EPA/540/AR-93/508
August 1993
EPA RREL's
Mobile Volume Reduction Unit
Applications Analysis Report
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Printed on Recycled Paper
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Notice
The information hi this document has been funded by the U.S. Environmental Protection Agency (EPA) under the
auspices of the Superfund Innovative Technology Evaluation (SITE) Program under Contract No. 68-CO-0048 to Science
Applications International Corporation (SAIC). It has been subjected to the Agency's peer and administrative review,
and it has been approved for publications as an EPA document. Mention of trade names or commercial products does
not constitute an endorsement or recommendation for use.
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Foreword
The Superfund Innovative Technology Evaluation (SITE) Program was authorized in the 1986 Superfund Amendments.
The Program is a joint effort between the U.S. Environmental Protection Agency's (EPA) Office of Research and
Development and Office of Solid Waste and Emergency Response. The purpose of the program is to enhance the
development of hazardous waste treatment technologies necessary for implementing new cleanup standards that require
greater reliance on permanent remedies. This is accomplished by performing technology demonstrations designed to
provide engineering and economic data on selected technologies.
This project consists of an analysis of the EPA Risk Reduction Engineering Laboratory's mobile Volume Reduction Unit.
The Demonstration Test took place at the Escambia Treating Company Superfund Site in Pensacola, Florida. The goals
of the study, summarized in this Applications Analysis Report, are: 1) to evaluate the technical effectiveness and
economics of this technology relative to its ability to treat soils contaminated with organics; and 2) to establish the
potential applicability of the process to other wastes and Superfund sites. The primary technical objective of this project
is to determine the ability of the process to reduce the concentration of organic contaminants in contaminated soil
through particle size separation and solubilization.
Additional copies of this report may be obtained at no charge from the EPA's Center for Environmental Research
Information, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268, using the EPA document number found on the
report's front cover. Once this supply is exhausted, copies can be purchased from the National Technical Information
Service, Ravensworth Building, Springfield, Virginia 22161, (800) 553-6847. Reference copies will be available in the
Hazardous Waste Collection at EPA libraries. Information regarding the availablity of other reports can be obtained
by calling the Office of Research and Development Publications at (513) 569-7562. To obtain further information
regarding the SITE Program and other projects within SITE, telephone (513) 569-7696.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
111
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Abstract
This document is an evaluation of the performance of the U.S. Environmental Protection Agency (EPA) Risk Reduction
Engineering Laboratory's (RREL's) mobile Volume Reduction Unit (VRU) and its applicability as a treatment technique
for soils contaminated with organics. Both the technical and economic aspects of the technology were examined.
A demonstration of the VRU was conducted in the fall of 1992 using RREL's pilot-scale unit at the Escambia Treating
Company Superfund Site in Pensacola, Florida. Operational data and sampling and analysis information were carefully
compiled to establish a database against which other available data, as well as the project objectives for the
demonstration, could be compared and evaluated. Conclusions concerning the technology's suitability for use in treating
contaminated soils with organic compounds through particle size separation and solubilization were reached.
Extrapolations regarding applications to different contaminants and soil types were made.
Under optimal conditions, when surfactant was added and pH and temperature of the wash water were increased, the
VRU achieved average removal efficiencies of 97 percent for pentachlorophenol (PCP) and 95 percent for polynuclear
aromatic hydrocarbon (PAH) contaminants. In addition, 86 percent of the solids in the feed soil were returned as washed
soil (on a normalized basis).
IV
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Contents
Section
Notice
Foreword
Abstract
Contents
Tables ™
Figure . ^
Abbreviations
Acknowledgments
1. Executive Summary
1.1 Introduction
1.2 Conclusions
1.3 Results
3
2. Introduction •
2.1 The SITE Program ^
2.2 SITE Program Reports 3
2.3 Key Contacts 4
3. Technology Applications Analysis
3.1 Introduction
3.2 Conclusions
3.3 Technology Evaluation "
3.3.1 VRU Operating Conditions 6
3.3.2 Contaminant Removal Efficiencies 7
3.3.3 Washed Soils Recovery 8
3.3.4 Mass Balances "
3.3.5 Particle Size and Fines Distribution 9
3.3.6 Water Treatment Effectiveness 10
3.4 Ranges of Site Characteristics Suitable for the Technology H
3.4.1 Site Selection 11
3.4.2 Load, Surface, and Subsurface Requirements H
3.4.3 Clearance and Site Area Requirements H
3.4.4 Climate Characteristics ^
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Contents (Continued)
Action
3.45 Geological and Topographical Characteristics 12
3.4.6 Utility Requirements 12
3.4.7 Size of Operation '.'.'.'.'.'.'.'.'.'. 12
35 Applicable Wastes 12
3.6 Regulatory Requirements 12
3.6.1 Federal Regulations 13
3.6.1.1 Clean Air Act (CAA) 13
3.6.1.2 CERCLA !3
3.6.1.3 RCRA 14
3.6.1.4 CWA 14
3.6.1.5 Safe Drinking Water Act (SDWA) '.'.'.'.'.'.'.'.'.'.'.'.'.'.'. 14
3.6.1.6 Toxic Substances Control Act (TSCA) '' 14
3.63. State and Local Regulations 15
3.7 Personnel Issues 15
3.7.1 Training J5
3.7.2 Health and Safety '.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'. 15
3.73 Emergency Response 15
3.8 References 15
4. Economic Analysis lg
4.1 Introduction ^
42 Conclusions *' * -^
43 Issues and Assumptions lg
43.1 Costs Excluded from Estimate 16
43.2 Utilities 16
433 Operating Times 17
4.3.4 Labor Requirements 17
435 Capital Costs ° 17
43.6 Equipment and Fixed Costs lg
4.4 Basis of Economic Analysis lg
4.4.1 Site Preparation Costs ' ig
4.4.2 Permitting and Regulatory Costs \ lg
4.43 Equipment Costs lg
4.4.4 Startup and Fixed Costs 19
4.4.5 Labor Costs 20
4.4.6 Supplies Costs 20
4.4.7 Consumables Costs 20
4.4.8 Effluent Treatment and Disposal Costs 20
4.4.9 Residuals and Waste Shipping, Handling, and Transport Costs 21
4.4.10 Analytical Costs 21
4.4.11 Faculty Modification, Repair, and Replacement Costs 21
4.4.12 Site Demobilization Costs 21
45 Results of Economic Analysis 21
4.6 References 24
VI
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Contents (Continued)
Section
Appendix A - Process Description 25
A.1 Introduction 25
A.2 Process Description 25
A.3 References 27
Appendix B - Developer Claims 29
B.I Introduction 29
B.2 SITE Demonstration Claims 29
Appendix C - SITE Demonstration Results 31
C.1 Introduction 31
C.2 Operating Conditions 31
C.3 Contaminant Removal 32
C.4 Washed Soils Recovery 33
C.5 Mass Balances 34
C.5.1 Total Material 34
C.5.2 Dry Solids 34
C.5,3 PCP 36
C.5.4 PAHs 36
C.6 Particle Size and Fines Distributions 37
C.7 Water Treatment Effectiveness 37
C.8 References 42
Appendix D - Case Studies 43
D.I Bench-and Pilot-Scale Treatment of Soil from a Wood Treating Facility 43
D.2 Pilot-Scale Treatment of Pesticide-Contaminated Soil 43
Vll
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Tables
Number
1
2
3
4
5
6
7
8
9
10
H
12
13
14
15
16
17
18
19
20
^H
VRU SITE Demonstration Test Results
Contaminant Concentrations in the Feed Soil
VRU SITE Demonstration Operating Conditions
PCP Reductions from Feed Soil to Washed Soil
PAH Reductions from Feed Soil to Washed Soil
Washed Soil Residual Contaminant Concentrations
Feed Soil Recovered as Washed Soil „
Average Mass Balance Closures
Distribution of Fines & Coarse Gravel and Sand
Average PCP and PAH Concentrations in CPI Underflow & Floc/Clarifier Solids
Water Treatment Subsystem Effluent Quality
Proportional Costs of Major Fixed Capital Investment Components
Excavation Costs
Fully Burdened Salaries for Onsite Personnel Using 10-tph VRU
Treatment Costs for 10-tph VRU Treating 20,000 Tons of Contaminated Soil
Treatment Costs as Percentages of Total Costs for 10-tph VRU
Treating 20,000 Tons of Contaminated Soil
Treatment Costs for 10-tph VRU Operating with a 90% On-line Factor
Treatment Costs as % of Total Costs for 10-tph VRU Operating with a 90% On-line Factor . . .
Treatment Costs for the Remediation of 200,000 Tons of Contaminated Soil Using
the VRU Operating with a 90% On-line Factor
Treatment Costs as Percentages of Total Costs for VRU
Treating 200,000 Tons of Contaminated Soil
viii
Page
2
6
7
8
8
8
9
9
10
10
11
17
18
20
22
22
23
23
24
24
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Tables (Continued)
Number
C-l Average Contaminant Concentrations in the Feed Soil 31
C-2 VRU SITE Demonstration Operating Conditions 32
C-3 Removal Efficiencies for PCP and PAHs . 33
C-4 Feed Soil Recovered as Washed Soil 34
C-5 Total Material Mass Balance 35
C-6 Dry Solids Mass Balance 35
C-7 PCP Mass Balance 36
C-8 PAH Mass Balance 37
C-9 Particle Size Distribution within the Feed Soil,
Washed Soil, and Fines Slurry 38
C-10 Particle Size Distribution within the Underflow from
the CPI and Floe Tank 39
C-ll Disposition of Fines 40
C-12 Disposition of Coarse Gravel and Sand • 40
C-13 PCP Concentration in Fines Slurry Solids 40
C-14 PAHs Concentration in Fines Slurry Solids 40
C-15 TOC Levels in Water Streams 41
C-16 TR Levels in Water Streams 41
D-l Heptachlor Results , 44
D-2 Dieldrin Results 44
IX
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Figure
Number
A-l Typical VRU Operational Setup
26
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Abbreviations
AAR Applications Analysis Report
ARAR Applicable or Relevant and Appropriate
Requirements
ASTM American Society for Testing and Materials
CAA Clean Air Act
CERCLA Comprehensive Environmental Response,
Compensation, and Liability Act
cfm cubic feet per minute
CFR Code of Federal Regulations
CPI Corrugated Plate Interceptor
CPR cardiopulmonary resuscitation
CWA Clean Water Act
DRE destruction and removal efficiency
EPA U.S. Environmental Protection Agency
gph gallons per hour
gpm gallons per minute
kWh kilowatt hours
MCL maximum contaminant level
MSW Municipal Solid Waste
NAAQS National Ambient Air Quality Standards
NPDES National Pollutant Discharge Elimination
System
ORD Office of Research and Development
OSC On-scene Coordinator
OSHA Occupational Safety and Health Act
OSWER Office of Solid Waste and Emergency
Response
PAH polynuclear aromatic hydrocarbon
PCB polychlorinated biphenyls
PCP Pentachlorophenol
PPE personal protective equipment
ppm parts per million
POTW Publicly-Owned Treatment Works
psi pounds per square inch
psig pounds per square inch gauge
RCRA Resource Conservation and Recovery Act
RPM Remedial Project Manager
RREL Risk Reduction Engineering Laboratory
SARA Superfund Amendments & Reauthorization
Act
SDWA Safe Drinking Water Act
SITE Superfund Innovative Technology
Evaluation
SVOC semi-volatile organic compound
TCLP Toxicity Characteristic Leaching Procedure
TDS total dissolved solids
XI
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Abbreviations (Continued)
TER Technology Evaluation Report
TOG total organic carbon
tph tons per hour
tpd tons per day
TR total residue
TSD Treatment, Storage, and Disposal
TSS total suspended solids
VOC volatile organic compounds
VRU Volume Reduction Unit
xu
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Acknowledgments
This report was prepared under the direction and coordination of Teri Richardson, U.S. Envirnomental Protection
Agency (EPA) Superfund Innovative Technology Evaluation (SITE) Program Manager in the Risk Reduction
Engineering Laboratory (RREL), Cincinnati, Ohio. The EPA (RREL, Cincinnati) contributors and reviewers for this
report were Ms. Laurel Staley and Mr. Jack Hubbard. The EPA (RREL, Edison) contributor and reviewer was Mr.
Richard Griffith.
This report was prepared for EPA's SITE Program by the Technology Evaluation Division of Science Applications
International Corporation (SAIC) in Cincinnati, Ohio for the U.S. EPA under Contract No. 68-CO-0048. The Work
Assignment Manager for this project was Ms. Margaret M. Groeber.
This report is dedicated to the memory of Mr. Patrick Augustin.
xui
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Section 1
Executive Summary
1.1 Introduction
This report summarizes the findings of an evaluation of
the mobile Volume Reduction Unit (VRU) developed by
the U.S. Environmental Protection Agency (EPA) Risk
Reduction Engineering Laboratory (RREL). The study
was conducted under the Superfund Innovative Technology
Evaluation (SITE) Program. A demonstration test and an
evaluation of the VRU technology were performed by
EPA as part of this study. The results of this test and
supporting data from other testing performed by RREL
constitute the basis for this report.
1.2 Conclusions
The demonstration took place at the former Escambia
Wood Treating Company site in Pensacola, Florida
between November 5 and November 13, 1992. The 26-
acre facility, now closed, used pentachlorophenol (PCP)
and creosote to treat wood products from 1943 to 1982.
The site is currently undergoing a Superfund cleanup being
managed by EPA Region IV.
During the demonstration, the VRU operated at a feed
rate of approximately 100 Ibs/h with a wash water-to-feed
ratio of about 6 to 1. The physical condition of the wash
water was modified during the demonstration as follows:
• Condition 1: no surfactant, no pH adjustment, no
temperature adjustment
• Condition 2: surfactant addition, no pH adjustment,
no temperature adjustment
• Condition 3: surfactant addition, pH adjustment,
temperature adjustment
The VRU soil washing system successfully separated the
contaminated soil into two unique streams: washed soil
and fines slurry. The washed soil was safely returned to
the site following treatment. The fines slurry, which
carried the majority of the pollutants from the feed soil,
underwent additional treatment to separate the fines and
contaminants from the water.
A review of the demonstration test data, as compared to
the established project objectives, indicates the following
results:
• One of the project objectives was to demonstrate the
VRU's ability to achieve an average PCP removal
from the feed soil of 90 percent or greater. Average
PCP removals were 76, 92, and 97 percent for
Conditions 1, 2, and 3, respectively.
• A second project objective was to demonstrate the
VRU's ability to achieve an average creosote-fraction
polynuclear aromatic hydrocarbon (PAH) removal
from the feed soil of 90 percent or greater. Average
PAH removals were 70, 83, and 95 percent for
Conditions 1, 2, and 3, respectively.
• The average percentages of feed soil returned as
washed soil on a normalized basis were 90, 88, and
86 for Conditions 1, 2, and 3, respectively. The
remaining solids were contained in the fines slurry
and underwent further treatment
• Total material balances in the soil washing segment
of the VRU achieved closures of 104, 113, and 98
percent for Conditions 1, 2, and 3, respectively. The
closures obtained for Conditions 1 and 3 met the
project objective of total material balance closures
between 90 and 110 percent. Although a closure of
113 percent was obtained for Condition 2, a sampling
procedure may have inflated this closure.
• Mass balances of total dry solids in the soil washing
segment of the VRU achieved closures of 106, 108,
and 94 percent for Conditions 1, 2, and 3,
respectively. The project objective for this mass
balance was closure between 85 and 115 percent.
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The project objectives for mass balances of PCP and
creosote-fraction PAHs in the soil washing segment
of the VRU were to demonstrate whether closures
between 80 and 175 percent could be achieved.
Closures within this range were achieved only for
Condition 1, which demonstrated closures of 101 and
87 percent for PCP and PAHs, respectively.
Surfactant added during Conditions 2 and 3 may
have adversely affected the PCP and PAH analyses,
which would have affected the mass balance
calculations.
The cost to remediate 20,000 tons of contaminated
soils using a 10-ton-per-hour (tph) soil washer is
estimated at $136.67 per ton when the system is on-
line 90 percent of the time.
1.3 Results
The objectives of this Applications Analysis Report (AAR)
are to assess the ability of the VRU process to comply
with Applicable or Relevant and Appropriate Require-
ments (ARARs) and to estimate the cost of using this
technology to remediate a Superfund site. This analysis
includes determining percent removals of PCP and
creosote-fraction PAHs. Table 1 summarizes the
performance during the demonstration test.
EPA has established target cleanup levels for the soil at
the Escambia Wood Treating Company Superfund site.
Although meeting these cleanup criteria was not a project
objective for this demonstration, they can be used for
comparison purposes. The target cleanup levels are 30
ppm PCP, 50 ppm carcinogenic creosote, and 100 ppm
total creosote. The target cleanup level for PCP was easily
met during Conditions 2 and 3 but was not met during
Condition 1. The cleanup criteria for total creosote was
easily met during Condition 3 but was not met during
Condition 1 or Condition 2. The target cleanup level for
carcinogenic creosote was met by the washed soil produced
during all three conditions.
Table 1. VRU SITE Demonstration Test Results
Parameter (%)
Condition 1
Condition 2
Condition 3
PCP removal
Average
Range
PAH removal
Average
Range
Feed soil collected as washed soil
Average
Range
Feed soil collected as washed soil,
normalized basis
Average
Range
76
69-81
70
59-77
95
85-114
90
89-90
92
91-93
83
83-84
95
86-103
85-90
97
97-98
95
95-96
82
69-94
86
85-87
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Section 2
Introduction
2.1 The SITE Program
In 1986, the U.S. EPA Office of Solid Waste and
Emergency Response (OSWER) and Office of Research
and Development (ORD) established the Superfund
Innovative Technology Evaluation (SITE) Program to
promote the development and use of innovative
technologies to clean up Superfund sites across the
country. Now in its eighth year, the SITE Program is
helping to provide the treatment technologies necessary to
implement new Federal and State cleanup standards aimed
at permanent remedies rather than quick fixes. The SITE
Program is composed of four major elements: the
Demonstration Program, the Emerging Technologies
Program, the Measurement and Monitoring Technologies
Program, and the Technology Transfer Program.
The major focus has been on the Demonstration Program,
which is designed to provide engineering and cost data for
selected technologies. EPA and developers participating
in the program share the cost of the demonstration.
Developers are responsible for mobilization, operation,
and demobilization of their innovative systems at chosen
sites, usually Superfund sites. EPA is responsible for
sampling, analyzing, and evaluating all test results. The
result is an assessment of the technology's performance,
reliability, and costs. This information is used in
conjunction with other data to select the most appropriate
technologies for the cleanup of Superfund sites.
Developers of innovative technologies apply to the
Demonstration Program by responding to EPA's annual
solicitation. EPA also accepts proposals any time a
developer has a Superfund waste treatment project
scheduled. To qualify for the program, a new technology
must be field-ready and offer some advantage over existing
technologies. Mobile technologies are of particular
interest to EPA.
Once EPA has accepted a proposal, EPA and the
developer work with the EPA regional offices and State
agencies to identify a site containing waste suitable for
testing the capabilities of the technology. EPA prepares
a detailed sampling and analysis plan designed to evaluate
the technology thoroughly and to ensure that the resulting
data are reliable. The duration of a demonstration varies
from a few days to several years, depending on the length
of time and quantity of waste needed to assess the
technology. After lie completion of a technology
demonstration, EPA prepares two reports, which are
explained in more detail in the following subsections.
Ultimately, the Demonstration Program leads to an
analysis of the technology's overall applicability to
Superfund problems.
The second principal element of the SITE Program is the
Emerging Technologies Program, which fosters the further
investigation and development of treatment technologies
that are still at the bench- and pilot-scale. Successful
validation of these technologies can lead to the
development of a system ready for field demonstration and
participation in the Demonstration Program. The third
element of the SITE Program, the Measurement and
Monitoring Technologies Program, provides assistance in
the development and demonstration of innovative
technologies that can be used to characterize Superfund
sites better. Technical information is disseminated to the
public and private sectors through the Technology Transfer
Program.
2.2 SITE Program Reports
The analysis of a technology participating in the
Demonstration Program is contained in two documents: a
Technology Evaluation Report (TER) and anAAR. The
TER contains a comprehensive description of the demon-
stration sponsored by the SITE Program and its results. It
gives detailed descriptions of the technology, the waste
used for the demonstration, sampling and analysis during
the test, the data generated, and the Quality Assurance
Program.
The scope of the AAR is broader than the TER's scope;
it encompasses estimations of Superfund applications and
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costs of a technology based on all available data. This
report compiles and summarizes the results of the SITE
demonstration, the developer's design and test data, and
other laboratory and field applications of the technology.
It discusses the advantages, disadvantages, and limitations
of the technology.
Costs of the technology for different applications are
estimated based on available data on pilot- and full-scale
applications. The AAR discusses the factors, such as site
and waste characteristics, that have a major impact on
costs and performance.
The amount of available data for the evaluation of an
innovative technology varies widely. Data may be limited
to laboratory tests on synthetic waste or may include
performance data on actual wastes treated at the pilot- or
full-scale level. In addition, there are limits to conclusions
regarding Superfund applications that can be drawn from
a single field demonstration. A successful field
demonstration does not necessarily ensure that a
technology will be widely applicable or fully developed to
the commercial scale. The AAR attempts to synthesize
the information that is available and draw reasonable
conclusions. This document is very useful to those
considering a technology for Superfund cleanups and
represents a critical step in the development and
commercialization of the treatment technology.
2.3 Key Contacts
For more information on the VRU demonstration, please
contact:
1. EPA Project Manager for the SITE
Demonstration Test:
Ms. Teri Richardson
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnati, Ohio 45268
(513) 569-7949
2. Process Developer:
Mr. Richard Griffith
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Woodbridge Ave., Building 10
Edison, New Jersey 08837
(908) 321-6629
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Section 3
Technology Applications Analysis
3.1 Introduction
This section addresses the applicability of soil washing to
soils contaminated with PCP and creosote-fraction
PAHs. Recommendations are based on the results
obtained from the SITE demonstration of the VRU as
well as additional data provided by the developer. The
results of the demonstration provide the most extensive
database, conclusions on the technology's effectiveness,
and information regarding its applicability to other
potential cleanups. A thorough description of the VRU
technology is provided in Appendix A. The developer's
claims are presented in Appendix B, a summary of the
demonstration results is provided in Appendix C, and
other case studies are presented in Appendix D.
3.2 Conclusions
The soil washing segment of the VRU successfully
separated the contaminated soil into two unique streams:
washed soil and fines slurry. The washed soil was safely
returned to the site following treatment, while the fines
slurry, which carried the majority of the pollutants from
the feed soil, underwent additional treatment to separate
the fines from the water. The water was further polished
and then discharged onsite, while the fines were disposed
in a secure area of the site.
In order to address system performance thoroughly
under a number of operating conditions, varying
combinations of caustic, surfactant, and temperature
were used to modify the physical conditions of the wash
water as follows:
• Condition 1: no surfactant, no pH adjustment, no
temperature adjustment
• Condition 2: surfactant addition, no pH
adjustment, no temperature adjustment
• Condition 3: surfactant addition, pH adjustment,
temperature adjustment
Three runs, 4 hours in duration, were performed for each
of Conditions 1 and 2. Two runs, 6 hours in duration,
were performed under Condition 3.
A review of the demonstration test indicates the following
results:
• One of the project objectives was to demonstrate the
VRU's ability to achieve an average PCP removal
from the feed soil of 90 percent or greater. Average
PCP removals were 76, 92, and 97 percent for
Conditions 1, 2, and 3, respectively.
• A second project objective was to demonstrate the
VRU's ability to achieve an average creosote-fraction
PAH removal from the feed soil of 90 percent or
greater. Average PAH removals were 70, 83, and 95
percent for Conditions 1, 2, and 3, respectively.
• The average percentages of feed soil returned as
washed soil on a normalized basis were 90, 88, and
86 for Conditions 1, 2, and 3, respectively. The
remaining solids were contained in the fines slurry
and underwent further treatment.
• Total material balances in the soil washing segment
of the VRU achieved closures of 104, 113, and 98
percent for Conditions 1, 2, and 3, respectively. The
closures obtained for Conditions 1 and 3 met the
project objective of total material balance closures
between 90 and 110 percent. Although a closure of
113 percent was obtained for Condition 2, a sampling
procedure may have inflated this closure.
• Mass balances of total dry solids in the soil washing
segment of the VRU achieved closures of 106, 108,
and 94 percent for Conditions 1, 2, and 3,
respectively. The project objective for this mass
balance was closure between 85 and 115 percent.
-------
The project objectives for mass balances of PCP
and creosote-fraction PAHs in the soil washing
segment of the VRU were to demonstrate whether
closures between 80 and 175 percent could be
achieved. Closures within this range were achieved
only for Condition 1, which demonstrated closures
of 101 and 87 percent for PCP and PAHs,
respectively. Surfactant added during Conditions 2
and 3 may have adversely affected the PCP and
PAH analyses, which would have affected the mass
balance calculations.
3.3 Technology Evaluation
The 100-lb/h VRU is a mobile research unit that was
developed for soil washing treatability studies on soils
containing a wide variety of contaminants. This unit is
composed of two distinct treatment segments: the soil
washing subsystem and the water treatment subsystem.
The soil washing portion of the VRU is used to separate
contaminated soils into two streams: washed soil and
fines slurry. Ideally, the washed soil is clean enough to
return to the site or to use in some other capacity. The
fines slurry, which carries the majority of the pollutants
present in the feed soil, requires additional treatment
using the water treatment subsystem. By isolating and
concentrating the contaminants within the fines, the
volume of material requiring additional treatment is
significantly reduced.
The VRU was developed by EPA, which by law cannot
develop commercial treatment systems. EPA can co-
develop technologies with private companies or license
EPA-developed technologies to private companies
through the Federal Technology Transfer Act of 1986
(15 USC 3702-3714) [1].
In November 1992 the VRU soil washing system was
tested under the SITE Program. Soil contaminated with
PCP and creosote-fraction PAHs was excavated from the
former Escambia Wood Treating Company site in
Pcnsacola, Florida and then treated by the VRU.
Contaminant levels in the soil ranged from the low parts
per million (ppm) to percent levels. For the SITE
demonstration, the excavated soil was homogenized and
manually processed through a Vi-inch screen before it
was fed to the VRU. Average contaminant
concentrations in the feed soil on a dry weight basis after
homogcnization and screening are summarized in Table
2.
The PAH concentrations presented hi Table 2 do not
include all PAHs. Analyses were conducted for
creosote-fraction PAHs, and five compounds from the
standard set of 16 creosote-fraction PAHs were not
consistently detected in the field soil. These five PAHs
were not included in this evaluation and are not included
in the PAH concentrations shown in Table 2.
Table 2. Contaminant Concentrations in the Feed Soil
(ppm, dry weight basis)
Contaminant
PAHs
PCP
Average
980
140
Range
550 to 1,700
48 to 210
33.1 VRU Operating Conditions
The VRU used during the demonstration test was
designed to be flexible in terms of equipment and wash
water additives used. During the demonstration test,
varying combinations of caustic, surfactant, and
temperature were employed to modify the physical
conditions of the wash water. Water is a polar substance;
PCP and PAHs (and other organic contaminants) are
nonpolar. Because polar substances do not dissolve
nonpolar substances well, the addition of a nonpolar
surfactant to the wash water can improve organic
contaminant removal significantly. Adjusting the pH and
temperature of the wash water can also increase
contaminant solubilities and improve removal efficiencies.
In July 1992 EPA conducted treatability studies at the
Escambia Wood Treating Company site. Twenty different
combinations of wash water temperature, pH, and
surfactant concentration were tested. These studies
provided the basis for the parameters tested during the
demonstration. During the treatability studies, PCP and
PAH removal efficiencies hi excess of 90 percent were
achieved under selected operating conditions.
Surfactant concentration and wash water pH and
temperature were monitored to determine whether the
VRU was functioning at the operating conditions specified
in the Demonstration Plan. The surfactant concentration
was determined by calculating the ratio of surfactant-to-
wash water on a mass basis. The pH was determined by
measuring the pH of the fines slurry stream. The
temperature was determined by measuring the
temperature of the wash water just before it entered the
soil washing segment of the VRU. Actual operating
conditions are summarized in Table 3.
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Table 3. VRU SITE Demonstration Operating Conditions
Condition 1
Average
Range
Condition 2
Average
Range
Condition 3
Average
Surfactant
Feed Rate Surfactant Flow Concentration in
(Ib/h) W/F Ratio (Ib/h) pH Wash Water (%)
84 8 0
64-95 7-10 0 7.1-7.3
104 6 13.7 - 0.22
97-108 6 13.4-14.1 6.9-7.0 0.22
133 5 11.4 - 0.18
117-148 4-5 11.0-11.7 10.1-10.2 0.17-0.18
Water
Temperature (°F)
57
55-60
61
59-65
142
139-145
33.2 Contaminant Removal Efficiencies
Most organic and inorganic contaminants present in soil
bind to fine-sized clay and silt particles (fines) primarily
by physical processes. Washing processes that separate
the fine particles from the coarser soil particles
effectively concentrate the contaminants into a smaller
volume. The clean larger fraction can be returned to the
site for continued use. This process can also remove
some contaminants by dissolving or suspending them in
the wash water.
One of the main objectives of the demonstration test was
to assess the VRU technology's ability to achieve
contaminant removals of 90 percent for PCP and
creosote-fraction PAHs.
Removal efficiencies for PCP and PAHs were
determined by comparing the total mass of each
contaminant, on a dry weight basis, detected in the
washed soil with the total in the feed soil. Removal
efficiencies are calculated using the following equation:
PCP removal efficiencies were calculated for Conditions 1,
2, and 3. Under Condition 3, which employed surfactant
addition and pH and temperature adjustment, an average
of 97 percent of the PCP was removed. Under
Condition 2, which employed surfactant addition only, an
average of 92 percent of the PCP was removed. These
removal efficiencies achieve the project objective of
demonstrating that the unit is capable of removing an
average of 90 percent of the PCP from the bulk of the
feed soil. An average of only 76 percent of the PCP was
removed from the feed soil treated under Condition 1.
These data, which illustrate the impact of surfactant
addition and pH and temperature adjustment on PCP
removal efficiencies, are listed in Table 4. PCP removal
efficiency is clearly enhanced by surfactant addition and
pH and temperature adjustment.
Creosote-fraction PAH removal efficiencies were
calculated for Conditions 1, 2, and 3. Under Condition 3,
which employed surfactant addition and pH and
temperature adjustment, an average of 95 percent of the
PAHs were removed. This removal efficiency achieves the
- , , Concentration of contaminant in feed - concentration of contaminant in -washed soil^
% removal= [ —.——- : :—. , J
concentration of contaminant in feed
-------
Table 4. PCP Reductions from Feed Soil to Washed Soil
(%, dry weight basis)
Table 6. Washed Soil Residual Contaminant Concentrations
(ppin, dry weight basis)
Condition 1
Condition 2
Condition 3
Average
76
92
97
Range
69-81
91-93
97-98
PCP
Total Creosote
PAHs
Carcinogenic
Creosote PAHs
project objective of demonstrating that trie unit is
capable of removing an average of 90 percent of the
PAHs from the bulk of the feed soil. Average PAH
removals of only 70 percent and 83 percent were
obtained for Conditions 1 and 2, respectively. These
data, which illustrate the impact of surfactant addition
and pH and temperature adjustment on PAH removal
efficiencies, are listed in Table 5. PAH removal
efficiency is clearly dependent on surfactant addition and
pH and temperature adjustment.
Table 5. PAH Reductions from Feed Soil to Washed Soil
(%, dry weight basis)
Condition 1
Condition 2
Condition 3
Average
76
92
97
Range
69 to 81
91 to 93
97 to 98
EPA has established target cleanup levels for the soil at
the Escambia Wood Treating Company Superfund Site.
Although meeting these cleanup criteria was not a
project objective for this demonstration, they can be used
for comparison purposes. The target cleanup levels are
30 ppm PCP, 50 ppm carcinogenic creosote, and 100
ppm total creosote; the concentrations of these
contaminants in the washed soil on a dry weight basis
are presented in Table 6.
For all three conditions, the average concentration of
PCP in the washed soil was below the target cleanup
level of 30 ppm. This target was, however, exceeded for
Run 3 of Condition 1. The cleanup criteria for total
creosote was easily met during Condition 3 but was not
met during Condition 1 or Condition 2. The target
cleanup level for carcinogenic creosote was met by the
washed soil produced during all three conditions.
Condition 1
Runl
Run 2
Run 3
Condition 2
Runl
Run 2
Run3
28
36
43
15
13
14
Condition 3
Run 1 2.4
Run 2 3.5
240
310
350
180
160
130
44
46
18
19
29
14
12
11
3.5
3.3
333 Washed Soils Recovery
As soil travels through the VRU system, the sand and
gravel fraction of the soil are separated from the
contaminated fines (i.e., fine clay and silt particles).
The relatively nonhazardous sand and gravel fraction exits
the system as washed soil. By comparing the mass of dry
solids in the feed soil with the mass of dry solids in the
washed soil, average solids recoveries of 96, 95, and 81
percent were calculated for soils treated under Conditions
1 through 3. Also calculated were normalized recoveries,
which were determined by dividing the mass of dry solids
in the washed soil by the total mass of dry solids exiting
the system (in the washed soil and fines slurry). The
recoveries shown in Table 7 achieve the project objective
of demonstrating that an average of at least 80 percent of
the solids present in the feed soil would be returned to the
site as washed soil.
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Table 7. Feed Soil Recovered as Washed SoH (dry weight basis)
% Recovered,
% Recovered normalized basis
Condition 1
Average 95 90
Range 85 -114 89 - 90
Table 8. Average Mass Balance Closures (%)
Condition 2
Average
Range
Condition 3
Average
Range
95
86 - 103
82
69-94
88
85-90
86
85-87
33.4 Mass Balances
Mass balances are prepared by comparing the mass
entering a system to the mass exiting the system. Mass
balance closure (or recovery) is calculated as follows:
.. „ , -,, r Mass Exiting System, 1ftn
Mass Balance Closure = [ —— ] x 100
Mass Entering System
The mass balance closures calculated for the VRU
demonstration are summarized in Table 8. Recoveries
were calculated for all materials present (total material
balance) and for specific materials (dry solids, PCP, and
creosote-fraction PAHs). For the total material balance,
the recovery is the percentage of the material entering
the system as feed soil and wash water that was
recovered from the system as washed soil and fines
slurry. The total material balances conducted for the
demonstration yielded average recoveries of 104 percent
for Condition 1, 113 percent for Condition 2, and 98
percent for Condition 3. The project objective for the
total material balances was average closures of between
90 and 110 percent. Except for high recovery obtained
for Condition 2, average closures for total material
balances met the project objectives. During Condition 2,
the operating procedure for mass flow measurement of
fines slurry was modified and may have inflated the
measurement. During Condition 3, the procedure was
readjusted to its original form, and the balance closures
returned to the acceptable range. This observation
indicates that measurement of the fines slurry generated
a high bias in the total materials balance for Condition
2.
Condition 1
Condition 2
Condition 3
Total
material
104
113
98
Dry solids
106
108
94
PCP
101
19
13
PAHs
87
28
13
Total dry solids recoveries during the VRU demonstration
ranged from 94 to 109 percent, meeting project objectives
'of recoveries between 85 and 115 percent. Under
Condition 1, the average mass balance closures for PCP
and PAHs were 101 and 87 percent, respectively. These
closures met the project objectives of PCP and PAH mass
balance closures between 80 and 175 percent. The average
PCP and PAH recoveries for Conditions 2 and 3 were well
below project objectives and indicate the presence of a
substantial negative bias. A closer inspection of the data,
including laboratory QA indicators, reveals that fines slurry
data are a likely source of negative bias. A possible
explanation for the poor data in Conditions 2 and 3 is
surfactant addition. During sample preparation, it is
possible that competition between the surfactant (which
tries to keep pollutants in solution) and the extraction
solvent (which tries to remove pollutants from solution for
analysis) may have had a detrimental effect. The fines
slurry samples were difficult to filter. As a result, a large
number of particles were included in the liquid portion of
the sample, which probably retained significant
concentrations of PCP and PAHs. The liquid samples,
with a significant mass of particulates, were extracted by
liquid extraction procedures, which are less rigorous for
particulates. Since PCP and PAHs were not well
accounted for, these data were of limited use.
33.5 Particle Size and Fines Distribution
The VRU system's effectiveness is based on its ability to
separate soil fines (particles that will pass through a 100-
mesh screen) from the coarser gravel/sand fraction of the
soil (particles that will not pass through a 100-mesh
screen). Significant contaminant concentration reductions
can be realized by the VRU, provided the majority of the
contaminants present in the feed soil concentrate within
the fines. By analyzing the dry solids mass balance data
and particle size distribution, the disposition of fines and
coarse gravel/sand can be calculated. Table 9 indicates
the percentage of the soil fines and coarser gravel/sand
fraction from the feed stream that were recovered in the
washed soil and in the fines slurry. The data indicate that
the majority of the small particles were partitioned to the
fines slurry.
-------
Table 9. Distribution of Fines and Coarse Gravel and Sand
(%, dry weight basis)
Condition
Soil Fines
123
Coarser Gravel/Sand
Fraction
Washed Soil 31 41 54 104 102 82
Fines Slurry 75 83 110 1 22
Closure 106 124 164 105 104 84
The partitioning of the coarser gravel/sand fraction to
the washed soil stream was excellent. Only 1 to 2
percent of the coarser gravel/sand particles from the
feed stream were detected in the fines slurry. The
partitioning of the soil fines to the fines slurry was less
complete, although the majority of these small particles
did partition to the fines slurry. As shown in Table 8, 31
to 54 percent of the soil fines from the feed stream were
recovered in the washed soil. A more complete
partitioning of the soil fines to the fines slurry would,
theoretically, lead to increased contaminant removals
from the washed soil.
33.5 Water Treatment Effectiveness
Pollutants were removed from the fines slurry stream by
a water treatment sequence consisting of settling,
flocculation, filtration, and carbon adsorption. Following
treatment in the Corrugated Plate Interceptor (CPI),
where the fines were separated by gravity, the overflow
was pumped to a flocculation/clarification system for
additional fines partitioning. Table 10 lists ranges of
PCP and PAH concentrations in the CPI and
floc/clarifier solids on a dry weight basis. As previously
discussed in Subsection 3.3.4, these samples were difficult
to filter and the analytical methods were inadequate,
which resulted in questionable data.
Clarified water was then pumped from the floe overflow
tank through cartridge polishing filters operated in parallel
to remove soil fines that would not pass through a 4 x 10"4
inch (10-micron) screen. Water exiting these filters then
passed through activated carbon drums for hydrocarbon
removal. The clarified water was analyzed for total
organic carbon (TOC) and total residue (TR), which is the
sum of total suspended solids (TSS) and total dissolved
solids (TDS). Table 10 lists the TOC and TR levels from
the floe tank overflow, effluent from the filters, activated
carbon, and wash water into the VRU.
The TR reduction from the filter unit was minimal,
indicating that a finer-sized filter is needed. The TOC
reduction decreased significantly when surfactant was
introduced into the system during Conditions 2 and 3.
The efficiency was affected because surfactant was
adsorbed on the carbon along with the contaminants.
TOC efficiency could be improved by removing the
surfactant before it enters the carbon canisters or by
utilizing another TOC removal technology.
The VRU was designed with the ability to recycle water
treatment subsystem effluent to the mini-washer. This
option was not evaluated during the demonstration
because the developer chose to operate the system without
recycling. Because water quality criteria for recycling have
not been defined, it is not possible to determine whether
the treated water produced during the demonstration was
appropriate for recycling. Based on the data presented in
Table 11, the levels of both TOC and TR during
Condition 1 were potentially low enough to permit
recycling; however, much higher levels were detected in
Conditions 2 and 3. During these conditions, additional
treatment may have been necessary to recycle the effluent
from the carbon canisters.
Table 10. Average PCP and PAH Concentrations in CPI Underflow Solids and Floc/CIarifier Solids (dry weight basis)
Condition
CPI underflow' solids
Floc/clarifier solids
1
51-69
92-6,500
PCP (ppml
2
46-85
190-1,300
3
*
83-150
1
1300-1,800
58-2,000
PAHs (ppm)
2
370-1,100
910-1,800
3
*
940-1,200
Unacceptable analysis resulted in questionable data.
10
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Table 11. Water Treatment Subsystem Effluent Qualify (ppm)
Wash water
Floe-tank Overflow
Filter Effluent
Activated Carbon Effluent
TOC
1 2
<1.0 <15
115 1,045
11 1,075
<1.0 283
3
<1.02
825
6975
305
1
70
260
2475
115
TR
2
73
2,200
2,025
5575
3
62
6,075
5,075
2550
3.4 Range of Site Characteristics Suitable
for the Technology
3.4.1 Site Selection
The VRU is a mobile research unit mounted on two
heavy-duty tractor trailers. The VRU is composed of a
number of subsystems (e.g., screening, gravity separation,
flocculation/ clarification, filtration, and carbon
adsorption). It is designed to be flexible, so that the
combination of subsystems and wash water additives
used can be modified to achieve cleanup goals cost-
effectively, based on site requirements. The system can
be assembled within the contaminated soil area or placed
offsite so that soil can be transported to the unit. The
treatment unit can be placed inside either a permanent
or a temporary building or it can be operated in the
open. The pilot-scale unit can be barge mounted.The
VRU can be scaled to a full-scale unit for site
remediation. For purposes of this document, a full-scale
unit is based on a processing rate of 10 tons per hour
(tph) of soil or sediment. Larger processing rates for a
full-scale unit could be used. Additional details on the
scale-up factors used and assumptions made for
economic analyses are provided in Section 4.
3.42 Load, Surface, and Subsurface Requirements
A level, graded area that is capable of supporting able
to support the weight of the unit, which was determined
by the developer to be 3,500 pounds per square inch
(psi) for both the pilot- and full-scale units. Additional
road construction may be necessary to support oversize
and heavy equipment.
Subsurface preparation is not required since all unit
processes occur above the ground. If the soil is to be
excavated and treated onsite, however, all subsurface
obstacles (underground cables, piping, etc.) must be
removed prior to excavation.
3.43 Clearance and Site Area Requirements
The site must be cleared to allow the unit to be assembled
and operated. The extent of clearing is dependent upon
the operational configuration selected. Cleared areas for
stockpiling, storage, and loading/unloading activities are
required. Clearing, other than for excavation of
contaminated soil, is not an issue if treatment is to be
conducted offsite.
The surface area required for the VRU soil washing
equipment is approximately 40 x 60 feet for the pilot-scale
unit and 300 x 400 feet for the full-scale unit. The vertical
height of the system is based on the height of the settling
tank as erected; 13.5 feet for the pilot-scale or 23 feet for
the full-scale unit. The system configuration will dictate
whether or not a concrete pad is required to support the
equipment. Additionally, separate areas should be
provided for storage for both feed materials and any waste
generated during the treatment process. The shape of the
site should allow convenient access to the equipment.
3.4.4 Climate Characteristics
The critical climate requirements for the operation of this
system include temperature range and wind conditions.
Low ambient temperatures will either adversely affect
treatment efficiency (if the wash water is not heated) or
increase energy costs (if the wash water is heated).
Temperatures below freezing would hinder the operating
capabilities of the soil washing system because the system
uses a significant amount of water in the treatment
process. Also, the slurries created from the treatment
process are adversely affected by freezing temperatures.
Windy conditions may affect the excavation, transport, and
feed of dry soils. Hazardous operating conditions would
also exist in severe storm conditions.
11
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To diminish the effects of climate, the system may be
erected in an enclosure. For the pilot-scale unit, this
may be a fixed structure or a tent covering the system.
The full-scale unit requires a fixed structure.
3.4.5 Geological and Topographical Characteristics
Except for soil-bearing capacity requirements applicable
to any heavy machinery, there are no geologic character-
istics that restrict the implementation of this technology.
The treatment unit must be flat, level, and stable.
Currently the unit has been used at land-based facilities
only.
3.4.6 Utility Requirements
Electricity and water are required to operate the VRU
soil washing system. The pilot-scale system is equipped
to operate using a generator to supply electrical power.
Otherwise a 3-phase power supply from the local electric
company is required. The full-scale system will require
a 3-phase electrical system to operate. The pilot-scale
system uses approximately 3.3 kilowatt hours (kWh) per
ton of soil processed during operation. This requirement
increases to 6.6 kWh/ton for the full-scale system.
Water required to operate the pilot-scale system is
approximately 80 gallons per hour (gph). This assumes
a recycle rate of 0 percent and an operational rate of 100
Ibs/h process feed material. The full-scale system
requires 1,600 gph. This assumes a 90 percent recycle
rate and a process throughput of 10 tph of process feed
material. An abundant water supply must be readily
available and accessible to operate the system. It is not
required that the water be potable, but it must be free of
debris. Water sources with debris may be used provided
the water is filtered prior to its use hi the system. Water
need not be obtained from the local utility but could be
from sources such as rivers, streams, lakes, or wells. If
the unit is operated with elevated wash water
temperatures, a water heater is required. Propane was
used to heat water in the pilot-scale unit; natural gas
could be used for a full-scale unit. The full scale unit
would require approximately 120 cubic feet per minute
(cfm) of natural gas.
Other utilities required include diesel fuel to operate the
generator and natural gas or fuel oil for the steam boiler.
The steam is required for the removal of volatile organic
compounds (VOCs) from the feed material prior to soil
washing. In this process, the steam is used to heat the
screw conveyor jacket, thereby increasing the
temperature to a point at which the volatile organics are
released from the soil. These are then collected and
treated by air stripping or some other treatment process.
The amount of steam required for the pilot-scale unit is
600 Ibs/h at of 50 psi, which requires approximately 10
cfm of natural gas or 4 gph of No. 2 fuel oil. Since no
substantial quantity of VOCs was present, the steam jacket
was not used during the demonstration.
3.4.7 Size of Operation
The capacity of the pilot-scale system used during the
demonstration test was 100 Ibs/h. The processing rate for
the full-scale system is assumed to be 10 tph. Currently,
the VRU Soil Washing System has only been tested as a
pilot-scale unit. No full-scale units exist at this tune.
3.5 Applicable Wastes
This technology may be used to treat soil contaminated
primarily with volatile and semivolatile organic compounds.
When the system is used to treat soils with volatile
organics, steam stripping and vapor phase adsorption
equipment is used. The unit has not been tested on
sediments, though it is potentially capable of treating them.
The contaminated soil or sediment should contain no more
than 30 to 40 percent fines, and maximum particle
diameter should be no more than Vz inch. However,
during the demonstration the pilot-scale was fed material
^-inch or less. The process is also less cost effective when
the surfactant concentration is high. A high surfactant
concentration also causes a foam problem that can inhibit
the ability of the unit to remove the contaminants from the
soil effectively.
The VRU soil washing system can be effectively used to
treat organic compounds such as PAHs, PCP, and
pesticides. In general, a wide variety of chemical
contaminants can be removed or concentrated through soil
washing applications. It has been shown that soil washing
is effective on coarse sand and gravel contaminated with
a wide range of organic and inorganic contaminants.
Based on other soil washing systems, potential
contaminants that may be suitable for soil washing include
petroleum and fuel residues and cyanides.
3.6 Regulatory Requirements
Operation of the VRU for treatment of contaminated soil
requires compliance with certain Federal, State, and local
regulatory standards and guidelines. Section 121 of the
12
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ComprehensiveEnvironmentalResponse, Compensation,
and Liability Act of 1980 (CERCIA) requires that,
subject to specified exceptions, remedial actions must be
undertaken in compliance with ARARs, Federal laws,
and more stringent promulgated State laws (in response
to release or threats of release of hazardous substances,
pollutants, or contaminants) as necessary to protect
human health and the environment.
The ARARs that must be followed in treating
contaminated media onsite are outlined in the Interim
Guidance on Compliance with ARARs, Federal Register,
Vol. 52, pp. 32496 et seq [2]. These are:
• Performance, Design, or Action-Specific
Requirements. Examples include Resource
Conservation and Recovery Act (RCRA) incineration
standards and Clean Water Act (CWA) pretreatment
standards for discharge to publicly-owned treatment
works (POTWs). These requirements are triggered
by the particular remedial activity selected to clean a
site.
• Ambient/Chemical-Specific Requirements. These set
health-risk-based concentration limits based on
pollutants and contaminants, e.g., emission limits and
ambient air quality standards. The most stringent
ARAR must be met.
• Locational Requirements. These set restrictions on
activities because of site locations and environs.
Deployment of the VRU will be affected by three main
levels of regulation:
• Federal EPA air, water, and solid/hazardous waste
regulations
• State air, water, and solid/hazardous waste
regulations t
• Local regulations, particularly Air Quality
Management District requirements
These regulations govern the operation of all
technologies. Other Federal, State, and local regulations
are discussed in detail in the following subsections as
they apply to the performance, emissions, and residues
evaluated from measurements taken during the
demonstration test.
3.6.1 Federal Regulations
3.6.1.1 Clean Air Act (CAA)
The CAA establishes primary and secondary ambient air
quality standards for the protection of public health and
emission limitations for certain hazardous air pollutants.
Permitting requirements under the CAA are administered
by each state as part of the State Implementation Plans
developed to bring each state into compliance with the
National Ambient Air Quality Standards (NAAQS). The
ambient air quality standards listed for specific pollutants
may be applicable to operation of the VRU due to
potential emissions when processing volatile compounds.
When volatile compounds are present in the feed, an air
pollution control device maybe required. Other regulated
emissions may be produced, depending on the waste feed.
The allowable emissions will be established on a case-by-
case basis depending on whether the site is located in an
area that is in attainment with the NAAQS.
3.6.1.2 CERCLA
CERCLA, as amended by the Superfund Amendments and
Reauthorization Act (SARA) of 1986, provides for Federal
funding to respond to releases of hazardous substances to
air, water, and land. Section 121 of SARA, Cleanup
Standards, states a strong statutory preference for
remedies that are highly reliable and provide long-term
protection. It strongly recommends that remedial action
use onsite treatment that "...permanently and significantly
reduces the volume, toxicity, or mobility of hazardous
substances." In addition, general factors that must be ad-
dressed by CERCLA remedial actions include:
• Overall protection of human health and the
environment
• Compliance with ARARs
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, or volume
• Short-term effectiveness
• Implementability
• Cost
• State acceptance
• Community acceptance.
13
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The ability of the VRU to concentrate the organic
contaminants originally present in the feed, as demon-
strated by removal efficiencies of 90 percent or greater
for PCP and PAH contaminants, indicates the VRU is
capable of significantly reducing the quantity of
contaminated waste requiring subsequent treatment or
disposal.
3.6.1.3 RCRA
The RCRA is the primary Federal legislation governing
hazardous waste activities. Although a RCRA permit is
not required for onsite remedial actions at Superfund
sites, the VRU must meet all of its substantive
requirements. Administrative RCRA requirements such
as reporting and recordkeeping, however, are not
applicable for onsite action. Subtitle C of RCRA
contains requirements for generation, transport,
treatment, storage, and disposal of hazardous waste.
Compliance with these requirements is mandatory for
CERCLA sites producing hazardous waste onsite. In
order to maintain compliance with RCRA, sites
employing the VRU must obtain an EPA generator
identification number and observe storage requirements
stipulated under 40 Code of Federal Regulations (CFR)
262. Alternatively, a Part B Treatment, Storage, and
Disposal (TSD) permit of interim status may be
obtained. Invariably, a hazardous waste manifest must
accompany offsite shipment of waste, and transport must
comply with Federal Department of Transportation
hazardous waste transportation regulations. Without
exception, the receiving TSD facility must be permitted
and in compliance with RCRA standards. The
technology or treatment standards applicable to the
media produced by the VRU will be determined by the
characteristics of the material treated and the waste
generated. The RCRA land disposal restrictions (40
CFR 268) preclude the land disposal of hazardous wastes
which fail to meet the stipulated treatment standards.
Wastes which do not meet these standards must receive
additional treatment to bring the wastes into compliance
with the standards prior to land disposal, unless a
variance is granted.
3.6.1.4 CWA
The CWA regulates direct discharges to surface water
through the National Pollutant Discharge Elimination
System (NPDES) regulations. These regulations require
point-source discharges of wastewater to meet estab-
lished water quality standards. The discharge of
wastewater to the sanitary sewer requires a discharge
permit or, at least, concurrence from State and local
regulatory authorities that the wastewater is in compliance
with regulatory limits.
If the treated water cannot be reused as wash water, then
it must be disposed. Disposal options include discharge to
a local POTW, discharge to surface water, or onsite
treatment. Discharge to a POTW will typically be
regulated according to the industrial wastewater
pretreatment standards of the POTW. These standards
are specified in the CFR for certain industries. Depending
on the site, the treated wash water may fall into one of the
specific industrial categories. If it does not, the
pretreatment standards for the wash water will be
determined by the POTW and depend on site-specific
parameters such as the flow rate of the wash water, the
contaminants present, and the design of the POTW.
Alternatively, the wash water can be treated onsite.
Pursuant to the National Contingency Plan, the
administrative and permitting requirements of RCRA do
not apply. However, substantive requirements of RCRA
do apply to onsite treatment facilities.
3.6.1.5 Safe Drinking Water Act (SDWA)
SDWA establishes primary and secondary national
drinking water standards. CERCLA refers to these
standards, and Section 121(d)(2) explicitly mentions two of
these standards for surface water or groundwater:
Maximum Contaminant Levels (MCLs) and Federal Water
Quality Criteria. Alternate Concentration Limits may be
used when conditions of Section 121 (d)(2)(B) are met and
cleanup to MCLs or other protective levels is not
practicable. Included in these sections is guidance on how
these requirements may be applied to Superfund remedial
actions. The guidance, which is based on Federal
requirements and policies, may be superseded by more
stringent promulgated State requirements, resulting in the
application of even stricter standards than those specified
in Federal regulations.
3.6.1.6 Toxic Substances Control Act (TSCA)
TSCA grants EPA the authority to prohibit or control the
manufacturing, importing, processing, use, and disposal of
any chemical substance that presents an unreasonable risk
of injury to human health or the environment. These
regulations may be found in 40 CFR 761. With respect to
hazardous waste regulation, TSCA focuses on the use,
management, disposal, and cleanup of polychlorinated
biphenyls (PCBs). Materials with less than 50 ppm PCB
are classified as non-PCB; those with PCB concentrations
between 50 and 500 ppm are classified as PCB-
contaminated; and those with PCB concentrations greater
14
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than or equal to 500 ppm are classified as PCBs. State
PCB regulations may be more stringent than TSCA.
While the soil used for the demonstration did not
contain PCBs, it is reasonable to assume that the full-
scale VRU could be utilized to clean soils that may
contain PCBs. The separation process could result in
elevated PCB concentrations in some output streams. If
the concentrations of PCBs in an output stream are too
high, the output stream will need to be handled as a
TSCA-regulated waste.
3.6.2 State and Local Regulations
Compliance with ARARs may require meeting State
standards that are more stringent than Federal standards
or that are the controlling standards in the case of non-
CERCLA treatment activities. Several types of State and
local regulations that may affect operation of the VRU
include:
• Permitting requirements for
construction/operation
• Limitations on emission levels
• Nuisance rules
3.7 Personnel Issues
3.7.1 Training
Since selected personnel involved with sampling or
working close to the VRU (especially the grizzly screen
and feed hopper) are required to wear respiratory
protection, 40 hours of Occupational Safety and Health
Act (OSHA) training covering personal protective
equipment (PPE) application, safety and health, emer-
gency response procedures, and quality assurance/quality
control are required. Additional training addressing the
site activities, procedures, monitoring, and equipment
associated with the technology is also recommended.
Personnel should also be briefed when new operations
are planned, work practices change, or if the site or
environmental conditions change.
procedures. Health and safety training covering the
potential hazards and provisions for exposure, monitoring,
and the use and care of PPE should be required. When
appropriate, workers should have medical exams. Health
and safety monitoring and incident reports should be
routinely filed and records of occupational illnesses and
injuries (OSHA Forms 102 and 200) should be main-
tained. Audits ensuring compliance with the health and
safety plan should be carried out.
Proper PPE should be available and properly utilized by
all onsite personnel. Different levels of personal
protection will be required based on the potential hazard
associated with the site and the work activities.
Site monitoring should be conducted to identify the extent
of hazards and to document exposures at the site. The
monitoring results should be maintained and posted.
3.73 Emergency Response
In the event of an accident, illness, explosion, hazardous
situation at the site, or intentional acts of harm, assistance
should be immediately sought from the local emergency
response teams and first aid or decontamination should be
employed when appropriate. To ensure a timely response
in the case of an emergency, workers should review the
evacuation plan, firefighting procedures, cardiopuhnonary
resuscitation (CPR) techniques, emergency decon-
tamination procedures, and routes to local hospitals before
operating the system. Fire extinguishers, spill cleanup kits,
emergency eye washes, alarms, evacuation vehicles, and an
extensive 'first aid kit should be onsite at all times.
3.8 References
1. Federal Technology Transfer Act of 1986. 15
USC 3702-3714.
2. Interim Guidance on Compliance with ARARs -
Federal Register, 52: pp.32496 et. seq.
3.7.2 Health and Safety
Personnel should be instructed on the potential hazards
associated with the operation of the VRU, recommended
safe work practices, and standard emergency plans and
15
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Section 4
Economic Analysis
4.1 Introduction
The primary purpose of this economic analysis is to
estimate costs (not including profits) for a commercial
treatment system utilizing the mobile VRU. This analysis
is based on the results of a SITE demonstration which
utilized a pilot-scale soil washing system. The pilot-scale
unit operated at a feed rate of 100 Ibs/h of contaminated
soil. It is projected the commercial unit will be capable of
treating approximately 10 tph of contaminated soil.
4.2 Conclusions
The commercial-scale VRU proposed by EPA appears to
be suited to the remediation of soils and other solid wastes
contaminated with organic compounds. Treatment costs
appear to be competitive with other available technologies.
The cost to remediate 20,000 tons of contaminated soil
using a 10-tph VRU is estimated at $137 per ton if the
system is on-line 90 percent of the time. Treatment costs
increase as the percent on-line factor decreases. Projected
unit costs for a smaller site (10,000 tons of contaminated
soil) arc $171 per ton; projected unit costs for a larger site
(200,000 tons) are $106 per ton.
4.3 Issues and Assumptions
Because the VRU appears to be capable of effectively
treating soils contaminated with organics, it is considered
potentially applicable to the remediation of Superfund
sites. In the following economic analysis, the costs
associated with this technology are calculated based on the
treatment of a small-to-medium hazardous waste site that
has approximately 20,000 tons of contaminated soil suitable
for treatment by soil washing. Approximately 3,600
pounds of contaminated soil were treated during the SITE
demonstration. While the pilot-scale VRU was designed
for the treatment of VOCs, the SITE demonstration did
not involve the treatment of VOCs. It is assumed that the
10-tph VRU will have and use equipment designed for the
treatment of VOCs.
Costs that are assumed to be the obligation of the
responsible party or site owner have been omitted from
this cost estimate and are indicated by a line (—) hi all
tables.
Important assumptions regarding operating conditions and
task responsibilities that could significantly affect the cost
estimates are presented in the following subsections.
43.1 Costs Excluded from Estimate
The cost estimates presented are representative of the
charges typically assessed to the client by the vendor but
do not include profit.
Many other actual or potential costs were not included as
part of this estimate. These costs were omitted because
site-specific engineering designs are beyond the scope of
this SITE project. Certain functions were assumed to be
the obligation of the responsible party or site owner and
were not included in this estimate.
Costs such as preliminary site preparation, permits,
regulatory requirements, initiation of monitoring programs,
waste disposal, sampling and analyses, and post-treatment
site cleanup and restoration are considered to be the re-
sponsible party's (or site owner's) obligation and are not
included. These costs tend to be site-specific and it is left
to the reader to perform calculations relevant to each
specific case. Whenever possible, applicable information
is provided on these topics so the reader may perform
calculations to obtain relevant economic data.
433 Utilities
To support the operation of the 10-tph VRU, a site must
have clean water available at a flow rate of at least 24
16
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gpm, assuming recycling with 10 percent blowdown. This
water will be used in the miniwasher and the floe clarifier.
Other uses of the water include cooling and miscellaneous
onsite applications such as cleaning and rinsing.
A natural gas source and the required piping must be
available and accessible to accommodate a natural gas
usage of approximately 7,800 cubic feet per hour at
standard conditions (60° F and 30 inches of mercury).
Alternatively, provisions may be made for the use of oil as
a supplemental fuel. The pilot-scale unit used for the
demonstration utilized propane as a fuel source for the
water heater. The steam boiler was not utilized since
VOCs were not present in the feed soil.
Electrical power is required for the operation of the
pumps, mixers, vibrating screens, and many smaller pieces
of equipment. The pilot-scale unit utilized an electrical
generator, but for the full-scale unit it is anticipated that
electrical power will be supplied from offsite source. It is
assumed that the cost of connecting the full-scale VRU to
an outside electrical source, including the transformer, is
the responsibility of the site owner. Maximum electrical
power consumption is estimated to be 66 kWh per ton of
contaminated soil treated.
For these cost calculations, it is assumed the site will
support all of these requirements. The cost of preparing
a site to meet these requirements can be high and is not
included in this analysis.
433 Operating Times
It is assumed the treatment operations will be conducted
24 hours per day, 5 days per week. It is further assumed
that site preparation will be conducted 8 hours per day, 5
days per week. Assembly and disassembly are assumed to
be carried out 8 hours per day, 7 days per week. Startup
and testing will be accomplished in one shift working 8
hours per day, 5 days per week. Training will be
concurrent with startup activities and be conducted 8 hours
per day for 3 days. Excavation activities for site
preparation will be concurrent with treatment (and may be
concurrent with assembly and shakedown and testing as
well). Assembly and disassembly are both assumed to
require 3 weeks. Shakedown, testing, and training are
expected to take 1 week. Except where noted, these
calculations are based on the treatment of a total of 20,000
tons of waste using a 10-tph system.
43.4 Labor Requirements
Treatment operations for a typical shift are assumed to
require five workers. These workers include a shift
supervisor, a maintenance person, a nonlocal operator, and
two local operators. With 3 shifts, there will be 24 hours
of coverage for those directly involved in operating the
system. In addition, a project manager, safety officer, and
local administrative person will each work a standard 40-
hour schedule at the site. When the safety officer is off-
duty, the shift supervisors will assume all safety
responsibilities.
43.5 Capital Costs
The purchased equipment cost consists of the VRU and
additional equipment such as VOC treatment system,
water heater, steam generator, and trailers. The fixed
capital investment (i.e., capital costs) consists of the
purchased equipment cost and other fixed costs such as
freight, sales tax, installation, piping, electrical,
instrumentation, engineering, and supervision. The
percentage of these major cost components are presented
in Table 12. Assumed proportions are based on ranges of
estimates given by Peters and Timmerhaus [1]. Since the
total equaled less than 100 percent the items were
normalized. Once the purchased equipment costs
(including freight and sales tax) are known, the total fixed
capital investment can be determined. Freight and sales
tax are estimated as percentages of the purchased
equipment cost, while the other fixed costs are estimated
as percentages of the total fixed capital investment.
Table 12. Proportional Costs of Major Fixed Capital Investment
Components
Assumed %
of Total
Normalized %
of Total
Equipment (Including
Freight & Sales Tax)
Equipment
Installation
Instrumentation
(Installed)
Piping (Installed)
Electrical (Installed)
Engineering &
Supervision
Total
40
13
5
12
85
47
11
15
6
14
100
17
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43t6 Equipment and Fixed Costs
Annualizcd equipment costs and other fixed costs have
been prorated for the duration of time that the equipment
is onsitc. The costs for equipment, contingency, insurance,
and taxes accrue during assembly, shakedown and testing,
treatment, and disassembly; scheduled maintenance costs
accrue during treatment only.
4.4 Basis of Economic Analysis
The cost analysis was prepared by breaking down the
overall cost into 12 categories. The cost categories, some
o£ which do not have costs associated with them for this
particular technology, are:
Site preparation
Permitting and regulatory
Equipment
Startup and fixed
Labor
Supplies
Consumables
Effluent treatment and disposal
Residuals and waste shipping, handling, and
transport
Analytical
Facility modification, repair, and replacement
Site demobilization
The 12 cost factors as they apply to the VRU and the as-
sumptions employed are described in the following
subsections.
4.4.1 Site Preparation Costs
It is assumed that preliminary site preparation will be
performed by the responsible party (or site owner). The
amount of preliminary site preparation will depend on the
site. Site preparation responsibilities include site design
and layout, surveys and site logistics, legal searches, access
rights and roads, preparations for support and
decontamination facilities, utility connections, and auxiliary
buildings. Since these costs are site-specific, they are not
included as part of the site preparation costs in this cost
estimate.
Certain site preparation activities, such as excavating
hazardous waste from the contaminated site, will be
required at all sites and are therefore included in this
estimate. Cost estimates for site preparation are based on
rental costs for operated heavy equipment, labor charges,
and equipment fuel costs. An excavation rate of 27 tph is
assumed for all cleanup scenarios using the 10-tph VRU.
It is assumed that the minimum rental equipment required
to achieve an excavation rate of approximately 27 tph
includes nine excavators, three box dump trucks, and three
backhoes. The operation of this equipment will consume
approximately 42 gph of diesel fuel. It is also assumed
that excavation activities will be conducted 8 hours per
day, 5 days per week. Excavation costs are itemized in
Table 13.
Table 13. Excavation Costs
Item
Excavator
Box dump truck
Backhoe
Supervisor
Excavator operator
Dump truck operator
Backhoe operator
Diesel fuel
Cost
$l,260/week
$525/week
$585/week
$40/hour
$30/hour
$30/hour
$30/hour
Si/gallon
4.42 Permitting and Regulatory Costs
Permitting and regulatory costs are generally the obligation
of the responsible party or site owner. These costs may
include actual permit costs, system monitoring
requirements, or the development of monitoring and
analytical protocols. Permitting and regulatory costs can
vary greatly because they are site- and waste-specific. No
permitting or regulatory costs are included hi this analysis.
Depending on the treatment site however, this may be a
significant factor since permitting activities can be both
expensive and time consuming.
4.43 Equipment Costs
The commercial-scale VRU will be capable of treating 10
tph of contaminated soil. System accessories will include
a steam generator for stripping volatile organics from the
feed soil, off-gas treatment system, and waste-water
treatment system. Major pieces of equipment include:
18
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Heated soil conveyor
Trommel screen miniwasher
Water heater
Floc-clarifier
Steam boiler
Membrane filter press
VOC treatment system
Miscellaneous equipment such as screens, pumps, mixers,
and tanks are included in equipment costs.
The developer supplied equipment and utility costs for the
pilot-scale and the 10-tph system. Total purchased
equipment cost for the 10-tph unit was estimated to be
$1,240,000; the total fixed capital investment (including
freight and sales tax, installation, instrumentation, piping,
electrical, and engineering and supervision during
construction) was projected to be $3,110,000.
It is assumed that no rental equipment or purchased
support equipment will be required for operation (with the
exception of trailers). Support equipment refers to
purchased equipment necessary for operation but not
integral to the system.
The total equipment cost is calculated and annualized
using the following formula:
A = C
where: A =
C =
i =
n =
(1 + 0" - 1
annualized cost, $
capitalized cost, $
interest rate, %
useful life, years
The annualized cost (rather than depreciation) is used to
calculate equipment costs incurred by a site. It is assumed
that the interest rate will be 10 percent. For the 10-tph
unit, a useful life of 10 years is assumed. The annualized
equipment cost is prorated to the actual time the unit is
commissioned to treat a hazardous waste (including
assembly, shakedown and testing, treatment, and
disassembly). The prorated annualized cost is estimated
to be $271,000. The prorated cost is then normalized
relative to the tons of soil treated.
4.4.4 Startup and Fixed Costs
Mobilization includes both transportation and assembly.
Transportation activities include moving the system and
the workers to and from the site. As a rough estimate, it
is assumed that five oversize and one legal load size
tractor trailers will be required to transport the
commercial-scale soil washing system. In addition, one
legal load size tractor trailer will be required for
miscellaneous equipment and spare parts. Travel costs
were developed based on 1,300 road miles at a rate of
$1.65 per mile per legal load and $3.30 per mile per
oversized load (including drivers). Transportation costs
for the 11 nonlocal onsite workers are based on two $220
one-way airfares per person. Two one-way airfares were
used instead of a round-trip airfare due to the restrictions
of a round-trip ticket and the difficulties in predicting
when the project would end.
Assembly consists of unloading the system from the trucks
and trailers and reassembling the VRU. It is assumed that
unloading the equipment will require the use of a 50-ton
crane and operator for 3 weeks at a cost of $6,360 per
week. Assembly is assumed to require 10 people (8
construction workers and 2 shift supervisors) working 8
hours per day, 7 days per week, for 3 weeks. Table 14
lists fully burdened salaries for all onsite personnel
involved with assembly as well as other phases of the
project (e.g., startup and testing, training, treatment, and
disassembly). Labor charges during assembly consist of
wages and living expenses for nonlocal personnel (refer to
Subsection 4.4.5) including two rental cars.
This cost estimate assumes that 1 week of shakedown and
testing will be required after assembly and prior to the
commencement of treatment. During this time, the system
components are tested individually. It is estimated that
eight workers will be required for 8 hours per day, 5 days
per week during shakedown and testing. The 8 workers
include a project manager, shift supervisor, safety officer,
maintenance worker, operator, administrator, and two
local operators. In addition, the four local operators will
be trained for 3 days during this week. Labor costs consist
of wages and living expenses for nonlocal personnel (refer
to subsection 4.4.5) including two rental cars.
Working capital consists of the amount of money currently
invested in supplies, energy, spare parts, and labor kept on
hand [1]. The working capital for this system is based on
maintaining a 1-month inventory of these items. For the
calculation of working capital, 1 month is defined as one-
twelfth of 1 year, or approximately 21.8 working days.
For the purposes of this estimate, insurance is assumed to
be 6 percent of the total purchased equipment costs;
property taxes are assumed to be 3 percent of the total
fixed capital investment [1]. These costs are annual and
have been prorated to the actual time the VRU is
commissioned to treat contaminated waste on a site
(including assembly, shakedown and testing, treatment, and
disassembly).
19
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Table 14. FWfy Burdened Salaries for Onsite Personnel Using
10-tpli VRU
Salary
Title
Project Manager
Shift Supervisor
Safety Officer
Non-local Operator
Maintenance Worker
Local Operator
Construction Worker
Administrative Personnel
Local
No
No
No
No
No
Yes
Yes
Yes
(S/h)
50
40
35
30
20
20
20
12
The cost for the initiation of monitoring programs has not
been included in this estimate. Depending on the site,
local authorities may impose specific guidelines for
monitoring programs. The stringency and frequency of
monitoring required may have a significant impact on the
project costs.
An annual contingency cost of 10 percent of the
annualizcd equipment capital costs is allowed to cover
additional costs caused by unforeseen or unpredictable
events, such as strikes, storms, floods, and price variations
II]. The annual contingency cost has been prorated to the
actual time the 10-tph VRU is commissioned to treat
hazardous waste (including assembly, shakedown and
testing, treatment, and disassembly).
4.4.5 Labor Costs
Labor costs consist of wages and living expenses.
Personnel requirements are discussed in Subsection 4.3.4.
Fully burdened rates are given in Table 14.
Living expenses depend on several factors: the duration of
the project, the number of local workers hired, and the
geographical location of the project. Living expenses for
all personnel who are not local hires consist of per diem
and rental cars, both charged at 7 days per week for the
duration of the treatment. Per diem varies by location,
but for the purposes of this report, it is assumed to be $70
per day per person. Four rental cars are required for 24-
hour operation and are available for $30 per day per car.
Depending on the length of the project, it may be more
practical to hire only local personnel and train them in the
operation of the unit, eliminating living expenses.
4.4.6 Supplies Costs
For this estimate, supplies consist of chemicals and spare
parts. Surfactant, alkali (sodium carbonate), alum,
polyelectrolyte (flocculent), and sulfuric acid requirements
for the VRU are estimated to cost approximately $420,000
for the entire project. Annual spare parts costs are
estimated to be 5 percent of the total purchased
equipment cost or approximately $22,000 for the entire
project. Expenses for personal protective equipment are
included in spare parts costs.
4.4.7 Consumables Costs
In order to heat wash water and steam strip VOCs from
the feed, the VRU consumes natural gas at a rate of
approximately 7.7 million Btu/h. The cost of natural gas
is estimated as $4.00 per million Btu with no monthly fee,
yielding a fuel cost of approximately $13,400 per month or
$31 per hour of operation.
The electricity requirement for the screw conveyor, pumps,
and mixers is approximately 66 kWh per ton of soil
treated. The estimated cost of electricity is $25,000 per
month or $48 per hour of operation. The cost estimate
assumes that electricity can be obtained for a flat rate of
$0.08 per kWh with no monthly charge.
The VRU has an estimated water requirement of 1,420
gallons per ton of soil treated. It is assumed that 90
percent of the water can be recovered and treated for
reuse (i.e., only about 24 gpm of makeup is needed). The
other 10 percent is discarded as blowdown or lost with
clean solids during separation processes. Water costs are
estimated at $2 per 1,000 gallons. One month's supply of
water (667,000 gallons) costs about $1,330, and the cost
per hour of operation is $2.56.
4.4.8 Effluent Treatment and Disposal Costs
The clean solids generated during the SITE demonstration
remained onsite. It is assumed that clean solids from a
full-scale cleanup will be used as fill material if found to
be nonhazardous. The fines will require further processing
by another technology. Recovery of at least 80 percent of
the solids present in the feed as washed soil is one of the
project objectives. The remainder (less than 20 percent)
is incorporated into the fines slurry.
20
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Most of the water from the water treatment system should
be suitable for recycling as wash water in the mini-washer.
A fraction of this water will be removed as blowdown and
require disposal or treatment. The responsible party or site
owner should obtain a discharge permit from the local
municipality if possible. If no sewer service is available,
the site owner or responsible party must obtain a direct
discharge permit or arrange for disposal by other means.
It should not be necessary to treat the blowdown water
prior to discharge, but this must be determined on a site-
specific basis.
Onsite treatment and disposal costs are restricted to onsite
storage of the blowdown water (if necessary) and are
assumed to be the obligation of the site owner or
responsible party. Offsite treatment and disposal costs
consist of wastewater disposal fees and are assumed to be
the obligation of the responsible party (or site owner).
These costs may significantly add to the total cleanup cost.
The cost of additional treatment of the fines is assumed to
be the obligation of the responsible party (or site owner).
4.4.9 Residuals and Waste Shipping, Handling, and
Transport Costs
It is assumed that the residuals generated by this process
will include the clean solids, fines, filters, spent carbon
canisters, and spent PPE. Residuals will also be generated
when the unit is decontaminated. Potential waste disposal
costs include storage, transportation, and treatment costs
and are assumed to be the obligation of the responsible
party (or site owner). These costs could significantly add
to the total cleanup cost.
4.4.10 Analytical Costs
No analytical costs are included in this cost estimate.
Standard operating procedures do require sampling and
analytical activities to determine when breakthrough has
occurred in equipment such as aqueous or vapor-phase
carbon absorption, reverse osmosis, or ultrafiltration
systems. The client may elect or may be required by local
authorities to initiate a sampling and analytical program at
their own expense. If specific sampling and monitoring
criteria are imposed by local authorities, these analytical
requirements could contribute significantly to the cost of
the project.
4.4.11 Facility Modification, Repair, and Replacement
Costs
Maintenance labor and material costs vary with the nature
of the waste and the performance of the equipment. For
estimating purposes, total annual maintenance costs (labor
and materials) are assumed to be 10 percent of annual
equipment costs. Maintenance labor typically accounts for
two-thirds of the total maintenance costs and has been
discussed in Subsection 4.4.5. Maintenance material costs
are estimated at one-thkd of the total maintenance cost
and are prorated to the entire period of treatment. Costs
for design adjustments, facility modifications, and
equipment replacements are included in the maintenance
costs.
4.4.12 Site Demobilization Costs
Demobilization costs are limited to disassembly costs;
transportation costs are included under mobilization.
Disassembly consists of taking the VRU apart and loading
it onto trailers for transportation. It requires the use of a
50-ton crane with operator, available at $6,360 per week,
for 3 weeks. Additionally, disassembly requires a 10-
person crew (8 construction workers and 2 shift
supervisors) working 8 hours per day, 7 days per week, for
3 weeks. Labor costs consist of wages (see Table 14) and
living expenses (refer to Subsection 4.4.5) including 2
rental cars.
Site cleanup and restoration are limited to the removal of
all equipment from the site. These costs have been
previously incorporated in the disassembly costs.
Requirements regarding the filling, grading, or
recompaction of the soil will vary depending on the future
use of the site and are assumed to be the obligation of the
responsible party (or site owner).
4,5 Results of Economic Analysis
The costs associated with the operation of the VRU, as
presented in this economic analysis, are defined by 12 cost
categories that reflect typical cleanup activities
encountered on Superfund sites. Each of these cleanup
activities is defined and discussed; together they form the
basis for the cost analysis presented in Table 15. The
percentage of the total cost contributed by each of the 12
cost categories is shown in Table 16.
21
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Table 15. Treatment Costs for 10-tph VRU Treating 20,000 Tons of
Contaminated Soil
Cost CS/tonl
70% 80% 90%
Item oa-line on-line on-line
Site preparation
Permitting end regulatory
Equipment
Startup and fixed
Labor
Supplies
Consumables
Effluent treatment
and disposal
Residuals and waste
shipping, handling,
and transport
Analytical
Facility modification,
repair, and replacement
Site demobilization
Total operating costs
34.61
—
16.13
29.91
32.04
21.33
8.65
—
—
0.54
3.18
14639
34.61
—
14.68
30.03
28.03
21.15
8.65
—
—
0.49
3.18
140.82
34.61
—
1356
30.29
24.92
21.01
8.65
—
—
0.45
3.18
136.67
Table 16. Treatment Costs as Percentages of Total Costs for 10-tph
VRU Treating 20,000 Tons of Contaminated Soil
Cost fas % of total cost")
Item
70%
on-line
80%
on-line
90%
on-line
Site preparation 23.6 24.6 25.3
Permitting and regulatory — — —
Equipment 11.0 10.4 9.9
Startup and fixed 20.4 21.3 22.2
Labor 21.9 19.9 18.2
Supplies 14.6 15.0 15.4
Consumables 5.9 6.1 6.3
Effluent treatment and — — —
disposal
Residuals and waste — — —
shipping, handling,
and transport
Analytical — — —
Facility modification, 0.4 0.3 0.3
repair, and replacement
Site demobilization 2.2 2.3 2.3
Total operating costs 100 100 100
The developer claims that the VRU can operate with an
on-line factor of over 90 percent. On-line factors of 90,
80, and 70 percent were used in the cost calculations in
order to determine the impact of this parameter. The on-
line factor is used to adjust the unit treatment cost to
compensate for the fact that the system is not on-line
constantly because of maintenance requirements,
breakdowns, and unforeseeable delays. Through the use of
the on-line factor, costs incurred while the system is not
operating are incorporated in the unit cost.
The VRU is believed to be capable of operating
continuously (24 hours per day, 7 days per week) for
extended periods of time; however, it was assumed that it
will be operated only 5 days per week. If the VRU is to
be to operated continuously, adjustments must be made to
prorated cost estimates.
The feed rate during the SITE Demonstration Test was
approximately 100 Ib/h and the pilot-scale system
consumed approximately 66 kWh per ton and 71 gph of
water (no recycling). The pilot-scale unit used propane to
heat the wash water; no steam was required since VOCs
were not present in the feed soil. Based on the pilot-scale
system, chemical usage rates per ton of soil for surfactant,
alkali, alum, and polyelectrolyte were 24, 12, and 18 and
0.18 Ibs, respectively.
The developer provided cost and capacity information for
both the pilot- and full-scale (10-tph) VRU units. All
costs are for 1993. It is assumed the commercial-scale unit
will have a feed rate of 10 tph and will require
approximately 24 gpm of water (assuming 90 percent
recycling), 66 kWh/ton of electricity, and 7.7 million Btu/h
of natural gas. For this feed rate, the results of the
analysis show a unit cost ranging from $137 per ton to
$147 per ton for 90 and 70 percent on-line conditions,
respectively.
Based on the information provided by the developer, the
estimated purchased equipment cost for a larger (100 tph)
VRU unit was calculated using the following formula:
F = P(R)n
where: F = Full-scale cost
P = Pilot-scale cost
R = Scale-up ratio (full-scale capacity/pilot-scale
capacity)
n = Scale-up factor
22
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This formula represents a typical cost verses capacity curve
[2]. Knowing the cost and capacity of the pilot and 10-tph
equipment, the scale-up factors were determined. These
values ranged from 0.32 to 0.97, but were typically between
0.4 and 0.7. Using the same factors and estimated scale-
up ratios, equipment costs for the 100-tph VRU unit were
calculated.
These costs are considered order-of-magnitude estimates
as defined by the American Association of Cost Engineers.
The actual cost is expected to fall between 70 and 150
percent of the estimated cost when scaling-up from a full-
scale unit to a larger full-scale unit. Since these costs were
estimated from scaling-up a pilot-scale unit to a full-scale
unit, the range may actually be wider.
Table 17 compares estimated unit treatment costs for sites
containing 10,000, 20,000, and 200,000 tons of
contaminated soil; Table 18 shows the percentage of the
treatment costs contributed by each of the 12 cost
categories. All variables except total amount of
contaminated soil are held constant. In particular, all
three estimates utilize a 10-tph VRU and a 90 percent on-
line factor. If the 10-tph VRU is used to remediate a site
containing less than 20,000 tons of contaminated soil (all
other variables remaining constant), the startup and fixed
costs will become more of a factor. Unit costs derived
from startup, demobilization, and from fixed expenses will
be higher, but unit costs derived from operating expenses
will remain approximately the same.
For example, if this system is applied to a site containing
10,000 tons of contaminated soil, the unit treatment costs
(using a 90 percent on-line factor) are estimated at $171
per ton of soil. If the 10-tph VRU is used at a site
containing over 20,000 tons of contaminated soil (all other
variables remaining constant), the startup, demobilization,
and fixed costs will become less of a factor. Unit costs
derived from startup, demobilization, and fixed expenses
will be lower, but unit costs derived from operating
expenses will remain approximately the same.
If this system is applied to the remediation of a site
containing 200,000 tons of contaminated soil, the unit
treatment costs (using a 90 percent on-line factor) are
estimated at $106 per ton of soil.
It will take nearly 4 years to remediate a site containing
200,000 tons of contaminated soil with the 10-tph system.
For this volume of soil, one or more larger units would be
more appropriate. In order to make a comparison, a
preliminary cost estimate was prepared for a system
capable of treating 100 tph of contaminated soil.
Table 17. Treatment Costs for 10-tph VRU Operating with a 90%
On-line Factor
Cost (S/ton)
Item
Site preparation
Permitting and
regulatory
Equipment
Startup and fixed
Labor
Supplies
Consumables
10,000
tons
34.61
— -
18.12
56.70
24.92
21.01
8.65
20,000
tons
34.61
—
13.56
30.29
24.92
21.01
8.65
200,000
tons
34.61
_
9.45
6.52
24.92
21.01
8.65
Effluent treatment
and disposal
Residuals and waste
shipping, handling,
and transport
Analytical
Facility modification,
repair, and replacement
Site demobilization
Total operating costs
0.60
6.36
170.97
0.45
3.18
136.67
0.31
0.32
105.79
Table 18. Treatment Costs as % of Total Costs for 10-tph VRU
Operating With a 90% On-line Factor
Cost fas % of total cost)
Item
Site preparation
Permitting and
regulatory
Equipment
Startup and fixed
Labor
Supplies
Consumables
10,000
tons
20.2
~
10.6
33.2
14.6
12.3
5.1
20,000
tons
25.3
_
9.9
22.2
18.2
15.4
6.3
200,000
tons
32.7
~~~
8.9
6.2
23.6
19.9
8.2
Effluent treatment
and disposal
Residuals and waste
shipping, handling,
and transport
Analytical costs
Facility modification,
repair, and replacement
Site demobilization
Total operating costs
0.4
3.7
100
0.3
2.3
100
0.3
0.3
100
23
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Table 19 compares estimated unit treatment costs for the
use of 10-tph and 100-tph systems at a site containing
200,000 tons of contaminated soil; Table 20 shows the
percentage of the treatment costs contributed by each of
the 12 cost categories. All process variables except feed
rate are held constant. In particular, both estimates utilize
a 90 percent on-line factor. This preliminary analysis
indicates that it will cost $72 per ton to remediate a site
containing 200,000 tons of contaminated soil using the 100-
tph system (assuming a 90 percent on-line factor). When
the larger system is used, the treatment time is
approximately 0.4 years and the equipment is onsite for
approximately 054 years. Transportation and onsite
assembly of the larger unit, however, could present
difficulties. More trailers and labor will be required for
mobilization and demobilization. It was assumed that one
extra local operator would be required per shift to operate
the larger unit. Scale-up to 100 tph from 10 tph was
accomplished by either increasing the scale-up ratio or the
number of units or a combination of both.
Table 19. Treatment Costs for the Remediation of 200,000 Tons of
Contaminated Soil Using the VRU Operating With a 90%
On-line Factor
Cost CS/tonl
Item
10-tph
System
100-tph
System
Site preparation 34.61 25.26
Permitting and rcgulatoiy — —
Equipment 9.45 2.35
Startup and fixed 652 11.90
Labor 24.92 2.71
Supplies 21.01 20.40
Consumables 8.65 8.65
Effluent treatment — —
and disposal
Residuals and waste shipping, — —
handling, and transport
Analytical — —
Facility modification, 0.31 0.08
repair, and replacement
Site demobilization 0.32 0.64
To«al operating costs 105.79 71.99
Table 20. Treatment Costs as Percentages of Total Costs for VRU
Treating 200,000 Tons of Contaminated Soil
Cost fas % of total cost")
Item
10-tph
System
100-tph
System
Site preparation 32.7 35.1
Permitting and regulatory — —
Equipment 8.9 3.3
Startup and fixed 6.2 16.5
Labor 23.6 3.8
Supplies 19.9 28.3
Consumables 8.2 12.0
Effluent treatment and disposal — —
Residuals and waste shipping, — —
handling, and transport
Analytical costs — —
Facility modification, repair, and 0.3 0.1
replacement
Site demobilization 0.3 0.9
, Total operating costs 100 100
The costs excluded from this cost analysis are described in
Subsections 4.3 and 4.4. This analysis does not include
values for 4 of the 12 cost categories, so the actual cleanup
costs incurred by the site owner or responsible party may
be significantly higher than the costs shown in this analysis.
While the volume of waste treated can be significantly
reduced, the contaminants are not destroyed or
immobilized, so another treatment technology will be
required to treat the fines removed from the VRU.
4.6 References
1. Peters, M.S. and Timmerhaus, K.D. Plant Design
and Economics for Chemical Engineers; Third
Edition; McGraw-Hill, Inc., New York, 1980.
2. Baasel, W. D. Preliminary Chemical Engineering
Plant Design; Elsevier Science Publishing Co.,
Inc., New York, 1976.
24
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Appendix A
Process Description
A.I Introduction
Section 121(b) of CERC1A mandates EPA to select
remedies that "utilize permanent solutions and alternative
treatment technologies or resource recovery technologies
to the maximum extent practicable" and to prefer remedial
actions in which treatment "permanently and significantly
reduces the volume, toxicity, or mobility of hazardous
substances, pollutants, and contaminants as a principal
element." The VRU was developed to meet those
objectives, as well as the objectives listed below:
• To make available to members of the research
community and the commercial sector the results of
government research on a flexible, multi-step, mobile,
pilot-scale soil washer capable of running treatability
studies on a wide variety of soils
• To demonstrate the capabilities of soil washing
• To provide data that facilitate scale-up to
commercial-size equipment
The VRU is a mobile, pilot-scale soil washing system for
stand-alone field use in cleaning soil contaminated with
hazardous substances. Removal efficiencies depend on the
contaminant as well as the type of soil. In general, soil
washing is effective on coarse sand and gravel
contaminated with a wide range of organic and inorganic
contaminants.
A.2 Process Description
The VRU is a mobile research unit developed for
treatability studies on soils contaminated with a wide
variety of contaminants. It was designed to be extremely
flexible in terms of equipment and wash water additives
used. It was not designed to be a commercial treatment
unit.
Soil washing is a water-based ex situ process for
mechanically scrubbing soils to remove undesirable
contaminants. The process removes contaminants from
soils by either dissolving or suspending them in the wash
solution (which is later treated by conventional wastewater
treatment methods) or by concentrating them into a
smaller volume of soil through simple particle size
separation techniques. The concept of reducing soil
contamination through the use of particle size separation
is based on the finding that most organic and inorganic
contaminants tend to bind to fine-sized clay and silt
particles primarily by physical processes [1]. Washing
processes that separate fine clay and silt particles from the
coarser sand and gravel soil particles effectively separate
and concentrate the contaminants into a smaller volume of
soil that can be further treated. The clean larger fraction
can be returned to the site for continued use. This set of
assumptions forms the basis for the volume-reduction
concept upon which the VRU has been developed.
The VRU is designed to decontaminate certain soil
fractions using state-of-the-art washing equipment.
The total system consists of process equipment and
support utility systems mounted on two heavy-duty tractor
trailers. The design capacity of the VRU is 100 Ibs/h.
The basic VRU system consists of the following
subsystems:
• Soil handling and conveying (grizzly)
• Soil washing and coarse screening trommel screen
(miniwasher and vibrating screens)
• Fines/floatables gravity separation (CPI tank)
• Fines flocculation/water clarification and solids
disposal (floe clarifier)
• Water treatment (filter, carbon drums,
blowdown tank, and makeup water tank)
• Utilities (electric generator, steam boiler, water heater
and air compressor)
25
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The electric generator, air compressor, water heater,
filters/carbon drums, water recycling pump, and blowdown
tank are located on the utility trailer. All remaining
equipment is located on the process trailer. Figure A-l is
a diagram of the typical VRU operational setup. (The
VRU setup at the Escambia Treating Company site
demonstration was modified slightly from this typical
setup.) The VRU system is controlled and monitored by
conventional industrial process instrumentation and
hardware including safety interlocks, alarms, and shutdown
features.
During the demonstration, feed soil was taken from
prepared test piles and manually processed through a V*-
inch screen. After screening, the demonstration was
conducted in accordance with the standard VRU operating
procedure, a description of which follows.
The screened soil is collected in a bucket for transfer to
the feed surge bin, and oversized soil is returned to the
site. From the feed surge bin, the soil less than V* inch is
conveyed through a screw conveyor to the miniwasher. The
conveyor flow is adjusted by a speed controller on the
conveyor motor. The solids pass through a motor-
operated rotary valve (which prevents air infiltration), and
then into the feed hopper of the miniwasher.
Soil is fed to the miniwasher at a controlled rate of
approximately 100 Ibs/h by the screw conveyor. Filtered
wash water is added to the soil in the feed hopper and
also sprayed onto an internal slotted trommel screen [with
a 10-mesh (2-mm) slot opening] miniwasher. Five
manually controlled levers can adjust the flow up to an
approximately 13 to 1 overall water-to-soil ratio. Two
vibrating screens continuously segregate soil into various
size fractions. The screens can be set at a variety of mesh
sizes. For the demonstration, 10-mesh (2-mm) and 100-
mesh (0.150-mm) screens were used.
Makeup Water Tank
Blowdown Tank
Water Heater
Screw Conveyor
Carbon Drums
Trommel Screen
Mini-Washer
Steam Boiler
Air Compressor
Electric Generator
Grizzly
Screened Soil Fractions
Figure A-l. Typical VRU Operational Setup.
26
-------
Miniwasher overflow (the stream exiting the top of the
washer), which contains the coarser solids, falls onto the
first 10-mesh (2-mm) vibrascreen. The first vibrascreen
overflow (less than 14 inch, greater than 10-mesh) solids
flow by gravity down to a recovery drum. The underflow
(the stream exiting the bottom) is pumped at a controlled
rate to the second 100-mesh (0.150-mm) vibrascreen where
it is joined by the miniwasher underflow.
The overflow from the second vibrascreen [less than 10-
mesh (2-mm), greater than 100-mesh (0.150-mm)] is
gravity fed to the same recovery drum containing the other
miniwashed coarse soil fraction. The second vibrascreen
underflow (a fines slurry) drains into a tank with a mixer.
Slurry from the 100-mesh (0.150-mm) screen (fines slurry)
tank is pumped to the CPI. Materials lighter than water
(floatables such as oil) flow over an internal weir, collect
in a compartment within the CPI, and drain by gravity to
a drum for disposal. CPI-settled solids [particles which
will pass through a 100-mesh (0.150-mm) screen] are
discharged by the bottom auger to a recovery drum.
An aqueous slurry, containing fines less than
approximately 400 mesh (38 fim), overflows the CPI and
gravity feeds into a tank with a mixer. The slurry is then
pumped to a static mixer located upstream of the floe
clarifier's mix tank. Flocculating chemicals, such as liquid
alum and aqueous polyelectrolyte solutions, are metered
into the static mixer tank to neutralize the repulsive
electrostatic charges on colloidal particles (clay/humus)
and promote coagulation. The slurry is then discharged
into the floe chamber, which has a variable-speed agitator
for controlled floe growth (sweep flocculation). Sweep
flocculation refers to the adsorption of fine particles onto
the floe (colloid capture) and continuing floe growth to
promote rapid settling of the floe. The floe slurry
overflows into the clarifier (another corrugated plate unit).
Bottom solids are augured to a drum for disposal.
Clarified water is polished with the objective of reducing
suspended solids and organics to low levels that permit
recycling of spent wash water. Water is pumped from the
floe settler overflow tank at a controlled rate through
cartridge-type polishing filters operating in parallel in
order to remove soil fines greater than 4 x 10"4 inch (10
^m). Water leaving the cartridge filter flows through
activated carbon drums for removal of hydrocarbons. The
carbon drums may be operated either in series or parallel.
Hydrocarbon breakthrough is monitored by sampling;
drums are replaced when breakthrough has been detected.
In order to recycle water and maintain suitable dissolved
solids and organic levels, aqueous bleed (blowdown) to the
boiler blowdown tank may be initiated at a controlled rate.
A.3 References
1. Ballard, R.B., BJ. Losack, and T.M. Murphy.
Treatment of Hydrocarbon and Lead Contamination
by Soil Washing at a Pipe Inspection Facility, Prudhoe
Bay, Alaska. Presented at the 86th Annual Meeting
of the Air & Waste Management Association, June
13-18, 1993.
27
-------
-------
Appendix B
Developer Claims
B.I Introduction
The VRU is a mobile, pilot-scale soil washing system. It
was designed to be a research platform to evaluate the
effectiveness of soil washing as a technology to remove
volatile organics, semivolatile organics, and metals from
soils, sludges, and sediments. Soil washing is a water-
based process which extracts and concentrates the
hazardous constituents into a smaller volume of soil and
sludge using chemical extraction and physical separation
methods.
The VRU is composed of two 40-foot trailers, a process
trailer, and a utilities trailer. The unit has a flexible design
to enable the formulation of wash fluids composed of
different combinations of water, surfactants, caustic, acids,
and chelating agents. In addition to soil washing and
physical separation, there is an onboard steam generator
and a jacketed screw conveyor to enable the evaluation
and use of steam stripping or low temperature thermal
desorption to remove volatile and semivolatile organics.
The VRU also has a solids separation and water
purification system to enable the treatment and recycling
of the wash water and to evaluate the effectiveness of
different water treatment chemicals (coagulants and
flocculants) and equipment.
Several treatability studies have been performed in
conjunction with EPA Regional staff and EPA's
Environmental Response Team (ERT). The VRU has
treated pentachlorophenol, creosotes, dioxin and furans at
the Escambia Wood Treating Sites and herbicides and
pesticides at the Sand Creek Superfund Site. These
studies have been performed primarily to help the
Remedial Project Managers (RPMs) and On-Scene
Coordinators (OSCs) determine the feasibility of soil
washing for their particular sites. The studies also enable
RREL staff to evaluate the effect of varying process
parameters such as the wash fluid temperature and pH;
liquid-solid ratio, the system contact time, and screen mesh
size were varied to evaluate their effect on the extraction
efficiency of the system. Various wash formulations and
surfactant concentrations have also been explored. Work
at several other sites will be performed this year looking
at contaminants such as diesel fuel, polychlorinated
biphenyls (PCBs), and heavy metals.
The VRU is designed to easily accommodate the addition
of other unit operations such as low temperature thermal
systems, chemical extraction processes, electron beam
oxidizers, and biotreatment units. Previous studies have
evaluated these types of units for treating the effluent from
the soil washing operation. RREL plans to publish the
research and treatability findings so RPMs, OSCs, and
project managers can make informed decisions about the
effectiveness of soil washing technology on the particular
sites.
B.2 SITE Demonstration Claims
During the spring of 1992, EPA's ERT performed site
investigations at four wood treating facilities. These sites,
located in the southeastern U.S., were contaminated with
organic (creosote and pentachlorophenol) and inorganic
(copper, chromium, and arsenic) wood preservative
compounds. Bench-scale soil washing studies were
performed on the soil from two of the sites. Aqueous
biodegradable surfactants were tested for their ability to
increase the solubility of PCP and creosote compounds,
and 280 ppm carcinogenic creosote compounds showed
removals of greater than 99 percent, 92 percent, and 95
percent after several washes with Tergitol NP-10 surfactant
at elevated pH and temperature. Dioxin and furan levels
were also reduced more than 91 percent.
Pilot studies using the VRU were performed in July 1992
by RREL and RBC at the Escambia Wood Treating Site
in Pensacola, Florida. Representative soil was
homogenized and washed under varying pH, temperature,
and surfactant concentrations. Twenty runs were
performed over a 2-week period. Concentration levels
29
-------
were reduced from an initial concentration of 150 ppm
PCP, 75 ppm carcinogenic creosote, and 1,250 ppm total
creosote to 1.7 ppm PCP, 3.5 ppm carcinogenic creosote,
and 80 ppm total creosotes. Nondetectable levels (<1
ppm, > 99 percent removal) were achieved for PCP and
carcinogenic creosote after a clean water rinse was applied
to the washed coarse samples. The total creosote residual
was reduced to less than 32 ppm, greater than 97 percent
removal.
Analysis indicated that only 1 weight percent of the feed
soil was below 115 mesh (0.125 mm). Thus, the VRU
used 100-mesh (0.150-mm) screens as the cut point.
Theoretically, volume reductions of 97 to 98 percent could
be achieved. Due to inefficiencies of the screening units,
the unit achieved volume reductions of approximately 90
to 93 percent.
The SITE Demonstration also took place at the Escambia
Site. Thus, the project claims and tests conditions were
based on the results of the previous treatability studies.
The specific claims and project objectives of this study are
as follows:
• The VRU will separate the coarse gravel and sand
(material which will not pass through a 100-mesh
screen) from the finer silt and clay particles. A
volume reduction of at least 80 percent will be
achieved.
• The coarse soils exiting the VRU will contain
residuals of total creosote and pentachlorophenol
contaminants at least 90 percent lower than the initial
values found in the feed soil.
30
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Appendix C
SITE Demonstration Results
C.I Introduction
This appendix summarizes the results of the SITE
Demonstration Test of the VRU developed by EPA.
These results are also discussed in Sections 1 and 3 of this
report. A more detailed account of the demonstration
may be found in the TER.
The ability of the VRU to reduce the concentration of
organic contaminants in excavated soils was evaluated.
Results from this demonstration include: percent
reductions for PCP; percent reductions for PAHs; percent
solids returned to the site as washed soil; and mass
balances for total material, dry solids, PCP, and PAHs.
VRU operating conditions were verified and the water
treatment system effectiveness was assessed based on wash
water quality before and after treatment by the VRU
system.
PAH- and PCP-contaminated soil from the former
Escambia Treating Company site in Pensacola, Florida was
treated during the demonstration. Contaminant levels in
the excavated soil from the site ranged from the low parts
per million to percent levels. For the SITE demonstration,
the excavated soil was homogenized and manually
processed through a VS-inch screen before it was fed to the
VRU.
Average contaminant concentrations in the feed soil on a
dry weight basis are summarized in Table C-1. Five
compounds from the standard set of creosote-fraction
PAHs were not detected in the feed soil samples. These
compounds [naphthalene, benzo(k)fluoranthene,
ideno(l,2,3-cd)pyrene, dibenzo(a,h)anthracene, and
benzo(g,h,i)perylene] were not included as PAHs for this
evaluation.
Table C-1. Average Contaminant Concentrations in the Feed Soil (dry
weight basis)
Contaminant
(ppm)
PAHs
Acenaphthylene
Acenaphthene
Fluoiene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo(a)anthracene
Chrysene
Benzo(b)fluoranthene
Benzo(a)pyrene
PCP
3
120
130
330
59
180
110
29
27
12
8
140
C.2 Operating Conditions
The target operating conditions were specified in the
Demonstration Plan [1]. Three runs, each 4 hours in
duration, were performed for each of Conditions 1 and 2.
Two runs, each 6 hours in duration, were performed under
Condition 3. Sampling was conducted in accordance with
the procedures outlined in the Demonstration Plan [1].
Surfactant concentration, and wash water pH and
temperatures were monitored to determine whether the
VRU was functioning at the specified operating conditions.
31
-------
The surfactant concentration was determined by
calculating the ratio of surfactant-to-wash water on a mass
basis. The pH was determined by measuring the pH of
the fines slurry stream. The temperature was determined
by measuring the temperature of the wash water just
before it entered the soil washing segment of the VRU.
Table C-2 lists the operating conditions experienced during
the demonstration.
By adding surfactant and increasing the pH and
temperature of the wash water, contaminant removal
efficiencies can be improved significantly. Water is a polar
substance while the contaminants, PCP and PAHs (and
other organic contaminants) are nonpolar. Because polar
substances do not dissolve nonpolar substances well, the
addition of a nonpolar surfactant to the wash water can
improve organic contaminant removal significantly.
Adjusting the pH and temperature of the wash water can
also increase contaminant solubilities and improve removal
efficiencies.
The conditions established for this demonstration were
based on earlier treatability studies conducted by EPA at
the Escambia Treating Company site. During these
studies, PCP and PAH removal efficiencies under varying
operating parameters (surfactant addition, pH and
temperature increases) ranged from 92.6 to 98.9 percent
and 85.2 to 97.1 percent, respectively.
The surfactant used during the demonstration was
Tergitol. In bench-scale tests conducted by EPA prior to
the demonstration, several surfactants were evaluated on
the Escambia soils. Tergitol was considered to be the
most effective in removing contaminants from the soil
samples and was therefore selected for use in the
demonstration.
C3 Contaminant Removal
Table C-3 lists the contaminant concentrations and
contaminant removal efficiencies obtained during the
demonstration. Contaminant removal efficiencies were
determined by comparing (on a dry weight basis) the mass
of the contaminant in the feed soil with the mass of the
contaminant in the washed soil. Removal efficiencies are
calculated using the following equation:
% removal- [Concentration of contaminant in feed - concentration of contaminant in washed soil, 1QQ
concentration of contaminant in feed
Table C-2. VRU SITE Demonstration Operating Conditions
Condition 1
Runl
Run 2
Run3
Condition 2
Runl
Run 2
Run3
Condition 3
Run 1
Run 2
Feed Rate
(Ib/h)
93
64
95
97
106
108
117
148
W/F Ratio
7
10
7
6
6
6
5
4
Surfactant Flow
(Ib/h)
0
0
0
13.4
13.7
14.1
11.0
11.7
Surfactant
Concentration in
pH Wash Water (%)
7.3
7.2
7.1
7.0 0.22
6.9 0.22
6.9 0.22
10.2 0.17
10.1 0.18
Water
Temperature
(°F)
60
56
55
59
60
65
145
139
32
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Table C-3. Removal Efficiencies for FCP and FAHs (dry weight basis)
Parameter
Condition 1
Runl
Run 2
Run 3
Range
Condition 2
Runl
Run 2
Run 3
Range
Condition 3
Runl
Run 2
Range
Feed Soil
(ppm)
150
170
140
130-180
170
180
160
150-210
100
110
48-190
PCP
Washed Soil
(ppm)
28
36
43
21-52
15
13
14
8-19
2.4
3.5
2-5
%
Reduction
81
78
69
91
93
91
98
97
Feed Soil
(ppm)
1,000
1,200
860
770-1,500
1,000
1,000
830
900-1,200
1,100
960
550-1,700
PAHs
Washed Soil
(ppm)
240
310
350
200-520
180
160
130
120-220
44
46
29-65
%
Reduction
77
74
59
83
84
84
96
95
PCP removal efficiencies were calculated for Conditions 1,
2, and 3. Under Condition 3, which employed surfactant
addition and pH and temperature adjustment, the average
PCP removal efficiency was 97 percent. Under
Condition 2, which employed surfactant addition only, the
average PCP removal efficiency was 92 percent. These
removal efficiencies achieve the project objective of
demonstrating that the unit is capable of removing 90
percent of the PCP from the bulk of the feed soil. The
average PCP removal efficiency for Condition 1 was only
76 percent. These data illustrate the impact of surfactant
addition and pH adjustment on PCP removal efficiencies.
PCP removal efficiency is clearly surfactant-dependent and
also appears to be slightly pH- and temperature-
dependent.
PAH removal efficiencies were calculated for Conditions
1, 2, and 3. Under Condition 3, which employed
surfactant addition and pH adjustment, the average PAH
removal efficiency was 95 percent. This removal efficiency
achieves the project objective of demonstrating that the
unit is capable of removing 90 percent of the PAHs from
the bulk of the feed soil. The average PAH removal
efficiencies for Conditions 1 and 2 were only 70 percent
and 83 percent, respectively. These results illustrate the
impact of surfactant addition and pH and temperature
adjustment on PAH removal efficiencies.
C.4 Washed Soils Recovery
The VRU system is designed to separate the sand and
gravel fraction of the soil from the contaminated fines (i.e.,
fine clay and silt particles). The larger sand and gravel
fraction exits the system as washed soil. By comparing the
mass of dry solids in the feed soil with the mass of dry
solids in the washed soil, solids recoveries of 95,95, and 82
percent were calculated for soils treated under Conditions
1 through 3. These recoveries were also calculated on a
normalized basis, yielding normalized recoveries of 90,88,
and 86 percent for Conditions 1, 2, and 3. These
recoveries, shown in Table C-4, achieve the project
objective of demonstrating that at least 80 percent of the
solids present in the feed soil would be returned to the site
as washed soil.
33
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Table C-4. Feed Son Recovered as Washed Soil (dry weight basis)
Condition 1
Runl
Run 2
Run3
Average
Condition 2
Runl
Run 2
Run 3
Average
Condition 3
Runl
Run 2
Average
Feed Soil
Ob/h)
86
62
90
—
90
101
104
-
101
132
-
Washed Soil
(Ib/h)
73
71
79
—
90
104
88
-
95
90
-
Fines Slurry
(Ib/h)
9
9
9
-
9
13
15
-
13
15
-
%
Recovery
85
114
86
95
97
103
86
95
94
69
82
Recovery
Normalized Basis
90
89
90
90
90
89
85
88
87
85
86
C.S Mass Balances
Mass balances were performed to assess material and
contaminant fate as well as system efficiency. Mass
balances were conducted for total materials, dry solids,
PCP, and PAHs. These balances were obtained by
comparing the mass of a given substance entering the
system (in all input streams) with the mass of that
substance exiting the system (in all output streams). Mass
balance closure (or recovery) is calculated as follows:
Mass Balance Closure = L Mass Eating System ^
Mass Entering System
C5.1 Total Material
The total mass of all material (feed soil and washwater)
entering the VRU was compared to the total mass of all
material (cleaned soil and fines slurry) exiting the system.
The mass balances for the total material are presented in
Table C-5. Closures of 104, 113, and 98 percent were
obtained during Conditions 1, 2, and 3, respectively.
During Condition 2, it was noted the mass flow rate
measurement of the fines slurry may have been affected by
sampling procedures employed during the demonstration.
This resulted in inflated mass flow rates. The procedure
was modified and the percent closures dropped to the
acceptable range. Except for this inflated closure of 113
percent for Condition 2, average closures for total material
balances met the project objectives of 90 to 110 percent.
C.5.2 Dry Solids
Dry solids mass balances were calculated by comparing the
total dry weight of the soh'ds entering soil washer per hour
as feed soil with the total dry weight of the solids exiting
the soil washer as washed soil and slurry fines. Except for
Run 2 of Condition 1, Run 2 of Condition 2, and Run 2 of
Condition 3, the closures obtained during the demonstra-
tion are consistent with project objectives specifying
closures of between 85 and 115 percent for solids treated
within the soil washing portion of the VRU system. Even
though closures for individual runs were outside of the
specified range, the average closures for Conditions 1, 2,
and 3 met project objectives. The mass balances for dry
solids are presented in Table C-6.
34
-------
Table C-5. Total Material Mass Balance
Inputs
Feed Soil Wash Water
(lb/h) (lb/h)
Condition 1
Run 1 93 692
Run 2 64 662
Run 3 95 626
Average — ~
Condition 2
Runl 97 593
Run 2 116 587
Run 3 108 604
Average — —
Condition 3
Run 1 117 622
Run 2 148 635
Average — —
Table C-6. Dry Solids Mass Balances
Solid Inputs
Feed Soil
(lb/h)
Condition 1
Runl 86
Run 2 62
Run 3 90
Average —
Condition 2
Run 1 93
Run 2 101
Run 3 104
Average —
Condition 3
Run 1 101
Run 2 132
Average —
Washed Soil
(lb/h)
88
88
95
—
110
130
108
—
121
112
-
Solid
Washed Soil
(lb/h)
73
71
79
—
90
104
88
—
95
88
'
Fines Slurry
(lb/h)
697
699
666
~~
677
688
697
—
644
653
-
Outputs
Fines Slurry
(lb/h)
9
9
9
—
9
13
15
—
12
15
-
%
Closure
100
108
105
104
112
116
111
113
101
95
98
%
Closure
94
128
96
106
108
116
101
108
108
80
94
35
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O5.3 PCP
At Condition 1, the average mass balance closure for PCP
was 101 percent, which meets the project objective of PCP
mass balance closures between 80 and 175 percent. The
average PCP closures for Conditions 2 and 3 were below
80 percent, and therefore did not meet the project
objective.
Average PCP closures for Conditions 2 and 3 were 19
percent and 13 percent, respectively. Because the low
PCP closures were experienced when surfactant was added
to the wash water, it seems probable that the surfactant
interfered with the PCP analyses. The PCP mass balances
are presented in. Table C-7.
C.5.4 PAHs
Like PCP, the majority of PAHs entering the VRU within
the feed soil exited in the slurry fines. At Condition 1, the
average mass balance closure for PAHs was 87 percent,
which meets the project objective of PAH mass balance
closures between 80 and 175 percent. The average PAH
closures for Conditions 2 and 3 were below 80 percent,
and therefore did not meet the project objective. Average
PAH closures for Conditions 2 and 3 were 28 percent and
13 percent, respectively. Like PCP the low PAH closures
were experienced when surfactant was added to the wash
water, and it seems probable that the surfactant interfered
with the PAH analyses. The PAH mass balances are
presented in Table C-8.
Table C-7. PCP Mass Balance
Condition 1
Runl
Run 2
Run 3
Average
Condition 2
Runl
Run 2
Run 3
Average
Condition 3
Runl
Run 2
Average
PCP Inputs
Feed Soil
13
10
12
-
13
19
16
-
10
15
-
PCP
Washed Soil
(lb/h)
2.0
2.6
3.3
-
1.5
1.4
1.3
-
0.54
0.31
-
Outputs
Fines Slurry
(lb/h)
9.0
8.4
10.0
-
1.3
2.1
1.4
-
1.3
1.3
-
% Closure
85
105
113
101
22
18
17
19
15
11
13
36
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Table C-8. PAH Mass Balance
Condition 1
Runl
Run 2
Run3
Average
PAH Inputs
Feed Soil
(Ib/h)
86
77
77
-
PAH
Washed Soil
(Ib/h)
17
22
26
-
Outputs
Fines Slurry
(Ib/h)
55
51
37
-
% Closure
82
95
85
87
Condition 2
Runl
Run 2
Run 3
Average
82
104
88
17
18
12
8.8
9.7
9.7
31
27
25
28
Condition 3
Runl
Run 2
Average
108
130
4.6
4.2
7.7
16
11
15
13
C.6 Particle Size and Fines Distribution
A number of steps were employed to control the size of
the various streams entering and exiting the soil washing
portion of the VRU system. The feed soil was screened
so that only particles less than *A inch hi size entered the
unit. The washed soil was composed of particulate matter
that would not pass through a 100-mesh (0.150-mm)
screen while the fines slurry contained particles that would
pass through a 100-mesh (0.150-mm) screen. Particle size
distribution data for the feed, washed soil, and fines slurry
are presented in Table C-9.
The underflows from the CPI and flocculation tank were
also analyzed for particle size distribution characteristics.
The underflow from the CPI should primarily contain
particles which will pass through a 100-mesh (0.150-mm)
screen but will not pass through a 200-mesh (0.075-mm)
screen; the underflow from the flocculation tank should
primarily contain particles which will pass through a 200-
mesh screen. Particle size distribution data for the
underflow streams from the CPI and the flocculation tank
are presented in Table C-10.
The VRU's effectiveness is based on its ability to separate
soil fines that will pass through a 100-mesh (0.150-mm)
screen from the coarser gravel/sand fraction of the soil,
which will not pass through a 100-mesh (0.150-mm)
screen. Dry solids mass balance data defining the
disposition of the fines and the gravel/sand portion of the
feed can be found in Tables C-ll and C-12, respectively.
Excellent results for partitioning the coarser sand/gravel
fraction to the washed soil were achieved. Approximately
1 to 2 percent of these particles were detected in the fines
slurry. While a majority of the soil fines partitioned into
fines slurry, the partitioning was less complete. As shown
in Table C-ll, 31 to 54 percent of the soil fines recovered
in the output stream were located in the washed soils. A
more complete partitioning of the soil fines to the fines
slurry would, theoretically, lead to increased contaminant
removals from the washed soils.
C.7 Water Treatment Effectiveness
The fines slurry stream was stripped of pollutants by
utilizing a settling, flocculation, filtration, and carbon
adsorption treatment sequence. The solids in the CPI and
floe clarifier were analyzed for PCPs and PAHs. The
results are presented in Tables C-13 and C-14.
Wash water into the VRU and the clarified water were
analyzed for TOC and TR, which is the sum of TSS and
TDS. The results of these analyses are summarized in
Tables C-15 and C-16.
37
-------
T*bJe C-9. Particle Size restriction wlMa the Feed Sofl, Washed Soi, snd Pines Stony (% Finer)
Feed SoU
Condition 1
Average
Range
Condition 2
Average
Range
Condition 3
Average
Range
Washed Soil
Condition 1
Average
Range
Condition 2
Average
Range
Condition 3
Average
Range
Fines Slurry
Condition 1
Average
Range
Condition 2
Average
Range
Condition 3
Average
Range
10 mesh 50 mesh
(2,000 ^m) (300 ftni)
99 28
99.1 - 100.0 23.1 - 315
99 25
98.8 - 100.0 20.4 - 30.8
99 17
98.1 - 100.0 133 - 205
100 18
99.4 - 99.9 10.7 - 245
100 17
99.3 - 99.9 13.2 - 25.6
98 15
955 - 99.6 7.4 - 54.8
100 100
100.0 - 100.0 96.8 - 99.9
100 99
100.0 - 100.0 98.2 - 100.0
100 99
100.0 - 100.0 94.8 - 99.9
100 mesh
(150 ^m)
14
12.0 - 112
12
10.4 - 17.8
9.7
8.9 - 10.9
4.6
1.9 - 16.3
5.2
1.9 - 16.7
65
0.8 - 47.3
91
65.6 - 99.1
84
54.6 - 99.2
88
643 - 98.7
200 mesh 250 mesh 400 mesh 4x10-* inch
(74 /«n) (63 /«n) (38 /mi) (10 fim)
10.0 83 65 62
8.6-13.6 7.4-9.8 5.9-75 5.7-6.7
9.0 16 5.9 5.7
7.9-14.2 6.6-10.2 45-83 4.4-7.4
75 65 5.6 5.4
6.8-8.6 5.9-7.1 4.8-6.9 4.8-6.4
3.1 2.0 1.1 0.9
0.9-15.9 1.0-7.7 0.7-1.6 0.7-1.4
3.1 2.1 0.8 0.6
0.6-15.8 1.0-7.6 0.3-15 0.3-1.1
6-0 3.1 05 03
0.3-46.9 03-21.3 0.0-1.3 0.0-0.8
63 59 52 46
47.4-89.4 37.7-70.4 26.8-66.7 9.8-61.0
68 65 60 54
33.7-945 31.1-94.9 253-95.4 21.9-82.8
66 64 60 56
395-90.8 33.1-90.8 23.6-90.8 19.2-875
2 x Iff4 inch
(Sftm)
5.7
55-6.1
5.4
4.4 - 6.6
5.0
3.8-5.9
0.8
05 - 1.4
0.6
0.1 - 1.0
0.3
0.0 - 0.8
40
3.9 - 56.6
51
21.0 - 79.8
50
14.3 - 875
-------
Table C-10. Particle Size Distribution within the Underflow from the CPI and Hoc Tank (% Rner)
CPI Underflow
Condition 1
Average
Range
Condition 2
Average
Range
Condition 3
Average
Range
Hoc Tank Underflow
Condition 1
Average
Range
Condition 2
Average
Range
Condition 3
Average
Range
10 mesh
(2,000 fim)
100
100.0 - 100.0
100
100.0 - 100.0
100
100.0 - 100.0
100
100.0 - 100.0
100
100.0 - 100.0
100
100.0 - 100.0
50 mesh
(300 ftm)
100
98.7 - 100.0
100
98.9 - 100.0
100
99.8 - 100.0
75
43.7 - 91.8
100
99.4 - 100.0
91
85.4 - 93.7
100 mesh 200 mesh
(150 ftm) (74ftm)
91 76
79.7 - 95.1 55.6 - 88.3
99 96
95.4 - 99.9 92.0 - 98.2
99 84
97.7 - 99.3 78.1 - 90.7
69 65
39.4 - 91.2 36.9 - 90.9
100 99
99.1 - 100.0 98.8 - 99.7
84 80
70.0 - 88.9 65.6 - 86.4
250 mesh 400 mesh 4 x 10"4 inch
(63 ftm) (38,um) (10 ftm)
73 67 59
51.2 - 87.0 42.6 - 84.1 30.6 - 80.6
95 94 88
90.0 - 98.3 85.3 - 98.6 76.9 - 96.6
80 75 69
723 - 88.7 62.1 - 87.9 585 - 80.8
64 60 50
35.2 - 90.2 32.6 - 88.6 245 - 82.7
98 94 89
93.9 - 99.6 78.6 - 99.1 70.1 - 985
77 67 56
64.1 - 81.8 56.8 - 71.4 45.2 - 62.9
2 x 10" inch
(5 ftm)
56
27.6 - 78.1
81
74.8 - 90.2
66
51.1 - 77.3
38
245 - 70.6
60
34.7 - 955
49
34.7 - 58.2
-------
Table C-ll. Disposition of Fines (dry weight basis)
Feed Soil
Washed Soil
Fines Sluny
Flow Rate How Rate Recovered
Ib/h Ib/h %
Condition 1 11 3.4 31
Condition 2 12 4.9 41
Conditions 11 5.9 54
Table C-12. Disposition of Coarse Gravel and Sand (dry weight basis)
Feed Soil Washed Soil
Flow Rate How Rate Recovered
Ib/h Ib/h %
Condition 1 68 71 104
Condition 2 87 89 102
Conditions 105 86 82
Table C-13. Range of FCP Concentrations in Fines Slurry Solids (ppm)
CPI Underflow
Condition 1 51-69
Condition 2 46-85
Condition 3 *
* Unacceptable analysis resulted in questionable data.
Table C-14. PAH Concentration in Fines Slurry Solids (ppm)
CPI Underflow
Condition 1 1,300 - 1,800
Condition 2 370 - 1,100
Condition 3 *
How Rate Recovered Total %
Ib/h % Recovered
8.2 75 106
10 83 124
12 110 164
Fines Sluny
Row Rate Recovered Total %
Ib/h % Recovered
1 1 105
2 2 104
2 2 84
Hoc/Clarifier
92 - 6,500
190 - 1,300
83-150
Hoc/Clarifier
58 - 2,000
910 - 1,800
940 - 1,200
* Unacceptable analysis resulted in questionable data.
40
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Table C-15. TOC Levds in Water Streams (ppm)
Condition 1
Condition 2
Condition 3
Wash Water
<1.0
-------
C,8 References
1. Demonstration Plan for USEPA RREL's Mobile
Volume Reduction Unit. Prepared by: Science
Applications International Corporation.
42
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Appendix D
Case Studies
D.I Bench- and Pilot-Scale Treatment of Soil
from a Wood Treating Facility
Bench-scale experimental studies were performed on
contaminated soil samples from wood treating facilities to
determine if soil washing was capable of removing
creosote and PCP from a soil matrix and collecting them
in a water matrix
The effectiveness of the study was based on soil cleanup
criteria set by EPA of 30 ppm PCP, 50 ppm carcinogenic
creosote compounds, and 100 ppm total creosote
compounds. Water-based biodegradable surfactants were
tested for their ability to increase the solubilization of PCP
and creosote compounds in water. Effects of elevated
temperature and pH were also tested.
The bench-scale studies were performed on soil with initial
contamination levels of approximately 420 ppm PCP; 4,200
ppm total creosote compounds; and 280 ppm carcinogenic
creosote compounds. During these studies, the soil was
subjected to three washes with Tergitol NP-100 surfactant
at elevated pH and temperature. These studies achieved
PCP, total creosote, and carcinogenic creosote removals of
greater than 99, 92, and 95 percent, respectively. Dioxin
and furan levels were also reduced more than 91 percent.
Due to the favorable results of the bench-scale studies, a
pilot-scale study was performed to test the applicability of
soil washing further. Representative soil samples were
washed at various pHs, temperatures, and surfactant
concentrations a VRU soil washer. Twenty runs were
performed over a 2-week period. Under the best
conditions, PCP concentrations were reduced from 120
ppm to less than 1 ppm (greater than 99.1 percent
removal), total creosote concentrations were reduced from
2,280 ppm to 2 ppm (greater than 99.9 percent removal),
and carcinogenic creosote concentrations were reduced
from 103 ppm to less than 1 ppm (greater than 99.0
percent removal). Cleanup criteria for PCP and
carcinogenic creosote compounds were met during all
pilot-scale runs; cleanup criteria for total creosote
compounds were met during all but 1 of the 20 pilot-scale
runs.
D.2 Pilot-Scale Treatment of Pesticide-
Contaminated Soil
The VRU was used to perform a pilot-scale study to
evaluate the ability of soil washing to remediate soils
primarily contaminated with organochlorine pesticides
(e.g., dieldrin, heptachlor, chlordane, 4,4'-DDT), herbicide
(2,4-D), and metals (chromium and arsenic). The Record
of Decision set cleanup levels of 0.155 ppm dieldrin and
0.553 ppm heptachlor.
The pilot-scale study included 23 runs conducted under
varied conditions. Test variables included surfactant type,
surfactant concentration, pH, temperature, liquid-to-soil
ratio, soil type, and number of washes. The concentrations
of heptachlor and dieldrin in the feed soil also varied
widely. The results of this pilot-scale study are
summarized in Tables D-l and D-2. Based on these
results, it is not possible to determine conclusively whether
soil washing is capable of meeting the cleanup levels.
Achieving cleanup levels may require a multistage washing
process that is more efficient than the single-stage VRU.
43
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Table D-l. Heptachlor Results
Minimum
Maximum
Average
Hcptachlor concentration in feed, ppm
Hcptachlor concentration in coarse treated solids, ppm
Heptachlor concentration in fine treated solids, ppm
Removal of heptachlor from feed to coarse treated solids, %
Removal of heptachlor from feed to fine treated solids, %
8
1.4
4.4
17
-107
460
50
340
99
97
159
22
88
79
34
Table D-2. Dieldrin Results
Minimum
Maximum
Average
Dieldrin concentration in feed, ppm
Dieldrin concentration in coarse treated solids, ppm
Dieldrin concentration in fine treated solids, ppm
Removal of dieldrin from feed to coarse treated solids, %
Removal of dieldrin from feed to fine treated solids, %
2.7
1-5'
0.93b
-44
-131
27
6.8
37
91
86
16
3
11
71
34
* The coarse treated solids from two other runs had dieldrin concentrations below the detection limit of 1.6 ppm.
b The fine treated solids from one other run had a dieldrin concentration below the detection limit of 1.6 ppm.
44
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