United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
EPA/5402-91 013A
July 1991
Guide for Conducting
Treatability Studies Under
CERCLA: Aerobic
Biodegradation
Remedy Screening
Interim Guidance
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EPA/540/2-91/013A
July 1991
GUIDE FOR CONDUCTING TREATABILITY STUDIES
UNDER CERCLA: AEROBIC BIODEGRADATION
REMEDY SCREENING
INTERIM GUIDANCE
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Office of Research and Development
Cincinnati, Ohio 45268
and
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
Washington, D.C. 20460
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DISCLAIMER
The information in this document has been funded wholly or in part by the
U.S. Environmental Protection Agency (EPA) under contract No. 68-C8-0061,
Work Assignment No. 2-10, to Science Applications International
Corporation (SAIC). It has been subjected 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.
The primary purpose of this guide is to provide standard guidance for
designing and implementing an aerobic biodegradation remedy
screening treatability study in support of remedy evaluation.
Additionally, it describes a three-tiered approach, that consists of 1)
remedy screening, 2) remedy selection, and 3) remedy design, to
aerobic biodegradation treatability testing. It also presents a guide for
conducting treatability studies in a systematic and stepwise fashion for
determination of the effectiveness of aerobic biodegradation in
remediating a CERCLA site. The intended audience for this guide
comprises Remedial Project Managers (RPMs), Potentially Responsible
Parties (PRPs), 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 aerobic biodegradation remedy screening treatability studies conducted
in support of remedy evaluation that is conducted prior to the Record of
Decision (ROD).
This manual presents a standard guide for designing and implementing an
aerobic biodegradation remedy screening treatability study. The manual
presents a description of and discusses the applicability and limitations of
aerobic biodegradation technologies and defines the prescreening and field
measurement data needed to determine if treatability testing is required. It
also presents an overview of the process of conducting treatability tests
and the applicability of tiered treatability testing for evaluating aerobic
biodegradation technologies. The specific goals for each tier of testing are
defined and performance levels are presented that should be met at the
remedy screening level before additional tests are conducted at the next tier.
The elements of a treatability study work plan are also defined with detailed
discussions on the design and execution of the remedy screening
treatability study.
The manual is not intended to serve as a substitute for communication with
the experts and/or regulators nor as the sole basis for the selection of
aerobic biodegradation as a particular remediation technology. In addition,
this manual is designed to be used in conjunction with the Guide for
Conducting Treatability Studies Under CERCLA, Interim Final/18) The
intended audience for this guide consists of Remedial Project Managers
(RPMs), Potentially Responsible Parties (PRPs), contractors, and
technology vendors.
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TABLE OF CONTENTS
DISCLAIMER 11
FOREWORD 111
ABSTRACT iv
FIGURES vi
TABLES vii
ACKNOWLEDGEMENTS viu
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 8
3. The Use of Treatability Studies in Remedy Evaluation 13
3.1 Process of Treatability Testing in Evaluating a Remedy 13
3.2 Application of Treatability Tests 15
4. Remedy Screening Treatability Study Work Plan 19
4.1 Test Goals 19
4.2 Experimental Design 20
4.3 Equipment and Materials 22
4.4 Sampling and Analysis 23
4.5 Data Analysis and Interpretation 24
4.6 Reports 24
4.7 Schedule 24
4.8 Management and Staffing 25
4.9 Budget 25
5. Sampling and Analysis Plan 27
5.1 Field Sampling Plan 27
5.2 Quality Assurance Project Plan 28
6. Treatability Data Interpretation 31
7. References 35
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FIGURES
Number Page
2-1. In Situ Bioremediation of Groundwater 4
2-2. Solid-Phase Bioremediation 5
2-3. Above-Ground Slurry-Phase Bioremediation 6
2-4. Slurry-Phase Bioremediation in Existing Lagoon 6
2-5. Soil Heap Bioremediation 7
2-6. Open Windrow Composting 7
3-1. Flow Diagram of the Tiered Approach 14
3-2. TheRoleof Treatability Studies in the RI/FS and RD/RA Process 15
4-1. Example Project Schedule for a Treatability Study 25
4-2. Organization Chart 26
6-1. Plot of Hydrocarbon Concentration versus Time 32
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TABLES
Number Page
4-1. Suggested Organization of Aerobic Biodegradation Remedy Screening Treatability Study Work Plan .... 19
4-2. Commonly Used Analytical Chemistry Methods for Soil Parameters 23
4-3. Major Cost Elements Associated With Aerobic Biological Remedy Screening Treatability Studies 26
5-1. Suggested Organization of the Sampling and Analysis Plan 28
6-1. Hydrocarbon Concentration (ppm) Versus Time 31
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ACKNOWLEDGMENTS
This guide was prepared for the U.S. Environmental Protection Agency,
Office of Research and Development (ORD), Risk Reduction Engineering
Laboratory (RREL), Cincinnati, Ohio, by Science Applications
International Corporation (SAIC) along with its subcontractor,
Environmental Resource Management, Inc. (ERM), under Contract No.
68-C8-0061. Mr. David Smith served as the EPA Technical Project
Monitor. Jim Rawe served as the primary technical author and SAIC's
Work Assignment Manager. Mr. Derek Ross served as a technical expert
and was ERM's Subcontractor Manager. The project team included Tom
Wagner, George Wahl, and Joe Tillman of SAIC; Jonathan Moyer of
ERM; and Mike Martinson of Delta Environmental Consultants, Inc.
Clyde Dial served as SAICs Senior Reviewer, and Natalie Barnes served
as the Technical Editor. The authors are especially grateful to Mr. Steve
Safferman of EPA, RREL, who has contributed significantly by serving as
a technical consultant during the development of this document.
Ms. Robin M. Anderson of the Office of Emergency and Remedial
Response (OERR) has been the inspiration and motivation for the
development of this document. The authors want to give special thanks to
Fran Kremer, EPA, CERI; Joe Healy, EPA, Region IX; Peter Chapman,
EPA, ORD; Carol Litchfield, Environment American, Inc.; Dick
Woodward, ENSR, Inc; Paul Flathman, O.H. Materials Corporation; John
R Smith, ReTeC, Inc.; and Ronald Crawford, University of Idaho, for
their continued involvement in the development of this document.
The following other Agency and contractor personnel have contributed
their time and comments by participating in the expert workshop and/or
peer reviewing the draft document:
Ron Lewis EPA, RREL
John Glaser EPA, RREL
RichHaugland EPA, RREL
Henry Tabak EPA, RREL
BenBlaney EPA, RREL
Ed Bates EPA, RREL
Pat McDonald EPA, Region VII
Chris Rascher EPA, Region I
Linda Fiedler EPA, Technical Information Officer
John Rodgers EPA, ERL - Athens
Maureen Danna ABB Environmental
Kate Devine Applied Biotreatment Association
Dick Bleam Bioscience Management
Durell Dobbins Biotrol
Tom Chresand Biotrol
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Keith Piontek
Tom Simpkin
Robert Finn
William Mahaffey
Ralph Baker
Barry Scott
John Cookson
Al Rozich
Gary Boettcher
Suxuan Huang
Ralph Portier
Anthony Bulich
Todd Stevens
Ralph Guttman
Phillip Launt
Hans Stroo
David Nutini
Rick Bartha
Larry N. Britton
Robert Irvine
James Early
Jim Spain
John A. Dickerson
Daniel Shelton
Brian Schepart
CffiMHill
CffiMHill
Cornell University
Ecova Corporation
ENSR, Inc.
ENSR, Inc.
General Physics Corporation
ERM
Geraghty & Miller, Inc.
Keystone Environmental Resources
Louisiana State University
Microbics
Pacific Northwest Laboratories
Polybac Corporation
Resource Appraisals & Management
ReTeC, Inc.
RNK Environmental, Inc.
Rutgers University
Texas Research Institute, Inc.
University of Notre Dame
University of Notre Dame
U.S. Air Force
USDA
USDA
Wastestream Technology
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 and
should be performed as soon as it is evident that
insufficient information is available to ensure the quality
of the decision. Conducting treatability studies early in
the remedial investigation/feasibility study (RI/FS)
process should reduce uncertainties associated with
selecting the remedy and provide a sounder basis for the
Record of Decision (ROD). Regional planning should
factorin the time and resources required for these studies.
Treatability studies conducted during the RI/FS phase
indicate whether a given technology can meet the
expected cleanup goals for the site, whereas treatability
studies conducted during the remedial design/remedial
action (RD/RA) phaseestablish the design and operating
parameters for optimization of technology performance.
Although the purpose and scope of these studies differ,
they complement one another (i.e., information obtained
in support of remedy selection may also be used to
support the remedy design).(26:i
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 (18), 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 equiva-
lent to remedy screening. Bench-scale testing is typically
used for remedy selection, but may fall short of providing
enough information for remedy selection. Bench-scale
studies can, in some cases, provide enough information
forfull-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 applicability
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 of treatability study testing may
be needed on a case-by-case basis. The need for and the
level of treatability testing required are managerial
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 quality of data available and on other decision factors
(e.g., State and community acceptance of the remedy and
experience with the technology at other sites). The use of
treatability studies in remedy selection is discussed
further in Section 3 of this document.
1.2 PURPOSE AND SCOPE
This guide is designed to ensure a credible approach is
taken to evaluate whether aerobic biodegradation should
be considered for site remediation. This guide discusses
only the remedy screening level. Remedy screening
studies are designed to provide a quick and relatively
inexpensive indication of whether biological degradation
is a potentially viable remedial technology. Remedy
selection studies will also be required to determine if
bioremediation is a viable treatment alternative for a site.
The remedy screening evaluation should:
Provide a preliminary indication that
reductions in contaminant concentration are
due to biodegradation and not abiotic
processes such as photo decomposition,
volatilization, or adsorption, and
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Produce the design information required for
the next level of testing, should the remedy
screening evaluation be successful.
The Aerobic Biological Remedy Screening Study should
not be the only level of treatability study performed
before final remedy selection.
1.3 INTENDED AUDIENCE
This document is intended for use by Remedial Project
Managers (RPMs), Potentially Responsible Parties
(PRPs), consultants, contractors, and technology
vendors. Each has a different role in conducting
treatability studies under CERCLA. Specific
responsibilities for each can be found in the generic
gmde.(18)
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 provides
background information on the role of treatability studies
in the RI/FS process, describes the purpose and scope of
the guide, and outlines the intended audience for the
guide. Section 2 describes the different types of aerobic
bioremediation processes currently available and
discusses how to conduct a preliminary screening to
determine if biological treatment is a potentially viable
remediation technology. Section 3 provides an overview
of the different levels of treatability testing and discusses
how to determine the need for treatability studies. Section
4 provides an overview of the remedy screening
treatability study, describes the contents of a typical work
plan, and dis-
cusses the major issues that need to be considered when
conducting a treatability study. Section 5 discusses the
Sampling and Analysis Plan, including the Field Sampling
and Quality Assurance Project Plans. Section 6 explains
how to interpret the data produced from a remedy
screening treatability study and how to determine if
further remedy selection studies are justified. Section 7
contains the references.
This guide, along with guides being developed for other
technologies, is intended to be used as a companion
document to the generic guide.(18) In an effort to avoid
redundancy, supporting information in other readily
available guidance documents is not repeated in this
document.
This document was reviewed by representatives from
EPA's Office of Emergency and Remedial Response
(OERR), Office of Research and Development (ORD),
Office of Waste Programs Enforcement, Technology
Innovation Office, and Regional offices, as well as by a
number of contractors and academic personnel. The
constructive comments received from this peer review
process have been integrated and/or addressed
throughout this guide.
As treatability study experience is gained, EPA
anticipates further comment and possible future revisions
to the document. For this reason, EPA encourages
constructive comments from outside sources. Comments
should be directed to:
Mr. David Smith
U. S. Environmental Protection Agency
Office of Research and Development
Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnati, Ohio 45268
(513) 569-7957
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SECTION 2
TECHNOLOGY DESCRIPTION AND
PRELIMINARY SCREENING
This section describes the various full-scale aerobic
biodegradation technologies currently available and
discusses the information necessary to screen the
technology prior to commitment to a treatability test
program. Subsection 2.1 describes several full-scale
aerobic biodegradation systems that potentially can be
used at Superfund sites. 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
Bioremediation generally refers to the breakdown of
organic compounds (contaminants) by microorganisms.
In situ, solid-phase, slurry-phase, soil-heaping, and
composting biological treatment techniques are
available for the remediation of contaminated
soils.(13)(23:) Aerobic biodegradation can be used as the
only treatment technology at a site or along with other
technologies in a treatment train. Use of aerobic
biodegradation, especially in situ, has been very limited
at CERCLA sites. However, the technology shows
promise for degrading, immobilizing, or transforming a
large number of organic compounds commonly found
at CERCLA sites to environmentally acceptable
compounds.
As of fiscal year 1989, biodegradation has been
selected as a component of the remedy for 22
Superfund sites having groundwater, soils, sludges, or
sediments contaminated with various volatile organics;
phenols; creosotes;polynucleararomatichydrocarbons
(PAHs); and benzene, toluene, ethyl benzene, and
xylene (BTEX) compounds.1-22-1
Information on the technology applicability, the latest
performance data, the status of the technology, and
sources for further information is provided in a series of
engineering bulletins being prepared by the EPA Risk
Reduction Engineering Laboratory (RREL) in
Cincinnati, Ohio.(16)(17)
2.1.1 In Situ Bioremediation
In situ bioremediation involves enhancing the microbial
degradation of contaminants in subsurface soil and
waterwithout excavation of the contaminated soil. The
technology usually involves enhancing natural
biodegradation processes by adding nutrients, oxygen
(if the process is aerobic), and in some cases,
microorganisms to stimulate the biodegradation of
contaminants. Moisture control may be required to
optimize biodegradation. If oxygen is the rate-limiting
parameter, oxygen sources such as air, highpurity
oxygen, or hydrogen peroxide are usually used to
increase the amount of oxygen available for
biodegradation. Laboratory studies indicate the
addition of methane or other substrates may aid in the
co-metabolic biodegradation of low molecular weight
chlorinated organics. Recent evidence has shown that
anaerobic processes that use nitrate as a terminal
electron acceptor may be effective for the in situ
treatment of benzene, toluene, xylenes, and some
PAHs.(4)
In situ bioremediation is often used in conjunction with
a groundwater-pumping and soil-flushing system to
circulate nutrients and oxygen through a contaminated
aquifer and associated soils. The process usually
involves introducing aerated, nutrient-enriched water
into the contaminated zone through a series of inj ection
wells or infiltration trenches and recovering the water
down gradient. Watersoluble contaminants are flushed
out of the soil; less soluble contaminants remain in the
soil and are biodegraded. The recovered water can then
be reintroduced or disposed of on the surface (Figure
2-1). Depending on the concentration of water-soluble
contaminants in the recovered water, additional
treatment may be required before the water can be
disposed of or recycled to the soil treatment system.
In situ bioremediation has primarily been used for the
treatment of saturated soils; however, in a few
instances, the technology has been used to treat
unsaturated soils. The in situ bioremediation of
unsaturated soils has typi-
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Injection Wells
Nutrients
Aeration
Microorganisms
i
Mixing
Optional
Treatment
Vadose Zone
Groundwater Flow Direction
Water
Table
Recovery
Well
> ' ..' . i . *". ..... .'.;. '... ..... i', 1 ' . '
I.I.I
. . .. .....
L,QVV Perm? ability, Bedrock -
J L
Figure 2-1. In situ bioremediation of groundwater.
cally been limited to fairly shallow depths over
groundwater that is already contaminated. The treatment
of unsaturated soils is difficult to control and relies on the
use of percolation techniques to enhance
nutrient-adjusted water and vacuum extraction techniques
to enhance air exchange in the soil matrix.
In situ bioremediation treats contaminants in-place,
eliminating the need for soil excavation and limiting the
release of volatiles into the air. Consequently, the risks
and costs associated with materials handling are reduced
or eliminated. Furthermore, in situ bioremediation has the
potential to clean up the source material responsible for
the groundwater contamination.
2.1.2 Solid-Phase Bioremediation
Solid-phasebioremediation (sometimes referred to as land
treatment) is a process that treats soils in an above-grade
treatment system using conventional soil management
practices to enhance microbial degradation of
contaminants. Solid-phase bioremediation can be
designed using shallow "tanks" to meet land-ban
requirements.
Solid-phase bioremediation at CERCLA sites usually
involves placing excavated soil in an above-grade soil
treatment area. If required, nutrients and microorganisms
are added to the soil, which is tilled at regular intervals to
optimize aeration and contact between the
microorganisms and the contaminants. During the
operation of a solid-phase bioremediation system, pH,
nutrient concentrations, and moisture content are
maintained within ranges conducive to microbial activity
(Figure 2-2). In some cases, the contaminated soil has to
be mixed with clean soil to reduce the concentration of
contaminants to levels that do not inhibit microbial
activity. Solid-phase treatment systems can be modified
to contain and treat soil leachate by adding underdrain
and liquid treatment system. Volatile organic compounds
(VOCs) can be contained by adding an optional cover.
Conventional VOC treatment can be added as part of a
treatment train.
A variety of processes influence the fate of contaminants
in solid-phase treatment systems. These include physical
and chemical processes (such as leaching, adsorption,
desorption,photodecomposition, oxidation, volatilization,
and hydrolysis) and biodegradation. The
physical, chemical, and biological properties
of the contaminants and soil interact with
site-specific variables to influence the fate of
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Excavation
Soil Screening
Microorganisms
Nutrients
Aeration
Air
Management
Unit
Leachate Collection System
Figure 2-2. Solid-phase bioremediation.
the contaminants. The contaminants are degraded,
immobilized, or transformed to environmentally
acceptable components. (6)
Decomposition and immobilization of the contaminants
occurwithin both the zone of incorporation, usually the
top 15 to 30 centimeters, and the underlying layers. The
zone of incorporation and the underlying soils, where
additional treatment and immobilization of the
contaminants occurs, are referred to as the treatment
zone. The treatment zone depth may be as much as 1.5
meters. Most of the transformations, immobilization,
and biodegradation occur in the zone of incorporation.
2.1.3 Slurry-Phase Bioremediation
(Liquid/Solids Treatment)
In slurry-phasebioremediation, excavatedcontaminated
soil is typically placed in an on-site, stirred-tank
reactor(s) where the soil is combined with water to form
a slurry. The solids content of the slurry depends on
the type of soil, the type of mixing and aeration
equipment available, and the rates of contaminant
removal that need to be
achieved. The water used in the process can be
contaminated surface or ground water, thus facilitating
the simultaneous treatment of contaminated soil and
water. If required, nutrients and microorganisms are
added to the slurry, which is then aerated and agitated
to optimize contact between the microorganisms,
nutrients, and oxygen so that efficient biodegradation
of the contaminants can occur. The process can be
operated in either a batch or a continuous mode (Figure
2-3).
As with solid-phase bioremediation, the process can be
designed to contain and treat volatile organic
compounds. Slurry-phase bioremediation systems can
be used to treat sludges and sediments in existing
lagoons and impoundments, thus eliminating the need
for soil excavation (Figure 2-4). An impermeable layer
should be present under the slurry-phase system to
prevent contaminant migration.
2.1.4 Soil Heaping
Soil heap bioremediation involves piling contaminated
soil in heaps of several meters in height. Aeration is
usually provided by pulling a vacuum through the
heap. Simple
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Excavation
Soil Screening
Water Recycle
Dewatered
Solids
J
r-i
Nutrients
Aeration
Microorganisms
" ft'1
Dewatering
Slurry Bioreactors
Figure 2-3. Above-ground slurry-phase bioremediation.
Nutrients
Aeration
Microorganisms
Impermeable
Liner
Figure 2-4. Slurry-phase bioremediation in existing lagoon.
irrigation techniques are generally used to maintain
moisture content, pH and nutrient concentrations within
ranges conducive to the biodegradation of contaminants.
The system can be designed to control the release of
volatile organic compounds by passing the exhaust from
the vacuum through activated carbon (Figure 2-5).
2.1.5 Composting
Composting involves the storage of biodegradable waste
with a bulking agent (e.g., chopped hay or wood chips).
The structurally firm bulking agent can be biodegradable,
but need not be so. Typically, two parts bulking agent are
mixed with one part contaminated soil to improve the soil
permeability. Adequate aeration, optimum temperature,
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Visqueen Cover
\
Soil Nutrients
Aeration
\ Microorganisms
\
\
a
Asphalt
Side View Plastic Piping
(compatible with contaminants)
Top View
Figure 2-5. Soil heap bioremediation.
moisture and nutrient contents, and the presence of an
appropriate microbial population are necessary to
enhance the decomposition of organic compounds. The
biodegradation process may be thermophilic. If so,
microorganisms that occur naturally in the decaying
organic matter biodegrade the contaminants of concern.
However, the elevated temperatures associated with
thermophilic bio-
degradation may limit the activity of indigenous and
exogenous organisms.
The three basic types of composting are open windrow
systems, static windrow systems, and in-vessel (reactor)
systems. In the open windrow system, the compost is
stacked into elongated piles (Figure 2-6). Aeration is
Windrow
Figure 2-6. Open windrow compositing.
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accomplished by tearing down and rebuilding the piles. In
the static windrow system piles of compost are aerated by
a forced air system (e.g., the piles are built on top of a grid
of perforated pipes). The in-vessel system involves
placing the compost into a closed reactor. Aeration is
accomplished by tumbling, stirring, and forced aeration.
2.2 PRELIMINARY SCREENING AND
TECHNOLOGY LIMITATIONS
As mentioned in Section 1, the determination of the need
for and the appropriate level of treatability studies
required depends on the literature information available
on the technology, expert technical judgment, and site-
specific factors. The first two elements - the literature
search and expert consultation - are critical in
determining if adequate data are available or whether a
treatability study is needed to provide those data. The
data and information on which this decision is made
should be documented.
2.2.1 Literature/Data Base Review
Several reports and electronic data bases exist that should
be consulted to assist in planning and conducting
treatability studies as well as to help prescreen
bioremediation 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 ClearinghouseAbstracts.
U.S. Environmental Protection Agency, Officeof
Emergency and Remedial Response,
Washington, D.C. EPA/540/2-89/001, March
1989.
The Superfund Innovative Technology
Evaluation Program: Technology Profiles. U.S.
Environ- mental 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.
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 fortreatability study reports will be maintained
at RREL in Cincinnati. The contact for this data base is
Glenn Shaul at (513) 569-7408.
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 within 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 1200 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
North Atlantic Treaty Organization (NATO)
International Data
Innovative Technologies Program Data
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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.
The RREL in Edison, New Jersey, contains a
Computerized On-Line Information Sy stem (COLIS), which
consolidates several computerized data bases by RREL in
Cincinnati and Edison. COLIS contains three files: Case
Histories, Library Search, and SITE Applications
Analyses Reports (AARs). The Case Histories file
contains historical information obtained from corrective
actions implemented at Superfund sites. The Library
Search system provides access to special collections and
research information on many RREL programs. The SITE
AARs file provides actual cost and performance
information. The contact is Pacita Tibay at (201) 906-6871.
2.2.2 Technical Assistance
The Technical Support Project (TSP) is made up of six
Technical Support Centers and two Technical Support
Forums. It is a joint service of OSWER, ORD, 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 alternatives, reviews RI/FS, assists in
selection and design of 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,
issues papers on groundwater topics, and
generic protocols
Assists in performance of treatability studies.
The following support centers provide technical
information and advice related to aerobic biodegradation
and treatability studies:
1. Ground-Water Fate and Transport Technical
Support Center
Robert S. Kerr Environmental Research
Laboratory (RSKERL), Ada, OK
Contact: Don Draper
FTS 743-2202 or (405) 332-8800
RSKERL in Ada, Oklahoma, is EPA's center for fate and
transport research, focusing 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 Technical Support Center
Risk Reduction Engineering Laboratory (RREL),
Cincinnati, OH
Contact: Ben Blaney
FTS 648-7406 or (513) 569-7406
The Engineering 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 mustbe obtained through
the EPA remedial project manager.
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REEL 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
Review of the treatability aspects of RI/F S
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 major parameter that influences the feasibility of
using biological processes is the biodegradability of the
compounds of concern. Prior to conducting a remedy
screening of bioremediation it is important to confirm that
the compounds of concern are indeed amenable to
biological treatment.
As discussed in Subsection 2.2.1, a literature search
should be performed for the compounds or wastes of
interest, including compounds of similar structure. The
key question to be answered is whether any evidence of
aerobic
biodegradation of these compounds or wastes exists. The
literature review should not be limited to a biodegradation
technology that has been chosen for preliminary
consideration. Evidence of aerobic biodegradation under
conditions not likely to be applicable to a site should not
be eliminated from consideration. Likewise, a literature
search indicating that biodegradation is unlikely should
not automatically eliminate aerobic biological
technologies from consideration. On the other hand,
previous studies indicating that pure chemicals will be
degraded must be viewed with caution. Chemical
interactions or inhibitory effects of contaminants can alter
the biodegradability of chemicals in complex mixtures
frequently found at Superfund sites.
The literature search should also investigate the chemical
and physical properties of the contaminants. The
volatility of the contaminants is one of the most important
physical characteristics. Knowledge of the contaminant
volatility is important in the prescreening step since
highly volatile contaminants may be difficult to degrade,
especially in stirred or highly aerated reactors because
they volatilize before thay can be degraded.
There is no steadfast rule that specifies when to proceed
with remedy screening and when to eliminate aerobic
biodegradation as a treatment technology based on a
preliminary screening analysis. An analysis of the existing
literature coupled with the site characterization will
provide the information required to make an educated
decision. However, when in doubt, a remedy screening
study is recommended. Several guidance documents are
available to aid in determining the key contaminant and
matrix characteristics which are needed to prescreen
various technologies.1-15-"-18^23'Example 1 is a hypothetical
literature search provided to illustrate some of the
complexities of this analysis.
Example 1.
A site is contaminated with an organic solvent. The contamination extends to a depth of 50 feet below
the surface. Considering the overall extent of the zone of contamination, removal of the soil for
above-ground treatment is not considered as a remediation technology for the site. However, a review
of the literature reveals only two previous studies on the biodegradation of the solvent of concern.
The first study showed that greater than 95 percent of the semi-volatile solvent could be removed over
a 3-week period with a slurry-phase biological treatment process utilizing naturally occurring soil
microorganisms. The study made no attempt to measure losses due to volatilization. However, a
12-percentloss of solvent was measured in a control reactorwhere biodegradation was inhibited with
mercuric chloride to account for abiotic losses (chemical degradation, sorption and volatilization).
Therefore, 83 percent of the contaminant was removed by biotic processes
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(biodegradation) during the study period. Even though above-ground slurry-phase
treatment is not appropriate for the site of concern, the previous study did show that,
under appropriate conditions, naturally occurring microorganisms can biodegrade a large
percentage of the solvent.
The second study was a remedy design (pilot-scale) demonstration that showed that
after 5 months the solvent could not be biodegraded in situ, even with the addition of
nutrients and oxygen. This study indicates that in situ biodegradation of the solvent is
not likely to occur.
At first glance, the literature review appears to rule out the use of in situ bioremediation
to clean up the solvent-contaminated subsurface soil. However, caution should be used
in excluding aerobic biodegradation on the basis of one study. The intent of the remedy
screening treatability study is to assess the potential of a technology at a minimum
cost. If there is any reason to believe aerobic biodegradation has the potential to
remediate the contaminant of interest, remedy screening studies should be considered.
The first study indicated that biodegradation is potentially a viable technology. However,
successful biodegradation in a slurry bioreactor is not an assurance that in situ
biodegradation will occur. The second study tends to indicate that in situ bioremediation
of this contaminant will not be possible. However, a simple change in pH or nutrient
composition, the removal of some inhibitory substance, or the use of a different microbial
population could result in successful in situ bioremediation of the solvent. In this case,
the RPM decided that a quick remedy screening study was warranted to assess the
feasibility of using biological treatment at the site of concern.
Examples of classes of compounds that are readily
amenable to bioremediation are petroleum hydrocarbons
such as gasoline and diesel fuel; wood-treating wastes
such as creosote and pentachlorophenol; solvents such
as acetone, ketones, and alcohols; and aromatic
compounds such as benzene, toluene, xylenes, and
phenols. Several documents and review articles that
present detailed information on the biodegradability of
compounds are listed in the reference
section.(3)(8)(11)(12)(20)(23) However, discretion should be
exercised when using these reference materials, as
microorganisms that can biodegrade compounds
traditionally considered non-biodegradable are
continually being discovered through ongoing research
and development efforts.
2.2.4 Technology Limitations
Many factors impact the feasibility of aerobic
biodegradation in addition to the inherent
biodegradability as measured in the screening test. These
factors should be addressed prior to the selection of
aerobic biodegradation and prior to the investment of time
and funds in further testing. Some of these factors are
discussed in this section. A detailed discussion is beyond
the scope of this document. The reader should consult
references 15 through 18, and others, for more information
on these factors.
The concentrations of contaminants and pH are examples
of parameters that influence the feasibility of using
biological treatment processes. However, it should be
noted that treatment systems can be designed and
engineered to accommodate wastes with high
contaminant concentrations and extreme pH values. For
example, diesel-contaminated soil with a pH of 2 can be
treated biologically. However, a neutralization step is
required to adjust the pH to within a range conducive to
biological treatment (generally 6.5 to 8.5) prior to
bioremediation. Likewise, if the concentrations of
contaminants are high enough to inhibit microbiological
activity, a dilution step can be introduced to reduce the
concentrations to within ranges conducive to biological
treatment. For example, solid-phase treatment systems are
generally operated at a maximum of 5 to 10 percent
extractable oil and grease. These concentrations of oil and
grease can be achieved by mixing less contaminated soil
with heavily oiled soils in above-ground processes.
Metals may be leached or complexed to reduce microbial
toxicity and improve the potential for contaminant
treatment.
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Non-uniform particle size distribution, the type of soil, and
the permeability of the soil to air and water are the soil
characteristics that most affect the aerobic biodegradation
process, especially in situ. Organic contaminants tend to
be adsorbed to fine particles such as silts and clays.
Therefore, non-uniform particle size distribution can cause
inconsistent degradation rates for in situ processes due
to variations in biological activity associated with variable
contaminant composition and concentrations. The
presence of significant quantities of decaying organic
matter (humus, peat, etc.) may cause high oxygen uptake
rates, depleting available oxygen supplies in the soil.
Materials handling and mixing in above-ground processes
are affected by particle size distribution and debris
present in the soil.
Low soil permeability can hinder the flow of air, moisture,
and nutrients, limiting the effectiveness of in situ
processes. Moisture, oxygen, and nutrient content in soils
and soil pH and temperature affect in situ microbial
activity. Generally, such characteristics can be controlled
or modified through engineering practices.
The presence of an active microbial population with the
capability to degrade the contaminants of interest is
essential to the success of in situ processes. The activity
and
concentration of soil microbes can be stimulated by
moisture, nutrient, and oxygen additions. Selected
microorganisms can be added to enhance the natural
population. However, the ability of these organisms to
compete in situ needs to be established on a case-by-case
basis. The addition of microbes and nutrients can be
severely limited by low soil permeabilities. Even in
relatively permeable soils, ion exchange and filtration
mechanisms can limit the effectiveness of microbial and
nutrient amendments.
The biodegradability of soil contaminants is affected by
the solubility, volatility, and partition coefficients of the
pure compounds. Interactions with the soil and other
contaminants may affect these chemical characteristics.
Aging of soil contaminants can lead to binding in soil
pores, which can limit the availability, even of soluble
compounds. Variable waste composition and
concentration will affect the efficiency of aerobic
biodegradation, especially in situ. The presence of
elevated levels of heavy metals, pesticides, highly
chlorinated organics, and some inorganic salts can inhibit
microbial activity.
The importance of these factors in deciding whether to
initiate or continue treatability studies can be illustrated
by the following example.
Example 2.
A remedy screening test shows that a contaminant is aerobically biodegradable.
However, soil sampling indicates the contaminant is located more than 25 feet deep in
a soil of very low permeability. In situ biodegradation is probably not feasible due to the
thickness of the low permeability soil layer and the depth of the contaminant. In this
case, it may not be worth spending the funds to perform remedy selection treatability
studies for in situ biological treatment processes.
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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 aerobic
biodegradation as the technology remedy under CERCLA.
It also provides a decision tree (Figure 3-1) 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 aerobic biodegradation technology as the
selected remedy.
3.1 PROCESS OF TREATABILITY TEST-
ING 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 for all three tiers of treatability
studies. This approach includes:
Establishing data quality objectives
Selecting a contracting mechanism
Issuing a 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.1-18-1 The generic guide presents general information
applicable to all treatability studies first, followed by
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 recognition of this possibility in the early
planning phases of the project. The work assignment,
work plan, and other supporting documents should
include all anticipated activities to ensure continuity in
the project as it moves from one tier to another.
There are three levels or tiers of treatability studies:
remedy screening, remedy selection, and remedy design.
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 quality of data available and on
other decision factors (e.g., State and community
acceptance of the remedy, new site data). The flow
diagram in Figure 3-1 shows the decision points and
factors to be considered in following the tiered approach
to treatability studies.
Technologies generally are evaluated first at the remedy
screening level and progress through the remedy
selection to the remedy design level. A technology may
enter, however, at whatever level is appropriate based on
available data on the technology and site-specific factors.
For example, a technology that has been studied
extensively may not warrant remedy screening to
determine whether it
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Remedial Investigation/
Feasibility Study (RI/FS)
Identification
of Alternatives
Record of
Decision
(ROD)
Remedy
Selection
Remedial Design/
Remedial Action -
(RD/RA)
Scoping
- the -
RI/FS
Literature
Screening
and
Treatability
Study Scoping
Site
Characterization
and Technology
Screening
REMEDY
SCREENING
to Determine
Technology Feasibility
Evaluation
of Alternatives
REMEDY SELECTION
to Develop Performance
and Cost Data
Implementation
of Remedy
REMEDY DESIGN
to Develop Scale-Up, Design,
and Detailed Cost Data
Figure 3-2. The role of treatability studies in the RI/FS and RD/RA process.
has the potential to work. Rather, it may go directly to
remedy selection to verify that performance standards can
be met. Figure 3-2 shows the relationship of three levels
of 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. Aerobic
biodegradation treatability study objectives must be
based upon the specific needs of the RI/FS. There are
nine evaluation criteria specified in the EPA's RI/FS
IntenmFmal Guidance Document (OSWER-9335:3-01); the
treatability studies can provide data upon which up to
seven of these criteria can be evaluated. 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 directly or
indirectly with the degree of contaminant reduction
achievable by the aerobic biodegradation process. How
"clean" will the treated soil be? Will the residual
contaminant levels be sufficiently low to meet the risk-
based contaminant levels established to ensure that the
treatment technology achieves and maintains protection
of human health and the environment? What are the
contaminant concentrations and physical and chemical
differences between the untreated and the treated soil
(e.g., has contaminant toxicity, mobility, and volume been
reduced through treatment?)? The fourth criterion,
short-term effectiveness, addresses the effects of the
treatment technology during the construction and
implemen-
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tation of a remedy until the response objectives have
been met.
The implementability assessment evaluates the technical
and administrative feasibility of alternatives and the
availability of required goods and services. The key to
assessing aerobic biodegradation under these criteria is
whether the contaminant is biodegradable under
site-specific conditions. Additionally, the assessment
evaluates whether vendors and process equipment are
available to perform the remediation, if adequate space
exists to perform treatment operations, and what materials
handling problems might be encountered if soil must be
excavated.
Long-term effectiveness assesses how effective treatment
technologies are in maintaining protection of human
health and the environment after response objectives
have been met. Basically, the magnitude of any residual
risk and the adequacy and reliability of controls must be
evaluated. The residual risk factor, as applied to aerobic
biodegradation, assesses the risks remaining from residual
contaminant concentrations at the conclusion of remedial
activities.
The final EPA evaluation criterion that can specifically be
addressed during a treatability study is cost. Aerobic
biodegradation is basically a process that biologically
degrades organic compounds to carbon dioxide and water
or to some intermediate degradation product. Remedy
design treatability studies provide data to estimate the
following important cost factors:
The initial design of the full-scale unit
The estimated capital and operating and
maintenance costs
Initial estimate of the time required to achieve
target concentrations.
hi some cases, remedy selection treatability studies can
provide preliminary estimates of the same cost factors.
3.2.1 Remedy Screening
Remedy screening is the first level of testing. It is used to
establish the validity of a technology to treat a waste.
These studies are generally low cost (e.g.,
$10,000-$50,000) and usually require 1 week to several
months to complete. They yield data that can be used as
a preliminary indication of a technology's potential to
meet performance goals and can identify operating
standards for investigation during remedy selection
testing. They generate little, if any, design or cost data
and should not be used as the sole basis for selection of
a remedy.
Typically, aerobic biological remedy screening studies are
performed in test reactors provided with sufficient
nutrients and oxygen. Generally, these studies are batch
processes. These reactors may be small sacrificial batch
reactors (approximately 40 ml to 1 liter in size) or larger
ecosystems (1 to 10 liters) that are subsampled to monitor
the progress of biodegradation. The reactors may contain
saturated or unsaturated soil or slurries in water. Slurry -
phase treatability tests optimize the availability of
nutrients and oxygen and offer the best chance of
success for remedy screening studies. Normally, pH and
contaminant loading rates are adjusted to increase the
chances of success. The microbial population can be
indigenous to the site, from another acclimated source
(i.e., wastewater treatment sludge or another area on site),
selectively cultured, a proprietary mixture provided by a
vendor, or any combination of the above. The bioreactors
are set up for replicate sampling at several time points.
The test reactors are compared to inhibited controls at
each time point to determine if aerobic biological
degradation occurred. The inhibited reactors are treated
with sterilization agents in an effort to reduce or eliminate
the biological activity in the control reactors. The mean
contaminant concentration in the inhibited control
replicates is compared to the mean contaminant
concentration in the test reactors. The goal for a
successful treatability test is a removal rate, due to
biological processes, that is greater than the analytical
error inherent in the test design. A reduction of the
contaminant concentration over a 3- to 6-week period of
20 percent (minimum) to 50 or 60 percent (corrected for
non-biological losses) would be typical of a successful
treatability study. However, for some contaminants,
slower degradation rates may still indicate favorable
results. More information on experimental design is
provided in Subsection 4.2.
Example 3 illustrates the type of information that might
result from a remedy screening study and the conclusions
that might be drawn from that information.
However, even if the remedy screening tests do not meet
the established goals, the test results should be examined
forthe potential cause(s) of failure. If such parameters can
be adjusted or corrected to improve the chances of
success of the remedy screening studies, the RPM or
contractor should consider running additional remedy
screening tests.
3.2.2 Remedy Selection
Remedy selection testing is the second level of testing. It
is used to identify the technology's performance on a
waste-specific basis for an operable unit. These studies
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Example 3.
A site contains 27,000 cubic yards of soil contaminated with chlorinated hydrocarbons.
A remedy screening study is being performed to determine if bioremediation is a viable
cleanup method for the soil. The objectives of the study in this case would be to
determine if biological processes could reduce the average chlorinated hydrocarbon
concentration by greater than 20 percent, as compared to a chemically inhibited
control, in a 6-week study. The mean contaminant concentration, corrected for the
abiotic control, shows a 38 percent reduction after two months. The RPM decides that
aerobic biodegradation is a potentially viable technology and that remedy selection
studies are warranted.
generally are of moderate cost (e.g., $50,000-$250,000) and
may require several weeks to months to complete. They
yield data that verify that the technology is likely to meet
expected cleanup goals and can provide information in
support of the detailed analysis of the alternative (i.e.,
seven of the nine evaluation criteria).
The remedy selection tier of testing for aerobic
biodegradation normally consists of bench-scale tests
which provide sufficient experimental controls such that
a quantitative mass-balance can be achieved. Such
studies often incorporate volatile traps. Toxicity testing of
residual contaminants and intermediate degradation
products is usually required. At the remedy selection
level, reduction of organic contaminants to the cleanup
goals, over a 1- to 3-month period, would signify the
treatability test was a success. The exact removal
efficiency specified as the goal for the remedy, selection
test is site specific.
Pilot-scale testing may be needed for remedy selection,
especially for complex sites where in situ biodegradation
is being considered. RREL is planning to develop
additional guidance on remedy selection treatability
studies for aerobic biodegradation.
3.2.3 Remedy Design
Remedy design testing is the third level of testing. It is
used to provide quantitative performance, cost, and
design information for remediating a site. This level of
testing also can produce data required to optimize
performance. These studies are of moderate to high cost
(e.g., $ 100,000-$500,000) and may require several months
or more to complete. Remedy design studies yield data
that verify performance to a higher degree than the
remedy selection studies and provide detailed design
information. They are performed 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
unit for non-mobile technologies. In some cases, remedy
design tests may be a continuation of remedy selection
tests using the same apparatus. A complete mass balance,
including all non-biological pathways, should be
performed at this level of testing. Typical testing periods
are from 2 to 6 months. For more complex sites (e.g., sites
with different types of contaminants in different areas or
with different geological structures in different areas),
longer testing periods may be required.
The goal of this tier of testing is to confirm the cleanup
levels and treatment times specified in Subsection 4.1.1.
This is achieved by operating a field unit under
conditions similar to those expected in the full-scale
remediation project.
Data obtained from the pilot-scale tests should be used as
follows:
Design full-scale unit
Determine feasibility of aerobic
biodegradation based on target cleanup
goals
Refine cleanup time estimates
Refine cost predictions.
Given the lack of full-scale experience with innovative
technologies, remedy design testing will generally be
necessary.
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SECTION 4
REMEDY SCREENING 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 that require detailed discussion because they relate
to the remedy screening level of aerobic biodegradation
treatability studies but are not presented in other sections
of the document. These elements include test goals,
experimental design and procedures, equipment and
materials, reports, schedule, management and staffing,
and budget. These elements are described in Subsections
4.1 through 4.9. Complementing these subsections are
Section 5, Sampling and Analysis Plan, which includes the
Quality Assurance Project Plan, and Section 6,
Treatability Data Interpretation, that address the sampling
and analysis and data analysis and interpretation ele-
ments of the Work Plan. The Work Plan elements are
listed in Table 4-1.
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, which is 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 also 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/18'
4.1 TEST GOALS
Setting goals for the treatability study is critical to the
ultimate usefulness of the data generated. Goals must be
defined before
Table 4-1. Suggested Organization of Aerobic Biodegradation
Remedy Screening Treatability Study Work Plan
1. Project Description
2. Remedial Technology Description
3. Test Goals (see Subsection 4.1)
4. Experimental Design and Procedures (see Subsection 4.2)
5. Equipment and Materials (see Subsection 4.3)
6. Sampling and Analysis (see Subsection 4.4)
7. Data Management
8. Data Analysis and Interpretation (see Subsection 4.5)
9. Health and Safety
10. Residuals Management
11. Community Relations
12. Reports (see Subsection 4.6)
13. Schedule (see Subsection 4.7)
14. Management and Staffing (see Subsection 4.8)
15. Budget (see Subsection 4.9)
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the treatability study is performed. Each tier of the
treatability study needs performance goals appropriate to
that tier. For example, to use remedy screening tests to
answer the question, "Does aerobic biodegradation work
on this contaminant?," it is necessary to define "work"
(i.e., set the goal ofthe study). A pollutant reduction of at
least 20 percent during the remedy screening tests may
satisfy the test for validity of the process and indicate
that further testing at the remedy selection level is
appropriate to determine if the technology can meet the
anticipated performance criteria ofthe ROD.
4.1.1 Remedy Screening Goals
The main goals ofthe remedy screening evaluation are to:
Provide an indication that reductions in
contaminant concentrations are due to
biodegradation and not abiotic processes
such as photodecomposition, volatilization,
and adsorption
Produce the design information required for
the next level of testing, should the screening
evaluation be successful.
Normally, the average contaminant concentration should
be reduced by at least 20 percent during a 6- to 8-week
study, as compared to an inhibited control, to conclude
aerobic biodegradation is a potential treatment
technology for the site under investigation. The
20-percent contaminant reduction is arbitrary, but is
designed to maximize the chances of success at the
remedy screening tier. The choice of a 6- to 8-week study
is to provide a consistent endpoint for remedy screening
studies. The choice of the remedy screening treatability
study goals (time and contaminant reduction) will be
site-specific decisions.
Example 4 is provided to demonstrate typical goals of a
remedy screening study and what decision can be made
when these goals are achieved.
4.2 EXPERIMENTAL DESIGN
A number of different approaches can be used to conduct
the remedy screening test. These range from simple shake
flask evaluations to soil pans or soil slurry reactors. The
soil may be either saturated orunsaturated, depending on
the goals ofthe study. Soil slurries will optimize mixing
and will tend to maximize biological degradation. Such
studies will maximize the chances, of success at the
remedy screening level. Unsaturated soils will often limit
mixing and result in slower degradation rates. However,
such systems will correlate better with field conditions in
many cases and result in better extrapolation to remedy
selection test systems. The object of this guidance
document is not to specify a particular remedy screening
method but rather to highlight those critical parameters
that should be evaluated during the laboratory test.
The test should include controls to measure the impact of
non-biological processes such as volatilization, sorption,
and photodecomposition on the concentrations of
contaminants. Inhibited controls can be established by
using formaldehyde, mercuric chloride, or sodium azide to
inhibit microbiological activity. However, care should be
exercised when selecting a sterilizing agent. For example,
sodium azide can, under certain circumstances, promote
spontaneous explosive reactions. Mercuric chloride
complexes certain petroleum hydrocarbons and results in
artificially low hydrocarbon concentrations. Soil structure
also can be modified by sterilization agents. Complete
sterilization of soils can be difficult to accomplish. Incom-
Example 4
The soil of a former wood-preserving site is contaminated with pentachlorophenol
(PCP) waste. The literature search indicated that PCP has been successfully
biodegraded atothersites. The RPM decided a remedy screening study was needed
to measure the potential for successful biodegradation at this site. A goal of 25
percent reduction ofthe PCP concentrations was set. The study period was set at 6
to 8 weeks. These study goals were established to maximize the chances of success
for biodegradation.
A remedy screening study was performed to determine if bioremediation is a viable
cleanup method for the soil. The average PCP concentration was reduced by 37
percent, over a 6-week period, after correction for the inhibited control. The RPM
decided that further treatability studies were warranted and elected to have a remedy
selection treatability study performed to attempt to optimize degradation.
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plete mixing of sterilization agents with soils can result in
pockets of surviving microbes in soil pores. In some
cases, microbial populations can transform and detoxify
sterilizing agents. Complete sterilization of the control is
not necessary provided that biological activity is inhibited
sufficiently so that a statistically significant difference
between the test and control means can be determined.
However, care should be taken in interpreting remedy
screening study results. Substantial degradation in the
control (e.g., 20-50 percent contaminant reduction, or
more) can mask the occurrence of biodegradation in the
test reactor. If the control reactor has the same or greater
percent degradation as the test reactor, a false negative
conclusion can result. Concluding that no biodegradation
occurred, when in fact there was some biodegradation,
can lead to elimination of this technology unnecessarily.
Alternatively, closed test systems with volatile traps can
be used to monitor the volatilization of compounds
instead of using inhibited controls to estimate abiotic
losses.(14)
A statistical experimental design should be used to
conduct the treatability study in order to support
decisions made from the treatability data. The various
parameters of interest are included as factors in the
experimental design. The treatability experiment should
include monitoring the concentration of chemicals of
interest over time. In general, at least three to four time
periods should be studied, including the time-zero (T0)
analysis. However, if the study goals are met after a
sampling period, then it is not necessary to continue
sampling at additional time periods. (For example, if
70-percent reduction was achieved after 1 week, it would
not be necessary to continue testing if the goal was to
achieve only a 20-percent reduction.)
The test system can consist of a single large reactor or
multiple small reactors. In the case of the single reactor,
small subsamples are removed at various times and
compared to subsamples from a second reactor in which
biological activity has been inhibited. Normally, triplicate
subsamples are taken at each time point. The mean
contaminant concentrations in the test and control
reactors are compared to see if a statistically significant
change in concentration has occurred, The mean
contaminant concentration in the inhibited control
subsample can be subtracted from that in the test
subsample to estimate the percentage the contaminant
has biodegraded at each time point. In this type of
system, heterogeneity within the soil system can lead to
variability in contaminant concentration among the
various subsamples and replicates. However, such system
variability can be overcome by thorough mixing of the soil
before it is distributed to the test and control systems.
Examples of this type of system are large flasks, soil pans,
and other large soil reactors. Care should be taken so that
the system size and design do not limit the availability of
oxygen and moisture and cause variability in degradation
rates within the reactor.
Multiple reactors may be set up in place of a large soil
system. Triplicate reactors are established for each test
reactor and control group at each time point. Each reactor
is filled with the same amount of soil and nutrient
additives. In this case, the complete reactor contents are
extracted and analyzed for each of the triplicate test and
control reactors at each time point. Examples of such
systems are serum bottles, slurry reactors, and aerated
soil reactors. The advantage of this type of experimental
apparatus is that the question of subsampling
representativeness is avoided. However, the
representativeness of any one reactor is questionable in
this design. Thorough mixing of the soil, before it is
distributed among the individual reactors, is important.
Triplicate samples provide a measure of the overall
precision of the measurements made. Surrogate spikes
should also be added to the matrix samples to ensure
consistent analytical performance. Matrix spikes should
be added to a percentage (approximately 10%) of the
samples to determine overall analytical accuracy. Method
blanks should be used to monitor potential contamination
of samples during laboratory handling.
Respirometric measurements or other measures of
biological activity can be used to predict the best times to
take samples. At the beginning of the experiment, activity
measurements should indicate minimal biological activity.
Continued monitoring can reveal either a rapid or
relatively slow onset of biological activity and indicate
when samples should be taken to monitor contaminant
reductions. However, respirometric measurements can
indicate the loss of oxygen through chemical oxidation in
addition to biodegradation.1-7'1-10'1-27-1
In formulating an experimental design, the total number of
samples taken depends on the desired difference in
concentrations that the experimenter wishes to detect, the
measurement variability (the analytical coefficient of
variation), and the type I and type II error probabilities.
Each of these factors is discussed below.
The goal of the remedy screening scale of treatability
testing is not to be able to ascertain whether the
biotreatment process can meet cleanup goals but rather
whether biodegradation is possible with the site-specific
waste material in question. Therefore, at the remedy
screening scale, it is usually not necessary to establish
complete removal of the contaminant of interest. As a
guide, the experiment should be designed so that a
difference of 20 to 50 percent removal of the contaminant
of interest can be detected between the treatment and the
inhibited control.
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In general, for sampling and analysis of soils and sludges,
the analytical variability can be quite high (on the order of
20 to 50 percent). Therefore, a sufficient number of
samples must be taken for statistically significant effects
to be observed. Additional information on sample size
selection is available in many statistical textbooks.(2)(5-"-9)
The type I error probability is the chance of the
experiment indicating that there is a statistically
significant treatment effect when, in reality, there is not.
Conversely, the type II error probability is the chance of
not detecting a significant treatment effect when, in
reality, the treatment was effective. Traditionally,
experimentaldesigns have been constructed so that these
error probabilities are on the order of 5 percent (i.e., 95
percent confidence levels). This error probability is not
appropriate for the remedy screening scale of treatability
testing. Error rates on the order of 10 to 20 percent (i.e., 80
to 90 percent confidence levels) are more consistent with
the philosophy of remedy screening.
It is beyond the scope of this document to go into great
detail on experimental design but many good texts on the
subject are available.1-2-"-9'
An example of a simple experimental design is included in
Example 5.
4.3 EQUIPMENT AND MATERIALS
The Work Plan should specify the types of equipment
and materials to be used during the treatability test. For
example, the size and type of glassware 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 references for the appropriate
containers to be used for the treatability studies.1-24-1
Normally, glass reactors with Teflonฎ fittings should be
used. Stainless steel also can be used with most
contaminants. Care should be taken when using various
plastic containers and Tygonฎ tubing. Such materials will
adsorb many contaminants and also can leach plasticizer
chemicals, such as phthalates, into the soil matrix.
Typically, such analytical equipment as gas
chromatograph (GC), high-pressure liquid chromatograph
(HPLC), total organic carbon (TOC) analyzers, and pH
meters will be required.
Example 5. Bioremediation Study
Twenty-four 20-gram samples of soil containing approximately 100 ppm phenol were
added to separate 500 ml flasks along with 80 ml of water containing phosphate
buffer (pH = 7.0), ammonium sulfate, and trace metals. Twelve of the resulting soil
slurries were inoculated with a suspension containing approximately 104 phenol
degrading bacteria/ml. The other 12 flasks were inoculated and then "sterilized" with
mercuric chloride to form the control group. The test and inhibited control flasks were
stoppered and stirred at moderate speed on stirring plates while incubating at 20ฐC.
Three test flasks were immediately sacrificed (T0) by adding 100 ml of methanol and
shaking vigorously to extract the phenol for analysis. One ml subsamples from each
flask were centrifuged at high speed in a microcentrifuge to remove soil particles.
Phenol was quantified via high-pressure liquid chromatograph. At each of three
subsequent time points (T,, T2, T3), three additional test flasks were sacrificed and
subsampled as previously described. Three inhibited control flasks were also
sacrificed at each time point. The mean phenol concentration of the three test flasks
was compared to the mean phenol concentration of the three control flasks at each
time point to see if significant biodegradation was occurring.
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4.4 SAMPLING AND ANALYSIS
The Work Plan should describe the sampling procedures
to be used during field sampling and remedy screening
treatability studies. Appropriate methods for preserving
samples and specified holding times for those samples
should be used. The procedures will be site-specific.
Standard EPA and American Society for Testing and
Materials (ASTM) methods are generally recommended;
however, the treatability study vendor may propose
modified or equivalent methods that are more suited to the
specific treatment process being studied. The EPA RPM
must determine the acceptability of these alternative
methods with respect to the test objectives and the
available method validation information provided by the
vendor. The Work Plan also should note that the
Sampling and Analysis Plan (SAP) will be prepared before
field sampling and treatability testing begins. Section 5
provides details for the preparation of the SAP including
the Field Sampling Plan (FSP) and the Quality Assurance
Project Plan (QAPjP).
4.4.1 Field Sampling
A sampling plan should be developed that directs the
collection of representative samples from the site for the
treatability test. The sampling plan should be site-specific
and describe the number, location, and volume of samples
to be collected. Typically, little information is available at
this point of the RI; therefore, good engineering judgment
must be used. An adequate volume of soil sample should
be collected from each sampling location to account for
replicate treatability tests and analytical quality
assurance/ quality control (QA/QC) requirements.
Depending upon the goals of the remedy screening
treatability study, samples representative of conditions
typical of the entire site or defined areas (i.e., hot spots)
within the site should be collected. 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.
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, care should be taken to minimize their loss when
they are composited. Compositing is usually appropriate
for soils containing non-volatile constituents; however,
compositing samples on ice is a good method of
minimizing the loss of volatile compounds.
4.4.2 Sampling During the Remedy
Screening Treatability Study
During the remedy screening treatability study, the extent
of biodegradation is assessed by removing samples from
a large test reactor, or sacrificing the entire contents of
smaller test systems, at predetermined time intervals. The
concentrations of contaminants, at a minimum, should be
determined at the beginning, at some intermediate time
point, and at the end of the experiment. Therefore, a
minimum of three sampling points is normally required. A
useful approach is to establish enough test systems so
that the remedy screening study can be extended or
additional samples can be removed and archived for
analysis, if required, The length of the study will be
determined by the biodegradability of the contaminants.
For example, treatability tests for BTEX wastes may be
conducted within 3 to 4 weeks. Tests involving PAHs
may take several months because microorganisms will
likely attack the structurally less complicated molecules
before more complex molecules. As discussed earlier,
measures of microbial activity may be useful in identifying
appropriate sampling times.
4.4.3 Analysis
The concentrations of some important matrix parameters
are determined by using standard analytical chemistry
methods (Table 4-2). These parameters should be
determined before the treatability study begins. These
parameters are important for the design of remedy
selection and remedy design studies; they should not be
used as an indication of the inappropriateness of the
technology.
Table 4-2. Commonly Used Analytical Chemistry
Methods for Soil Parameters
Methods
Analysis
Liquid/Sludge Soil
Moisture 160.3(19) ASTM2216(1)
Nitrate 9200<24>/300.0<25>
Total Organic Carbon 9060<24>/415.1<19> 9060<24>
Total Kjeldahl Nitrogen 351.2(19) ASTM E 778(1)
Soluble Orthophosphate 365.1(19)
Soluble Ammonia 350.1<19>
pH 9040<24>/150.1<19> 9045(24)
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Contaminant concentrations should be determined at the
beginning of the study and at the sample times chosen in
the experimental design. Consult U.S. EPA SW-846(24) for
the appropriate methods. When determining volatile and
semi-volatile organics, GC or other appropriate methods
(e.g., HPLC) should be used whenever possible, rather
than gas chromatography/mass spectrometry (GC/MS)
methods, to minimize costs. All sampling and analysis
should be performed in accordance with the SAP (Section
5).
4.5 DATA ANALYSIS AND
INTERPRETATION
The Work Plan should discuss the techniques to be used
in analyzing and interpreting the data. The following data
should be reported for each treatability test:
Concentration of chemicals in samples at the
time of sampling (field concentration) and
before the samples are added to the reactors
(T0 reactor concentration)
Amount of soil used in the reactors and a
description of all modifications to the reactors
Quantity of residual chemical(s) in each of the
reactors at each sampling time
Quantity of chemical(s) lost due to abiotic
processes
Temperature profile over the entire experiment
recorded in a written log indicating type,
extent, and time of any action
Any other additions, removals, changes,
manipulations, or mishaps that occur during
the course of the experiment should be
recorded in a written log indicating type,
extent, and time of any action
All cited analytical and microbiological
procedures (recorded in a written log)
All quality control data (e.g., recovery
percentage of spikes; contaminant
concentrations, if any, in experimental and
analytical blanks).
Additional information on the interpretation of treatability
study data is presented in Section 6 of this document.
4.6 REPORTS
The Work Plan should discuss the organization and
content of interim and final reports. Once the data have
been gathered, analyzed, and interpreted, they must be
incorporated into a report. A suggested organization for
the treatability study report is provided in Subsection 4.12
of the generic guide/18'
If the report indicates aerobic biodegradation has
potential (see Section 6 for guidance on interpretation of
treatability data), the project can progress to the next
level. In general, if the average reduction in contaminant
concentration attributable to biodegradation exceeds 20
percent during a 6- to 8-week test period, the remedy
screening is considered positive. Additional studies will
be required before selecting a remedy in the ROD.
4.7 SCHEDULE
The Work Plan should discuss the schedule for
completing the remedy screening treatability study. When
preparing a schedule for conducting treatability studies,
it is advantageous to break down the entire process into
distinct tasks that are common to most studies.
Listed below are specific tasks that should always be
considered when scheduling:
Work Plan preparation
SAP preparation
Sample collection and disposal
Field sample analysis
Treatability test (including analyses)
Data validation
Report preparation.
The tasks that have the greatest potential for time
variance are usually the Work Plan preparation and the
treatability tests. The treatability test schedule is
unpredictable without a firm understanding of the
contaminant types and concentrations involved. For
example, remedy screening treatability tests for BTEX
wastes may be conducted within a couple of weeks; tests
involving PAHs may take several months for the reasons
discussed in Subsection 4.4.2.
The schedule itself is usually most helpful if displayed in
the form of a bar chart, such as the one shown in Figure
4-1.
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TASK
Taskf
Task 2
RAP HQP A PPP Prana ration
Tasks
Treatability Study Execution
Task 4
Data Analysis & Interpretation
Tasks
Tasks
Residuals Management
Span,
Weeks
4
12
2
12
Weeks from Project Start
,|2|3|,
M-I M
(
*
5678
-2
r
M
9 10 !l|l2
-3 M-4
( M
I3J14 is] is
-5 N
r ^
17J]8J19|20
6 M-7
/
(
\
\M-8
VJl^ -
21J22|23|24
M-9
(
7
2SJ2SJ27 28
M-12 M
-- ^ ^
29J30
13 M
r j
15
i 1
M-10 M-ll M-14 M-16
1
ซ n Administrative approval, document review, or sample turnaround
M-l Submit Work Plan Wk2
M-2 Receive Work Plan Approval Wk4
M-3 Submit SAP, HSP.CRP Wk8
M-4 Receive SAP, HSP Approvals Wk10
M-S Collect Sample Wk12
M-6 Receive Sample Characterization Results Wk16
M-7 Collect Treatability Study Samples Wk18
M-8 Collect Project Residual Samples Wk18
M-9 Receive Treatability Study Analytical Results Wk 22
M-10 Receive Project Residual Analytical Results Wk 22
M-ll Submit Waste Disposal Approval Form Wk24
M-12 Submit Draft Report Wk26
M-13 Receive Review Comments Wk 28
M-14 Receive Waste Disposal Approval Wk28
M-15 Submit Final Report; Conduct Briefing Wk 30
M-16 Ship Wastes to TSDF Wk30
4.8 MANAGEMENT AND STAFFING
The Work Plan should discuss the management and
staffing of the remedy screening treatability study and
identify the personnel who will be responsible for
executing the treatability study at this level. Generally, the
following expertise is needed for the successful
completion of the remedy screening treatability study:
Project manager (work assignment manager)
Chemist
Microbiologist ,environmental scientist/
engineer, or bioengineer
Lab technician
Quality assurance manager.
Responsibility for various aspects of the project is
typically shown in an organizational chart such as the one
in Figure 4-2.
4.9 BUDGET
The Work Plan should discuss the budget for completion
of the remedy screening treatability study. The cost of
biotreatability evaluations varies tremendously.
Historically, the cause of this wide variation has been
significant differences in the scope of work associated
with specific site characteristics. The lack of established
standard procedures, to date, for performing
biotreatability evaluations has led remediation firms to
develop their own "standard procedures." This guide will
serve as an important aid in accurately defining data that
should be produced from a biotreatability remedy
screening evaluation and ensuring that the data will be
sufficient for deciding whether to proceed to the next
phase of development of the bioremediation process.
The cost of the remedy screening phase is directly related
to the method of sample collection, the number of samples
collected, the type and number of chemical analyses
performed on samples, and the number of replicate remedy
screening tests performed. The factor which is most likely
to influence the cost of the remedy screening is the ana-
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CONTRACTOR or WORK
ASSIGNMENT MANAGER
Report to EPA Remedial
Project Manager
Supervise overall project
MICROBIOLOGIST (ENVIRONMENTAL
SCIENTIST/ENGINEER or
BIOENGINEER)
Oversee Treatability
Study execution
Prepare applicable sections
of Report and Work Plan
QUALITY ASSURANCE MANAGER
Oversee Quality Assurance
Prepare applicable sections
of Report and Work Plan
CHEMIST
Oversee sample collection
and analysis
Prepare applicable sections
of Report and Work Plan
LAB TECHNICIAN
Perform Treatability Study
Sample collection and analysis
Figure 4-2. Organization chart.
lytical costs which are directly tied in with the number of rather than GC/MS methods also should help to minimize
replicates. One method to minimize costs is to use an
inexpensive analysis of an indicator parameter and to
perform a limited number of analyses for the more
expensive volatile and semi-volatile priority pollutants.
UseofGC
costs. Table 4-3 summarizes the major cost elements
associated with remedy screening treatability tests for
biodegradation of a contaminated site.
Table 4-3. Major Cost Elements Associated with Aerobic
Biological Remedy Screening Treatability
Studies
Cost Element
Work Plan Preparation
SAP Preparation
Field Sample Collection
Field Sample Chemical Analysis
Laboratory Setup/Materials
Treatability Test Chemical Analysis
Data Presentation/Report
TOTAL COST RANGE
Cost Range
(thousands of dollars)
i~5
1 -5
1 -5
2-10
2-10
2-10
1 -5
10-50
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SECTION 5
SAMPLING AND ANALYSIS PLAN
The SAP consists of two parts - the Field Sampling Plan
(FSP) and the QAPjP. This section identifies the contents
of and aids in the preparation of these plans. A SAP is
required for all field activities conducted during the RI/FS.
The purpose of the SAP is to ensure that samples
obtained for characterization and testing are
representative and that the quality of the analytical data
generated is known. 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 the
Work Plan is approved.
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 necessary
equipment and procedures for collecting the samples; the
sample chain-of-custody procedures; and the required
packaging, labeling, and shipping procedures.
Field samples are taken to provide baseline contaminant
concentrations and material for the treatability studies.
The sampling objectives must be consistent with the
treatability test objectives. Because the primary objective
of remedy screening studies is to provide a first-cut
evaluation of the extent to which specific chemicals are
removed from the soil by biological process, the primary
sampling objectives should include, in general:
Acquisition of samples representative of
conditions typical of the entire site or defined
areas within the site. Because this is a fast-cut
evaluation, elaborate, statistically designed
field sampling plans may not be required.
Professional judgment regarding the sampling
locations should 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. This
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.
From these two primary objectives, more specific
objectives should be developed. When developing the
more detailed objectives, the following types of questions
should be considered.
Will samples be composited to provide more
representative samples for the treatability test,
or will the potential loss of target VOCs
prohibit this sample collection technique?
Are there adequate data to determine sampling
locations indicative of the more contaminated
areas of the site?
Is sampling of a worst-case scenario warranted
to determine if either indigenous or inoculated
microorganisms are able to break down
contaminants at their highest known
concentrations in the field.
After the sampling objectives are clearly identified, an
appropriate sampling strategy should be described.
Specific items that should be briefly discussed are:
Sampling objectives
Calibration procedures
Sample location selection
Sample collection
Sampling procedures
Sample transportation
Sampling equipment
Responsible persons
Sample media type
Sampling strategy
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Sample location map
Sample history recording procedures
Sample preservation methods/holding times
Sample custody and chain-of-custody
procedures
Table 5-1 presents the suggested organization of the
SAP.
TABLE 5-1. Suggested Organization of the Sampling
and Analysis Plan
Field Sampling Plan
1. Site Background
2. Sampling Objectives
3. Sample Location and Sampling Frequency
4. Sample Designation
5. Sampling Equipment and Procedures
6. Sample Handling and Analysis
Quality Assurance Project Plan
1. Experimental Design
2. Quality Assurance Objectives
3. Sampling and Analytical Procedures
4. Approach to QA/QC
5.2 QUALITY ASSURANCE PROJECT
PLAN
The QAPjP should be consistent with the overall
objectives of the treatability study. At the remedy
screening level, the QAPjP should not be overly
detailed.
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; however, all details of the
experimental design not finalized in the Work Plan
should be defined in this section.
The following items should be included:
Number of samples (area) to be studied
Identification of treatment conditions
(variables) to be studied for each sample
Type of reactors to be used for each sample
Target compounds for each sample
Number of replicates per condition per
sampling event
Number and time of each sampling event.
The project description should clearly define and
distinguish the types of critical measurements or
observations that will be made, as well as any system
conditions (e.g., process controls or operating
parameters) that will need to be monitored routinely.
Critical measurements are those measurement,
data-gathering, or data-generating activities that directly
affect the technical objectives of aproject. At aminimum,
the determination of the target compound (identified
above) in the initial soil and treated soil samples will be
critical measurements.
The purpose of the remedy screening treatability study is
to determine whether biological treatment is potentially
applicable to the site under consideration. An example of
a criterion for this determination is a 20 percent reduction
in concentration of the select target compounds at the 80
percent confidence level. If a 20 percent reduction is
obtained, then additional remedy selection studies would
be indicated to optimize the treatment and determine the
cost-effectiveness in comparison to other technologies.
5.2.2 Quality Assurance Objectives
Section 2 should list the QA objectives for each type of
critical measurement and for each type of sample matrix
defined in Section 1, for each of the six data quality
indicators: precision, accuracy, completeness,
representativeness, comparability, and, where applicable,
method detection limit. See reference 21 for additional
information on the preparation of a QAPjP.
5.2.3 Sampling and Analytical Procedures
The procedures used to obtain the field samples for the
remedy screening treatability study are described in the
FSP and need not be repeated in this section, but should
be incorporated by reference.
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Section 3 of the QAPjP, therefore, should contain a
credible plan for subsampling the material for the remedy
screening treatability study. Also, if the reactor contents
are sacrificed for analysis, the methods for aliquoting the
residual material in each reactor for different analytical
methods must be described.
This section should also describe or reference an
appropriate analytical method and a standard operating
procedure for implementing the analytical method for each
type of critical measurement to be made. In addition, the
calibration procedures and frequency of calibration
should be discussed or referenced for each analytical
system, instrument, device, or technique used to obtain
critical measurement data.
The methods used for analyzing the treatability study
samples should be the same as those used for chemical
characterization of field samples. Preference should be
given to methods in "Test Methods for Evaluating Solid
Waste." (24) If applicable, methods other than GC/MS
methods are recommended to conserve costs.
5.2.4 Approach to QA/QC
The treatability study is designed to compare the results
of a biological reactor to an inhibited control reactor over
a period of time. Replicate samples (three) are taken of
both experimental setups at T0, Tb and at least a T2. The
inhibited control is run and analyzed to account for losses
of the target compounds due to any cause other than
biodegradation (e.g., volatilization, adsorption).
The intended purpose of this study is to determine if the
concentration of the target compounds decreases at least
20 percent in the biological reactor compared to
the inhibited control at an 80 percent confidence level.
Only the relative accuracy of the analytical measurements
and the overall precision of the experiments are important.
The suggested QC approach will consist of:
Triplicate samples of both reactor and
inhibited control at each sampling time
The analysis of surrogate spike compounds in
each sample
The extraction and analysis of a method blank
with each set of samples
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 80 percent
confidence level. The analysis of the surrogate spike will
determine if the analytical method performance is
consistent (relatively accurate). The matrix spike will be
used to measure overall analytical accuracy. The method
blank will show if laboratory contamination has had an
effect 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.
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SECTION 6
TREATABILITY DATA INTERPRETATION
This section is designed to help the RPM or contractor to
interpret treatability data in screening and selecting a
remedy. The information and results gathered from the
remedy screening are used to determine if bioremediation
is a viable treatment option and to determine if additional
remedy selection and remedy design studies are needed
prior to the implementation of a full-scale bioremediation
process. A threshold of greater than 20 percent reduction
in the concentrations of the compounds of concern, com-
pared to the abiotic control, indicates that bioremediation
is potentially a viable cleanup method and further testing
is warranted. For some compounds or sites, a period of
time longer than the typical 6-8 weeks may be indicative
of a successful remedy screening study. An example
method for interpreting the results from a remedy
screening treatability study is provided below. Other valid
statistical methods may be used as appropriate.
Example 6.
In a remedy screening treatability study for soil contaminated with a solvent, the average
solvent concentrations in both the inhibited control and in the biologically active system were
1 300 ppm at T0 . The average solvent concentration in the inhibited control was reduced to 550
ppm (T3), a reduction of greater than 57 percent (Table 6-1). The average hydrocarbon
concentration In the biologically active system was reduced to 200 ppm CQ, a reduction of
greater than 84 percent for the same time period.
Table 6-1. Hydrocarbon Concentration (ppm) Versus Time
SAMPLE
Inhibited Control (C)
Replicate 1
Replicate 2
Replicate 3
Mean Value
Concentration Change
(Ci0-Ci,) (1 = 0,1,2,3)
Bioreactor (CJ
Replicate 1
Replicate 2
Replicate 3
Mean Value
Concentration Decrease
(Cb0-Cbt) (T = 0,l,2,3)
T0 Tt T2 T3
1220 1090 695 575
1300 854 . 780 580
1380 1056 6Jฃ 495
1300 (Ci0) ioqo (eg 721 (eg 550 (eg
0 -300 -579 -750
1327 982 550 225
1320 865 674 310
1253 703 666 65
1300 (Cb0) 850 (Cb,) 630 (Cb2) 200 (Q>3)
0 -450 -670 -1100
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The average contaminant concentration of the bioreactor, at each time point, is corrected
by the average contaminant concentration of the inhibited control, at the same time point, to
measure the biodegradation at that time point. The inhibited control accounts for contaminant
losses due to volatilization, adsorption to soil particles, and chemical reactions. Some
contaminant loss in the control due to biodegradation may occur since total sterilization is
difficult to accomplish. However, if a statistically significant difference between the test and
control means exists, then biodegradation has occurred in the test bioreactor. The difference
between the two means is tested using Analysis of Variance (ANOVA) methods at the 80
percent confidence level for each of the test times. If the difference between the two means
is significant at T,, no further test measurements are required. If the difference between the
two means is not significant at T,, then the remedy screening test continues until some T2.
This process is repeated until a statistically significant difference between the two means is
found or the treatability study is determined to be unsuccessful and is discontinued. In this
example, a statistically significant difference between the two means occurs at T3. The data,
therefore, indicate that bioremediation is a viable treatment option and that further remedy
selection studies are appropriate. The 80% confidence interval about each mean is shown in
Figure 6-1 to graphically describe the variation associated with each mean.
E
Q.
CO
O
!
X
g
1
t-j
CD
O
c
O
O
1.5
1.4-
1.3-
1.2-
1.1-
1
0.9-
0.8-
0.7-
0.6-
0.5-
0.4-
0.3-
0.2-
0.1-
0
T1 T2
Time
A inhibited control non-inhibited control
Table 6-1. Plot of hydrocarbon concentration versus time.
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If the remedy screening indicates that bioremediation is a
potential cleanup option then remedy selection studies
should be performed. Remedy selection testing is the
second level of testing. It is used to identify the
technology performance on a contaminant-specific basis.
Costs for these studies generally range from $50,000 to
$250,000. They yield data that verify that the technology
can meet expected clean up goals and can provide
information in support of the detailed analysis of the
alternative (i.e., the nine evaluation criteria).
During the remedy selection studies, microcosms
designed to simulate the proposed full-scale
bioremediation system are generally established.
Specifically,the goals of the remedy selection microcosms
are to:
Estimate the rate at which the contaminants
can be biodegraded
Determine the impact of parameters such as
nutrient addition, loading rate, and inoculation
on the rate of biodegradation
Estimate the cleanup levels achievable
Develop design parameters for the next level of
testing
Develop preliminary cost and time estimates
for full-scale bioremediation.
If required, several bioremediation processes can be
evaluated simultaneously to determine which process or
combination of processes is most appropriate for the
cleanup of a given site. For example, if the affected
materials at a site can be effectively remediated with either
a solid-phase or a slurry-phase biological treatment
process, both of these processes may be evaluated
simultaneously. The biodegradation rates measured
during the solid-phase and slurry-phase remedy selection
evaluations can then be used to estimate the treatment
time, equipment, and land area required by each treatment
process. This procedure permits determination of which
process or combination of processes can achieve most
cost-effectively, the required cleanup levels in the
required period of time. If sufficient design and cost
information are acquired during the remedy selection tests
to permit full-scale system design, furtherremedy design
testing may be unnecessary.
Remedy design testing is the third level of testing in the
RI/FS process. These studies generally range from
$100,000 to $500,000. As discussed in the preceding
paragraph, remedy design studies are not always required.
When remedy design tests are performed, they are
typically post-ROD. Therefore, if a remedy design
programis conducted, it should produce the data required
forfinal full-scale remedy design and costing. The remedy
design program is usually conducted on-site and should
test all equipment and processes so that accurate
specifications can be made for the full-scale system.
Example 7 demonstrates the decision process to proceed
fromremedy screening, through remedy selection, and on
to remedy design. This example is a continuation of
Example 4 on page 20.
The size and scope of the remedy design program may be
decided by several factors including the quantity of
material available for testing, the complexity of the
process, cost, time, and equipment availability. An
important factor that should not be overlooked when a
remedy design program is being set up is that the
equipment must be sized so that realistic scale-up factors
can be used for going to full-scale operation.
In conclusion, technologies generally are evaluated first
at the remedy screening level and progress through the
remedy selection to the remedy design level. A
technology may enter, however, at whatever tier or level
is appropriate based on available data on the technology
and site-specific factors. For example, a technology that
has been studied extensively may not warrant remedy
screening to determine whether it has the potential to
work. Rather, it may go directly to remedy selection
testing to verify that performance standards can be met.
Example?.
Even though the reduction in PCP concentration during the remedy screening study was
sufficient to justify continuing to the remedy selection tier of treatability testing, the percentage
of degradation, as compared to the control, indicated that process changes were needed at the
remedy selection tier. High PCP concentrations may have been inhibiting microbial activity. The
RPM decided to investigate mixing less contaminated soil with the highly contaminated soil to
lower PCP concentrations and stimulate biodegradation. Remedy selection studies, using the
design modifications suggested by the remedy screening studies, resulted in an average
removal of 93 percent of the PCP. Remedy design studies were performed to provide design
information for a full-scale system, which was used to remediate the site successfully.
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SECTION 7
REFERENCES
1. American Society for Testing and Materials. 1987.
Annual Book of ASTM Standards.
2. Box, G.E.P., W.G. Hunter, and J.S. Hunter. Statistics
for Experimenters. Wiley, 1978.
3. Gibson, D.T. Microbial Degradation of Organic
Compounds. Microbiology Series. Marcel Dekker,
Inc., New York, 1984.
4. Kukor, J.J., and R. H. Olsen. Diversity of Toluene
Degradation Following Long Term Exposure to BTEX
In Situ. In: Biotechnology and Biodegradation.
Daphne Kanely, A. Chakrabarty, and G. Omenn, eds.
Gulf Publishing Co., Houston, Texas, 1989. pp. 405-
421.
5. Lentner, M., and T. D. Bishop. Experimental Design
and Analysis. Valley Book Company, Blacksburg,
Virginia, 1986.
6. Loehr, R-C. L and Treatment as a Waste Management
Technology: An Overview. Land Treatment: A
Hazardous Waste Management Alternative. R.C.
Loehr, et al., eds. Center for Research in Water
Resources, The University of Texas at Austin, 1986.
pp. 7-17.
7. Marinucci, A.C., and R. Bartha. Apparatus for
Monitoring the Mineralization of Volatile 14C-Labeled
Compounds. Applied and Environmental
Microbiology, 38(5): 1020-1022, 1979.
8. Munnecke, D.M., L.M. Johnson, H.W. Talbot, and S.
Barik. Microbial Metabolism and Enzymology of
Selected Pesticides. In: Biodegradation and
Detoxification of Environmental Pollutants. A.M.
Chakrabarty, ed. CRC Press, Boca Raton, Florida,
1982.
9. Odeh, R.E. and M. Fox. Sample Size Choice. Marcel
Dekker, Inc., New York, 1975.
10. Pramer,D., andR. Bartha.PreparationandProcessing
of Soil Samples for Biodegradation Studies.
Environmental Letters, 2(4):217-224, 1972.
11. Fitter, P., and J. Chudoba, Biodegradability of
Organic Substances in the Aquatic Environment.
CRC Press, Boca Raton, Flonda, 1990.
12. Reineke, W., and H. J. Knackmuss. Microbial
Degradation of Haloaromatics. Ann. Rev. Microbial.
42:263-287,1988.
13. Ross, D. Application of Biological Processes to the
Clean Up of Hazardous Wastes. Presented at The
17th Environmental Symposium: Environmental
Compliance and Enforcement at DOD Installations in
the 1990's, Atlanta, Georgia, 1990.
14. Sims, R. C. Treatment Potential for 56 EPA Listed
Hazardous Chemicals In Soil. EPA/600/6-88/001, U.S.
Environmental Protection Agency, 1988.
15. U.S. Environmental Protection Agency. A
Compendium of Technologies Used in the Treatment
of Hazardous Wastes. EPA/625/8-87/014, 1987.
16. U.S. Environmental Protection Agency. Engineering
Bulletin: In Situ Biodegradation Treatment. EPA/
540/0-00/000, unpublished.
17. U.S. Environmental Protection Agency. Engineering
Bulletin: Slurry Biodegradation. EPA/540/2-90/016,
1990.
18. U.S. Environmental Protection Agency. Guide for
Conducting Treatability Studies Under CERCLA,
Intenm Final. EPA/540/2-89/058, 1989.
19. U.S. Environmental Protection Agency. Methodsfor
ChemicalAnalysis of Water and Wastes. EPA/600/4-
79/020, 1979.
20. U.S. Environmental Protection Agency.
Microbiological Decomposition of Chlorinated
Aromatic Compounds. EPA 600/2-86/090, 1986.
21. U.S. Environmental Protection Agency, Preparation
Aids for the Development of Category IV Quality
Assurance Project Plans. EPA/600/8-91/006, 1991.
22. U. S. Environmental Protection Agency. ROD Annual
Report: FY 1989. EPA/540/8-90/006, 1989.
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23. U.S. Environmental Protection Agency. Technology 26. U.S. Environmental Protection Agency. Treatability
Screening Guide for Treatment of CERCLA Soils and Studies Under CERCLA: An Overview. Office of
Sludges. EPA/540/2-88/004, 1988. Solid Waste and Emergency Response, Directive
9380.3-02FS, 1989.
24. U.S. Environmental Protection Agency. Test
Methods for Evaluating Solid Waste. 3rd Ed., SW846, 27. 40 CFR, Section 796.3400.
1986.
25. U.S. Environmental Protection Agency. TestMethod:
The Determination of Inorganic Anions in Water by
Ion Chromatography -Method 300.0.
EPA-600/4-84/017, 1984.
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