United States Office of Emergency and EPA/540/2-91/020A

Environmental Protection Remedial Response September 1991

Agency Washington, D.C. 20460 

Guide for Conducting

Treatability Studies

Superfund

Under CERCLA:

Soil Washing

Interim Guidance

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EPA/540/2-91/020A

September 1991

GUIDE TO CONDUCTING 

TREATABILITY STUDIES UNDER CERCLA:

SOIL WASHING

I N T E R I M G U I D A N C E

Risk Reduction Engineering Laboratory 

Office of Research and Development 

U.S. Environmental Protection Agency 

Cincinnati, OH 45268

and

Office of Emergency and Remedial Response 

Office of Solid Waste and Emergency Response 

U.S. Environmental Protection Agency 

Washington, D.C. 20460

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DISCLAIMER

This material has been funded wholly or in part by the United States

Environmental Protection Agency (EPA) under contract No. 68-C8-0061,

Work Assignment No. 2-06, to Science Applications International Corporation (SAIC). It has been subject to the Agency’s peer and administrative

reviews and it has been approved for publication as an EPA document.

Mention of trade names or commercial products does not constitute

endorsement or recommendation for use.

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FOREWORD

Today’s rapidly developing and changing technologies and industrial

products and practices frequently carry with them the increased

generation of materials that, if improperly dealt with, can threaten both

public health and the environment. The U.S. Environmental Protection

Agency (EPA) is charged by Congress with protecting the Nation’s land,

air, and water resources. Under a mandate of national environmental laws,

the Agency strives to formulate and implement actions leading to a

compatible balance between human activities and the ability of natural

systems to support and nurture life. These laws direct the EPA to perform

research to define our environmental problems, measure the impacts, and

search for solutions.

The Risk Reduction Engineering Laboratory (RREL), is responsible for

planning, implementing, and managing research, development, and

demonstration programs to provide an authoritative, defensible

engineering basis in support of the policies, programs, and regulations of

the EPA with respect to drinking water, wastewater, pesticides, toxic

substances, solid and hazardous wastes, and Superfund-related activities.

This publication is one of the products of that research and provides a

vital communication link between the researcher and the user community.

This document provides guidance for planning, implementing, and

evaluating soil washing treatability tests to support the remedy evaluation

process for Comprehensive Environmental Response, Compensation, and

Liability Act (CERCLA) sites. Additionally, it describes a three-tiered

approach, which consists of 1) remedy screening, 2) remedy selection, and

3) remedy design, to soil washing treatability testing. It also presents a

guide for conducting treatability studies in a systematic and stepwise

fashion to determine the effectiveness of soil washing in remediating a

CERCLA site. The intended audience for this guide comprises Remedial

Project Managers (RPMs), On-Scene Coordinators (OSCs), Potentially

Responsible Parties (PRPs), consultants, contractors, and technology

vendors.

E. Timothy Oppelt, Director 

Risk Reduction Engineering Laboratory

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ABSTRACT

Systematically conducted, well-documented treatability studies are an

important component of the remedial investigation/feasibility study

(RI/FS) process and the remedial design/remedial action (RD/RA) process

under the Comprehensive Environmental Response, Compensation, and

Liability Act (CERCLA). These studies provide valuable site-specific data

necessary to aid in the selection and implementation of the remedy. This

manual focuses on soil washing treatability studies conducted in support

of remedy selection prior to developing the Record of Decision (ROD).

This manual presents guidance for designing and implementing a soil

washing treatability study. The manual gives an overview of general

information for determining whether soil washing technology may be

effective, guidance on designing and conducting soil washing treatability

studies for remedy selection, assistance in interpreting data obtained from

remedy selection treatability studies, and guidance for estimating costs

associated with remedy design and full-scale soil washing remedial action.

The manual is not intended to serve as a substitute for communication

with experts or regulators nor as the sole basis for the selection of soil

washing as a particular remediation technology. Soil washing must be

used in conjunction with other treatment technologies since it generates

residuals. This manual is designed to be used in conjunction with the

Guide for Conducting Treatability Studies Under CERCLA (Interim

Final).(15) The intended audience for this guide comprises Remedial Project

Managers (RPMs), On-Scene Coordinators (OSCs), Potentially

Responsible Parties (PRPs), consultants, contractors, and technology

vendors.

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TABLE OF CONTENTS

Section Page

DISCLAIMER ................................................................................. ii

FOREWORD ................................................................................. iii

ABSTRACT .................................................................................. iv

FIGURES ..................................................................................... vi

TABLES .................................................................................... vii

ACKNOWLEDGMENTS ...................................................................... viii

1. Introduction ................................................................................... 1

1.1 Background ........................................................................... 1

1.2 Purpose and Scope ..................................................................... 1

1.3 Intended Audience ..................................................................... 2

1.4 Use of This Guide ...................................................................... 2

2. Technology Description and Preliminary Screening ................................................. 3

2.1 Technology Description ................................................................ 3

2.2 Preliminary Screening and Technology Limitations ......................................... 5

3. The Use of Treatability Studies in Remedy Evaluation ............................................... 9

3.1 Process of Treatability Testing in Evaluating a Remedy ..................................... 9

3.2 Application of Treatability Tests ........................................................ 11

4. Treatability Study Work Plan ................................................................... 15

4.1 Test Goals ............................................................................ 15

4.2 Experimental Design ................................................................... 18

4.3 Equipment and Materials ............................................................... 20

4.4 Sampling and Analysis ................................................................. 21

4.5 Data Analysis and Interpretation ........................................................ 22

4.6 Reports .............................................................................. 24

4.7 Schedule ............................................................................. 25

4.8 Management and Staffing .............................................................. 26

4.9 Budget ............................................................................... 26

5. Sampling and Analysis Plan .................................................................... 29

5.1 Field Sampling Plan .................................................................... 29

5.2 Quality Assurance Project Plan ......................................................... 30

6. Treatability Data Interpretation .................................................................. 33

6.1 Technology Evaluation ................................................................ 33

6.2 Estimation of Costs .................................................................... 34

7. References ................................................................................... 37

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FIGURES

Figure Page

2-1. Schematic Diagram of the Major Elements of the Aqueous Soil Washing Process ........................ 3

3-1. Flow Diagram of the Tiered Approach ............................................................. 10

3-2. The Role of Treatability Studies in the RI/FS and RD/RA Process ..................................... 11

4-1. Soil Washing Applicable Particle Size Range ....................................................... 23

4-2. Hypothetical Contaminant Distribution by Soil Fraction Before and After Treatment .................... 23

4-3. Plot of Agitated Contact Time Versus Contaminant Removal Efficiency and Final 

Contaminant Concentration in the >2 mm Soil Fraction .............................................. 24

4.4. Example Project Schedule for a Treatability Study ................................................... 25

4-5. Organization Chart ............................................................................. 26

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TABLES

Table Page

2-1. Physical Prescreening Soil Characterization Tests ................................................... 7

4-1. Suggested Organization of Soil Washing Treatability Study Work Plan ................................ 15

4-2. Major Cost Elements Associated with Remedy Selection Soil Washing Studies ......................... 26

5-1. Suggested Organization of Sampling and Analysis Plan ............................................. 30

6-1. Potential Major Cost Estimate Components in a Remedy Design Soil Washing Field Test ................ 35

6-2. Major Cost Estimate Components in a Full-Scale Soil Washing Operation .............................. 36

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ACKNOWLEDGMENTS

This document was prepared for the U.S. Environmental Protection

Agency, Office of Research and Development, Risk Reduction

Engineering Laboratory (RREL), Cincinnati Ohio, by Science Applications

International Corporation (SAIC), with the support of its subcontractors,

Bruck, Hartman & Esposito, Inc., and Chapman, Inc., under Contract No.

68-C8-0061. Mr. Mike Borst and Ms. Malvina Wilkens served as the EPA

Technical Project Monitors. Dr. Thomas Fogg and Mr. Jim Rawe were

SAIC’s Work Assignment Managers. The project team included Kathleen

Hurley, Curtis Schmidt, Cynthia Eghbalnia, and Yueh Chuang of SAIC; Pat

Esposito of Bruck, Hartman & Esposito, Inc.; and James Nash of

Chapman, Inc. Dr. Robert Shokes and Mr. Clyde Dial served as SAIC’s

Senior Reviewers, and Robert Coleman served as Technical Editor.

The following Agency and Contractor personnel have contributed their

time and comments by participating in the protocol workshop and/or peer

reviewing the draft document:

Michael Amdurer Ebasco

Robin Anderson EPA, OERR

Ben Blaney EPA, RREL

Clyde Dial SAIC, Cincinnati

Chi-Yuan Fan EPA, RREL

Howard Feiler SAIC, Paramus

Frank Freestone EPA, RREL

Paul Leonard EPA, Region III

Jim Orban EPA, Region IV

Caroline Roe EPA, OERR

Ronald Taylor USDA, Soil Conservation Service

Richard Traver EPA, RREL

Thomas Wagner SAIC, Cincinnati

Darlene Williams EPA, RREL

Andre Zownir EPA, OSWER

The document was also reviewed by the Office of Waste Programs

Enforcement and the Technology Innovation Office. We sincerely hope

we have not overlooked anyone who participated in the development of

this guide.

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SECTION 1 

INTRODUCTION

1.1 BACKGROUND

Section 121 (b) of the Comprehensive Environmental

Response, Compensation, and Liability Act (CERCLA)

mandates the Environmental Protection Agency (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 that “permanently

and significantly reduces the volume, toxicity, or mobility of

the hazardous substances, pollutants, and contaminants is a

principal element.” Treatability studies provide data to

support treatment technology selection and remedy

implementation. If treatability studies are used, they should

be performed as soon as it is evident that insufficient

information is available to support the remedial decision.

Conducting treatability studies early in the remedial

investigation/feasibility study (RI/FS) process reduces

uncertainties associated with selecting the remedy and

provides a sound basis for the Record of Decision (ROD).

EPA Regional planning should factor in the time and

resources required for these studies.

Treatability studies conducted during the RI/FS phase

indicate whether the technology can meet the cleanup goals

for the site. Treatability studies conducted during the

remedial design/remedial action (RD/RA) phase establish

design and operating parameters for optimization of

technology performance. Although the purpose and scope of

these studies differ, they complement one another since

information obtained in support of remedy selection may also

be used to support the remedy design.(24)

This document refers to three levels or tiers of treatability

studies: remedy screening, remedy selection, and remedy

design. Three tiers of treatability studies are also defined in

the Guide for Conducting Treatability Studies Under

CERCLA, Interim Final(15), referred to as the “generic

guide” hereafter in this document. The generic guide refers

to the three treatability study tiers, based largely on the scale

of test equipment, as laboratory screening, bench-scale

testing, and pilot-scale testing. Laboratory

screening is typically used to screen potential remedial

technologies and is equivalent to remedy screening.

Bench-scale testing is typically used for remedy selection,

but may not provide enough information for remedy

selection. Bench-scale studies can, in some cases, provide

enough information for full-scale design. Pilot-scale studies

are normally used for remedial design, but may be required

for remedy selection in some cases. Because of the overlap

between these tiers, and because of differences in the

application of each tier to different technologies, the

functional description of treatability study tiers (i.e., remedy

screening, remedy selection, and remedy design) has been

chosen for this document.

Some or all of the levels may be needed on a case-by-case

basis. The need for and the level of treatability testing

required are management decisions. The time and cost

necessary to perform the testing are balanced against the

improved confidence in the selection of treatment

alternatives. These decisions are based on the quantity and

perceived quality of data available and on other factors (e.g.,

State and community acceptance of the remedy or new site

data on experience with the technology). Section 3 discusses

using treatability studies in remedy selection in greater detail.

1.2 PURPOSE AND SCOPE

This guide helps ensure a reliable and consistent approach in

evaluating soil washing as a consideration for site

remediation. This guide discusses the remedy screening and

remedy selection levels of treatability testing. Remedy

screening studies provide a quick and relatively inexpensive

indication of whether soil washing is a potentially viable

remedial technology. The remedy selection treatability test

provides data to help determine if reductions in contaminant

volumes will allow cost-effective treatment of residual

contamination to meet cleanup goals. Remedy selection

studies also provide preliminary estimates of the cost and

performance data necessary to design either a remedy

design study or a full-scale soil washing system.

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In general, remedy design studies will also be required to

determine if soil washing is a viable treatment alternative for

a site. Remedy design studies are conducted after the ROD

and are typically vendor-specific. Therefore, remedy design

is not discussed in this guidance document.

1.3 INTENDED AUDIENCE

This document is intended for the use of Remedial Project

Managers (RPMs), On-Scene Coordinators (OSCs),

Potentially Responsible Parties (PRPs), consultants,

contractors, and technology vendors. Each has different roles

in conducting treatability studies under CERCLA. Specific

responsibilities for each can be found in the generic guide.(15)

1.4 USE OF THIS GUIDE

This guide is organized into seven sections, which reflect the

basic information required to perform treatability studies

during the RI/FS process. Section 1 is an introduction which

provides background information on the role of the guide and

outlines its intended audience. Section 2 describes different

soil washing processes currently available and discusses how

to conduct a remedy screening to determine if soil washing

is a potentially viable remediation technology. Section 3

provides an overview of the levels of treatability testing and

discusses how to determine the need for treatability studies.

Section 4 provides an overview of the remedy screening and

remedy selection treatability studies, describes the contents

of a typical work plan, and discusses the major issues to

consider when conducting a treatability study. Section 5

discusses sampling and analysis and quality assurance project

plans. Section 6 explains how to interpret the data produced

from treatability studies and how to determine if further

remedy design testing is justified. Section 7 lists the

references.

This guide, along with guides being developed for other

technologies, is a companion document to the generic guide.

In an effort to limit redundancy, supporting information in the

generic guide and other readily available guidance documents

is not repeated in this document.

The document is not intended to serve as a substitute for

communication with regulators and/or experts in the field of

soil washing. This document should never be the sole basis

for selecting soil washing as a remediation technology or

excluding soil washing from consideration.

As treatability study experience is gained, EPA anticipates

further comment and possible revisions to the document. For

this reason, EPA encourages constructive comments from

outside sources. Direct written comments to:

U.S. Environmental Protection Agency

Releases Control Branch (MS 104)

Risk Reduction Engineering Laboratory

2890 Woodbridge Ave.

Bldg. 10, 2nd Floor

Edison, New Jersey 08837-3679

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SECTION 2 

TECHNOLOGY DESCRIPTION AND 

PRELIMINARY SCREENING

This section presents a description of various full-scale soil

washing technologies and a discussion of the information

necessary for prescreening the technology before committing

to a treatability test program. Subsection 2.1 describes

several full-scale soil washing systems. Subsection 2.2

discusses the literature and data base searches required, the

technical assistance available, and the review of field data

required to prescreen these technologies. Technology

limitations are also reviewed in this subsection.

2.1 TECHNOLOGY DESCRIPTION

Soil washing is a physicallchernical separation technology in

which excavated soil is pretreated to remove large objects

and soil clods and then washed with fluids to remove

contaminants. To be effective, soil washing must either

transfer the contaminants to the wash fluids or concentrate

the contaminants in a fraction of the original volume, using

size separation techniques.(12) In either case, soil washing

must be used in conjunction with other treatment

technologies. Either the washing fluid or the fraction of soil

containing most of the contaminant, or both, must be treated.

Figure 2-1 presents a schematic diagram of a soils washing

process.(12)

The first stage in the soil washing process is preparation of

the excavated soil. Soil preparation involves mechanical

screening of the soil feedstock to remove debris such as

rocks, roots, etc. The maximum size of particles allowed

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in the feedstock varies with the equipment used, ranging

from 10 mm (3/8 inch) up to 50 mm (2 inches).

The next stage is the soil washing process. Typically, soil

washing involves mixing, washing, rinsing, and size separation

steps. During mixing, the wash fluid is introduced to the soil

in measured proportions. At some installations, this is a

separate step. Other installations combine mixing and

washing into one step (as shown in Figure 2-1).

The intimate energetic mixing of the wash fluid with soil

constitutes the “washing” step. Intensive contact between

the soil grains and the wash fluid causes the soil

contaminants to dissolve and disperse into the water. Energy

is introduced into the mixture by high-pressure water jets,

vibration devices, and other means, depending upon the

equipment.

After the appropriate contact time, treated soil is separated

from the wash water. Coarse soil particles are separated

with a trammel or vibrating screen device. Fine particles are

separated in a sedimentation tank, sometimes with the

addition of flocculating agents. Silt is removed in a

hydrocyclone or centrifuge device. The coarse soil fraction

is rinsed with clean water to remove residual contaminants

and fine soil particles which may stiff be adhering to coarse

particles. The coarse fhaction is recovered from the process

as clean soil.

The final steps treat the remaining fine soils (fine silt and

clay) and the contaminated water mixture. The contaminated

water mixture may require precipitation and clarification to

remove the metals and fine soils as a sludge. If organic

contaminants are present, the clarifier effluent may require

treatment, typically using activated carbon, before recycling.

The fine soils, in which contaminants have been

concentrated, will normally require further treatment. If

contaminants are volatile, emission controls may be required.

In actual operation, there are more sidestreams and

equipment involved than shown in the Figure 2-1. This

equipment typically includes soil feedstock and treated soil

conveyors and earthmoving equipment for stockpiling soil.

This equipment is, however, ancillary and not critical to

understanding the basic soil washing process.

2.1.1 Soil Washing by Phase Transfer

During soil washing, some contaminants dissolve or become

suspended in the aqueous wash fluid and are removed for

further treatment. If the washed soil meets the established

cleanup goals in the ROD, it may be returned to the original

excavation site. If unacceptable levels of contaminants

remain, the soil should be stockpiled or fed directly to the

next step for additional treatment.

Chemical agents may be added to the wash water to

increase the efficiency of contaminant removal. Acids, such

as hydrochloric acid, sulfuric acid, and nitric acid, may be

added to improve the solubility of certain contaminants,

especially heavy metals. Sodium hydroxide, sodium

carbonate, and other bases can be used to precipitate

contaminants in the extraction fluid. Clay and humus

fractions, which may contain a large percentage of organic

contaminants, are dispersed by bases.(10) Dispersion of oily

contaminants can be facilitated by the addition of surface

active agents. Various chelating or sequestering agents, such

as citric acid, ammonium acetate, nitrilotriacetic acid (NTA),

and ethylenediaminetetraacetic acid (EDTA), will remove

the available fraction of inorganic contaminants. Combining

chemicals may improve process performance in some cases,

although limited information is available on the performance

of these combinations. Contaminant removal may be

improved, in certain cases, by elevation of the extraction

temperature or by chemical oxidation of the contaminants

using an oxidizer (e.g., hydrogen peroxide or ozone).(3)

2.1.2 Soil Washing Using Particle Size

Separation

EPA research shows that a large percentage of soil

contamination (especially organic) is sometimes associated

with, or bound to, very small (silt and clay) soil particles. In

these situations, a physical separation of the large soil

particles (sand and gravel) from the silt, clay, and humic

material effectively concentrates the contaminants. Soil

washing significantly reduces the volume of contaminated

soil when this condition occurs. Following mixing and

washing, sand particles larger than 50 to 80 μm can be easily

separated from the washing fluid because of their relatively

high settling velocity. Simple, inexpensive equipment, such as

settling chambers, can be used.

Most of the clay particles and humus remain suspended in

the wash water supernatant after sand and gravel

sedimentation. These small, slow-settling particles pass

through the settling chambers. They ultimately end up in the

wastewater treatment sludge.(3)

2.1.3 Use In Conjunction With Other

Treatment Technologies

Soil washing is not usually a stand-alone technology.

Typically, both the fine soils (silts and clays) recovered after

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washing and the spent wash water are subject to further

specific treatment and disposal techniques, as appropriate, to

complete the cleanup. Wash water is normally treated using

standard wastewater treatment practices. Sludges generated

during wash water treatment may need subsequent treatment

by such methods as solidification/stabilization, biodegradation,

and incineration. The EPA document entitled, “Technology

Screening Guide for Treatment of CERCLA Soils and

Sludges,” contains a detailed description of potential

treatment technologies.(22) Sidestreams generated during

treatment, such as spent solvents, exhausted resins, air

emissions, etc., must also be treated.

2.2 PRELIMINARY SCREENING AND

 TECHNOLOGY LIMITATIONS

The need for and the appropriate level of treatability studies

required are dependent on available literature, expert

technical judgment, and site-specific factors. The first two

elements--the literature search and expert consultation--are

critical factors in determining if adequate data are available

or whether a treatability study is needed to provide those

data.

2.2.1 Literature/Data Base Review

Several reports and electronic data bases exist which should

be consulted to assist in planning and conducting treatability

studies, and to help prescreen soil washing for use at a

specific site. Existing reports include:

• Guide for Conducting Treatability Studies Under

CERCLA, Interim Final. U.S. Environmental Protection

Agency, Office of Research and Development and

Office of Emergency and Remedial Response,

Washington, D.C. EPA/540/2-89/058, December 1989.

• Guidance for Conducting Remedial Investigations and

Feasibility Studies Under CERCLA, Interim Final. U.S.

Environmental Protection Agency, Office of Emergency

and Remedial Response, Washington, D.C.

EPA/540/G-89/004, October 1988.

• Superfund Treatability Clearinghouse Abstracts. U.S.

Environmental Protection Agency, Office of Emergency

and Remedial Response, Washington, D.C.

EPA/540/2-89/001, March 1989.

• The Superfund Innovative Technology Evaluation

Program: Technology Profiles. U.S. Environmental

Protection Agency, Office of Solid Waste and

Emergency Response and Office of Research and

Development, Washington, D.C. EPA/540/5-90/006,

November 1990.

• Summary of Treatment Technology Effectiveness for

Contaminated Soil. U.S. Environmental Protection

Agency, Office of Emergency and Remedial Response,

Washington, D.C., 1989 (in press).

• Technology Screening Guide for Treatment of CERCLA

Soils and Sludges. U.S. Environmental Protection

Agency. EPA/540/2-88/004, 1988.

• U.S. Environmental Protection Agency, Applications

Analysis Report - CF Systems Organics Extraction

System, New Bedford, MA, EPA Report to be

published.

Currently, RREL in Cincinnati is expanding its Superfund

Treatability Data Base. This data base will contain data from

all treatability studies conducted under CERCLA. A

repository for treatability study reports will be maintained at

RREL in Cincinnati. The contact for this data base is Glenn

Shaul at (513) 569-7408.

Office of Research and Development (ORD) headquarters

maintains the Alternative Treatment Technology Information

Center (ATTIC), a comprehensive, automated information

retrieval system that integrates hazardous waste data into a

unified, searchable resource. The intent of ATTIC is to

provide the user community with technical data and

information on available alternative treatment technologies

and to serve as an initial decision support system. Since

ATTIC functions as a focal point for users, it facilitates the

sharing of information with the user community and creates

an effective network of individuals and organizations involved

in hazardous waste site remediation.

The information contained in ATTIC consists of a wide

variety of data obtained from Federal and State agencies.

The core of the ATTIC system is the ATTIC Data Base,

which contains abstracts and executive summaries from over

1,200 technical documents and reports. Information in the

ATTIC Data Base has been obtained from the following

sources:

• The Superfund Innovative Technology Evaluation (SITE)

Program

• California Summary of Treatment Technology

Demonstration Projects

• Data collected for the Summary of Treatment

Technology Effectiveness for Contaminated Soil

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• North Atlantic Treaty Organization (NATO)

International Data

• Innovative Technologies Program Data

• Removal Sites Technologies Data

• Resource Conservation and Recovery Act (RCRA)

Delisting Actions

• USATHAMA Installation Restoration and Hazardous

Waste Control Technologies

• Records of Decision (from 1988 on)

• Treatability Studies

• Superfund Treatability Data Base (also available through

ATTIC)

In addition, the ATTIC system contains a number of resident

data bases that have been previously developed, as well as

access to on-line commercial data bases. For more

information, contact the ATTIC System Operator at (301)

816-9153.

The Office of Solid Waste and Emergency Response

(OSWER) maintains an Electronic Bulletin Board System

(BBS) as a tool for communicating ideas and disseminating

information and as a gateway for other Office of Solid

Waste (OSW) electronic data bases. Currently, the BBS has

eight different components, including news and mail services

and conferences and publications on specific technical areas.

The contact is James Cummings at (202) 382-4686.

2.2.2 Technical Assistance

Technical assistance can be obtained from the Technical

Support Project (TSP) team, which is made up of six

Technical Support Centers and two Technical Support

Forums. It is a joint service of the Office of Solid Waste and

Emergency Response, the Office of Research and

Development, and the Regions. The TSP offers direct

site-specific technical assistance to On-Scene Coordinators

(OSCs) and RPMs and develops technology workshops,

issue papers, and other information for Regional staff. The

TSP:

• Reviews contractor work plans, evaluates remedial

atternatives, reviews RI/FS, and assists in the selection

and design of the final remedy

• Offers modeling assistance and data analysis and

interpretation

• Assists in developing and evaluating sampling plans

• Conducts field studies (soil gas, hydrogeology, site

characterization)

• Develops technical workshops and training, issue papers

on groundwater topics, and generic protocols

• Assists in performing treatability studies.

The following support centers provide technical information

and advice related to soil washing and treatability studies:

1. Groundwater Fate and Transport Technical Support

Center

Robert S. Kerr Environmental Research Laboratory

(RSKERL), Ada, Oklahoma

Contact: Don Draper 

FTS 743-2202 or (405) 332-8800

RSKERL in Ada, Oklahoma, is EPA’s center for fate and

transport research. It focuses its efforts on transport and fate

of contaminants in the vadose and saturated zones of the

subsurface, methodologies relevant to protection and

restoration of groundwater quality, and evaluation of

subsurface processes for the treatment of hazardous waste.

The Center provides technical assistance, such as evaluating

remedial alternatives; reviewing RI/FS and RD/RA work

plans; and providing technical information and advice.

2. Engineering and Treatment Technical Support

Center

Risk Reduction Engineering Laboratory (RREL), 

Cincinnati, OH 

Contact: Ben Blaney 

FTS 648-7406 or (513) 569-7406

The Engineering and Technical Support Center (ETSC) is

sponsored by OSWER but operated by RREL. The center

handles site-specific remediation engineering problems.

Access to this support Center must be obtained through the

EPA Remedial Project Manager.

RREL offers expertise in contaminant source control

structures; materials handling and decontamination; treatment

of soils, sludges and sediments; and treatment of aqueous

and organic liquids. The following are examples of the

technical assistance that can be obtained through ETSC:

• Screening of treatment alternatives

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• Review of the treatability aspects of RI/FS

• Review of RI/FS treatability study Work Plans and final

reports

• Oversight of RI/FS treatability studies

• Evaluation of alternative remedies

• Assistance with studies of innovative technologies

• Assistance in full-scale design and start-up

2.2.3 Prescreening Characteristics

The need for a treatability study is determined near the

beginning of the RI/FS when a literature survey of remedial

technologies is performed. Remedial technologies are

identified based on compatibility with the type of

contaminants and the media (soil, water, etc.) present at the

site, and the anticipated cleanup objectives. Remedial

technologies are prescreened for effectiveness,

implementability, and cost. The prescreening is done using

available technical literature, data bases and manufacturer’s

information. Based on this initial technology prescreening, soil

washing may be one of several candidate remedial

technologies eliminated before or during the RI/FS. See the

generic guide for more specific details on screening of

treatment technologies and on determining the need and type

of treatability tests which may be required for evaluating

treatment technology alternatives.(15)

Prescreening activities for soil washing treatability testing

include interpreting any available site-related field

measurement data. The purpose of prescreening is to gain

enough information to eliminate from further treatability

testing treatment technologies that have little chance of

achieving the cleanup goals.

Table 2-1 lists physical parameters that may be measured or

available before designing treatability tests. Particle size

distribution and cation exchange capacity (CEC)

measurements are particularly useful when evaluating soil

washing.

If contamination exists at different soil zones, a soil

characterization profile should be developed for each soil

type or zone. Available chemical and physical data (including

averages and ranges) and the volumes of the contaminated

soil requiring treatment should be identified. Hot spots require

separate characterizations so they can be properly addressed

in the treatability tests. Soil washing may be applicable to

some, but not all, parts of a site.

Characterization test results should be broadly representative

of the waste profile of the site. Grab samples taken from the

site ground surface may represent only a small percentage of

the contaminated soils requiring remediation. Deeper,

subsurface strata affected by contaminants may vary widely

in composition (grain size, clay content, cation exchange

capacity, total organic carbon, and contamination levels) from

those found at the surface and should also be characterized.

If significant sand or clay lenses are present in the

contaminated zone, the location and volume should be

estimated. This information is critical to determine the mix of

feedstocks to be used. The quantity and distribution of rubble

and debris should also be determined as part of the

characterization. This material must be removed from the

feedstock material during any full-scale treatment operations.

In general, existing commercial soil washers cannot accept

material larger than 3/8 to 2 (10 to 50 mm) inches in

diameter.

The three most important soil parameters to be evaluated

during prescreening and remedy screening tests are the

grain size distribution, clay content, and cation exchange

capacity. Soil washing performance is closely tied to

TABLE 2-1. Physical Prescreening Soil Characterization Tests

Parameter Description of Test

Standard Analytical

Method Reference

Grain size analysis/

particle size distribution

Sieve screening using #10

and #60 screens or

equivalent

ASTM D422 1

Cation exchange capacity

(CEC)

Ammonium acetate

Sodium acetate

Method 9080

Method 9081

23

23

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these three factors. Soils with relatively large percentages of

sand and gravel (coarse material >2 mm) respond better to

soil washing than soils with small percentages of sand and

gravel. Larger percentages of clay and silt (fine particles

smaller than 0.25 mm) reduce contaminant removal

efficiency. In general, soil washing is most appropriate for

soils that contain at least 50 percent sand/gravel, i.e., coastal

sandy soils and soils with glacial deposits. Soils rich in clay

and silt tend to be poor candidates for soil washing. Cation

exchange capacity measures the tendency of the soil to

exchange weakly held cations in the soil for cations in the

wash solution. Soils with relatively low CEC values (less than

50 to 100 meq/kg) respond better to soil washing than soils

with higher CEC values. Early characterization of these

parameters and their variability throughout the site provides

valuable information for the initial screening of soil washing

as an alternative treatment technology. Appendix C of the

generic guide lists other specific characterization

parameters.(15)

Chemical and physical properties of the contaminant should

also be investigated. Solubility in water (or other washing

fluids) is one of the most important physical characteristics.

Reactivity with wash fluids may, in some cases, be another

important characteristic to consider. Other contaminant

characteristics such as volatility and density may be

important for the design of remedy screening studies and

related residuals treatment systems. Speciation, is important

in metal-contaminated sites. Specific metal compounds

should be quantified rather than total metal concentration for

each metal present at the site. Soil prescreening

characterization data should be assembled and organized in

a concise tabular form before designing the remedy

screening tests.

2.2.4 Soil Washing Limitations

Soil washing limitations may be defined as characteristics

that hinder cost-effective soil treatment. The limitation may

be due to the soil particle distribution (high percentage of silt,

clay, or organic matter), the contaminant (high concentration

of mineralized metals or hydrophobic organics), or the

process itself. High concentrations of additives may be

required in some cases to meet the necessary performance

goals. Difficulties are sometimes encountered in treating and

recycling additives in the spent wash water. If these

conditions occur, process costs may be prohibitive due to the

cost of treating washing fluids and replenishing additives. 

Hydrophobic contaminants can be difficult to separate from

soil particles into the aqueous washing fluid. Estimated

aqueous distribution coefficients (Kd), also known as partition

coefficients.(Kp), indicate the fraction of the contaminant

expected to remain on the soil particle versus the fraction of

the contaminant dissolved in the water. (6) Alternative

methods can be used to estimate these values when tabulated

values cannot be located.(8) A contaminant with a high Kd

(e.g., PCB > 10,000) is more difficult to wash off the soil

particles using water than a contaminant with a lower Kd

(e.g., TCE=3). Additives such as surfactants may be

required to improve removal efficiencies. However, larger

volumes of washing fluid may be needed when additives are

used.

Complex mixtures of contaminants in the soil, such as a

mixture of metals, nonvolatile organics, sernivolatile organics,

etc., make it difficult to formulate a single suitable washing

fluid that will remove all the different types of contaminants

from the soil. Sequential washing steps, using different

additives, may be needed. Frequent changes in the

contaminant type and concentration in the feed soil can

disrupt the efficiency of the soil washing process. To

accommodate changes in the chemical or physical

composition of the feed soil, modifications to the wash fluid

formulation and the operating settings may be required.

Alternatively, additional feedstock preparation steps, such as

blending soils to provide a consistent feedstock; may be

appropriate.

High humic content in the soil makes separation of

contaminants very difficult. Humus consists of decomposed

plant and animal residues and offers binding sites for

accumulation of both organics and metals. A high percentage

of clay and silt (e.g., more than 30 to 50 percent) in the soil

usually indicates that soil washing will be unfavorable due to

the amount of time and money required to treat this volume

of contaminated soil. A volume reduction process like soil

washing is most cost-effective when the cleaner soil fraction

is much larger than the more contaminated soil fraction.

Chelating agents, surfactants, solvents, and other additives

are often difficult and expensive to recover from the spent

washing fluid and then recycle in the soils washing process.

The presence of additives may make the spent washing fluid

difficult to treat by conventional treatment processes such as

settling, chemical precipitation, or activated carbon. The

presence of additives in the contaminated soil and treatment

sludge residuals may cause increased difficulty in disposing

of these residuals.

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SECTION 3

THE USE OF TREATABILITY STUDIES 

IN REMEDY EVALUATION

This section presents an overview of the use of treatability

tests in confirming the selection of soil washing as the

technology remedy under CERCLA. It also provides a

decision tree that defines the tiered approach to the overall

treatability study program with examples of the application of

treatability studies to the RI/FS and remedy evaluation

process. Subsection 3.1 presents an overview of the general

process of conducting treatability tests. Subsection 3.2

defines the tiered approach to conducting treatability studies

and the applicability of each tier of testing, based on the

information obtained, to assess, evaluate, and confirm soil

washing technology as the selected remedy.

3.1 PROCESS OF TREATABILITY

 TESTING IN EVALUATING A

 REMEDY

Treatability studies should be performed in a systematic

fashion to ensure that the data generated can support the

remedy evaluation process. This section describes a general

approach that should be followed by RPMs, PRPs, and

contractors during all levels of treatability testing. This

approach includes:

• Establishing data quality objectives

• Selecting a contracting mechanism

• Issuing the Work Assignment

• Preparing the Work Plan

• Preparing the Sampling and Analysis Plan

• Preparing the Health and Safety Plan

• Conducting community relations requirements

• Complying with regulatory requirements

• Executing the study

• Analyzing and interpreting the data

• Reporting the results

These elements are described in detail in the generic guide.

(15) That document gives information applicable to all

treatability studies. It also presents information specific to

each of the levels of treatability testing.

Treatability studies for a particular site will often entail

multiple tiers of testing. Duplication of effort can be avoided

by recognizing this possibility in the early planning phases of

the project. The Work Assignment, Work Plan, and other

supporting documents should include all anticipated activities.

There are three levels or tiers of treatability studies: remedy

screening, remedy selection, and remedy design testing.

Some or all of the levels may be needed on a case-by-case

basis. The need for and the level of treatability testing

required are management decisions in which the time and

cost necessary to perform the testing are balanced against

the risks inherent in the decision (e.g., selection of an

inappropriate treatment alternative). These decisions are

based on the quantity and perceived quality of data available

and on other decision factors (e.g., State and community

acceptance of the remedy or new site data). The flow

diagram for the tiered approach in Figure 3-1 traces the

stepwise review of data with the decision points and factors

to be considered.

Technologies generally are evaluated first at the remedy

screening level and progress through remedy selection to the

remedy design testing. A technology may enter the selection

process, however, at whatever level is appropriate based

on available data on the technology and site-specific

factors. For example, a technology that has been

successfully applied at a site with similar conditions and

contaminants may not require remedy screening to determine

whether it has the potential to work. Rather, it may

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go directly to remedy selection testing to verify that

performance standards can be met and generate preliminary

cost estimates. Treatability studies, at some level, will

normally be needed to assure that the technology can

achieve site target cleanup goals even if previous studies or

actual implementation have encompassed similar site

conditions. Figure 3-2 shows the relationship of the three

levels of a treatability study to each other and to the RI/FS

process.

3.2 APPLICATION OF TREATABILITY

 TESTS

Before conducting treatability studies, the objectives of each

tier of testing must be established. Soil washing treatability

study objectives are based on the specific needs of the

RI/FS. There are nine evaluation criteria specified in the

document, Guidance for Conducting Remedial Investigations

and Feasibility Studies Under CERCLA (Interim Final);(14)

the treatability studies provide data for up to seven of these

criteria. These seven criteria are:

• Overall protection of human health and environment

• Compliance with applicable or relevant and appropriate

requirements (ARARs)

• Reduction of toxicity, mobility, or volume through

treatment

• Short-term effectiveness

• Implementability

• Long-term effectiveness and permanence

• Cost

The first four of these evaluation criteria deal with the

degree of contaminant reduction achieved by the soil

washing process. What will be the remaining contaminant

concentrations? Will the residual contaminant levels be

sufficiently low to meet the established ARARs and the

risk-based contaminant cleanup levels? What are the

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ences between the untreated and the washed soil fractions

(i.e., has contaminant toxicity, mobility, and volume been

reduced)? The fourth criterion, short-term effectiveness,

addresses the risks posed by the treatment technology during

construction and implementation of a remedy.

The implementability assessment evaluates the technical and

administrative feasibility of the technology and the availability

of required goods and services. The following questions must

be answered in order to address the implementability of soil

washing:

• What is the percentage of clay, silt, and humic matter

requiring additional treatment?

• What additives will be required (e.g., chelating agents or

surfactants) that might make residuals treatment and

disposal difficult?

• What are the characteristics and the volume of the

sludge that will be produced?

• Is sufficient water available at the site, and is it suitable

for process use?

Normally, the required equipment and washing solutions are

available. However, alterations to process design may be

necessary on a site-by-site basis to accommodate different

soils and contaminants. Sidestreams and residual soil from

the soil washing process require additional treatment. The

implernentability assessment must include these additional

treatments.

Long-term effectiveness assesses how effective treatment

technologies are in maintaining protection of human health

and the environment after response objectives have been

met. The magnitude of any residual risk and the adequacy

and reliability of controls must be evaluated. Residual risk, as

applied to soil washing, assesses the risks associated with the

treatment residuals at the conclusion of all remedial activities.

Analysis of residual risk from sidestream and other treatment

train processes should be included in this step. An evaluation

of the reliability of treatment process controls assesses the

adequacy and suitability of any long-term controls (such as

site access restrictions and deed limitations on land use) that

are necessary to manage treatment residuals at the site. Such

assessments are usually beyond the scope of a remedy

selection treatability study, but may be addressed

conceptually based on remedy selection results. Performance

objectives must consider the existing site soil contaminant

levels and relative cleanupgoals for the site. In previous

years, cleanup goals often reflected background site

conditions, Attaining background cleanup levels through

treatment has proven impractical in many situations. The

present trend is toward the development of site-specific

cleanup target levels that are risk-based rather than based on

background levels.

The final EPA evaluation criterion that can specifically be

addressed during a treatability study is cost. Soil washing is

basically a volume reduction technology that uses wash

water to separate contaminated soil into two fractions: a

large fraction of relatively clean, coarse soil and a smaller

fraction of fine soil/sludge containing the concentrated

contaminants.

Remedy selection treatability studies can provide data to

estimate the following important cost factors:

• Recoverable clean soil fraction (the achievable volume

reduction)

• The volume and characteristics of the concentrated fine

soil and sludge fractions requiring treatment or disposal

• The degree to which the additives can enhance the

process efficiency

• The degree to which the additives can be recovered and

recycled

• The ratio of additives to soil

• The ratio of soil to wash water

The first three factors provide information about the costs of

downstream treatments by determining the amount and

character of the contaminated residuals. The last three

factors help estimate the costs of supplies and utilities.

3.2.1 Remedy Screening

Remedy screening is the first testing level. It establishes the

ability of a technology to treat a specific waste. These

studies are generally low cost (e.g., $10,000 to $50,000) and

usually require hours to days to complete. The lowest level

of quality control is required for remedy screening studies.

They yield data enabling qualitative assessment of a

technology’s potential to meet performance goals. Remedy

screening tests can identify operating conditions for

investigation during remedy selection or remedy design

testing. They generate little, if any, design or cost data and

should never be used as the sole basis for selection of a

remedy.

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Soil washing treatability studies are frequently skipped during

remedy screening. Often, there is enough information about

the physical and chemical characteristics of the soil and

contaminant to allow an expert to evaluate the potential

success of soil washing at a site. When performed, remedy

screening tests are jar tests. However, remedy selection tests

are normally the first level of treatability study executed.

3.2.2 Remedy Selection

Remedy selection testing is the second level of testing.

Remedy selection tests identify the technology's performance

for a site. These studies have a moderate cost (e.g., $20,000

to $100,000) and require several weeks to complete. Remedy

selection tests yield data that verify that the technology can

meet expected cleanup goals, provide information in support

of the detailed analysis of alternatives (i.e., seven of the nine

evaluation criteria), and give indications of optimal operating

conditions.

The remedy selection tier of soil washing testing typically

consists of laboratory tests which provide sufficient

experimental controls such that a semi-quantitative mass

balance can be achieved. Toxicity testing of the cleaned soil

is typically employed in the remedy selection tier of

treatability testing. The key question to be answered during

remedy selection testing is how much of the soil will be

treated by either particle size separation or solubilization to

meet the cleanup goal by this process. The exact removal

efficiency needed to meet the specified goal for the remedy

selection test is site-specific. Pilot-scale tests may be

appropriate to support the remedy selection phase for

innovative technologies such as soil washing. Typically, a

remedy design study would follow a successful remedy

selection study. 

3.2.3 Remedy Design

Remedy design testing is the third level of testing. It provides

quantitative performance, cost, and design information for

remediating an operable unit. This testing also produces the

remaining data required to optimize performance. These

studies are of moderate to high cost (e.g., $ 100,000 to

$500,000) and require several months to complete. For

complex sites (i.e., sites with different types or

concentrations in different areas or with different soil types

in different areas), longer testing periods may be required,

and costs will be higher. Remedy design tests yield data that

verify performance to a higher degree than remedy selection

tests and provide detailed design information. They are

performed after the ROD during the remedy implementation

phase of a site cleanup.

Remedy design tests usually consist of bringing a mobile

treatment unit onto the site, or constructing a small-scale

(pilot) unit for nonmobile technologies. Permit exclusions may

be available for offsite treatability studies under certain

conditions. The goal of this tier of testing is to confirm the

cleanup levels and treatment times specified in the Work

Plan (see Section 4.1.1). This is best achieved by operating

a field unit under conditions similar to those expected in the

full-scale remediation project.

Data obtained from the remedy design tests are used to:

• Design the full-scale unit

• Refine cleanup time estimates

• Refine cost predictions

Given the lack of full-scale experience with innovative

technologies, remedy design testing will generally be

necessary to support remedy selection and implementation.

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SECTION 4

TREATABILITY STUDY WORK PLAN

Section 4 of this document is written assuming that a

Remedial Project Manager is requesting treatability studies

through a work assignment/work plan mechanism. Although

the discussion focuses on this mechanism, it would also apply

to situations where other contracting mechanisms are used.

This section focuses on specific elements of the Work Plan

for soil washing treatability studies. The elements include test

objectives, experimental design and procedures, equipment

and materials, reports, schedule, management and staffing,

and budget. These elements are described in Sections 4.1–

4.9. Complementing the above subsections are Section 5,

Sampling and Analysis Plan, which contains a Field Sampling

Plan and a Quality Assurance Project Plan, and Section 6,

Treatability Data Interpretation. These sections address the

Sampling and Analysis and Data Analysis and Interpretation

elements of the Work Plan. Table 4-1 lists the other

remaining Work Plan elements

Carefully planned treatability studies are necessary to ensure

that the data generated are useful for evaluating the validity

or performance of a technology. The Work Plan, prepared

by the contractor when the Work Assignment is in place, sets

forth the contractor’s proposed technical approach for

completing the tasks outlined in the Work Assignment. It

assigns responsibilities and establishes the project schedule

and costs. The Work Plan must be approved by the RPM

before initiating subsequent tasks. For more information on

each of these sections, refer to the generic guide.(15.)

4.1 TEST GOALS

Setting goals for the treatability study is critical to the

ultimate usefulness of the data generated. Objectives must

be defined before starting the treatability study. Each tier of

treatability study needs performance goals appropriate to that

tier. For example, remedy selection tests are used to answer

the question, “Will soil washing work on this soil/

contaminant matrix?” It is necessary to define “work”

TABLE 4-1. Suggested Organization of Soil Washing

Treatability Study Work Plan

No. Work Plan Elements

subsection

1. Project Description

2. Remedial Technology Description

3. Test Objectives 4.1

4. Experimental Design and

Procedures

4.2

5. Equipment and Materials 4.3

6. Sampling and Analysis 4.4

7. Data Management

8. Data Analysis and Interpretation 4.5

9. Health and Safety

10. Residuals Management

11. Community Relations

12. Reports 4.6

13. Schedule 4.7

14. Management and Staffing 4.8

15. Budget 4.9

(i.e., set the goal of the study). A contaminant reduction of

approximately 90 percent in the >2 mm soil fraction indicates

that further testing for remedy design is appropriate.

The ideal technology performance goals are the cleanup

criteria for the site. For several reasons, such as ongoing

waste analysis and ARARs determination, cleanup criteria

are sometimes not finalized until the ROD is signed, long

after treatability studies must be initiated. Nevertheless,

treatability study goals need to be established before the

study is performed so that the success of the treatability

study can be assessed. In many instances, this may entail an

educated guess as to what the final cleanup levels may be.

In the absence of set cleanup levels, the RPM can estimate

performance goals for the treatability studies based on the

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16

ability study results may provide the basis for an estimate of

the treatability study goals in this case.

4.1.1 Remedy Screening Goals

Remedy screening tests are not always performed for soil

washing processes (see Section 3). If remedy screening tests

are performed, an example of the goal for those tests would

be to show that the wash fluid will solubilize or remove a

sufficient percentage (e.g., 50 percent) of the contaminants

to warrant further treatability studies, Another goal might be

to show that contaminant concentrations can be reduced by

at least 50 percent in the >2 mm soil fraction, using particle

size separation techniques.

These goals are only examples. The remedy screening

treatability study goals must be determined on a site-specific

basis.

Achieving the goals at this tier merely indicates that soil

washing has a chance of success and that further studies

will be useful. Frequently, such information is available based

on the type of soil and contaminant present at the site. Based

on such information, experts in soil washing technology can

often assess the potential applicability of soil washing without

performing remedy screening.

Example 1 describes a hypothetical site and a series of

simple jar tests that were used to evaluate the potential to

Example 1. Remedy Screening

An industrial facility in the southeastern United States was built in 1960 and operated until 1990. During that

time, various electronic component assembly and electroplating operations were conducted at the site.

Between 1960 and 1980, sludges and other process related wastes generated at the plant were buried in

onsite landfills. Sometimes, plating/etching solutions and other liquids were disposed of by open dumping

onto the ground or into sand-filled pits constructed for this purpose.

As a results of these past practices, soils in several areas at the site are contaminated with heavy metals,

namely copper, chromium, lead, nickel, and cadmium. Initial site investigations have shown that the average

and maximum sample values for metals found in soil borings are as follows:

Metal

Copper

Lead

Chromium

Nickel

Cadmium

Average 

(MgLkg)

2,500

1,000

1,200

450

75

Maximum

20,000

7,500

4,000

790

200

Soil borings at the site have shown that most of the contamination is located 4 to 6 feet below grade. About

5,000 to 10,000 cubic yards of soil are believed to be affected by the metals and volatile organic compounds

(VOCs).

Soils were described in the boring logs as clayey sands. A sample of soil, composited from soil borings

cuttings from various areas and depths in the contaminated zone, was sent to the lab for dry sieve particle

size analysis (ASTM methods); results indicated that 38 to 45 percent of the soil particles are >2 mm in

diameter, and 5 to 11 percent are between 1 mm and 2 mm in diameter.

Soil washing was considered as a potential technology to reduce the volume of contaminated soil for two

reasons. First, the sieve analysis showed that a large percentage of the soil (38 to 45 percent) was coarse

sand or gravel (>2 mm in particle size diameter). This indicated that a large percentage of the soil was likely

to respond favorably to soil washing and therefore could be eliminated from further treatment. Research at

the EPA and elsewhere has shown that soil washing is typically most effective in removing contaminants

from the >2 mm fraction. Second, the large quantity of soil affected by metal contaminants could potentially

justify the cost of assembling and operating on onsite washing system.

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A series of simple jar tests was conducted on the site using both hot and cold water to wash a composite

soil sample that broadly represented soil areas known to be contaminated with metals. Equal quantities of

soil and water were placed in a jar, shaken, and then poured across a #10 sieve screen. The particles lying

on the top of the sieve were rinsed with water and allowed to drip dry. The dry soil was then placed in a

clean, tared sample jar, weighed, and sent to the laboratory for total metal analysis. The tests were repeated

three times to measure variability. Average results showed that the soil washed with hot water (>2 mm

fraction) responded the best; the average metal concentrations in the soil before and after hot water washing

are shown below:

Metal

Soil Concentration 

Before Washing 

(i.e., whole soil, mg/kg)

Soil Concentration After

Hot Water Washing 

(i.e., >2 mm fraction, mg/kg)

Copper 2,000 500 (75% red.)

Lead 1,200 300 (75% red.)

Chromium 800 100 (88% red.)

Nickel 400 50 (88%red.)

Cadmium 50 15 (70% red.)

The test results indicate that metal reductions on the order of 70 to 88 percent are readily achievable with hot water.

Product/soil recovery rates on the order of 30 to 50 percent (based on comparison of recovered weights versus starting

weight of soil in each test) are achievable. In order to further confirm these initial findings and to maximize the efficiency

of the treatment process, bench tests are indicated.

use soil washing to remediate the site. The example

illustrates how to decide whether the remedy selection

treatability studies using soil washing should be performed.

4.1.2 Remedy Selection Treatability

Study Goals

The main objectives of this tier of testing are to:

• Measure the percentage of the contaminant that can

be removed from the soil through solubilization or from

the >2 mm. soil fraction by particle size separation

• Produce the design information required for the next

level of testing, should the remedy selection evaluation

indicate remedy design studies are warranted.

The actual goal for removal efficiency must be based on

site- and process-specific characteristics. The specified

removal efficiency must meet site cleanup goals, which are

based on a site risk assessment, or ARARs.

Example 2 illustrates the goal of a remedy selection

treatability study at the Superfund site introduced in

Example 1. In this example, the remedy selection

treatability studies

Example 2. Remedy Selection

As followup to the jar test results discussed in Example 1, a series of bench tests were designed to more

accurately determine the feasibility of using soil washing to reduce the volume of contaminated soil at the

facility. The bench tests included a series of studies, each designed to measure a single variable while

holding all others constant. The following treatment process variables were evaluated:

• Ratios of soil and wash water

• Washing/mixing/agitation time

• Wash water temperature

• Additives such as acids, surfactants, and chelating agents

• Rinse system cycles
18

In all, 24 different tests were completed and each test was performed in duplicate, as a measure of variance,

for a total of 48 tests. Soils recovered on the sieves and from wash waters (filtered to remove very fine soil

particles) were analyzed for the five metals of interest using standard EPA SW846 methods. The bench

tests also evaluated the possibility of altering screen sizes to capture a larger segment of clean soil (particles

>1 mm).

The bench test results for the >2 mm fraction showed that optimal results (as measured by total metal

concentration reductions) were obtained under the following conditions:

• Soil to wash water ratio of 1:2

• Mixing/agitation time of 15 minutes

• Wash water temperature of at least 100°F

• Wash water pH of 4-5

• Single 60 second rinse of the screened soil using pressure sprayer

This set of process conditions was able to reduce the concentration of all metals in the recovered >2 mm

fraction by at least 90 percent, and some by as much as 95 percent. Surfactants and chelating agents were

found to be counterproductive. They fouled the screening operations, and were not recommended for further

evaluation for this site. The tests also showed that similar results (85 to 90 percent effective reductions in

metal concentrations) could be obtained for the 1 to 2 mm particle size soil fraction. By separating the

washed soil into >1 mm and <1 mm size groups, over 50 percent of the original soil volume could be

effectively treated. However, particles smaller than 1 mm were not effectively cleaned by the process. In fact,

the <1 mm soil fraction carried higher concentrations of metals after sieving than the whole soil carried

before treatment. Hence, most of the metal contamination in these site soils is associated with soil particles

1 mrn or less in diameter.

Results from the study were compared to the proposed risk-based soil cleanup goals for the site. Based on

this comparison, the study showed that the proposed cleanup goals could be met for a least 50 percent of

the soil volume through the applied use of soil washing technology.

show that site cleanup goals can be met. Soil washing is

chosen as the selected remedy in the ROD.

4.2 EXPERIMENTAL DESIGN

4.2.1 Remedy Screening Tier

A jar test can be rapidly performed in an onsite laboratory to

evaluate the potential performance of soil washing as an

alternative technology. Jar tests are performed at the

equivalent of Analytical Levels I and II, which correspond to

field screening and field analysis, respectively.(11)

When assessing the need for jar tests, the investigator should

use available knowledge of the site location and any

preliminary analytical data on the type and concentration of

contaminants present. Soil engineering properties are

available from Soil Conservation Surveys. At this level of

treatability study, the most significant soil property is particle

size distribution. In survey documents, particle size

distribution is categorized into five groupings: fragments or

particles greater than 3 inches in diameter, and fragments

passing through #4 (4.75 mm), #10 (2.0 mm), #40 (0.425

mm), and #200 (0.07 mm) sieves. Generally, soils with a 10

to 15 percent passing rate through a #200 mesh screen have

proven ideal for soil washing. However, soil particle size is

not the only property to consider. The collective effect of all

soil and contaminant properties must be investigated. Even

soil characterized by a 95 percent passage through a #200

screen may be a possible candidate for soil washing if the

contaminant is water soluble or loosely bound to soil

particles.

Contaminant characteristics to examine during remedy

screening include solubility, miscibility, and dispersibility.

Properties of organic contaminants are generally easier to

evaluate than those of inorganic contaminants. Inorganics,

such as heavy metals, can exist in many compounds (e.g.,

oxides, hydroxides, nitrates, phosphates, chlorides, sulfates,

and other more complex mineralized forms), which can

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greatly alter their solubilities. Metal analyses typically provide

only total metal concentrations. More detailed analyses to

determine chemical speciation may be warranted.

The liquid used in the jar test is typically water, or water with

additives that might enhance the effectiveness of the soil

washing process. To save time and money, chemical

analyses should not be performed on the samples until there

is visual evidence that physical separation has taken place in

the jar tests. Jar tests can yield three separate fractions from

the original soil sample. These include a floating layer, a

wastewater with dispersed solids, and a solid fraction.

Chemical analysis can be performed on each fraction.

When performing the jar test, observe if any floating

materials can be skimmed off the top. Observe whether an

immiscible, oily layer forms, either at the top or the bottom,

indicating release of an insoluble organic material. Observe

and time the solids sealing rate and depth. Sand and gravel

settle first, followed by the silt and clay. The rate and the

relative volume of the settling material will provide some

indication of the particle size distribution in the contaminated

matrix and the potential for soil washing as a treatment

alternative. Further evidence can be gained by analyzing the

settled and filtered wash water for selected indicator

contaminants of concern. If simple washing releases a large

percentage of these contaminants into the wash water, then

soil washing can be viewed favorably, and more detailed

laboratory and bench tests must be conducted.

Variations on the jar tests can include the addition of

surfactants, chelants, or other dispersant agents to the water;

sequential washing; heated water washing versus cold water;

acidic or basic wash water; and tests that include both a

wash and a rinse step. The rinse water and fine soil fraction

(<2 mm particle size) should be separated from the coarse

soil fraction (>2 mm particle size) using a #10 sieve. No

attempt should be made during jar tests to separate the soil

into discrete size fractions; this is done at the remedy

selection tier of testing as described in Section 4.2.2.

Normally, only the coarse soil fraction should be analyzed for

contamination. In general, at least a 50 percent reduction in

total contaminant concentration in the >2 mm soil fraction is

considered adequate to proceed to the remedy selection tier.

The separation of approximately 50 percent of the total soil

volume as clean soil also indicates remedy selection studies

may be warranted.

To reduce analytical costs during the remedy screening tier,

a condensed list of known contaminants must be selected as

indicators of performance. The selection of indicator analytes

to track during jar testing should be based on the following

guidelines:

1) Select one or two contaminants present in the soil that

are most toxic or most prevalent.

2) Select indicator compounds to represent other chemical

groups if they are present in the soil (i.e., volatile and

sentivolatile organics, chlorinated and nonchlorinated

species, etc.)

3) If polychlorinated biphenyls (PCBs) and dioxins are

known to be present, select PCBs as indicators in the jar

tests and analyze for them in the washed soil. It is

usually not cost-effective to analyze for dioxins and other

highly insoluble chemicals in the wash water generated

from jar tests. Check for them later in the wash water

from remedy selection tests.

4.2.2 Remedy Selection Tier

This series of tests requires electricity, water, and additional

equipment be available. The tests are run under more

controlled conditions than the jar tests. The response of the

soil sample to variable washing conditions is fully

characterized. More precision is used in weighing, mixing,

and particle size separation. There is an associated increase

in quality assurance/quality control (QA/QC) costs. Treated

soil particles are separated during the sieve operations to

determine contaminant partitioning with particle size.

Chemical analyses are performed on the sieved soil particles

as well as on the spent wash waters. The impact of process

variables on washing effectiveness is quantified. This series

of tests is considerably more costly than jar tests, so only

samples showing promise in the remedy screening phase (jar

test) should be carried forward into the remedy selection tier.

If sufficient data are available in the prescreening step, the

remedy screening step may be skipped. Soil samples showing

promise in the prescreening step are carried forward to the

remedy selection tier. The objective of the remedy selection

soil washing design is to meet the goals discussed in Section

4.1.2.

A series of tests should be designed that will provide

information on washing and rinsing conditions best suited to

the soil matrix under study. The RREL data base should be

searched for information from previous studies. To establish

percent of contaminant removal, particle size separation, and

distribution of contaminants in the washed soil, the following

should first be studied: 1) wash time, 2) wash water-to-soil

ratio, and 3) rinse water-to-wash water ratio. Following those

studies, the effect of wash water additives on performance

should be evaluated.

Several factors must be considered in the design of soil

washing treatability studies. A remedy selection test design

should be geared to the type of system expected to

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be used in the field. Soil-to-wash water ratios should be

planned using the results from the jar tests, if jar tests are

performed. In general, a ratio of 1 part of soil to 3 parts of

wash water will be sufficient to perform remedy selection

tests. The soil and wash water should be mixed on a shaker

table for a minimum of 10 minutes and a maximum of 30

minutes. The soil-to-wash water ratio and mix times

presented here are rules of thumb to be used if no other

information is available.

Another factor to consider is the variability of the grain size

distribution. Gilsen Wet Sieve devices are recommended for

remedy selection studies. Ro-Tap or similar sieve systems

may also be used. Such devices will enhance the

completeness and reproducibility of grain size separation.

However, they are messy, expensive, and very noisy when

in operation. An alternate choice is to complete a series of

four to six replicate runs under exactly the same set of

conditions to obtain information on the variability of the grain

size separation technique. Variability in the separation

technique can be evaluated by comparing sieve screen

weights across runs and soil contaminant data for the same

fractions from each run. By identifying the range of

variability associated with repeated runs at the same

conditions, estimates can be made of the variability that is

likely to be associated with other test runs under slightly

different conditions.

Normally, only the wash water and the soil particles captured

by the sieve screen need to be analyzed for contaminants.

Experience has shown that little additional contaminant

removal is likely to be found in the rinse water. Rinsing is

important and must be included in the procedure since it

improves the efficiency of the grain size separation/sieving

process. Rinsing separates the fine from the coarse material.

This can result in a cleaner coarse fraction and more

contaminant concentrated in the fine fraction. Contaminant

concentration in the rinse water may be determined

periodically (e.g., 10 percent of the samples) to evaluate the

performance of the wash solution. However, very little

contamination is typically dissolved in the rinse solution.

Therefore, analyses of the rinse solution may have limited

value in verifying wash solution performance.

Initially, only the coarse soil fraction and the wash water

should be analyzed for indicator contaminants. If the removal

of the indicator contaminants confirms that the technology

has the potential to meet cleanup standards at the site,

additional analyses should be performed. All three soil

fractions and all wash and rinse waters must be analyzed for

all contaminants to perform a complete mass balance. The

holding time of soil fractions in the lab before extraction and

analysis can be an important consideration for some

contaminants.

The decision on whether to perform remedy selection testing

on hot spots or composite soil samples is difficult and must be

made on a site-by-site basis. Hot spot areas should be

factored into the test plan if they represent a significant

portion of the waste site. However, it is more practical to test

the specific waste matrix that will be fed to the full-scale

system over the bulk of its operating life. If the character of

the soil changes radically (e.g., from clay to sand) over the

depth of contamination, then tests should be designed to

separately study system performance on each soil type,

Additional guidance on soil sampling techniques and theory

can be found in Soil Sampling Quality Assurance User’s

Guide.(21) and Methods for Evaluating the Attainment of

Cleanup Standards.(18)

Additives such as oil and grease dispersants and chelating

agents can aid in removing contaminants from some soils.

However, they can also cause processing problems

downstream from the washing step. Therefore, use of such

additives should be approached with caution. Use of one or

a combination of those additives is a site-by-site

determination, Some soils do not respond well to additives.

Surfactants and chelating agents may form suspensions and

foams with soil particles during washing. This can clog the

sieves and lead to inefficient particle size separation during

screening. The result can be the recovery of soil fractions

with higher contamination than those cleaned by water alone.

Such results can make the data impossible to understand.

Additives can also complicate the rinse water process that

might follow the soil washing. Recent studies have shown

that counter-current washing-rinsing systems, incorporating

the use of hot water for the initial wash step, offer the best

performance in terms of particle size separation, contaminant

removal, and wastewater management (treatment, recycling

and discharge). Additional details regarding the performance

of surfactants and chelating agents in reducing lead

contamination in soils from battery recycling Superfund sites

can be found in Lead Battery Site Treatability Studies,

Project Summary(16)

4.3 EQUIPMENT AND MATERIALS

The Work Plan should specify the equipment and materials

needed for the treatability test. For example, the size and

type of glassware or containers to be used during the test

should be specified. Standard laboratory methods normally

dictate the types of sampling containers that can be used

with various contaminant groups. The RPM should consult

such methods for the appropriate containers to be used for

the treatability studies,(23) Normally, glass containers should

be used. Stainless steel can also be used with most

contaminants. Care should be taken when using

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various plastic containers and fittings. Such materials will

absorb many contaminants and can also leach plasticizer

chemicals, such as phthalates, into the soil matrix.

Appropriate methods for preserving samples and specified

holding times for those samples should be used.

The following equipment is recommended for remedy

selection soil washing tests:

Basic Equipment

• Reciprocating shaker table

• Four to six 10-liter glass jars and lids 

• pH meter

• Electric hot plate/magnetic stir mixer 

• Top-loading balance

• Four 2-liter graduated cylinders 

• Timer

• Stainless steel sieve screens (#10 and #60) - two sets

• Four collection pans/buckets for rinse and wash water

collection

• Sample jars 

• Scoops (disposable)

• Spray device for rinsing (stainless steel garden sprayers

work well)

• Filter and media 

• Vacuum pump

Optional Equipment

• Ro-Tap 

• Gilsen Wet Sieve

4.4 SAMPLING AND ANALYSIS

The Work Plan should describe the procedures to be used in

field and treatability study sampling. The procedures to be

used will be site-specific.

4.4.1 Field Sampling

A sampling plan should be developed that directs the

collection of representative soil samples from the site for the

treatability test. The sampling plan is site-specific. It

describes the number, location, and volume of samples.

Heterogeneous soils, variations in the contaminant

concentration profile, and different contaminants in different

locations in the site will complicate sampling efforts. If the

objective of the remedy screening or remedy selection

treatability tier study is to investigate the performance of soil

washing at the highest contaminant concentration, the sample

collection must be conducted at a “hot spot.” This will

require conducting a preliminary site sampling program to

identify the locations of highest contaminant concentration.

(This information is generated early in the RI process.) If the

soil and types of contaminants vary throughout the site,

extensive sampling may be required. If soil washing is being

considered only for certain areas of the site, the sampling

program may be simplified by concentrating on those areas.

If the objective of the remedy selection study is to investigate

the use of the technology for a more homogenous waste, an

“average” sample for the entire site must be obtained. This

will require a statistically based program of mapping the site

and selecting sampling locations that represent the variety of

waste characteristics and contaminant concentrations

present. The selection of soil sampling locations should be

based on knowledge of the site. Information from previous

soil samples, soil gas analysis using field instrumentation, and

obvious odors or residues are examples of information that

can be used to specify sample locations.

Chapter 9 of Test Methods for Evaluating Solid Waste(23)

presents a detailed discussion of representative samples and

statistical sampling methods. Additional sources of

information on field sampling procedures can be found in the

Annual Book of ASTM Standards,(1) and NIOSH Manual of

Analytical Methods (February 1984).(9) The EPA

publications Soil Sampling Quality Assurance User’s

Guide(21) and Methods for Evaluating the Attainment of

Cleanup Standards(18) should be consulted to plan effective

sampling programs for either simple or complex sites.

The method of sample collection is site-specific. For

example, drill rigs or hand augers can be used to collect

samples, depending on the depth of the sample required and

the soil characteristics. If the target contaminants are volatile

and the samples are composited, care should be taken to

minimize the loss of volatile compounds. Compositing

samples on ice is a good method for minimizing the loss of

volatile compounds. Compositing is usually appropriate for

soils containing nonvolatile constituents.

4.4.2 Waste Analysis

Section 2.2.3 detailed the physical tests that are useful in

characterizing the soil matrix at the site during the

prescreening step. The key for successful soil washing

treatability studies is to properly select the soil feedstock

(e.g., sand, loam, clay, etc.) based on the initial prescreening

and additional soil characterizations. Other important soil

characteristics include the pH and moisture content of the

soil. The pH is important in determining the compatibility of

soil washing fluids. The speciation of metal compounds

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may also be affected by soil pH. The soil moisture content is

an important consideration for materials handling.

Standard analyses for contaminants at Superfund sites should

identify the contaminants of concern. It is important to

determine the solubility and volatility of organics.

Contaminant solubility will give an indication of whether

washing solution additives will be required. Volatility will be

an important consideration for materials handling. If high

concentrations of volatiles are present, pretreatment (e.g.,

using soil vapor extraction) or collection and treatment of air

emissions may be required. Metal speciation will be an

important consideration in determining metal solubility.

The spatial distribution and variations in the concentrations of

contaminants will be important for the design of treatability

studies. Complex mixtures of contaminants may be difficult

to treat economically. A number of wash stages and

additives may be required to successfully remove many

contaminants. The cost of such a system may be prohibitive.

Frequent changes in contaminant composition can cause

dramatic changes in removal efficiencies.

4.4.3 Process Control Sampling and

 Analysis

This is not applicable to remedy screening and remedy

selection.

4.4.4 Treatment Product Sampling and

Analysis

Soil washing is not a stand-alone process (see Section 2.1.

1). It generates residuals that must be treated further and

disposed of properly. Because the nature of soil washing

equipment and procedures varies greatly between

manufacturers, remedy design testing is necessary to

evaluate the type, quantity, and properties of residuals.

Analyze the washed soil and each of the various

wastestreams (wash water, fine sediment, etc.) for the

contaminants identified in the original soil analyses. In many

cases, indicator contaminants, which are representative of a

larger group of contaminants, can be analyzed in place of a

full scan. Caution must be exercised in using indicator

contaminants since soil washing efficiencies can vary from

one contaminant to another. The process efficiency may be

either understated or overstated when analyzing for indicator

compounds.

If several soil washing studies are run to test the effects of

operating parameters on washing efficiency (i.e., the addition

of surfactants, chelating agents, etc.), samples should be

taken of each test before and after soil washing. Typically,

these tests are run in triplicate.

4.4.5 Sampling and Analysis Plan (SAP)

and Quality Assurance Project

Plan (QAPjP)

A SAP is required for all field activities conducted during the

RI/FS. The SAP consists of the Field Sampling Plan and the

QAFjP. This section of the Work Plan describes how the

RI/FS SAP is modified to address field sampling, waste

characterization, and sampling activities supporting

treatability studies. It describes the samples to be collected

and specifies the level of QA/QC required. See Section 5 for

additional information on the SAP.

4.5 DATA ANALYSIS AND

 INTERPRETATION

The Work Plan should discuss the techniques to be used in

analyzing and interpreting the data. The objective of data

analysis and interpretation is to provide sufficient information

to the RPM and EPA management to assess the feasibility

of soil washing as an alternative technology. After remedy

selection testing is complete, the decision must be made

whether to proceed to the remedy design testing tier, to a

full-scale soil washing remediation, or to rule out soil washing

as an alternative. The data analysis and interpretation are a

critical part of the remedy selection process.

Methods commonly used to analyze and interpret data

generated in the soil washing process, such as particle size

distribution of the soil, chemical analysis of the contaminants

present, and test process variables, apply to all three tiers of

the soil washing treatability study.

The particle size distribution of the soil is a standard physical

characterization technique. Recent studies indicate that

contamination is often distributed as a function of soil particle

size. Treatment efficiency is a function of particle size as

well. Three particle size ranges have been frequently studied:

>2 mm, 0.25 to 2 mm, and <0.25 mm. These fractions are

obtained from U.S. Standard Sieve Series #10 and #60.

Figure 4-1 shows the applicable particle size ranges plotted

against the sieve throughput percent by weight.(12.)

Range I consists of coarse soils. Soils in Range I are

economically washed with simple particle size separation

when contaminants are concentrated in the smaller particles.

When fractionation does not occur, as is the case
23

with lead, there is no improvement in the economics of

separation when the soil is in Range I.

Soils in the area to the right of Range I are primarily stone

and large gravel. Particle size separation is normally not

feasible for these materials due to their, large size. However,

soluble contaminants may be removed from such soils in the

wash water.

Most contaminated soils lie in Range II. The types of

contaminants present govern. the composition of wash fluids

and affect the overall process efficiency. Process efficiency

is also affected by soil particle distribution patterns and the

fractionation of contaminants in fine particles. Both particle

size separation and contaminant solubilization can be

important for cost-effective treatment of soils in Range II.

Soils in Range III consist primarily of fine sand, silt, and clay.

Frequently, such soils have high humic content and organics

may be strongly adsorbed. Particle size separation may be

effective in concentrating contaminants adsorbed to particles

in this size range into a smaller volume.(12)

Figure 4-2 is a hypothetical contaminant distribution

histogram for soil. The histogram represents results of

chemical analyses on contaminated bulk and fractionated soil

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24

before and after two treatments. The soil was treated with

water at ambient temperature and hot water. The data show

that contaminant is concentrated in the <2 mm soil fractions.

Water at ambient temperature was able to reduce the

contamination in the >2 mm fraction to 10 parts per million

(ppm) (a contaminant reduction of approximately 94

percent). Hot water improved the performance by reducing

the contaminant concentration to 0.45 ppm in the >2 min

fraction (a contaminant reduction of over 99 percent).

Contaminant concentrations in the other fractions (0.25 to 2

mm and <0.25 nun) were not appreciably affected by soil

washing.

Figure 4-3 shows a plot of agitated contact time against

contaminant removal efficiency and final contaminant

concentration in the >2 mm soil fraction. The contaminant

concentration in each soil fraction would normally be plotted

at each time point. In this graph, the initial concentration is

500 ppm and the contaminant cleanup goal is 200 ppm. It is

apparent that the agitated contact time must be a minimum

of 14 minutes to provide contaminant removal efficiencies

that meet the cleanup goals. The effectiveness of treatment

can be expressed as a percent reduction of contaminant. In

this case, there is a 60 percent reduction in contaminant

concentration in the >2 mm soil fraction at 14 minutes. The

figure also demonstrates that, for the soil studied, mixing

times of greater than 14 to 15 minutes result in diminishing

returns. The shape of this curve will be different for each

soil.

An objective of the remedy selection soil washing treatability

testing is to determine how the treatment is affected by the

process design variables. These variables may include

soil-to-wash water ratio, type of mechanical agitation used,

agitated contact time, rinse-water-to-wash water volume

ratio, wash water temperature, system pH, and wash water

additives. Often, two or more of these variables may affect

the results. Statistical analysis of the data can be performed

using standard techniques to differentiate sources of change

and interactions between these sources. For a detailed

discussion of the ANOVA techniques, refer to the document

entitled Statistical Analysis of Groundwater Data at RCRA

Facilities (Interim Final)(20) and Brookes, et al.(5)

4.6 REPORTS

The last step of the treatability study is reporting the results.

The Work Plan discusses the organization and content of

interim and final reports. Complete, accurate reporting is

critical because decisions about implementability will be

partly based on the outcome of the study. The RPM may not

require formal reports at each soil washing study tier. Interim

reports should be prepared after each tier. Project briefings

should be made to interested parties to determine the need

for and scope of the next tier of testing. To facilitate the

reporting of results and comparisons between treatment

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25

gested table of contents is presented in the generic guide.(15)

At the completion of the study, a formal report is always

required.

OERR requires that a copy of all treatability study reports be

submitted to the Agency’s Superfund Treatability Data Base

repository. One copy of each treatability study report must

be sent to:

U.S. Environmental Protection Agency 

Superfund Treatability Data Base 

ORD/RREL 

26 West Martin Luther King Dr. 

Cincinnati, Ohio 45268

4.7 SCHEDULE

The Work Plan includes a schedule for completing the

treatability study. The schedule gives the anticipated starting

date and ending date for each of the tasks described in the

Work Plan and shows how the various tasks interface.

The time span for each task accounts for the time required

to obtain the Work Plan, subcontractor, and other approvals

(e.g., disposal approval from a commercial TSDF); sample

curing time, if necessary; analytical turnaround time; and

review and comment period for reports and other project

deliverables. Some slack time also should be built into the

schedule to accommodate unexpected delays (e.g., bad

weather, equipment downtime) without affecting the project

completion date.

The schedule is usually displayed in the form of a bar chart

(Figure 4-4). If the study involves multiple tiers of testing, all

tiers should be shown on one schedule. Careful planning

before the start of the tests is essential. Depending on the

review and approval process, planning can take up to several

months. Barring any difficulties, such as acquiring sampling

equipment and site access, the field work phase can

generally be accomplished in two weeks. Setup of the

laboratory and procurement of necessary equipment and lab

supplies for treatability studies may take a month. Analytical

results can be available in less than 30 days, depending on

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vided. Shorter analytical turnaround time can be requested

but this will normally double the costs. Compounds such as

pesticides and PCBs may require longer turnaround times

due to the extractions and analyses involved. Depending on

the objectives,, the duration of treatability tests may be

longer.

Interpretation of the results and final report writing may take

1 to 2 months, but this is highly dependent on the review

process. Remedy screening tests typically take from a few

hours to several days. It is not unusual for the remedy

selection soil washing treatability test to be a 2 to 3 month

project.

4.8 MANAGEMENT AND STAFFING

The Work Plan discusses the management and staffing of

the remedy selection treatability study. The Work Plan

specifically identifies the personnel responsible for executing

the treatability study by name and qualifacations. Generally,

the following expertise is needed for the successful

completion of the treatability study:

• Project Manager (Work Assignment Manager)

• Chemist

• Geologist

• Lab Technician

Responsibility for various aspects of the project is typically

shown in an organizational chart such as the one in Figure

4.5

4.9 BUDGET

The Work Plan discusses the budget for completion of the

remedy selection treatability study. Testing costs for remedy

selection depend on a variety of factors. Table 4-2 provides

a list of potential major cost estimate components this tier.

For most tests, the largest single expense is the

analytical program.

TABLE 4-2.Major Cost Elements Associated with 

Remedy Selection Soil Washing Studies

Cost Element

Cost Range 

(1,000s of dollars)

Initial Data Review 1 - 10

Work Plan Preparation 1 - 5

Field Sample Collection 1 - 10

Field Sample Chemical Analysis 5 - 25

Laboratory Setup/Materials 5 - 25

Treatability Test Chemical Analysis 5 - 20

Data Presentation/Report 2 - 5

TOTAL COST RANGE 20 -100

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Sites where the soil types, contaminant types, and

contaminant concentration vary widely will usually require

more samples than sites where the soil and contamination is

more homogeneous. It is not unusual for the sampling,

analysis, and QA activities to represent 50 percent of the

total testing cost. In general, the costs for analyzing organics

are more expensive than for metals. Actual costs will vary

according to individual laboratories, required turnaround

times, volume discounts, and any customized testing.

Sampling costs will be influenced by the contaminant types

and depth of contamination found in the sod. The health and

safety considerations during sampling activities are more

extensive when certain contaminants (e.g., volatile organics)

are present in the soil. Level B personal protective equipment

(PPE) rather than Level D PPE can increase the cost

component an order of magnitude. Sampling equipment for

surface samples is much less complicated than equipment

used for depth samples. Depending on the number of

samples and tests specified, residuals management (e.g.,

contaminated soil fraction and wash waters) will require

proper treatment and/or disposal. Treatment and disposal of

the residuals as hazardous wastes increases costs

significantly.

Other factors to consider include report preparation and the

availability of vital equipment and laboratory supplies.

Generally, an initial draft of the report undergoes internal

review prior to the final draft. Depending on the process,

final report preparation can be time consuming as well as

costly. Procurement of testing equipment (e.g., reciprocating

shaker table) and laboratory supplies (e.g., reagents and

glassware) will also increase the costs.

Typical costs for remedy selection tests are estimated to be

from $20,000 to $100,000. Remedy screening, with its

associated lack of replication and detailed testing, ranges

from 25 to 50 percent of these costs. These estimates are

highly dependent on the factors discussed above. Not

included in these costs are the costs of governmental

procurement procedures, including soliciting for bids,

awarding contracts, etc.

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SECTION 5 

SAMPLING AND ANALYSIS PLAN

The Sampling and Analysis Plan (SAP) consists of two

parts–the Field Sampling Plan (FSP) and the Quality

Assurance Project Plan (QAPjP). The purpose of this

section is to identify the contents and aid in the preparation

of these plans. The RI/FS requires a SAP for all field

activities. The SAP ensures that samples obtained for

characterization and testing are representative and that the

quality of the analytical data generated is known and

appropriate. The SAP addresses field sampling, waste

characterization, and sampling and analysis of the treated

wastes and residuals from the testing apparatus or treatment

unit. The SAP is usually prepared after Work Plan approval.

5.1 FIELD SAMPLING PLAN

The FSP component of the SAP describes the sampling

objectives; the type, location and number of samples to be

collected; the sample numbering system; the equipment and

procedures for collecting the samples; the sample

chain-of-custody procedures; and the required packaging,

labeling, and shipping procedures.

The sampling objectives must be consistent with the

treatability test objectives. The primary objective of remedy

selection treatability studies is to evaluate the extent to which

specific chemicals are removed from the soil. The primary

sampling objectives include:

• Acquisition of samples representative of conditions

typical of the entire site or defined areas within the site.

Because a mass balance is required for this evaluation,

statistically designed field sampling plans may be

required. However, professional judgment regarding the

sampling locations may be exercised to select sampling

sites that are typical of the area (pit, lagoon, etc.) or

appear above the average concentration of contaminants

in the area being considered for the treatability test.

Selection may be difficult because reliable site

characterization data may not be available early in the

remedial investigation.

• Acquisition of sufficient sample volumes necessary for

testing, analysis, and quality assurance and quality

control (QA/QC). 

From these two primary objectives, more specific objectives

are developed. When developing the more detailed

objectives, consider the following types of questions:

• Will samples be composited to provide more

representative samples for the treatability test, or will the

potential loss of target volatile organic compounds

prohibit this sample collection technique?

• Is there adequate data to determine sampling locations

indicative of the more contaminated areas of the site?

Contaminants may be widespread or isolated in small

areas (hot spots). Contaminants may be mixed with other

contaminants in one location and appear alone in others.

Concentration profiles may vary significantly with depth.

• Are the soils homogeneous or heterogeneous? Soil types

can vary across a site and will vary with depth. Changes

in soil composition can reduce the effectiveness of soil

washing.

• Is sampling of a “worst-case” scenario warranted? The

decision on whether to perform remedy selection testing

on specific areas or composite samples is difficult and

must be made on a site-by-site basis. Hot spots and

areas with soils that may be difficult to treat should be

factored into the test plan if they represent a significant

portion of the waste site.

After identifying the sampling objectives, an appropriate

sampling strategy is described. Specific items that should be

briefly discussed in the FSP and QAPjP are listed in Table

5-1.

Table 5-1 presents the suggested organization of the Sampling and Analysis Plan.

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TABLE 5-1. Suggested Organization of Sampling and

Analysis Plan

Field Sampling Plan

1 . Site Background

2. Sampling Objectives

3. Sample Location and Frequency

– Selection 

– Media Type

– Sampling Strategy

– Location Map

4. Sample Designation

– Recording Procedures

5. Sample Equipment and Procedures

– Equipment

– Calibration

– Sampling Procedures

6. Sample Handling and Analysis

– Preservation and Holding Times

– Chain-of-Custody

– Transportation

Quality Assurance Project Plan

1. Project Description

– Test Goals

– Critical Variables

– Test Matrix

2. Project Organization and Responsibilities

3. QA Objectives

– Precision, Accuracy, Completeness

– Representativeness and Comparability

– Method Detection Limits

4. Sampling Procedures

5. Sample Custody

6. Calibration Procedures and Frequency

7. Analytical Procedures

8. Data Reduction, Validation, and Reporting

9. Internal QC Checks

10. Performance and System Audits

11. Preventive Maintenance

12. Calculation of Data Quality Indicators

13. Corrective Action

14. QC Reports to Management

15. References

16. Other Items

5.2 QUALITY ASSURANCE PROJECT

 PLAN

5.2.1 Experimental Design

Section 1 of the QAPjP must include an experimental project

description that clearly defines the experimental design, the

experimental sequence of events, each type of critical

measurement to be made, each type of matrix (experimental

setup) to be sampled, and each type of system to be

monitored. This section may reference Section 4 of the Work

Plan. All details of the experimental design not finalized in

the Work Plan should be defined in this section.

Items to be included, but not limited to, are:

• Number of samples (area) to be studied

• Identification of treatment conditions (variables) to be

studied for each sample (i.e., wash time, wash waterto-soil ratio, rinse water-to-wash water ratio, and

additives to be evaluated)

• Soil size fractions

• Target compounds for each sample

• Number of replicates per treatment condition

The Project Description clearly defines and distinguishes the

critical measurements and observations made and system

conditions (e.g., process controls, operating parameters, etc.)

routinely monitored. Critical measurements are those

measurements, data gathering, or data generating activities

that directly affect the technical objectives of a project. At a

minimum, the determination of the target compound

(identified above) in the untreated and treated soil samples

and the particle size distribution of the untreated soil will be

critical measurements.

The purpose of the remedy selection treatability study is to

determine whether soil washing can meet cleanup goals and

provide information to support the detailed analysis of

alternatives (i.e., seven of the nine evaluation criteria). An

example of a criterion for this determination is a removal of

approximately 90 percent of the contaminants. The exact

removal efficiency specified as the goal for the remedy

selection test is site specific.

5.2.2 Quality Assurance Objectives

Section 2 lists the QA objectives for each critical

measurement and sample matrix defined in Section 1. These

objectives are presented in terms of the six data quality

indicators: precision, accuracy, completeness,

representativeness, comparability, and, where applicable,

method detection limit.

5.2.3 Sampling Procedures

The procedure used to obtain field samples for the treatability

study is described in the FSP. They need not be
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repeated in this section, but should be incorporated by

reference.

Section 3 of the QAPjP contains a description of a credible

plan for subsampling the material delivered to the laboratory

or the treatability study. The methods for aliquoting the

residual material in each size fraction for different analytical

methods must be described.

5.2.4 Analytical Procedures and

 Calibration

Section 4 describes or references appropriate analytical

methods and standard operating procedures for the analytical

method for each critical measurement made. In addition, the

calibration procedures and frequency of calibration are

discussed or referenced for each analytical system,

instrument, device, or technique for each critical

measurement.

The methods for analyzing the treatability study samples are

the same as those for chemical characterization of field

samples. Preference is given to methods in “Test Methods

for Evaluating Solid Waste, SW-846, 3rd. Ed., November

1986.(23) Other standard methods may be used, as

appropriate.(17) Methods other than gas

chromatography/mass spectra (GC/MS) techniques are

recommended to conserve costs when possible.

The purpose of the remedy selection treatability study is to

detennine whether soil washing can meet cleanup goals and

provide information to support the detailed analysis of

alternatives (i.e., seven of the nine evaluation criteria). An

example of a criterion for this determination is a removal of

approximately 90 percent of contaminants. The exact

removal efficiency specified as the goal for the remedy

selection test is site-specific. The suggested QC approach

will consist of:

• Triplicate samples of both reactor and controls

• The analysis of surrogate spike compounds

• The extraction and analysis of method blanks

• The analysis of a matrix spike in approximately 10

percent of the samples.

The analysis of triplicate samples provides for the overall

precision measurements that are necessary to determine

whether the difference is significant at the chosen

confidence level. The analysis of the surrogate spike will

determine if the analytical method performance is consistent

(relatively accurate). The method blank will show if

laboratory contamination has had an impact on the analytical

results.

Selection of appropriate surrogate compounds will depend on

the target compounds identified in the soil and the analytical

methods selected for the analysis.

5.2.5 Data Reduction, Validation and

 Reporting

Section 5 includes, for each critical measurement and each

sample matrix, a specific presentation of the following items:

• The data reduction planned for the collected data

• All equations used to calculate the final resultant value(s)

from the raw critical measurement data, all unit

conversions required and definitions of all terms, as well

as the procedures for correcting analytical recovery

• The procedures used to validate data during data

collection, transfer, storage, recovery, processing, and

reporting steps

• The methods used to identify and treat outliers (i.e., data

that fall outside the specified QA objective windows for

method precision and accuracy)

• The data reporting scheme, including the flow from raw

data through transfer, storage, recovery, processing, and

validation; a flowchart is usually needed

• Identification of the specific individuals responsible for

data handling at each step in the reporting scheme.

5.2.6 Internal Quality Control Checks

Section 6 describes and references each specific internal QC

method followed, and indicates the frequency of use. (The

terminternal refers to both soil washing tests and laboratory

activities, and applies to all organizations and individuals

involved in the project.) Examples of the types of QC checks

include the following:

• Split samples

• Replicate samples

• Replicate check standards

• Matrix-spiked samples
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• Matrix-spiked replicates

• Laboratory pure water spikes (e.g., QC check samples)

• Surrogate spike compounds

• Internal standards

• Blanks (method, reagent, and/or instrument)

• Control charts (e.g., for calibration acceptance limits)

• Calibration standards and devices (traceable)

• Reagent checks (for all sample preparation and analysis

methods involving the use of laboratory reagents)

• In-house proficiency testing prograrn to determine

analyst’s capabilities (including documented procedures).

5.2.7 Performance and Systems Audits

Section 7 describes the internal performance evaluation and

technical system audits planned to monitor the capability and

performance of the systems for obtaining critical

measurement data.

At a minimum, a person independent of the analysis submits

a quality control sample for all or some of the target

compounds to the analytical laboratory. The results of the

extraction and analysis document the capabilities of the

personnel with the prescribed procedures.

5.2.8 Calculation of Data Quality

Indicators

Section 8 describes the specific procedures that assess, on a

routine basis, the precision, accuracy, completeness, and

method detection limit (MDL) characteristic of each critical

measurement for each sample matrix. Specifically, the

following items are included:

• A brief description of each test procedure for each data

quality indicator, measurement, and sample type

• Identification of the specific QC data used in each test

procedure

• A brief discussion defining the statistical or mathematical methods used 

• Specific equations used to calculate each data quality

indicator, including definitions of reporting units of each

term in the equations

• A statement of the frequency of each type of test.

5.2.9 Corrective Action

Section 9 describes the criteria and procedures by which

initial corrective actions are implemented. These descriptions

include the following elements:

• The predetermined limits for data acceptability; data

outside these limits require corrective action

• The procedures for corrective action, from initial

recognition of the condition requiring corrective action,

through reporting of the condition, approval of the

appropriate corrective action to be taken,

implementation, and reporting of the results

• Identification of the individuals responsible for initiating,

approving, implementing, and reporting the effectiveness

of corrective actions.

5.2.10 Quality Control Reports

Section 10 describes the QA/QC information that will be

included in the final project report. As a minimum, reports

include:

• Changes to the QA Project Plan, if any

• Limitations or constraints on the applicability of the data,

if any

• The status of QA/QC programs, accomplishments and

corrective actions

• Results of technical systems and performance evaluation

QC audits

• Assessments of data quality in terms of precision,

accuracy, completeness, method detection limit,

representativeness, and comparability.

The final report contains all the QA/QC information to

support the credibility of the data and the validity of the

conclusions. This information may be presented in an

appendix to the report. Additional information on data quality

objectives(11), quality assurance programs(13), and preparation

of QAPjPs(19) is available in EPA guidance documents.
33

SECTION 6

TREATABILITY DATA INTERPRETATION

Proper evaluation of the potential of soil washing for

remediating a site must compare the test results (described

in Section 4.5) to the test objectives (described in Section

4.1) for each tier. The evaluation is interpreted in relation to

seven of the nine RI/FS evaluation criteria, as appropriate.

The remedy screening tier establishes the general

applicability of the technology. The remedy design tier

provides information in support of the evaluation criteria. The

test objectives are based on established cleanup goals or

other performance-based specifications (such as waste

volume reduction). Soil washing testing must consider the

technology as part of a treatment train.

Section 4.6 of this guide discusses the need for the

preparation of interim and final reports and provides a

suggested format. In addition to the raw and summary data

for the treatability study and associated QC, the treatability

report should describe what the results mean and how to use

them in the feasibility study in screening/selecting

alternatives. The report must evaluate the performance of

the technology and give an estimate of the costs of further

treatability studies and final remediation with the technology.

6.1 TECHNOLOGY EVALUATION

Remedy screening treatability studies typically consist of

simple jar tests. The contaminant concentration in the soil

before washing is compared to the contaminant

concentration in the coarse soil fraction after washing. A

reduction of approximately 50 percent of the soil

contaminants during the test indicates additional treatability

studies are warranted. Contaminant concentrations can also

be determined for wash water and fine soil fractions. These

additional analyses add to the cost of the treatability test and

may not be needed. Before and after concentrations can

normally be based on duplicate samples at each time period.

The mean values are compared to assess the success of the

study. A number of statistical texts are available if more

information is needed.(4)(7)

Jar tests can frequently be skipped when information about

the soil type and contaminant solubilities is sufficient to

decide whether remedy selection studies will be useful. An

example of a prescreening evaluation and decision to bypass

ajar test is provided in Example 3.

Example 3

A site in New Jersey has been used for the manufacture and storage of arsenic-containing pesticides. Soils

at the site are contaminated with arsenic at levels ranging from 10 to 1,500 mg/ kg. The arsenic

contamination is limited to the top 3 feet of soil. Sieve testing has shown that the upper 3 feet of soil contains

75 percent coarse sand and gravel (75 percent >2 mm diameter particles) by weight. Risk assessment

studies conducted during the RI suggest that a cleanup goal of 100 mg/kg arsenic in onsite soils would be

acceptable.

Previous studies indicated that many contaminants tend to be adsorbed on fine soil particles. Given this

scenario, one can predict that there is at least a moderate chance that soil washing will be effective. It is

entirely possible that the process will be able to reduce the arsenic content in 75 percent of the soil to 100

mg/kg or less. In this case, screening tests may be skipped in favor of conducting remedy selection tests

that would determine optimal soil washing conditions (pH, additives, temperature, mixing/contact time,

wastewater treatment) and performance at bench scale.

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34

Sections 4.1 and 4.2 of this guide discuss the goals and

design of remedy selection treatability studies, respectively.

Typically, soil contaminant concentrations before soil

washing and contaminant concentrations in the coarse

fraction after soil washing are measured in triplicate. A

reduction of approximately 90 percent in the mean

concentration indicates soil washing is potentially useful in

site remediation. A number of other factors must be

evaluated before deciding to proceed to remedy design

studies.

The final concentrations of contaminants in the recovered

(clean) soil fraction, in the fine soil fraction and wastewater

treatment sludge, and in the wash water are important to

evaluating the feasibility of soil washing. The selection of

technologies to treat the fine soil and wash water wastestreams depends on the types and concentrations of

contaminants present. The volume reduction achieved is also

important to the selection of soil washing as a potential

remediation technology.

In scaling the cost and performance estimates from remedy

selection testing to remedy design testing or a full-scale soil

washing system, the factors for consideration are:

Performance capabilities of the soil washing process,

including design parameters

• Contaminants and contaminant concentrations in the

coarse soil fraction

• Contaminants and contaminant concentrations in the

used wash water and in the fine soils and wastewater

treatment sludges

• Risk analysis evaluation for worker and community

protection

• Quantity of large rocks, debris, arid other screenable

material

The design parameters for the soil washing process include

soil throughput, in dry tons per hour, and optimum wash

water usage in gallons per dry ton of soil. The dosage of

additives, if used, mixed with wash water is also important

for cost and performance estimates.

It is important to estimate the volume and physical and

chemical characteristics of each soil fraction. Estimates of

the volume of and contaminant concentrations in the fine soil

fraction are needed to design treatment systems and estimate

disposal costs. Recycled water can be used to evaluate the

cost of filtration and other dewatering equipment. The ability

to remove contaminants from spent wash water and recycle

the water through the system is an important cost

consideration.

Wash water is treated for recycle in the washing process.

Treatment includes separation of fine soil particles. Other

treatment steps may be necessary to remove organics,

inorganics, and additive chemicals. Scale-up design requires

estimates of wash water volume and quality.

Contamination in excavated soil can pose safety concerns for

workers and the community. Worker protection may be

required during soil excavation. The need for such protection

is a site-specific decision. Health and safety plans should be

prepared and risk analysis conducted for the site.

The quantity of large rocks, debris, and other screenable

material that must be removed is an important measurement.

While this is not a “laboratory” measurement, it is important

to determine which treatment method is most suitable for

preparing the bulk soil for entry into the soil washing process

(i.e., screening to remove large rocks, stumps, debris, and

crushing of oversize rocks, etc.).

6.2 ESTIMATION OF COSTS

Accurate cost estimates for remedy design treatability

studies and full-scale remediation are crucial to the feasibility

study process. Comparisons of various technologies must be

based on the most complete and accurate estimates

available, Remedy screening treatability studies cannot

provide this type of information. Remedy selection treatability

studies can provide relatively accurate cost estimates for

remedy design studies. Preliminary cost estimates for

full-scale remediation may be made from remedy selection

data. Such estimates may be good enough for comparisons

to other technologies at the same tier of testing. On this basis,

the estimates can form the basis of the ROD. Remedy

design studies may be necessary to provide a more accurate

estimate of the eventual cost of full-scale soil washing

remediation. This is especially true since soil washing will

form only one component of a treatment train. The treatment

costs for sludge and wastewater from the soil washing

process must also be evaluated.

6.2.1 Soil Washing Remedy Design

Cost Estimates

If the results of remedy selection treatability testing indicate

that soil washing can be effective, consideration may be

given to remedy design testing. Remedy design tests

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35

yield more accurate estimates of full-scale performance and

costs. This discussion provides general guidance on the cost

estimating and scheduling of remedy design soil washing

demonstrations.

Few remedy design soil washing demonstrations have been

done in the United States. A solid data base of cost

estimating and scheduling information does not yet exist. The

information in this section is largely derived from EPA RREL

experience with its portable soil washing unit, informational

estimates by the few manufacturers offering remedy design

soil washing equipment, and recent experience with the EPA

SITE Program. A summary of the performance data and a

review of the technology are presented in a Soil Washing

Engineering Bulletin.(12)

Remedy Design Soil Washing Equipment Availability:

As of Fall 1989 only three sources of a portable remedy

design soil washing units were identified:

• BioTrol, Inc., Chaska, Minnesota

• Ecova Corp., Redmond, Washington

• EPA RREL Laboratory, Edison, New Jersey

Mitarri, Inc., Golden, Colorado, reportedly plans to develop a

remedy design unit. For the SITE Program, a remedy design

BioTrol soil washing unit was recently demonstrated and

evaluated in New Brighton, Minnesota.

Remedy Design Testing Cost: Many of the cost considerations in a remedy design soil washing test are similar to

those of the remedy selection. Table 6-1 lists potential major

cost estimate components in a remedy design soil washing

field test. Some of the items in this table also pertain to

remedy selection testing. The cost considerations include

planning, treatment, laboratory testing, and report

preparation. Substantial planning is necessary to assure that

tests meet desired objectives. Additional insurance and

permits may be required. As with remedy selection

demonstrations, the analytical program can be the largest

cost component. It is not unusual for the sampling, analysis,

and QA activities to represent 50 to 60 percent of the total

remedy design testing cost. Remedy design testing requires

personnel safety protection for soil excavation and handling.

Working under Level A or B protection can easily triple labor

costs. The treatment and disposal of contaminated residuals

(soil, sludge, water) can be a major expense. For these

reasons, remedy design testing costs are highly variable

depending on a variety of factors discussed above.

The cost of remedy design testing is highly site-specific and

dependent upon the test objective. As a rough estimate,

remedy design field tests could be expected to range from as

low as $100,000 up to $500,000 (1989 costs) or more.

TABLE 6-1. Potential Major Cost Estimate

Components in a Remedy Design Soil

Washing Field Test

1. Planning-- substantial advanced planning is usually

necessary to assure that the demonstration

proceeds smoothly and meets the desired

objectives, including any necessary insurance,

permits, etc.

2. Excavation, transport (if needed), and storage (if

needed) of the soil to be treated during the

demonstration.

3. Design and construction (as required) of temporary

onsite support facilities, including water supply,

power , wastewater discharge, storage of additive

chemicals, and personnel facilities (office, storage,

field testing space, restrooms, showers, etc.). A

detailed sampling analysis and QAPjP is

necessary.

4. Analytical support, e.g., local laboratory, mobile

field laboratory, etc. A detailed sampling analysis

and QAPjP is necessary.

5. Treatment and/or disposal of contaminated

residuals, e.g., the contaminated soil fraction,

sludges, screened-out debris, etc.

6. Supply of chemicals, water, power, spare parts,

personnel protection equipment, etc.

7. Lease or rental of the remedy design unit and

auxiliary equipment including transport to the site.

8. Provision for operating, maintenance, and

analytical labor. Usually, personnel are trained for

handling hazardous materials safely in addition to

their other job-specific qualifications.

9. Implementation of the remedy design

demonstration in accordance with the detailed

Work Plan.

10. Decontamination, demobilization, and return

transport of remedy design soil washing unit and

auxiliary equipment.

11. Return of operating site to pre-agreed condition.

12. Laboratory testing.

13. Report preparation.

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6.2.2 Full-Scale Soil Washing Cost

Estimates

There are no full-scale soil washing operations in use at

Superfund sites identified at the present time. A limited

number of firms (e.g., Ecova, BioTrol) are marketing their

soil washing processes. In Europe, full-scale soil washing

facilities are operating in Germany and the Netherlands. Cost

information is largely in technical articles written by

representatives of the German firm, Harbauer GmbH. The

capital cost of the Harbauer facility is reported to be

approximately $6 million (1986 dollars) for a 15 to 20 ton/hr

facility. The reported operation and maintenance (O&M)

costs for processing alone at the Harbauer Site are $150 per

ton of soil, including the cost of water treatment, but not

including sludge disposal. If sludge weight was assumed to

be 20 percent of the incoming soil weight, and sludge disposal

cost assumed to be $250 per ton, the estimated cost per ton

of treated soil would be about $200 including sludge disposal.

Other European soil washing operations that are less

complex than the Harbauer GmbH Berlin operation report

soil washing processing costs of about $80 to $120 per metric

ton or $73 to $110 per ton. Their costs are generally

presented in mid-1980's dollars and details of how these

costs were determined are lacking. Table 6-2 lists the major

cost components for a hypothetical full-scale soil washing

operation.

TABLE 6-2. Major Cost Estimate Components in a

Full-Scale Soil Washing Operationa

1. Soil excavation.

2. Transport of excavated soil to the processing unit.

3. Temporary stockpiling of excavated soil.

4. Prevention of contaminant releases to the

environment during Steps 1 through 3 above due to

rain, wind, volatilization, carelessness, etc.

5. Bulk soil pretreatment steps such as screening,

crushing, and physicat/chemical characterization.

6. Management of the screened-out rocks, roots,

debris, etc.

7. Wash water supply facilities, e.g., storage tanks,

pumps, piping, controls, etc.

8. Additive (if any) supply facilities, e.g., storage

tanks, pumps, piping, controls, etc.

9. The soil washing process unit, which may consist

of a series of mixers, washers, screens,

conveyors, cyclones, and other units. It is

assumed that generally this cost will be obtained

from the manufacturer.

10. Temporary stockpiling, transport, and deposition of

the adequately clean, washed soil product fraction.

11. The dirty wash water treatment process, which is

usually a treatment train that may include

clarifiers, chemical reactors, filters, carbon

contactors, dewatering presses, and tanks, etc.

12. Recycle or disposal of the treated wastewater

fraction.

13. Further treatment and disposal of the dirty soil

fraction.

14. Further treatment and disposal of the water

treatment sludge.

15. Permitting and legal services.

16. Engineering design.

17. Service during construction.

18. Contingencies.

a. Note: where applicable, the engineer performing the cost

estimate will usually break down the cost estimate

components listed above into:

(1) construction (e.g., roads, foundations, buildings, etc.)

(2) process equipment (e.g., mixers, tanks, screens, pumps,

clarifiers, etc,)

(3) material handling equipment (eg., power shovel, bulldozer ,

portable conveyor, trucks, etc.)

(4) labor (e,g., operators, supervisors, analytical, etc.), energy

(e.g., electrical power, diesel fuel, etc.), utilities (e.g., water,

sewage, etc.), materials (e.g., chemical additives, spare

parts, etc.), and various overhead administrative and profit

items
37

SECTION 7 

REFERENCES

1. American Society for Testing and Materials. Annual

Book of ASTM Standards. November 1987.

2. American Society of Agronomy, Inc. Methods of Soil

Analysis, Part 1, Physical and Mineralogical Properties

Including Statistics of Measurement and Sampling. 1982

3. Assink, J.W., and W. Van den Brink. Extractive

Methods for Soil Decontamination: A General Survey

and Review of Operational Treatment Installations. In:

Proceedings from the First International TNO

Conference on Contaminated Soil, Ultrecht, Netherlands,

1985.

4. Bevington, P.R. Data Reduction and Error Analysis

for the Physical Sciences. McGraw-Hill, Inc., New

York, NY, 1969.

5. Brookes, C.J., I.G. Bettefley, and S.M. Loxston.

Fundamentals of Mathematics and Statistics for Students

of Chemistry and Allied Subjects. John Wiley & Sons,

Chichester, Great Britain, 1979.

6. Hites, R.A., and S.J. Eisenreich. Sources and Fates of

Aquatic Pollutants. American Chemical Society,

Washington, D.C., 1987.

7. Kleinbaum, D.G., and L.L. Kupper. Applied Regression

Analysis and Other Multivariable Methods. Duxbury

Press, North Scituate, MA, 1978.

8. Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt.

Handbook of Chemical Property Estimation. Methods,

Environmental Behavior of Organic Compounds.

American Chemical Society, Washington, D.C., 1990.

9. National Institute for Occupational Safety and Health

(NIOSH) Manual of Analytical Methods.

U.S. Department of Health and Human Services,

February 1994.

10. U.S. Environmental Protection Agency. Cleaning

Excavated Soil Using Extraction Agents: State-ofthe-Art Review. EPA/600/2-89/034, 1989.

11. U.S. Environmental Protection Agency. Data Quality

Objectives for Remedial Response Activities.

EPA/540/G-87/004, OSWER Directive 9355.0-713,

1987.

12. U.S. Environmental Protection Agency. Engineering

Bulletin: Soil Washing. EPA/540/2-90/017, 1990.

13. U.S. Environmental Protection Agency. Generic Quality

Assurance Project Plan for Land Disposal Restrictions

Program (BDAT). EPA/530-SW-87-011, 1987.

14. U.S. Environmental Protection Agency. Guidance for

Conducting Remedial Investigations and Feasibility

Studies Under CERCLA, Interim Final. EPA/

540/G-89/004, OSWER-9335.3-01, 1988.

15. U.S. Environmental Protection Agency. Guide for

Conducting Treatability Studies Under CERCLA, Interim

Final. EPA/540/2-89/058, 1989.

16. U.S. Environmental Protection Agency. Lead Battery

Site Treatability Studies, Project Summary. 1989.

17. U.S. Environmental Protection Agency. Methods for

Chemical Analysis of Water and Wastes. EPA/

600/4-79/020, 1979.

18. U.S. Environmental Protection Agency. Methods for

Evaluating the Attainment of Cleanup Standards, Volume

1: Soils and Solid Media. EPA/730/ 2-89/042, 1989.

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38

19. U.S. Environmental Protection Agency. Preparation.

Aid for HWER’Ls Category III Quality Assurance

Project Plans. 1987.

20. U.S. Environmental Protection Agency. Statistical Test

Analysis of Groundwater Data at RCRA Facilities,

Interim Final. 1989.

21. U.S. Environmental Protection Agency. Soil Sampling

Quality Assurance User's Guide. EPA/ 600/4-84/043,

1984

22. U.S. Environmental Protection Agency. Technology

Screening Guide for Treatment of CERCLA Soils and

Sludges. EPA/540/2-88/004, 1988.

23. U.S. Environmental Protection Agency. Test Methods

for Evaluating Solid Waste. 3rd Ed., SW-846,1986.

24. U.S. Environmental Protection Agency. Treatability

Studies Under CERCLA: An Overview. OSWER

Directive 9380.3-02FS, 1987.

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United States

Environmental Protection

Agency

Center for Environmental Research

Information

Cincinnati OH 45268-1072

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

Official Business

Penalty for Private Use, $300

EPA/540/2-91/020A

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