment Efficiency
A recent publication indicates that no contaminated aquifers have been remediated to date
to acceptable EPA or State standards using pump and treat technology49. Table 3-24, which
presents groundwater monitoring data collected during a pump and treat corrective action
3-48
-------
Table 3-24
Groundwater Pump Effluent Monitoring Data
Site Location Number
California (2) Well 1
California (2) Well 2
Sampling Date
(Cumulative Count)
8/5/87 (0)
12/6/88 (489)
3/2/89 (575)
7/12/89 (707)
9/29/89 (786)
2/22/90 (932)
8/5/87 (0)
12/6/88 (489)
3/2/89 (575)
7/12/89 (707)
9/29/89 (789)
2/22/90 (932)
Benzene Concentration
(ppm)
20
2.1
17.7
11
5
10
15
9.7
22.3
22
10
19
Removal Efficiency (%)
-
90
12
45
75
50
-
35
-49"
-47a
33
-27"
Negative numbers indicate that the measured concentration after the initiation of pumping was greater
than the initial concentration measured.
activity, illustrates the limitations to this treatment approach. These data were collected by the
Office of Underground Storage Tanks as part of another EPA study. In the first case, after 900
days the concentration of benzene in the groundwater was reduced only 50 percent, to 10 ppm.
In the second case, after 932 days the concentration of benzene in the groundwater increased 27
percent, to 19 ppm. Corrective action activities had not reduced dissolved benzene
concentrations to levels acceptable to state environmental agencies in either case.
The effectiveness of the pumping well effluent treatment, however, is considerably better.
Once the contaminated groundwater has been removed, ex-situ treatment technologies are
capable of substantially reducing contaminant levels although reported removal efficiencies vary
widely. Removal efficiencies for halogenated organics reported in the literature for air stripping
technologies ranged from 70 to 90 percent for diffused aeration, 10 to 90 percent for tray
aeration, and 90 to more than 99 percent for packed towers. Granulated activated carbon (GAC)
units can remove aromatic compounds by more than 99 percent. Air stripping and GAC in
series can remove more organics and produce a treated water of higher quality than either system
alone14.
3-49
-------
3.4.2.3 Operating Parameters that Affect Treatment Performance
The design of a pump and treat groundwater remediation system is dependent upon the
characteristics of the site to be remediated, including factors such as depth to groundwater,
permeability of the porous medium (e.g., soil or rock), stratigraphy of the subsurface, type of
contamination and geographic, political, economical and territorial restrictions to the placement
of extraction wells and equipment. There are, therefore, a variety of potential design and
associated operating parameters. Two basic design philosophies are:
1. Installation of few large diameter deep extraction wells with large volume pumps that are
capable of affecting the flow of a large area: Under this design, the water table is
significantly depressed and extracted groundwater is circulated through large volume
treatment or disposal systems. This design may be more advantageous when space
restrictions limit the placement of extraction and treatment equipment.
2. Installation of numerous, small diameter wells, that are screened through the
contaminated zone: In this design, small volume pumps are used to collect the
groundwater and circulate through treatment or disposal systems.
The treatment performance of pump and treat systems under either approach is highly dependent
on site-specific conditions.
3.5 SUMMARY AND CONCLUSIONS
This chapter has provided an overview of information documenting the performance of
remediation technologies most commonly used at UST sites under the current Subtitle I program,
in terms of contaminant removal efficiency, operating parameters that affect contaminant
removal efficiency, residuals generated, and costs. The information was compiled from a
variety of sources, including published literature, state agencies, and equipment vendors. No
new data was generated in developing this overview.
Major findings for each of the technology alternatives are as follows:
1. For low temperature thermal stripper (LTTS) systems, treatment costs range from $74
to $184 per ton, while additional costs can be greater if stringent gas treatment is
performed. Treatment efficiencies for volatile organic constituents in soils of more than
99 percent have been reported, although available data indicates a wide range of removal
efficiencies has been experienced (as low as 27%). Major factors contributing to this
variation include the concentrations of contaminants in soils and soil conditions.
However, information that comprehensively characterizes the effects of operating
3-50
-------
parameters and soil/contaminant characteristics on treatment effectiveness for petroleum
contaminated soils has not been documented.
2. Soils treatment in hot mix asphalt plants currently ranges from about $50 to $100 per
ton. More than 99 percent removal efficiency of benzene in soils has been reported,
although treatment performance is highly variable. The extent to which each of the
various treatment mechanisms involved (including desorption, oxidation, and
encapsulation of contaminants) contributes to removal and destruction of petroleum
compounds has not been documented. Data that provides a definitive characterization
of the effects of variations in operating parameters and soil/contaminant characteristics
on treatment effectiveness is not available.
3. Land treatment of soils costs from $5 to $70 per ton. Treatment efficiencies for organic
contaminants ranging from 70 to greater than 99 percent have been reported after five
months of treatment. The extent to which these reductions can be attributed to
physical/chemical/biological processes in the soil and to volatilization to the atmosphere
has not been documented.
4. Disposal of soils generated at UST sites in municipal solid waste landfills is currently the
most common practice in states contacted during this study. Disposal costs range from
$4 to $132 per ton, with a national average of $27 per ton reported in 1988. No data
characterizing the extent to which petroleum contaminated soils contribute to
contaminants in leachates generated at municipal landfills were found during this study.
5. In-situ treatment of soil by soil vapor extraction is considered to be cost effective when
the volumes of soil are greater than 500 cubic yards. Reported costs range from as low
as $11 per ton to as high as $75 per ton. While data on treatment effectiveness at UST
sites is limited, results indicate that removal of 98 to 99 percent'of volatile constituents
has been achieved at some sites.
6. In-situ bioremediation is gaining popularity in a number of state UST programs.
Treatment costs and effectiveness are dependent on site-specific conditions. Reported
costs range from $7 to $138 per ton. Reductions of organic constituents by more than
80 percent can be achieved at certain sites.
7. Free product recovery is very commonly used at UST sites at the initial stage of
groundwater treatment. Recovery costs range from $2 to $93 per gallon of recovered
product. In four case studies, recovery of about 25 percent of the initial spill volume
was observed. No free product recovery system can remove the entire volume of
released product.
3 -51
-------
8. Pump and treat methods are commonly used for treating contaminated groundwater at
UST sites. The most common methods for treating groundwater that is pumped to the
surface is oil/water separation followed by air stripping or carbon adsorption. Costs of
$0.05 to $0.25 per thousand gallons of influent have been reported for air stripping,
while costs as low as $0.22 per thousand gallons to as high as $2.52 per thousand gallons
have been reported for carbon adsorption. Carbon adsorption and air stripping units are
capable of removing more than 90 percent of volatile organic compounds from
contaminated groundwater.
3.6 REFERENCES
1. On-site Technical Hydrocarbon Contaminated Soils. Prepared for Western States
Petroleum Association by Environmental Solutions Inc., Irvine, CA, 1991.
2. Johnson, P.C., Salanitro, J.P., Dicks, W.R., Deeley, G.M., Marsden, Jr., A.R., and
Rixey, W.G., Soil Remediation Workshop. Presented at the September 1990 Amherst
Conference on Contaminated Soil.
3. Study and Report on Use of Incinerators for Contaminated UST Sites in California.
prepared for the U.S. Environmental Protection Agency by Midwest Research Institute,
Contract No. 68-WO-0015, March 22, 1991.
4. Macinski, E.R., and Powell, J.L., "On-site Answer to Cradle to Grave Liability." Soils.
November-December 1990, pp. 24-25.
5. Thermo Process Systems Inc., marketing material, 1991.
6. Freeman, Harry M., Standard Handbook of Hazardous Waste Pretreatment and Disposal.
McGraw-Hill Book Company, New York, N.Y., 1989.
7. Soil Vapor Extraction VOC Control Technology Assessment. U.S. Environmental
Protection Agency, EPA-450/4-89-017, September 1989.
8. Remedial Technologies for Leaking Underground Storage Tanks. Electric Power
Research Institute and Edison Electric Institute, Lewis Publishers, Chelsea, MI, 1988.
9. Summary of Treatment Technology Effectiveness for Contaminated Soil. U.S.
Environmental Protection Agency, EPA/540/2-89/053, June 1990.
10. File data provided by the Minnesota Pollution Control Agency.
3-52
-------
11. Personal communication with a representative of Cleansoil, Inc., a mobile thermal
treatment vendor.
12. Cudhay, J.J., and Troxler, W. L., Thermal Remediation Industry Update-II. Proceedings
of the 1990 RD A/A & WMA International Symposiums on Hazardous Waste Treatment:
Treatment of Contaminated Soils. Cincinnati, OH, February 1990.
13. Rexroad, Richard. Contaminated Soils Cleanup Technologies: An Overview. Tenth
Annual ITLA Operating Conference. Houston, TX, June 1990.
14. Cleanup of Releases from Petroleum USTs: Selected Technologies. U.S. Environmental
Protection Agency, EPA/530/UST-88/001, April 1988.
15. Personal communication with a representative of the Asphalt Institute.
16. Personal communication with Mr. Steve Bergstrom, Massachusetts Department of
Environmental Protection.
17. Kostecki, Paul T., and Calabrese, Edward J., Petroleum Contaminated Soils Volume I.
Remediation Techniques. Environmental Fate. Risk Assessment. Lewis Publishers,
Chelsea, MI, 1989.
18. Calabrese, Edward J., and Kostecki, Paul T., Petroleum Contaminated Soils Volume II.
Remediation Techniques. Environmental Fate. Risk Assessment. Analytical
Methodologies. Lewis Publishers, Chelsea, MI, 1989.
19. Personal communication with Mr. Robert Dullinger, Minnesota Pollution Control
Agency.
20. Information provided by the Alaska Department of Environmental Conservation.
21. Petroleum Contaminated Soil Treatment in Asphalt Plants Test Burn Results, prepared
for Minnesota Pollution Control Agency-Underground Storage Tank Program by Barr
Engineering, Minneapolis, MN., May 1990.
22. Newton, Jim, "Remediation of Petroleum Contaminated Soils", Pollution Engineering.
Vol. 22., No. 22.
23. Personal communication with a representative of the Minnesota Pollution Control
Agency.
3-53
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24. Guidance for the Land Application of Petroleum Contaminated Soil: Single Application
Sites. Minnesota Pollution Control Agency, Tanks and Spills Section, April 25, 1990.
25. Loehr, Raymond C., and Overcash, Micheal R., " Land Treatment of Wastes: Concepts
and General Design," Journal of Environmental Engineering. Vol. Ill, No. 2, April
1985.
26. Information provided in Vermont guidance document.
27. Bioremediation of Contaminated Surface Soils. U.S. Environmental Protection Agency,
EPA/600/9-89/073, August 1989.
28. Handbook. Permit Writer's Guide to Test Burn Data Hazardous Waste Incineration.
U.S. Environmental Protection Agency, Office of Research and Development,
EPA/625/6-86/012, Washington D.C.
29. Hansen, Eric R., "New Way to Burn Hazardous Waste."Rock Products. April 1990.
30. Bioremediation of Contaminated Surface Soils. U.S. Environmental Protection Agency,
EPA/660/9/89/673/August 1989.
31. Von Wedel, Randall J., Augmented Bioremediation of Excavated Soil Contaminated with
Petroleum Hydrocarbons. SUPERFUND '90 Conference, Biotreatment Session,
Washington D.C., November 26-28, 1990.
32. Commercial vendor marketing brochure (1991).
33. Kampbell, Don H., Wilson, John T., Read, Harvey W. and Stocksdate, Thomas T.,
"Removal of Volatile Aliphatic Hydrocarbons in a Soil Bioreactor," Journal of the Air
Pollution Control Association. Vol. 37, No. 10, October 1987.
34. Personal communication with Mr. Paul Hunt of ENSR, Inc.
35. Results of Petroleum Contaminated Soils Sampling Program, Iowa Department of Natural
Resources Solid Waste Section, October 9, 1989.
36. International Waste Technologies/Geo-Con In-Situ Stabilization/Solidification.
Applications Analysis Report. U.S. Environmental Protection Agency, EPA/540/A5-
89/004, August 1990.
37. Patel, Yogesh B., Shah, Mahabal K., Cheremisinoff, Paul N., 1990. "Methods of Site
Remediation," Pollution Engineering. Vol. 22, No. 12, November 1990.
3-54
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38. Soliditech. Inc. Solidification/Stabilization Process. Applications Analysis Report. U.S.
Environmental Protection Agency, EPA/540/A5-89/005, September 1990.
39. Fielder, Fritz R., and Shevenell, Thomas C., How to Solve the Remediation Twin
Dilemmas: How Much? and How Long? A Case Study Using Vapor Extraction
Techniques for Gasoline Contaminated Soil. Proceedings of the Fourth National Outdoor
Action Conference on Aquifer Restoration, Ground Water Monitoring and Geophysical
Methods, May 14-17, 1990, Las Vegas, NV.
40. "Soil Vapor Extraction: Applicability and Design Considerations," The Hazardous Waste
Consultant. Vol. 8. Issue 2, March/April 1990.
41. Personal communication with Mr. Curt Kruger, Midwest Research Institute.
42. Terra Vac In Situ Vacuum Extraction System. Applications Analysis Report. U.S.
Environmental Protection Agency, EPA/540/A5-89/003, July 1989.
43. Brown, Richard A., Johnson, John, Oppenheim, James, and Harper, Cliff, Application
of In-situ Bioreclamation to a Low Permeability Heterogeneous Formation: Evolution of
a System in Response to Regulatory and Technical Issues. Proceedings of the Fourth
National Outdoor Action Conference on Aquifer Restoration, Ground Water Monitoring
and Geophysical Methods, May 14-17, 1990 Las Vegas, NV.
44. International Evaluation of In-situ Biorestoration of Contaminated Soil and Groundwater.
U.S. Environmental Protection Agency, EPA/540/2-90/012, September 1990.
45. Enhanced Bioremediation Utilizing Hydrogen Peroxide as a Supplemental Source of
Oxygen A Laboratory and Field Study. U.S. Environmental Protection Agency,
EPA/600/2-90/006, February 1990.
46. Commercial vendor marketing brochure (1991).
47. Corrective Action: Technologies and Applications. U.S. Environmental Protection
Agency, EPA/625/4-89/020, September 1989.
48. UST Corrective Action Technologies. U.S. Environmental Protection Agency,
EPA/625/6-87-015, January 1987.
49. Travis, Curtis C., and Doty, Carolyn B., "Can Contaminated Aquifers at Superfund Sites
be Remediated?," Environmental Science and Technology. Vol. 24, No. 10, 1990.
3-55
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50. Tillman, D.A., Rossi, AJ. and Vick, K.M. "Rotary Incineration Systems for Solid
Hazardous Wastes," Chemical Engineering Progress. July 1990.
51. Ground Water Issue: Performance of Evaluation of Pump and Treat Remediation. U.S.
Environmental Protection Agency, EPA/540/4-89/005, October 1989.
52. Assessing UST Corrective Action Technologies: Early Screening of Clean-up
Technologies for the Saturated Zone. U.S. Environmental Protection Agency,
EPA/600/2-90/027, June 1990.
53. Draft Background Document. Regulatory Impact Analysis (RIA~) of Proposed Revisions
to Substitute Criteria for Municipal Solid Waste Landfills. U.S. Environmental Protection
Agency, Office of Solid Wastes, August 1988.
54. NSWMA Annual Tip Fee Survey. 1988. National Solid Wastes Management
Association, Washington, D.C.
55. DiGiulio, Dominic C., Soo Cho, Jong, Dupont, R. Ryan, and Kemblowski, Marian W.,
Conducting Field Tests for Evaluation of Soil Vacuum Extraction Application.
Proceedings of the Fourth National Outdoor Action Conference on Aquifer Restoration,
Ground Water Monitoring and Geophysical Methods, May 14-17, 1990 Las Vegas, NV.
56. Contaminated Soil Treatment Technologies - Mobile Thermal Treatment. Four Seasons
Industrial Services Inc., marketing material 1991.
3-56
-------
APPENDIX A
SUMMARY OF STATE REQUIREMENTS FOR MANAGEMENT OF PETROLEUM
CONTAMINATED SOIL GENERATED AT UST CORRECTIVE ACTION SITES
A.I SUMMARY OF STATE REQUIREMENTS
As part of this study, EPA performed a review of selected state programs under RCRA
Subtitle I in order to identify the types of state requirements currently in place for managing
petroleum contaminated soils generated at UST corrective action sites, from initial generation
and characterization through their final treatment and/or disposal. Table A-l is a summary of
these requirements in each of the 26 states contacted during this study. The information in each
column of the table describes state requirements for each major step in the corrective action
process, from the characterization of the media and debris through the ultimate disposition of
these materials. The table provides a snapshot of the state requirements based on examples
provided by states through the first quarter of 1991. It is not intended to be a comprehensive
compilation of all current requirements that could affect selection of corrective action
technologies.
A.2 CORRECTIVE ACTION TECHNOLOGIES USED IN EACH STATE
A number of ex-situ and in-situ corrective action technologies are currently used to treat
petroleum contaminated media and debris generated at UST corrective action sites in accordance
with applicable state requirements. As discussed in Chapter 2, states contacted during this
review indicated that the following technologies are commonly used to treat petroleum
contaminated soils: low temperature thermal strippers, asphalt plants, landfarming, landfilling,
soil vapor extraction, and ex-situ and in-situ bioremediation. Table A-2 list the ex-situ and in-
situ corrective action technologies reported by selected states to be in current use.
A- 1
-------
Table A-l"
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Arizona
(K)
California
(IX)
Colorado
(Vm)
Connecticut
(D
Delaware
an)
Florida
(IV)
TESTING REQUIREMENTS
SAMPLING
Site-specific
Three different sampling
methods based on
suspected level of
soil/groundwater
contamination: core/trowel
sampling (no evidence of
contamination), soil boring
(known contamination),
and grab sampling
(ground water).
Field screening used as
guidance for location, type
and number of sample
selections. Grab sampling
to characterize area and
borings to locate maximum
concentration. Minimum
of 3 samples below each
tank excavated.
Sampling in pit; Grab
samples from stockpiles
(minimum number based
on volume).
Sampling in pit at points
of maximum
contamination; Composite
samples from stockpiles
(minimum number based
on volume).
Number of samples
determined on a site-
specific basis, dependent
on the size of the
excavation and degree of
potential contamination.
Composite and grab
sampling are used.
ANALYSIS
BTEX (EPA Method 8020)
TPH (Modified EPA
Method 8015 for gasoline;
modified 4 18.1 for
diesel/waste oil).
Sample analysis dependent
on type of sample and
substance to be analyzed:
BTEX (EPA 8020), TPH
(Dept. of Health Services
Method), and HVO (EPA
8010) for gasoline; TPH
(DHS Method), TRPH
(EPA 418.1) for diesel.
All samples analyzed for
BTEX. If the contaminant is
unknown, then Hydrocarbon
Scan for all tests. Known
contaminants: TVH for
gasoline, TEH for diesel
and weathered gas,
oil/grease method for oil
and grease.
BTEX (EPA Method
8010/8020);
EP Tox.
BTEX (EPA Methods
3810/8020; 5030/8020;
3810/8240);TPH (Modified
EPA Method 418.1); APHA
Methods 5520E/5520C;
APHA Methods
503B/503E).
Organic vapor analysis
(OVA) to determine level of
soil contamination.
CLEANUP STANDARDS
Specific concentration levels
(guidance);
Site-specific risk-based
levels are optional.
Standards are established on
a site-specific basis using
several analyses (leaching
potential analysis and
general/ alternative risk
appraisals). CAEPA
recommended maximum
contaminant levels are: 10-
l.OOOppmTPH for gas, 100
to 10,OOOppmTPHfor
diesel, 0.3-lppm benzene,
0.3-50ppm toluene, 1-
50ppm xylene, l-50ppm
ethylbenzene.
Three Remedial Action
Categories (RAC) based on
groundwater usage
determine standards. Soils
in contact with RAC
groundwater should be
remediated accordingly:
<20-100mg/kgBTEX,
< 100 - 500mg/kg TPH.
Site-specific based on
designated water quality in
area.
Action levels for BTEX and
TPH based on site category
(3 categories, based on
risk).
Standards vary - excavated
soils taken to thermal
treatment facility must meet
"criteria for clean soil" in
accordance with Dept. rule;
if remediated in another
manner, other criteria
apply, but are not mandated
by Dept. rule.
REGULATORY
STATUS OF PCS
Solid waste permit
generally required unless
PCS treated on-site within
12 months.
Soils classification is
dependent on the
determined contaminant
concentrations. Soils failing
classification standards are
considered hazardous.
If PCS are not
characterized as hazardous
wastes, they are considered
as solid wastes and require
disposal in accordance with
the Solid Waste Disposal
Act or at regulated UST
facilities.
Hazardous waste if total
hydrocarbons (BTEX) >
50 ppm or if EP Toxicity
exhibited.
Regulated as "regulated
substance waste" under
state solid waste program.
500 ppm - excessively
contaminated, should be
remediated but not
required; 10 to 500 ppm -
contaminated, cleanup may
be necessary; < 10 ppm -
not contaminated,
remediation not necessary.
A-2
-------
Table A-l (continued)*
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Arizona
(K)
California
(K)
Colorado
(VIII)
Connecticut
(I)
Delaware
(III)
Florida
(IV)
TREATMENT/DISPOSAL
RESTRICTIONS
ON-STTE
Soil meeting cleanup
standards may be returned
to excavation.
Permitting required for
mobile or fixed treatment of
hazardous wastes. Air
permits typically are
required to control
emissions from incineration
systems. Waste discharge
permits typically required
for all post-treatment use of
PCS. Non-hazardous waste
is regulated by local
jurisdictions, not the
CAEPA.
On site (excavated or in-
situ) PCS exceeding
appropriate RAC levels
must be managed in
accordance with an
approved corrective
action/contaminated
materials handling plan.
N/A
The state recommends on-
site treatment of PCS as a
succession to the
removal/abandonment of an
UST. Must complete
remediation within a year or
more aggressive measures
will be required.
Mobile thermal treatment
units must be permitted.
OFF-SITE
Solid waste permit required.
For treatment, substantial
information must be
submitted prior to approval.
Same as onsite.
PCS > appropriate RAC
levels managed off-site may
be: disposed of at approved
facility, with incorporated
approval at asphalt batch
plant for construction
application. Recycled PCS
with certification used in
road construction are not
considered solid waste.
Soils with total BTEX < 50
ppm and which pass EP
Tox may be disposed in
Solid Waste landfills.
Otherwise, must go to
permitted hazardous waste
facility.
Regulated under solid waste
program.
Thermal treatment facilities
are permitted, regulated and
have specific sampling and
analysis requirements for all
accepted wastes.
TRANSPORTATION
REQUIREMENTS
Solid waste permit
required.
"Hazardous" soils
require a manifest and
transport by a
registered hauler.
N/A
Hazardous waste must
be transferred by
licensed hazardous
waste handlers.
N/A
N/A
ON-S1TE STORAGE
REQUIREMENTS
Stockpiles must be on
impervious liner,
covered, and bermed.
For long-term storage,
air permit may be
required.
Local authorities may
require management
activities to minimize
off-site migration.
Stockpiles should be
placed on plastic liner
or asphalt, bermed and
covered to prevent
contaminant migration.
Stockpiles must be on
'impervious liner and
covered.
Soils must be secured
with plastic lining to
prevent erosion,
runoff, leaching, air
emissions and
unauthorized access.
On-site storage is
limited to one year.
PCS stored on-site
must be stockpiled on
an impermeable liner
and covered.
A-3
-------
Table A-l (continued)9
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Indiana
(V)
Iowa
(VII)
Kentucky
(TV)
Louisiana
(VI)
Maine
00
Maryland
(ffl)
Massachusetts
(I)
TESTING REQUIREMENTS
SAMPLING
Number of samples is
dependent on the number
of tanks removed and the
size of the excavation.
Grab sampling is the
preferred approach.
Samples are collected from
beneath the tank bottom.
The number of samples
depends on the size of the
tanks. Only grab samples
are accepted.
Sample number and
location dependent on
excavation size and
whether contamination is
suspected or not.
Sampling is designed to
demonstrate that soil
remaining on site is clean.
Samples are collected
below tank pad in an
excavation. If these
samples are contaminated
then a total site assessment
is required.
Sample location and
numbers determined on a
site by site basis.
Determined on site-specific
basis.
Sampling in pit; Grab
samples from stockpile
(minimum number based
on volume).
ANALYSIS
TPH analysis using
California modified 8015.
Landfill operators may
require TCLP analysis prior
to acceptance of waste.
Total Organic Hydrocarbons
(from Iowa Method OH-1
and OH-2)
Landfills require EPA paint
filter test, PAH and BTEX
for diesel contaminated soil,
TPH and BTEX for
gasoline, EP Tox (lead) for
old gas and a metals screen
for waste oil contaminated
soils.
Gasoline contaminated soils:
BTEX (EPA Method 8020);
Diesel contaminated soils:
TPH (modified California
procedure); waste oil
contaminated soils: EP
Tox, oil and grease (Method
503E), total organic
halogens (D808) and
volatile hydrocarbon scan
(EPA Method 8240).
Testing is dependent on
released compound. Use
department developed
hydrocarbon analyses: total
gasoline or total fuel
analysis. TPH only in rare
circumstances (e.g. heavy
oils).
TPH and BTEX are
required.
Jar Headspace Field
screening procedure for
gasoline; TPH for other
petroleum products.
CLEANUP STANDARDS
Site by site basis. Attempt
to remediate the soil to "as
clean as possible."
Soils are "clean" if Total
Organic Hydrocarbons is
below 100 ppm.
Background or detection
limits.
Established on a case by
case basis.
No uniform requirements,
but 50 ppm total gasoline
hydrocarbon typically
required. New risk based
policy in development.
100 ppm TPH for soils;
Non-measurable level for
free product; Attainment of
asymptotic level for ground
water.
Site-specific risk based
levels.
REGULATORY
STATUS OF PCS
PCS classified as special
wastes.
PCS considered a special
waste.
PCS regulated as a
"pollutant" requiring
notification and proof of
remediation via a receipt
(similar to a manifest).
Only soils exceeding EP
Toxicity standards for lead
are considered hazardous.
Soils removed from a site
are considered a solid
waste.
Regulated as special solid
waste.
No unique regulatory
status.
Waste petroleum products
are listed hazardous wastes.
A-4
-------
Table A-l (continued)'
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Indiana
(V)
Iowa
(VII)
Kentucky
(IV)
Louisiana
(VI)
Maine
(I)
Maryland
(in)
Massachusetts
0)
TREATMENT/DISPOSAL
RESTRICTIONS
ON-STTE
Permission of the state
required prior to initiation
of corrective action.
Technology employed must
be demonstrated effective
under the given conditions.
Special approval required
before bioremediation may
be employed. Passive
remediation - monitoring
and continued assessment.
On-site remedial treatment
must comply with the air
emissions standards and
other safeguards. Most
forms of remediation are
acceptable provided
feasibility study is
performed to demonstrate
effectiveness.
On-site aeration is permitted
as a means of reducing
contaminant levels so that
soils may be returned to the
excavation. Its use is
limited to areas where there
is no potential risk to human
health.
No specific permits are
required. There are siting
and operation and
maintenance restrictions.
If > 100 TPH, can be
stored on site for more than
48 hours, and can be
returned to pit only if
monitoring well is installed:
if < 100 TPH, can be
returned to pit.
On-site re-use is restricted
based on concentrations of
contaminants in soils and on
environmental vulnerability
of site.
OFF-SITE
Permitted special waste
landfills and hazardous
waste disposal facilities.
Landfill must land treat soils
until TPH is < 100 ppm
when the soil is used as
cover material. Incineration
- emission standard with
continual approval.
Landfills that incorporate
certain technologies are
permitted to accept PCS.
Landfarming operations
require a registration for
> SOOT and a special permit
for <500T, as do all other
alternative remedial
technologies.
Only disposal options are
designated commercial and
hazardous waste landfills.
Landfills are restricted in
the volume of soil they can
accept each year. Land
application is restricted to
petroleum products from
known sources with
extensive siting restriction
criteria.
No specific requirements.
Soils with > 1800 ppm
total headspace volatiles or
> 3000 mg/kg TPH cannot
be disposed of in landfills.
Operational restrictions for
landfilling PCS are
specified.
TRANSPORTATION
REQUIREMENTS
Permit required.
N/A
N/A
Soils removed from a
site are governed by
the regulations
governing the
transport of solid
waste.
Currently none.
No specific
requirements.
Bill of lading must be
signed by state.
ON-SITE STORAGE
REQUIREMENTS
PCS stockpile must be
stored on plastic and
covered.
Site-specific
requirements,
temporary option.
Soils isolated with
thick plastic sheeting.
Receipt must indicate
duration of storage.
Excavated PCS must
be stored on plastic
and encircled by a
protective berm to
contain run-off.
Stockpile must be
stored on plastic and
covered .
Stockpile must be on
impervious liner and
covered . Storage may
not be allowed if odor
problem exists.
Stockpiles must be on
impervious liner and
covered, with public
access minimized;
Storage limited to 4
months.
A-5
-------
Table A-l (continued)*
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Minnesota
(V)
Missouri
(VII)
Montana
(Vffl)
New Jersey
(ID
New Mexico
(VI)
TESTING REQUIREMENTS
SAMPLING
Grab samples from
stockpiles; minimum
number based on volume
of soil.
Composite and grab
samples in pit.
Site-specific for sites with
confirmed releases;
Sampling requirements in
pit specified for clean
closures.
Recommended targeting
of areas of potential
contamination. One sample
for every 20 cubic yards;
up to 5 samples per
analysis. For total VOC
analyses, one subsurface
sample for every 50 cubic
yards. Total VOC is only
used to determine if PCS
is below regulatory
concern (BRC).
Minimum number of 3
samples collected from
variety of locations. A
discrete sample must be
taken from the excavation.
ANALYSIS
BTEX (EPA Method 8015)
TPH, and lead for soils with
regular gasoline and
aviation fuel;
TPH, metals and PCB,
(EPA Method 8080) for
soils with waste oils.
BTEX (EPA Method 8020
or 8240); TPH (modified
EPA Method 418.1). For
soils with waste oils, EP
Tox.
BTEX and/or TPH (site-
specific) for gasoline;
TPH for diesel and heavy
oils.
Recommended to determine
if PCS is BRC: gasoline
contaminated soils - TPH
and Total VOC analyses;
other Virgin fuels - TPH
only; if source is unknown -
TPH, Priority Pollutant
Metals and VOC using a
Photo- lonization
Detector/Organic Vapor
Analyzer; if VOC level >
background, test Total
VOC. For classification
purposes: TPH, PCBs,
cyanide and sulfur
reactivity, and TCLP metals
for 1/10 of all samples. If
only one sample, TCLP
required.
Gasoline contaminated soils:
EPA Method 8240, 8020,
or modified 8015; Diesel
fuel, motor oil and other
heavy petroleum products:
EPA Method 4 18. lor
another approved method.
CLEANUP STANDARDS
Gasoline and aviation fuels:
10 ppm vapor headspace;
TPH < 50 ppm. Other
contaminants: vapor
headspace above
background.
Site-specific risk-based
levels for BTEX and TPH.
Site-specific, but normally
100 ppm TPH and lOppm
BTEX is maximum.
Site-specific depending on
classification of soils into
one of three categories.
Classification determined by
specific contamination
limits: Hazardous waste
(HW) > Nonhazardous
waste (NHW), NHW >
Category 3 limits, Below
Regulatory Concern (BRC)
< Category 3 limits.
Soil contamination is
reduced to levels which will
not contaminate ground
water or produce harmful
vapors . Gasoline
contaminated soils: Total
BTEX < 50 ppm and B <
10 ppm. Diesel, motor oil,
kerosene or jet aviation:
TPH < 100 ppm.
REGULATORY
STATUS OF PCS
Distinct Regulatory
Classification.
Disposal of soil
contaminated with virgin
fuel oil or gasoline does
not require permission
prior to disposal. Soil
contaminated with waste oil
is restricted as "special
waste".
N/A
Regulated according to soil
classification: HW soils
must be managed as HW in
accordance with NJAC
7:26-1, NHW soils have
various options (disposal,
landfill covering, reuse)
BRC soils do not need to
be classified and may be
used without treatment or
prior approval (conditions
apply).
"Highly contaminated
soils" are saturated with
petroleum products to the
extent that free product is
observable in the soil. Soils
which are not saturated but
have benzene
concentrations > cleanup
standards must be
remediated under
conditions defined by the
state.
A-6
-------
Table A-l (continued)"
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Minnesota
(V)
Missouri
(VII)
Montana
(VIII)
New Jersey
(II)
New Mexico
(VI)
TREATMENT/DISPOSAL
RESTRICTIONS
ON-SFTE
PCS below action levels
may be used as backfill only
at original site. Landfarming
on-site with approval.
Soils must have < 10 ppm
TPH or < 1 ppm total
BTEX to be used as clean
fill.
If landfarming 1 to 100 yd3
on PCS owner's property -
require verbal approval
from state and possible
sampling and monitoring. If
landfarming > 100 yd3 at
any site - require written
approval from state and soil
sampling and monitoring.
Soil reuse plan must be
approved by NJDEP. Soils
should not be stockpiled on-
site longer than 6 months
from time of excavation.
Soil meeting cleanup
standards for benzene may
be returned to the
excavation or used as road
mix. Soil excavation and
disposal is dependent on the
site conditions, depth to
ground water and
contaminant levels.
OFF-SITE
Landfilling not allowed.
Landfarming or thermal
treatment require approval,
subject to specific
restrictions.
Soil contaminated with
waste oil requires state
approval prior to disposal in
solid waste landfills; soil
contaminated with virgin
fuel oil or gasoline does not
require approval.
If landfarming 1 to 100 yds
on another's property -
require verbal approval
from state, written
permission from owner, and
possible soil and
groundwater monitoring. If
applying > 100 yd, from
more than 1 site - permit
required.
Must follow NJ Waste Flow
Management Program for
PCS disposal. HW soils
require a manifest; removal
and disposal must be
conducted by a registered
contractor. Options for
NHW soils are subject to
Department approval.
Landfarming operations are
required to meet certain
design and operation
standards. Landfarms and
landfills are permitted
operations.
TRANSPORTATION
REQUIREMENTS
N/A
N/A
N/A
N/A
N/A
ON-SITE STORAGE
REQUIREMENTS
Stockpiles must be on
impervious liner,
covered, and
contoured.
N/A
Must choose location
which will not cause
groundwater, soil, or
air pollution. State can
require covering
and/or berming. Local
authorities should be
contacted prior to
storage.
Stockpiles should be
completely isolated,
preventing any
hazardous materials
from contact or release
into the environment.
,
On-site storage
requirements are based
in part on the depth to
ground water.
Typically require
storage of PCS on an
impervious layer in a
bermed area.
A-7
-------
Table A-l (continued)"
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
New York
(II)
Oregon
(X)
Tennessee
(IV)
Texas
(VJ)
TESTING REQUIREMENTS
SAMPLING
Guidelines are site-
specific for sampling from
the tank pit, stockpile,
processed soils and non-
excavated soils.
Sampling requirements are
site specific and based on
site complexity. Samples
should represent soils
remaining on site. No
composite samples are
allowed.
Number of samples
dependent on the size of
the excavation and tanks
removed. Grab samples in
pit. Samples are required
from the stockpiled soil to
determine disposal options.
In general, minimum
requirements dictate 1
sample must be collected
from each wall of the
excavation, 1 from the pit
bottom, 1 from under the
dispensing islands and 1
from any stockpiled soils.
ANALYSIS
EPA Method 8020 for
gasoline, EPA Method 8270
Base/Neutrals for fuel
contaminated soils.
Hazardous waste
determination regarding
ignitability and toxicity from
lead. Proposed guidance
provides both TCLP extract
analysis and direct sample
analysis by the above
methods.
Gasoline contaminated soils,
DEQ Lab Method TPH-G;
Diesel or non-gasoline
fraction hydrocarbons, DEQ
Lab Method TPH-D. For all
soils: Hydrocarbon
identification (DEQ Lab
Method TPH-HCID). Waste
oil contaminated soils:
analysis for volatile
chlorinated solvents and
volatile aromatic solvents.
TCLP analysis for metals.
PCBs by method 8080;
DEQ Lab Method TPH-
4 18.1 Modified.
Benzene in TCLP extracts:
EPA Method 8020 or 8240
or equivalent tests. TPH in
TCLP extract: California
GC Method. Lead
concentration in TCLP
extract: EPA Method 6010,
7240, 7421 or equivalent.
Unleaded gasoline
contaminated soils: TPH
and BTEX analysis; leaded
gasoline contaminated soils:
TPH, BTEX, EP Tox for
lead; Diesel contaminated
soils: TPH and BTEX;
Waste oil contaminated
soils: EP Tox, total organic
halogen scan and additional
tests as deemed necessary.
BTEX (EPA Method 8020
with EPA Method 5030
purge and trap). TPH (EPA
Method 3540 or 3550
quantified using EPA
Method 418.1 or ASTM
d3328-78 Method B)
CLEANUP STANDARDS
Proposed cleanup standards
are compound specific,
being protective of human
health, fish and wildlife,
groundwater quality, and
aesthetics.
Site specific numeric clean-
up criteria, based on depth
to ground water, mean
annual precipitation, nature
of soil and rock, sensitivity
of uppermost aquifer, and
potential receptors.
BTX levels < 10 ppm.
Goals are site specific and
designed to prevent public
exposure. A LUST
Remediation Index has been
established to set
remediation goals when only
soil is contaminated.
REGULATORY
STATUS OF PCS
PCS regulated as industrial
solid wastes. Proposed
guidance: PCS are
unregulated if they pass a
TCLP test based on the
state's water quality
standards, or if
contaminant levels are
below maximum values set
by the Water-Soil Partition
model.
Specified waste under
Oregon Administrative
Rules (OAR 340-61-060).
Special waste approvals
required before waste with
BTX between 10 and 100
ppm can be disposed of in
landfills.
Have special regulatory
status outside of Hazardous
and Solid wastes rules
unless they are deemed
hazardous through
ignitability.
A-8
-------
Table A-l (continued)*
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
New York
(H)
Oregon
(X)
Tennessee
(IV)
Texas
(VI)
TREATMENT/DISPOSAL
RESTRICTIONS
ON-SITE
Non-excavated soils may be
subject to the same
standards as excavated soils,
but are not regulated as
solid or hazardous waste
until after excavation (site
specific parameters apply).
Permitting required only for
on-site treatment of
hazardous PCS. Proposed:
PCS must meet "clean" soil
criteria for on-site disposal.
Regulated under UST
permit modification.
On-site or in-situ remedial
activities must submit the
results of periodic sampling.
On-site aeration allowed if
air pollution would not
result. Permits and
approval may be required in
order to perform on-site
remediations.
OFF-SITE
Hazardous PCS must be
disposed of at a permitted
hazardous waste facility.
Non-hazardous PCS must be
treated or landfilled at
permitted facilities, except
for fuel oil soils which may
supply approved asphalt
plants. Proposed: "clean"
soil to be re-used, returned
to excavation, or landfilled.
For soils from regulated
tank sites: landfilling only
for specified wastes with
authorization, one-time
authorization and
performance standards for
off-site treatment of soils.
Soil from non-regulated
tanks subject to TCLP
analysis and possibly
restricted to hazardous
waste disposal facilities.
Disposal and treatment
options are based on
concentration levels.
Currently landfills can not
accept soils with BTEX
levels > 500 ppm or TPH
levels > 1000 ppm. Soon
landfills will not be allowed
to accept PCS.
TRANSPORTATION
REQUIREMENTS
Hazardous PCS must
be manifested to a
permitted hazardous
waste facility; none
required for non-
hazardous PCS .
Appropriate transport
permits are required
for both types of soils.
Proposed: "clean"
soils to be transported
without permits.
Licensed by Oregon
Public Utilities
Commission for
transportation of
general commodities if
soils are non-
hazardous; special
license required for
hazardous waste
transportation.
N/A
N/A
ON-SITE STORAGE
REQUIREMENTS
Excavated soils must
be placed on and
covered by impervious
material with the sides
banked to
control/contain run-off.
PCS cannot be stored
on-site for more than
90 days without on-site
treatment approval.
Permit required
ensuring that soils are
managed to prevent
fire hazards and runoff
contamination.
Contaminated soils
stored separately from
non-contaminated
during excavation.
On-site storage is
regulated to prevent
public exposure. PCS
must be stored on an
impervious material,
have run-off and run-
on protection and be
covered if on-site
aeration is not allowed.
A-9
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Table A-l (continued)*
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Utah
(Vffl)
Virginia
(ID)
Washington
(X)
Wyoming
(VIII)
TESTING REQUIREMENTS
SAMPLING
Minimum of 4 samples are
required per excavation.
Composite samples
(minimum number based
on volume), if intend to
excavate and dispose in
landfill. Must have
discrete samples for on-
site disposal.
Sampling requirements are
being developed .
A single representative
grab sample is required
from location of maximum
potential contamination.
ANALYSIS
TPH (California modified
8015 or approved
equivalent). Oil and waste
oil contaminated soils are
analyzed for total oil and
grease (EPA Method
413.1). Samples for grain
size analysis must also be
collected.
BTEX, free liquid, TOX,
TPH (EPA Method 418.1);
EP Toxicity and Ignitability
(if applicable). Additional
testing requirements applied
on a site-specific basis.
TPH analysis (Dept. Lab
Method) is required of all
excavated soils. BTEX
analysis is required for all
gasoline contaminated soils.
No laboratory analysis of
gasoline, diesel fuel or
crude oil is required.
Analysis required for waste
oil or other petroleum
products.
CLEANUP STANDARDS
Established on a site by site
basis.
Standards are site specific
and are based on risk and
technology.
100 ppm TPH for gasoline
200 ppm TPH for diesel
0.5 ppm for benzene
20 ppm ethylbenzene
40 ppm toluene
20 ppm xylenes
250 ppm lead
Interim standards are based
on depth to ground water.
TPH > 100 ppm must be
mitigated. TPH > 10 ppm
and GW < 50 ft. must be
mitigated.
REGULATORY
STATUS OF PCS
Various local Department
of Health ordinances apply.
Status is determined by
analytical results, and may
fall either under the Solid
or Hazardous Waste
Management Program.
Defined as "problem
wastes" under state's solid
waste regulation; specific
requirements are lacking.
New guidance is being
developed.
Soils contaminated with
gasoline, diesel, fuel oil or
crude oil are regulated.
Soil contaminated with
waste oil or any other
petroleum product needs
specific authorization for
disposal.
Note: "N/A" means that either there are no specific requirements for petroleum contaminated soils, or that information regarding such
requirements was not available to EPA.
A- 10
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Table A-l (continued)*
Summary of State Requirements for Management of Petroleum Contaminated Soils
STATE
(REGION)
Utah
(Vffl)
Virginia
(III)
Washington
(X)
Wyoming
(VIII)
TREATMENT/DISPOSAL
RESTRICTIONS
ON-SITE
Local health departments
may restrict on-site activity.
A hazardous waste
management permit is
required for the on-site
treatment or disposal of
hazardous PCS. If the soil is
a solid waste, treatment may
be performed under
direction of the State Water
Control Board.
N/A
On-site treatment is
permitted only in case of
emergencies, provided
certain restrictions are met.
Air quality permits are
required for soil vapor
treatment operations.
OFF-SITE
At the state level, landfills
are not regulated as to what
they can accept. Regulation
and permitting is controlled
by the local agencies.
Off-site disposal/treatment
of hazardous soils must be
performed at authorized
hazardous waste
management facilities. Off-
site treatment is available at
approved thermal treatment
units.
Currently no specific
guidelines in place that
dictate ultimate disposal
options. Proposed guidance
will probably indicate a
number of disposal options
based on contamination
levels.
Soils contaminated with
gasoline, diesel, fuel oil or
crude oil may be routinely
accepted for landfill disposal
at permitted facilities. Soils
contaminated with waste oil
or other petroleum products
need special approval before
acceptance and only after
certain requirements are met
by the disposal facility.
TRANSPORTATION
REQUIREMENTS
N/A
Hazardous PCS must
be transported by a
Virginia-permitted
transporter under a
manifest. There are no
specified requirements
for non-hazardous
PCS.
N/A
N/A
ON-SITE STORAGE
REQUIREMENTS
Excavated PCS should
be stored on plastic
and comply with air
emission standards.
Stockpiling of soils is
strongly discouraged
until waste has been
properly characterized.
Soils should be stored
in containers or tanks.
Non-putrescible solid
wastes are required to
be disposed at intervals
less than thirty days.
Stockpile management
requirements are being
developed.
PCS are usually loaded
directly into a dump
truck. PCS stockpiled
on site required to be
stored on a liner and
covered.
The table provides a snapshot of the state requirements based on examples provided by states through the first quarter of 1991. It
is not intended to be a comprehensive compilation of all current requirements that could affect selection of corrective action
technologies.
A- 11
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