United States Office of Emergency EPA/540/1 -89/00 \A
Environmental Protection And Remedial Response OSV.'ER directive 9265.7-01
Agency Washington. DC 20460 March 1989
Superfund
SEPA Risk Assessment Interim
Guidance For Final
Superfund -
Environmental
Evaluation Manual
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OSWER Directive 9285.7-01
DISCLAIMER
The policies and procedures set forth here are intended as
guidance to Agency and other government employees. They do not
constitute rulemaking by the Agency, and may not be relied on to
create a substantive or procedural right enforceable by any other
person. The Government may take action that is at variance with
the policies and procedures in this manual.
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OSWER Directive 9285.7-01
ACKNOWLEDGMENTS
This manual vas prepared by The Cadmus Group, Inc., for the
U.S. Environmental Protection Agency, Office of Solid Waste and
Emergency Response through Contract No. 68-03-3348. Project
Directors and principal authors were Michael J. Dover (Cadmus),
Patricia Mundy (EPA) and John Bascietto (EPA).
Many individuals contributed to this document. We especi-
ally wish to acknowledge the assistance provided by Dr. James
Gillett of Cornell University, who served as a review consultant
to Cadmus and offered many valuable comments that were incorpor-
ated into this version of the manual. Other Cadmus contributors
include Dr. David Burmaster (consultant to Cadmus), Beverly Brown
Cadoretta, Scott T. Campbell, Gene E. Fax, Joseph P. Foran,
Kenneth W. Mayo, and Theodore R. Schwartz.
This manual is the product of an extensive planning and
review process within EPA. The EPA Work Group, which also in-
cluded representatives from the National Oceanic and Atmospheric
Administration (NOAA) and the U.S. Fish and Wildlife Service
(USFWS), listed on the following page conferred several times to
discuss the organization, content, and policy implications of the
document. The Work Group members reviewed and provided extensive
comments on each of several drafts of the manual. In the early
stages of the project, members of the Region III Bioassessment
Work Group—Dr. David Charters (EPA Environmental Response Team),
Dr. Alyce Fritz (NOAA, Region III), and Ronald Preston (Environ-
mental Services Division, EPA Region III)—provided invaluable
planning assistance.
The authors were privileged to have as a reference a draft
version of a manual prepared by the Ecological Risk Assessment
Subcommittee of the EPA Region I Risk Assessment Work Group. The
document, titled Guidance for Ecological Risk Assessments, was
issued as a Draft Final in February 1989. Concepts and some
wording of the Region I document were adapted for use in several
parts of this manual. We gratefully acknowledge the Subcommit-
tee's cooperation (in particular, Susan Norton of the Office of
Health and Environmental Assessment) in making their draft
available to us.
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OSWER Directive 9285.7-01
ENVIRONMENTAL EVALUATION MANUAL
EPA WORK GROUP
EPA Headquarters
Office of Emergency and Remedial Response:
Office of Waste Programs Enforcement:
Office of Solid Waste:
Office of Solid Waste and Emergency
Response:
Office of Air and Radiation:
Office of Federal Activities:
David Bennett
Karen Burgan
David Charters
Steve Golian
Sandra Lee
Arthur Weissman
Jack Schad
Sherry Sterling
Alec McBride
Ossi Meyn
Tom Pheiffer
Gary Snodgrass
Phillip Ross
Judy Troast
office
of
General Counsel:
Joseph Freedman
Office
of
Information Resource
Management:
Barbara Lamborne
Office
of
Marine and Estuarine
Protection:
Bob Zeller
Office
of
Policy, Planning and
Evaluation:
Dexter Hinckley
Office of Research and Development:
Office of Toxic Substances:
Office of Underground Storage Tanks:
Office of Water Enforcement and Permits:
Office of Water Regulations and Standards:
Office of Wetlands Protection:
iii
Diane Niedzialkowski
Craig Zamuda
Thomas Baugh
Will LeVeille
Susan Norton
Jim Gilford
Iris Goodman
Martha Segall
Suzanne Marcy
John Maxstead
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OSWER Directive 9285.7-01
EPA Regional Offices
Region 1: Dorothy Allen
Michael Bilger
Susan Svirsky
Region 2: Peter Grevatt
Mark Sprenger
Region 3: Jeff Pike
Ron Preston
Region 4: Elmer Akin
Russ Todd
Region S: Pamela Blackley
Wayne Davis
Allison Hiltner
Pranas Panckevicius
Region 6:
Region 7:
Region 8:
Region 9:
Region 10:
Pat Mammack
John Rauscher
Robert Fenemore
Robert Morby
Jay Silvernale
Greg Baker
Greg Eckert
Pat Cirone
Wayne Grotheer
Evan Hornig
EPA Laboratories
Athens, GA:
Cincinnati, OH:
Corvallis, OR:
Duluth, MN:
Gulf Breeze, FL
Las Vegas, NV:
Narragansett, RI:
Robert Ambrose
Cornelius Weber
Hal Kibby
Nelson Thomas
Hap Pritchard
Chuck Nauman
Gerald Pesch
Other Agencies
National Oceanic and Atmospheric
Administration:
Oak Ridge National Laboratory:
U.S. Fish and Wildlife Service:
U.S. Forest Service:
(Areata, CA)
Sharon Christopherson
Thor Cutler
Ken Finkelstein
Alyce Fritz
John McCarthy
Lee Barclay
Peter Escherich
Hart Welsh
IV
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TABLZ 07 CONTENTS
Acknowledgments ii
Environmental Evaluation Manual—EPA Work Group iii
List of Figures viii
List of Tables ix
Preface x
1- INTRODUCTION 1-1
1.1 What is Ecological Assessment? 1-3
1.2 Ecological Assessment in the Superfund Process 1-3
1.3 Who Should Read this Manual 1-7
1.4 Organization of the Manual 1-7
2. STATUTORY AND REGULATORY BASIS OF ECOLOGICAL
ASSESSMENT 2-1
2.1 CERCLA/SARA Authorities 2-2
2.2 The National Contingency Plan 2-3
2.3 Removal Action Guidance 2-5
2.4 Remedial Investigation and Feasibility Study
(RI/FS) Guidance 2-8
2.5 CERCLA Compliance with other Environmental
Statutes (ARARs) 2-11
3. BASIC CONCEPTS FOR ECOLOGICAL ASSESSMENT 3-1
3.1 Objects of Study in Ecology 3-1
3.2 Types of Ecosystems 3-7
3.3 Effects of Contaminants on Ecosystems 3-13
3.3.1 Reduction in Population Size 3-14
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OSWER Directive 9285.7-01
3.3.2 Changes in Community Structure 3-14
3.3.3 Changes in Ecosystem Structure and
Function 3-15
3.4 Factors Influencing the Ecological Effects
of Contaminants 3-16
3.4.1 Nature of Contamination 3-16
3.4.2 Physical/Chemical Characteristics of
the Environment 3-21
3.4.3 Biological Factors 3-23
4. THE ROLE OF TECHNICAL SPECIALISTS IN ECOLOGICAL
ASSESSMENT 4-1
4.1 Site Characterization 4-2
4.2 Site Screening and Identification of
Information Gaps 4-6
4.3 Advice on Work Plans 4-7
4.4 Data Review and Interpretation 4-9
4.5 Advice on Remedial Alternatives 4-11
4.6 Enforcement Considerations 4-10
5. PLANNING AN ECOLOGICAL ASSESSMENT 5-1
5.1 Determination of Need, Objectives, and
Level of Effort for Ecological Assessment 5-2
5.2 Evaluation of Site Characteristics 5-4
5.2.1 Nature and Extent of Contaminated Area 5-4
5.2.2 Sensitive Environments 5-5
5.3 Contaminant Evaluation 5-6
5.3.1 Identification and Characterization 5-6
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5.3.2 Biological and Environmental
Concentrations 5-7
5.3.3 Toxicity of Contaminants 5-9
5.3.4 Potential ARARs and Criteria 5-13
5.4 Potential for Exposure 5-13
5.5 Selection of Assessment and Measurement
Endpoints 5-16
5.5.1 Ecological Endpoints 5-16
5.5.2 Evaluation of Potentially Affected
Habitats 5-19
5.5.3 Evaluation of Potentially Affected
Populations 5-22
5.6 Sampling and Analysis Plan 5-2 4
5.6.1 Field Sampling Plan 5-25
5.6.2 Quality Assurance 5-2 6
6. ORGANIZATION AND PRESENTATION OF AN ECOLOGICAL
ASSESSMENT 6-1
6.1 Specify the Objectives of the Assessment 6-1
6.2 Define the Scope of the Investigation 6-2
6.3 Describe the Site and Study Area 6-2
6.4 Describe Contaminants of Concern 6-5
6.5 Characterize Exposure 6-6
6.6 Characterize Risk or Threat 6-11
6.7 Describe the Derivation of Remediation
Criteria or Other Uses of Quantitative
Risk Information 6-13
6.8 Describe Conclusions and Limitations of
Analysis 6-15
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LIST OF FIGURES
1.1 Relationship Between Health and Environmental
Evaluations 1-6
1.2 Logical Organization of this Manual 1-9
3.1 Levels of Organization of Matter 3-2
3.2a Examples of Typical Food Chains 3-5
3.2b A Greatly Simplified Terrestrial Food Web 3-6
3.3 Thermal Stratification of a North Temperate Lake 3-11
6.1 Example of Study Area Map 6-4
6.2 Graphic Display of Contaminant Concentrations 6-7
6.3 Map Display of Contaminant Concentrations 6-3
6.4a Map Display of Toxicity Test Results 6-9
6.4b Map Display of Toxicity Test Results 6-10
6.5 Graphic Display of Species Diversity Indices 6-16
6.6 Graphic Display of Trophic Structure 6-17
viii
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OSWER Directive 9285.7-01
LIST OF TABLES
1.1 Additional EPA Documents to be Consulted 1-2
3.2 Forest Food Chain for DDT 3-28
6.1 Example of Presentation of Criteria Exceedences 6-14
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RISK ASSESSMENT GUIDANCE FOR SUPER7UND
ENVIRONMENTAL EVALUATION MANUAL
HUMAN HEALTH EVALUATION MANUAL
This document is part of a two-manual set entitled Risk
Assessment Guidance for Superfund. One manual, the Environmental
Evaluation Manual, provides guidance for ecological assessment at
Superfund sites? the other, the Human Health Evaluation Manual,
provides guidance for health risk assessment at these sites.
Guidance in both areas is needed so that EPA can meet the
requirements of sections 121(b)(1) and (d) of the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA),
namely, that selected remedial actions be protective of human
health and the environment. This risk assessment guidance also
can assist EPA in complying with other CERCLA directives. For
example, Section 121(c) requires, future reviews to ensure that
human health and the environment: continue to be protected at
sites where contaminants remain after remedial actions were
completed.
The Risk Assessment Guidance for Superfund manuals were
developed to be used during the Removal and Remedial Investiga-
tion/Feasibility Study (RI/FS) processes at Superfund sites. The
analytical framework and specific methods described in the man-
uals, however, may also be applicable to evaluations of hazardous
wastes and hazardous materials for other purposes. For the RI/FS
process, these manuals are companion documents to EPA's Guidance
for Conducting Remedial Investigations and Feasibility Studies
Under CERCLA (October 1988), and users should be familiar with
that guidance. The two Superfund risk assessment manuals were
developed with extensive input from EPA workgroups composed of
both Regional and Headquarters staff. These manuals are interim
final guidance; final guidance will be issued after the revisions
to the National Oil and Hazardous Substances Pollution Contingen-
cy Plan (NCP), proposed in December 1988, become final.
Although environmental evaluation and human health evalua-
tion are different processes, they share certain information
needs and generally will use some of the same chemical and other
data for a site. Planning for both evaluations should begin
during the scoping stage of the RI/FS, and site sampling and
other data collection activities to support the two evaluations
should be coordinated. An example of this type of coordination
is the sampling and analysis of fish or other aquatic organisms;
if done properly, data from such sampling can be used in assess-
ing human health risks from ingestion of fish and shellfish and
x
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OSWER Directive 9285.7-01
in assessing impacts to, and potential effects on, the aquatic
ecosystem.
The two manuals in this set have somewhat different target
audiences. The Environmental Evaluation Manual primarily
addresses Remedial Project Managers (RPMs) and On-Scene Coor-
dinators (OSCs), who are responsible for ensuring a thorough
evaluation of potential environmental effects at sites. The
Environmental Evaluation Manual is not a detailed "how-to" type
of guidance, and it does not provide "cookbook" approaches for
evaluation. Instead, it identifies the kinds of help that RPMs
or OSCs are likely to need and where to find that help. Then it
describes an overall framework for considering environmental
effects. A detailed discussion of environmental evaluation
methods may be found in Ecological Assessments of Hazardous Waste
Sites: A Field and Laboratory Reference Document (EPA/600/3-
89/013) , published by EPA's Office of Research and Development.
The Human Health Evaluation Manual, available in 1989,
provides a basic framework for health risk assessment at
Superfund sites. The health evaluation manual is addressed
primarily to the individuals actually conducting health risk
assessments for sites and who are frequently contractors to EPA,
States, or potentially responsible parties. It is also targeted
to EPA staff, including those responsible for ensuring a thorough
evaluation of human health risks (i.e., RPMs). The Human Health
Evaluation Manual replaces a previous EPA guidance document, The
Superfund Public Health Evaluation Manual, or SPHEM (October
1986), which should be used until the Interim Final Human Health
Evaluation Manual is available. The new manual incorporates
lessons learned from application of the earlier manual and
addresses a number of issues raised since publication of the
SPHEM.
xi
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1. INTRODUCTION
This manual is intended to help Remedial Project Managers
(RPMs) and On-Scene Coordinators (OSCs) manage environmental
evaluation of Superfund sites. This is an important part of the
Remedial and Removal processes. Since RPMs and OSCs have primary
responsibility for managing these processes, it is important for
them to understand basic ecological concepts and how they relate
to hazardous waste remediation.
The purpose of this document is to provide a scientific
framework for designing studies that will evaluate pertinent eco-
logical aspects of a site for the Remedial and Removal processes,
including:
Living resources at or near the site requiring protec-
tion,
Effects of the site's contaminants on those resources,
and
Effects of remedial actions.
This manual does not offer detailed descriptions of specific
field or laboratory methods; these are discussed in a companion
publication prepared by EPA's Office of Research and Development.
In addition, the Superfund Exposure Assessment Manual describes
methods for estimating and modeling the fate and transport of
contaminants in the environment. Other information that should
be used to supplement this manual may be found in the publica-
tions listed in Table 1.1.
The manual is based on the assumption that RPMs and OSCs
will obtain assistance from technical specialists as early as
possible in the assessment process, and is designed to facilitate
communication between the RPM or OSC and these specialists.
Support for designing and evaluating ecological assessments is
available from technical assistance groups in those EPA Regions
that have formed them. In other Regions, ecologists may be found
on the staffs of other EPA offices and contractors, or on the
staffs of other Federal agencies. The role of these specialists
is discussed in greater detail in Chapter 4.
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I
to
Additional
Table 1.1
EPA Documents to be Consulted
Title
Source
Reference No.
Superfund Exposure Assess-
ment (1988)
Office of Solid Waste
and Emergency Response
EPA/540/1-88/001
OSWER Dir. 9285.5-1
Ecological Assessment of
Hazardous Haste Sites:
A Field and Laboratory
Reference Document (1989)
Office of Research and
Development--Corvallis
Environmental Research
Laboratory
EPA/600/3-89/013
Ecological Information
Resources Directory
(1989)
Office of Information
Resource Management
In Preparation
User's Guide to the Con-
tract Laboratory Program
(1989)
Office of Emergency
Remedial Response
OSWER Dir. 9240.0-1
Estimating Toxicity of
Industrial Chemicals to
Aquatic Organisms Using
Using Structure Activity
Relationships (1988)
Office of Toxic
Substances
EPA/560/6-88/001
CERCLA Compliance With
Other Laws Manual (1988)
Office of Solid Waste
and Emergency Response
OSWER Dir. 9234.1-01
Guidance for Conducting
Remedial Investigations
and Feasibility Studies
under CERCLA (Interim
Final, 1988)
Office of Solid Waste
and Emergency Response
OSWER Dir. 9355.3-01
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INTERIM FINAL March 1989
OSWER Directive 9285.7-01
1.1 What is Ecological Assessment?
Although "environmental evaluation" has been a commonly used
term for this process, ecological assessment is a more precise
description of the activity, and will be used throughout this
manual.
Ecological assessment, as discussed in this manual, is a
qualitative and/or quantitative appraisal of the actual or po-
tential effects of a hazardous waste site on plants and animals
other than people and domesticated species. It is important to
emphasize, however, that the health of people and domesticated
species is inextricably linked to the quality of the environment
shared with other species. Information from ecological studies
may point to new or unexpected exposure pathways for human
populations, and health assessments may help to identify
environmental threats.
The purpose of ecological assessment at Superfund sites is
to provide decision makers with information on threats to the
natural environment associated with contaminants or with actions
designed to remediate the site. Decisions such as those made on
Superfund sites are necessarily made with varying degrees of
uncertainty. The ecological assessment is intended to reduce the
uncertainty associated with understanding the environmental ef-
fects of a site and its remediation, and to give specific bound-
aries to that uncertainty. However, it is important to recognize
that ecological assessments of Superfund sites are not research
projects: they are not intended to provide absolute proof of dam-
age, nor are they designed to answer long-term research needs.
1.2 Ecological Assessment in the Superfund Process
The Comprehensive Environmental Response, Compensation and
Liability Act (CERCLA), as amended by the Superfund Amendments
and Reauthorization Act of 1986 (SARA), calls upon EPA to protect
human health and the environment with respect to releases or
potential releases of contaminants from abandoned hazardous waste
sites. The proposed National Contingency Plan (NCP) calls for
the identification and mitigation of environmental impacts of
these sites and the selection of remedial actions that are "pro-
tective of environmental organisms and ecosystems." Numerous
Federal and State laws and regulations concerning environmental
1-3
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OSWER Directive 9285-7-01
protection are also potentially "applicable or relevant and
appropriate requirements" (ARARs). Compliance with these laws
and regulations may require evaluation of a site's ecological
e£fect3 and the measures needed to mitigate those effects. The
specific legislative and other mandates for ecological assessment
are discussed in Chapter 2 of this manual.
Ecological assessment may take place before, during and
after remedial actions. Removal actions, directed by the OSC,
are generally taicen in response to an immediate hazard. When an
emergency response is under consideration, the ecological assess-
ment associated vith removal actions must be performed quickly.
Existing information, augmented by any field data that can be
collected in a short period of time, will be used to:
Decide if removal is necessary based on ecological con-
siderations ,
Predict the ecological effects of removal actions, and
Provide preliminary information to support a Remedial
Investigation if one is needed.
Ecological data should also be gathered before and during
remedial action. These data will be used to:
Determine the appropriate level of detail for the ecolo-
gical assessment,
Decide if remedial action is necessary based on ecologi-
cal considerations,
Evaluate the potential ecological effects of the remedial
action itself,
Provide information necessary for mitigation of the
threat, and
Design monitoring strategies for assessing the progress
and effectiveness of remediation.
A detailed assessment may be required to determine whether
or not the potential ecological effects of the contaminants at a
site warrant remedial action. Although human health is frequent-
ly the major concern, the ecological assessment may serve to ex-
pand the scope of the investigation, enlarging the area under
consideration, and/or redefining remediation criteria. There-
fore, when appropriate, the Scope of Work for the Remedial Inves-
1-4
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OSWER Directive 9285.7-01
tigation/Feasibility Study (RI/FS) should be written to incorpo-
rate ecological investigations as early as possible in the pro-
cess.
The RPM also evaluates the alternatives outlined in the
RI/FS to determine whether the proposed remedial action itself
will have any deleterious environmental effects. For example, if
dredging is included in a remedial alternative, the effects of
the dredging on aquatic organisms living on or in the sediments
will very likely need to be considered. If a remediation plan
proposes channeling a stream into a new drainage area, the down-
stream effects on wetlands may require investigation.
Finally, ecological assessment may suggest strategies for
monitoring the progress and effectiveness of remediation at or
near a site. For example, toxicity tests of soils, sediments,
and water have been used to supplement chemical residue data in
establishing cleanup criteria. On-site toxicity tests may be
more sensitive to low levels of contaminants than other monitor-
ing methods, and may indicate toxicity of mixtures of contami-
nants more readily than single-chemical criteria.
Environmental evaluation and human health evaluation are
parallel activities in the evaluation of hazardous waste sites.
As Figure 1.1 illustrates, much of the data and analyses relating
to the nature, fate, and transport of a site's contaminants will
be used for both evaluations. At each point of these common
stages, however, analysts should be sensitive to the possibility
that certain contaminants and exposure pathways may be more im-
portant for the' environmental evaluation than for the health
evaluation, or vice versa. It is also important to recognize
that each of the two evaluations can sometimes make use of the
other's information. For example, the potential of a contaminant
to bioaccumulate may be estimated for a health evaluation but be
useful for the environmental evaluation, or measurement of con-
taminant levels in sport and commercial species for an environ-
mental evaluation may yield valuable information for the health
evaluation.
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OSWER Directive 9285.7-01
Figure 1-1
Relationship Between Health and Environmental Evaluations
IDENTIFY CONTAMINANTS OF CONCERN
Health-
Specific
General Concern
(Health and Environmental)
Environment-
Specific
QUANTIFY RELEASE, MIGRATION AND FATE
Run
Fate and Transport
Models
Measure
Environmental
Concentrations
IDENTIFY EXPOSURE ROUTES
Health-
Specific
General Concern
(Health and Environmental)
Environment-
Specific
3F
w
Potentially
Exposed
Habitats
Human
Populations at
Risk
Health Effects
Studies
V
Potentially
Exposed
Populations
Sport or
Other
Commercial
Species
Species
Ecological
Effects Studies
and Tests
HUMAN HEALTH
EVALUATION
\V
ENVIRONMENTAL
EVALUATION
1-6
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OSWER Directive 9285.7-01
1.3 Who Should Read this Manual
This manual is designed for use by Remedial Project Managers
and On-Scene Coordinators. In addition, the following may also
find the manual useful for understanding the ecological assess-
ment process as it relates to Superfund sites:
- EPA Regional Office managers of RPMs or OSCs,
- State hazardous waste officials who wish to undertake
ecological assessments of their own,
- EPA contractors and others who may perform ecological
assessments,
- Ecologists who have no past experience with Superfund
ecological assessments, and
Potentially Responsible Parties (if they are performing
the worJc at the site) .
1.4 Organization of the Manual
This manual is intended to address the following questions:
How does ecological assessment help EPA meet its statu-
tory responsibilities?
What is the underlying scientific basis for ecological
assessment?
How should the RPM or OSC use technical specialists in
managing ecological assessments?
What kinds of data are necessary for ecological assess-
ments?
The Chapters following this Introduction are
Chapter 2: Statutory and Regulatory Basis of Ecological
Assessment,
Chapter 3: Basic Concepts for Ecological Assessment,
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INTERIM FINAL March 1989
OSWER Directive 9285.7-01
- Chapter 4: The Role of Technical Specialists in Ecologi-
cal Assessment,
- Chapter 5: Planning an Ecological Assessment, and
- Chapter 6: Organization and Presentation of an
Ecological Assessment
As Figure 1.2 illustrates, Chapters 2 through 4 provide in-
troductions to different aspects of the ecological assessment
process. Chapters 5 and 6 then provide more specific guidance on
the information needed in an ecological assessment.
Chapter 2 describes the authority provided by CERCLA (as
amended by SARA), requirements contained in the National Contin-
gency Plan, and references to ecological assessment in the RI/FS
and Removal Guidances. The chapter also discusses Federal stan-
dards, requirements, criteria, or limitations that are potential
ARARs.
Chapter 3 describes the basic scientific concepts underlying
ecological assessment. It is intended to assist the RPM or OSC
in working with the ecologists who will provide technical advice
or perform the studies, by describing the conceptual framework
within which these specialists make their judgments. This chap-
ter defines numerous terms that are used later in the manual.
Those readers familiar with the concepts and terminology of eco-
logy and environmental chemistry may choose to skim this chapter
or skip it entirely.
Chapter 4 details the role of technical specialists in
ecological assessment. Their primary function is to assist the
RPM and the OSC in directing the collection and evaluation of in-
formation on ecological effects. They nay serve as advisers or
actually perform the ecological assessment under the direction of
the RPM or the OSC.
Chapter 5 discusses the process of developing an appropriate
study design for assessment of a site, including evaluation of
contaminants of concern, site characteristics, and ecological as-
sessment endpoints. Besides specifying study objectives, this
phase must also address quality assurance and quality control
(QA/QC) issues associated with the assessment.
1-8
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OSWER Directive 9285.7-01
Figure 1-2
Logical Organization of this Manual
1-9
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OSWER Directive 9285.7-01
Chapter 6 describes a basic outline for an assessment.
Although each site's assessment will differ according to the
details of the contaminants, exposure routes, potentially-
affected habitats and species, this chapter provides a checklist
of items for the RPM or OSC to expect when overseeing the
preparation of an assessment. For any individual site, expansion
of the topics here may be needed, with appropriate explanations.
This manual is em introduction to a complex subject. As-
sessments of actual sites require a detailed knowledge of the
habitats and species that are potentially exposed, the activity
and movement of contaminants in the environment, and the sampling
and analytical methods needed to make scientifically defensible
judgments. Use of this manual will provide a basis for the
successful management of such assessments.
1-10
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2. STATUTORY AND REGULATORY BASIS
OF ECOLOGICAL ASSESSMENT
Ecological assessment of hazardous waste sites is an essen-
tial element in determining overall risk and protecting public
health, welfare, and the environment. The Agency considers
ecological factors in assessing hazards and in reviewing alterna-
tive remedial actions because:
- Through the authority found in CERCLA (as amended by
SARA) and other statutes'1, the Agency seeks to protect
wildlife, fisheries, endangered and threatened species,
and valued habitats.
- From a scientific viewpoint, the Agency needs to examine
ecological effects and routes of exposure so that (a)
important impacts and transport pathways are not over-
looked, and (b) reasonable estimates are made of health
and environmental effects.
This chapter describes the statutory and regulatory frame-
work underlying ecological assessment. Certain provisions of
CERCLA and SARA are especially important in this regard:
The statutes require that remedial actions selected for a
site be sufficient to protect human health and the envi-
ronment.
- Compliance with applicable or relevant and appropriate
requirements (ARARs) entails consideration of numerous
Federal and State laws and regulations concerning natural
resource preservation and protection when evaluating pos-
sible response actions.
SARA calls upon EPA to notify Federal natural resource
trustees of negotiations with potentially responsible
parties and to encourage trustees' participation in the
negotiations if a release or threatened release.may re-
sult in damages to protected natural resources.
The chapter begins with a discussion of the authority
provided in the amended CERCLA for conducting ecological assess-
ments. Section 2.2 describes the implementation of CERCLA as
outlined in the proposed revisions to the National Contingency
Plan. Guidance documents for removal actions and the RI/FS
process are discussed in Sections 2.3 and 2.4, respectively. A
wide array of potential ARARs is the subject of Section 2.5. It
is important to note, however, that this section is not intended
to be an exhaustive survey of potential ARARs; the RPM or OSC
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OSWER Directive 9285.7-01
will need to ascertain the specific Federal and State require-
ments that apply to each site, depending on the contaminants of
concern and the characteristics of the site.
2.1 CERCLA/SARA Authorities
The Comprehensive Environmental Response, Compensation and
Liability Act, as amended by the Superfund Amendments and Re-
authorization Act of 1986, requires EPA to ensure the protection
of the environment in (1) selection of remedial alternatives and
(2) assessment of the degree of cleanup necessary. Several
sections of CERCLA make reference to protection of health and the
environment as parts of a whole. Section 105(a) (2) calls for
methods to evaluate and remedy "any releases or threats of
releases . . . which pose substantial danger to the public health
or the environment." Section 121(b)(1) requires selection of
remedial actions that are "protective of human health and the
environment." Section 121(c) calls for "assurance that human
health and the environment continue to be protected." And
Section 121(d) directs EPA to attain a degree of cleanup "which
assures protection of human health and the environment."
CERCLA Section 104(b)(2) calls upon EPA to notify the
appropriate Federal and State natural resource trustees promptly
about potential dangers to protected resources. The Federal
natural resource trustees include:
- The U.S. Fish and Wildlife Service (USFWS), the National
Park Service (NPS), and the Bureau of Land Management
(BLM) of the Department of the Interior;
- The National Oceanic and Atmospheric Administration
(NOAA) of the U.S. Department of Commerce; and
- The U.S. Department of Agriculture Forest Service.
State agencies and Indian tribes are also designated trus-
tees for natural resources under their jurisdiction.
Section 122(j) of the amended CERCLA requires the Agency to
notify the Federal natural resource trustees of any negotiations
regarding the release of hazardous substances that may have re-
sulted in natural resource damage. Section 122(j) (1) also calls
upon EPA to encourage Federal natural resource trustees to par-
ticipate in negotiations with potentially responsible parties
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OSWER Directive 9285-7-01
(PRPs). If EPA seeks to settle with a PRP by signing a covenant
not to sue, the Federal natural resource trustee must agree to
this covenant in writing. Section 122(j)(2) states that:
The Federal natural resource trustee may agree to such a
covenant if the potentially responsible party agrees to
undertake appropriate actions necessary to protect and
restore the natural resources damaged by such release or
threatened release of hazardous substances.
The ecological assessment directed by the OSC or RPM should
not be confused with the Preliminary Natural Resource Survey
(PKRS) or the Natural Resource Damage Assessment (NRDA), which
are performed by natural resource trustees. PNRSs are simple
screening studies, based on readily available information, that
may be conducted by trustees to determine whether or not (a)
trustee resources may have been affected, and (b) further atten-
tion to trustee resources is warranted at a particular site. The
NRDA may be conducted by one or more trustees if a response ac-
tion will not sufficiently restore or protect natural resources
damaged by a release. The purpose of the NRDA is to determine
the appropriate level of compensation from a responsible party.
Data collected in an ecological assessment may prove helpful to
the trustees in carrying out their responsibilities. It is im-
portant to encourage the natural resource trustee to participate
in the Superfund process at the earliest possible stage. In this
way, the trustee can be assured that any potential environmental
concerns are addressed, and conclusion of actions may be ex-
pedited..
2.2 The National Contingency Plan
As required by SARA Section 105, EPA has revised the Na-
tional Contingency Plan (NCP)1, which provides for effective re-
sponse to discharges of oil and releases of hazardous substances.
Section 300.120 of the proposed NCP charges the site-specific OSC
USEPA, National Oil and Hazardous Substances Pollution
Contingency Plan 40 CFR Part 300. EPA Proposed Revisions
to the NCP at 53 Fed. Reg. 51395 {Proposed Rule, December
21, 1988). All references to the "proposed NCP" in this
manual are to this proposed rule. Quotations from the
NCP used in this section are from the Preamble.
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OSWER Directive 9285.7-01
or RPM with (1) identifying potential impacts on public health,
welfare, and the environment, and (2) setting priorities for this
protection.
Like CERCLA, the proposed NCP refers throughout to health
and environment as aspects of the evaluation and remediation
processes. For example, in discussing the baseline risk assess-
ment in a Remedial Investigation, the purpose is defined as de-
tennining "whether the site poses a current or potential risk to
human health and the environment in the absence of any remedial
action." The exposure assessment in the RI "is conducted to
identify the magnitude of actual or potential human or environ-
mental exposures ..." The toxicity assessment "considers . . .
the types of adverse health or environmental effects associated
with chemical exposures." In addition, the proposed NCP states
that "Superfund remedies will ... be protective of environ-
mental organisms and ecosystems.n
Sections 300.17 5 and 3 00.180 of the proposed NCP direct the
RPM or OSC to coordinate with other Federal and State agencies.
USFWS and NOAA are specifically cited with respect to endangered
or threatened species. Under Section 300.430, the RPM or OSC is
to notify affected land management agencies and natural resource
trustees regarding any release or discharge that affects natural
resources under their jurisdiction. According to the proposed
NCP, "when trustees are notified of or discover possible damage
to natural resources, they may conduct a preliminary survey of
the area to determine if natural resources under their trust are
affected." The document adds an important proviso:
Although a trustee may be responsible for certain natu-
ral resources affected or potentially affected by a re-
lease, it is important that only one person (i.e., the
lead agency OSC or RPM) manage activities at the site
of a release or potential release. The OSC or RPM
shall coordinate responsibilities for CERCLA section
104 assessments, investigations, and planning, includ-
ing Federal trustees' participation in negotiations
with PRPs as provided in CERCLA section 122(j)(i).
Close communication and coordination between OSCs/RPMs
and trustees is essential.
If, after the remedial action is completed, any hazardous
substances remain on a site "above levels that allow for unlimit-
ed use and unrestricted exposure for human and environmental re-
ceptors," the proposed NCP would require the lead Agency to
review the remedial action every five years to ensure that the
environment continues to be protected.
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OSWER Directive 9285.7-01
2.3 Removal Action Guidance
The Guidance covering removal actions calls upon the OSC to
consider threats to the environment in addition to public health
when preparing the Action Memorandum required for all removals.2
For example, in discussing the role of the National Response Team
(NRT), the Guidance states that the NRT "should be activated as
an emergency response team if [a] release . . . (i]nvolves sig-
nificant population threat or national policy issues ... or
substantial threats to natural resources." In the section on
determining the need for and urgency of a removal, the manual
specifies:
At any release, regardless of whether the site is on
the NPLr where the OSC determines that there is a
threat to public health, welfare or the environment,
. . . the OSC may take any appropriate action to abate,
minimize, stabilize, mitigate or eliminate the actual
or potential release and the resulting threat.4
For those incidents not categorized as "classic emergen-
cies," the Guidance indicates that "the OSC should conduct more
extensive data collection and analysis to document more complete-
ly the actual or potential health and environmental threat." As
an example, the manual calls on the OSC to "make a concerted ef-
fort to use existing environmental and health standards as trig-
gers for initiating response and as guidelines in determining re-
sponse act i ons."5
In describing the contents of the preliminary assessment,
the Guidance points out that "the OSC must incorporate any spe-
cial procedures or technical criteria EPA has established for a
variety of special, complex cases," which include floodplains and
2 Superfund Removal Process (OSWER Directive 9360.0-038).
EPA Office of Emergency and Remedial Response, February
1988.
3
Ibid.,
P-
111-10.
4
Ibid.,
P-
Ill—14.
5
Ibid..
P-
111-15.
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OSWER Directive- 9285.7-01
wetlands.6 Among the determinations that need to be made at the
conclusion of the preliminary assessment, the Guidance includes
the following:
If the OSC determines that natural resources have been
or are likely to be damaged, the OSC should ensure that
the trustees of the affected natural resources are no-
tified in order that they may initiate appropriate ac-
tions ....7
The Guidance devotes a section to removal actions in flood-
plains and wetlands, pointing out that such actions "should be
consistent to the extent possible with Federal policy and proce-
dures for the protection of floodplains and wetlands." Descrip-
tions and references for the specific regulations are given in
Section 2.5, below. Under the policy established by the Office
of Emergency and Remedial Response, specific actions are required
of the OSC:
"[As] part of the preliminary assessment, . . . determine
whether the release is in, near or affecting a floodplain
or wetland."
If "the release is in proximity to or has the potential
to affect a floodplain or wetland," evaluate
"Possible impact of proposed response actions on the
floodplain/wetland,"
"Alternate response actions . . . ,11 and
"Measures to minimize potential adverse impacts."
"[D]ocument the results of this evaluation in the Action
Memorandum."
"[E]nsure that the implementation of approved response
actions minimizes adverse impacts on the floodplain/wet-
land. "a
6 Ibid. . p. Ill-n.
7 Ibid.. p. 111-12.
8 Ibid.. pp. IV-12 and IV-13.
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OSWER Directive 9285.7-01
The Guidance also makes specific reference to environmental
threats in the Appendices describing the Action Memorandum. For
example, demonstration of actual or potential "catastrophic envi-
ronmental damage1* may be cited as the reason for activating an
OSC's $50,000 authority in a time-critical removal. In describ-
ing the characteristics of an incident, the OSC is asked to dem-
onstrate "that the incident already has posed or imminently vill
pose an imminent and significant danger to the public or to the
environment.1* One way of demonstrating this is to show "proximi-
ty to . . . significant natural resources." The Guidance goes on
to ask several key questions whose answers will help determine if
the incident is time-critical:
Are there confirmed reports of injuries to natural re-
sources or injuries to or deaths of flora and fauna?
Are more anticipated? How sensitive/critical are these
resources (e.g., protected wildlife refuge)? Is there
catastrophic environmental damage?
Even if the incident does not appear to be time-critical,
the Guidance cautions the OSC that "[s]ome environmental threats
are not urgent, but nevertheless are significant." To aid in
demonstrating that failure to respond "will create an unaccept-
able impact on natural resources and the environment," the Guid-
ance poses these questions:
"What additional information (beyond that requested in
the time-critical screen) documents the threat to the en-
vironment (e.g., monitoring or other data verifying in-
jury to or destruction of natural resources, critical"
habitats)?"
"What are the known short- and long-term effects that are
likely if there is no response or response is delayed?
When is that threat likely to manifest itself?"9
For removals that will take less than 12 months and cost
less than $2 million, Appendix 6 of the Guidance provides a model
Action Memorandum to assist the OSC in meeting the requirements
of CERCLA and the proposed NCP. Under the heading "Site Descrip-
tion," the model reminds the OSC to describe "areas adjacent to
the incident or site in terms of vulnerable or sensitive popula-
tions, habitats and natural resources." The section goes on to
cite sensitive areas such as wetlands, floodplains, "sensitive
9 Ibid.. Appendix 5, pp. 3-5.
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OSWER Directive 9235.7-01
ecosystems," or wild and scenic rivers. Under the heading
"Threats to the Environment," the model calls upon the OSC to:
List all the current and potential threats . . . that
adversely affect the environment (e.g., damage to eco-
system, animals, ground water). Identify any natural
resource or environmental damage that already has oc-
curred and the extent of exposure (e.g., acute or
chronic). Indicate whether there have been reports of
deaths of flora or fauna (e.g., fish kills). . . .
Discuss potential damage to the environment and indi-
cate a time frame within which damage will occur if
response actions are not taken.
Discuss all actual or potential impacts on the affected
area. Describe any anticipated exposure and whether it is
imminent. Indicate whether the release threatens endangered
species, critical wetlands, or other resources protected
under law. State whether natural resources trustees have
been notified.10
2.4 Remedial Investigation and Feasibility Study (RI/FS)
Guidance
Remedial Project Managers are responsible for all phases of
the remedial process, including but not limited to the RI/FS.
Ecological assessment of appropriate detail may be conducted at
any of these phases. The nature, extent, and level of detail of
the ecological assessment will be determined according to the
phase of the remedial process, the specific study objectives, and
the characteristics of the site and its contaminants. These de-
cisions should be made in close consultation with technical advi-
sers , as discussed in Chapter 4.
This Section focuses on ecological components of the RI/FS
process as outlined in EPA's RI/FS Guidance.11 In the scoping
10 Ibid. , Appendix 6, pp. 6-7.
11 Guidance for Conducting Remedial Investigations and Feas-
ibility studies under CERCLA (Interim Final). OSWER Di-
rective 9355.3-01. EPA Office of Emergency and Remedial
Response. October 1988.
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OSWER Directive 9285.7-01
phase, the RPM develops a project plan to define the problem and
identify solutions. Among the activities at this stage are
collecting and analyzing existing data to develop a
conceptual model that can be used to assess both the
nature and the extent of contamination and to identify
potential exposure pathways and Dotential human health
and/or environmental receptors.
As part of the collection and analysis of existing data, the
Guidance specifically mentions "evidence of . . . biotic contam-
ination," identification of "biotic migration pathways," informa-
tion on ecology of the area, and data on "environmental recep-
tors ." The Guidance further states:
Existing information describing the common flora and
fauna of the site and surrounding areas should be col-
lected. The location of any threatened, endangered, or
rare species, sensitive environmental areas, or criti-
cal habitats on or near the site should be identi-
fied.13
A limited field investigation may be undertaken in this
phase of the RI/FS process. The Guidance includes a preliminary
"ecological reconnaissance" in the list of possible components of
this field investigation.
The project planning stage is also the time for the RPM to
begin preliminary identification of ARARs and To Be Considered
(TBC) information. The Guidance points out that some require-
ments "may set restrictions on activities within specific loca-
tions such as floodplains or wetlands."14
Characterized as the most important part of the scoping
process, the identification of data needs includes determining
the information required to "define source areas of contamina-
tion, the potential pathways of migration, and the potential re-
ceptors and associated exposure pathways." The objective is to
'2 Ibid.. p. 2-2.
13 Ibid. . p. 2-7.
14 Ibid. . p. 2-13.
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OSWER Directive 9285.7-01
determine "whether, or to what extent, a threat to human health
or the environment exists."15
The culmination of the project planning stage is the prepa-
ration of the Work Plan and the Sampling and Analysis Plan (SAP) .
The Work Plan includes a preliminary evaluation of (a) potential
pathways of contaminant migration and (b) public health and envi-
ronmental impacts. The SAP is a key step in the assessment pro-
cess, because it defines what data are to be sought, why the data
are needed, where and how the data will be collected, and how the
data will be analyzed and interpreted. Equally important, the
SAP specifies the data quality objectives and quality assurance
plan for the study, indicating the levels of precision and accu-
racy that are expected in data collection and analysis, and de-
scribing how the expected precision and accuracy will be main-
tained.
It is at this stage that data collection for ecological as-
sessment should be planned, including field surveys, toxicity
testing, bioaccumulation studies, and sampling to determine the
extent of contamination.14 As with other aspects of the SAP, the
planning process for ecological assessment may be iterative: that
is, analysis of early data may indicate that the sampling and an-
alysis need revision. This may entail expanding the area to be
sampled or planning new toxicity tests. It may also point to a
reduction in effort if anticipated results fail to materialize.
In describing the baseline risk assessment for the RI, the
RI/FS Guidance makes frequent reference to the ecological side of
the assessment. The baseline risk assessment is intended to
"provide an evaluation of the potential threat to human health
and the environment in the absence of any remedial action." The
process includes among its tasks the identification and charac-
terization of (a) levels of contamination in relevant media, in-
cluding biota, and (b) "potential human and environmental recep-
tors." The toxicity assessment component "considers . . . the
types of adverse health or environmental effects associated with
individual and multiple chemical exposures." The risk character
55 Ibid. , p. 2-14.
16 See EPA/ORD, Ecological Assessments of Hazardous Waste
Sites: A Field and Laboratory Reference Document
(EPA/600/3-89/013) for specific information on field and
laboratory methods.
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OSWER Directive 9285.7-01
ization component entails estimating "carcinogenic risks, noncar-
cinogenic risks, and environmental risks."1 The Guidance speci-
fies further:
Characterization of the environmental risks involves
identifying the potential exposures to the surrounding
ecological receptors and evaluating the potential ef-
fects associated with such exposure(s). Important fac-
tors to consider include disruptive effects to popula-
tions (both plant and animal) and the extent of pertur-
bations to the ecological community.13
The Feasibility Study involves screening of remediation
alternatives for their effectiveness, including their "potential
impacts to human health and the environment during the construc-
tion and implementation phase.1*19 Alternatives are expected to
be evaluated during the screening process "to ensure that they
protect human health and the environment from each potential
pathway of concern."20
2.5 CERCLA Compliance with other Environmental Statutes (ARARs)
Section 121(d)(2)(A) of CERCLA requires that the Superfund
remedial action meet Federal and State standards, requirements,
criteria, or limitations that are "applicable or relevant and ap-
propriate requirements" (ARARs). The OSC or RPM is responsible
for identifying potential ARARs for each site.
The RPM or OSC should use the EPA ARARs Manual21 to assist
in identifying potential ARARs on a case-by-case basis. Some of
the Federal environmental statutes and regulations that may be
ARARs for a particular site include:
Ibid.. pp. 3-3 5 through 3-43.
18 Ibid. . p. 3-43.
19 Ibid. , p. 4-24 .
20 Ibid. . p. 4-30.
21 CERCLA Compliance With Other Laws Manual. (OSWER Direc-
tive 9234.1-01) EPA Office of Emergency and Remedial Re-
sponse. Draft, August 8, 1988.
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OSWER Directive 928S.7-01
The Resource Conservation and Recovery Act of 1976. as
Amended. RCRA requirements for groundwater protection,
surface impoundments, waste piles, underground storage
tanks and surface treatment are all considered to be po-
tentially applicable for both human health and protection
of the environment at sites that contain RCRA-listed or
characteristic wastes and where waste management activi-
ties took place after the effective date of the relevant
RCRA Subtitle. The RPM or OSC should consult with the
appropriate Regional RCRA staff to make this determina-
tion.
The Federal Water Pollution Control Act, as Amended.
This law, also known as the Clean Water Act, includes
numerous sections that may pertain to remediation of Su-
perfund sites. The OSC or RPM should consult the ARARs
Manual for a detailed discussion of relevant sections.
Section 404, which requires protection of wetlands, is of
special importance- for environmental evaluation of Super-
fund sites.
The Clean Air Act of 1970. as Amended. Under the CAA,
EPA has established National Ambient Air Quality Stan-
dards for key pollutants. In the development of these
standards, the Agency prepares Air Quality Criteria docu-
ments that investigate various effects of exposure to the
subject pollutants, including those that occur on vegeta-
tion. These criteria documents and the standards devel-
oped from them may help establish remediation criteria
where airborne exposure is possible. In addition, EPA
has established limitations for numerous chemicals in its
National Emission Standards for Hazardous Air Pollutants
and the New Source Performance Standards. The OSC or RPM
may wish to determine the utility of these standards for
the protection of natural resources from airborne expo-
sure to contaminants.
The Toxic Substances Control Act of 1976. Section 2601
(b) of the Toxic Substances Control Act states the policy
of the United States that, ". . . adequate data should be
developed with respect to the effect of chemical substan-
ces and mixtures on health and the environment . . . ."
Data collected under TSCA concerning ecological effects
may prove useful in determining protective levels of con-
taminants. The OSC or RPM should refer to the ARARs Man-
ual for other information on applicability of TSCA.
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OSWER Directive 9285.7-01
The Federal Insecticide. Fungicide and Rodenticide Act of
1947. as Amended. FIFRA requires that all pesticides be
registered with EPA. To obtain registration, manufac-
turers must supply EPA with certain data concerning
environmental fate and transport, health effects, and
ecological effects. EPA's Office of Pesticide Programs
(OPP) has issued Registration Standards, which summarize
the Agency's assessment of many pesticide active ingredi-
ents, some of which are found at Superfund sites. The
analyses contained in these documents may assist in the
evaluation of hazards and in determining protective lev-
els of contaminants. OPP's regulatory positions on the
continued registration of individual pesticides may also
provide guidance on controlling environmental hazards.
Endangered Species Act of 1973. as Reauthorized in 1988.
Section 7 of the Act requires Federal agencies to ensure
that their actions will not jeopardize the continued ex-
istence of any endangered or threatened species. The
U.S. Fish and Wildlife Service and the National Marine
Fisheries Service have primary responsibility for this
Act.
Fish and Wildlife Conservation Act of 1980. Section 2903
requires States to identify significant habitats and de-
velop conservation plans for these areas. Although it is
unlikely that a Superfund site would be located in one of
these significant habitats, the RPM should confirm this
with the responsible State agency.
Marine Protection. Research and Sanctuaries Act of 1972.
Section 1401 declares the U.S. policy of regulating dump-
ing to ". . . prevent or strictly limit the dumping into
ocean waters of any material which would adversely affect
human health, welfare, or amenities or the marine envi-
ronment, ecological systems, or economic potentialities."
This legislation may be relevant for cleanup and removal
actions at or near the ocean.
Coastal Zone Management Act of 1972. This legislation is
designed to (a) encourage States to develop management
plans to protect and preserve the coastal zone, and (b)
ensure that Federal actions are consistent with these
management plans. The RPM or OSC would need to obtain
these management plans if remedial or removal actions
will take place in the coastal zone.
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OSWER Directive 9285.7-01
- Wild and Scenic Rivers Act of 1972. Section 2171 de-
clares that certain rivers "... possess outstanding re-
markable scenic, recreational, geologic, fish and wild-
life, historic, cultural, or other similar value" and
should be preserved. < If remedial or removal action is
taking place at or near a river, the RPM or osc should
determine whether it has been designated as "wild and
scenic," and whether there are any action-specific ARARs
regarding the site or its contaminants. The National
Park Service has primary responsibility for this Act.
- Fish and Wildlife' Coordination Act, as Amended in 1965.
Section 662(a) states that the Fish and Wildlife Service
must be consulted when bodies of water are diverted or
modified by another Federal Agency. The facility is to
be constructed "with a view to the conservation of wild-
life resources by prevention of loss, or damage to such
resources as well, as providing for the development and
improvement thereof . . . ." The RPM should consult with
USFWS or NOAA if remedial action entails altering streams
or wetlands.
The Mioratorv Bird Treaty Act of 197 2 implements many
treaties involving migratory birds. This statute pro-
tects almost all species of native birds in the U.S. from
unregulated "take," which can include poisoning at hazar-
dous waste sites. The Act is a primary tool of the U.S.
Fish and Wildlife Service and other Federal agencies m
managing migratory birds.
The Marine Mammal Protection Act of 1972. This law pro-
tects all marine mammals, some but not all of which are
endangered species. The National Oceanic and Atmospheric
Administration has primary responsibility for this Act.
The Fish and Wildlife Service also has responsibility for
some species.
Under the authority of the Clean Water Act, EPA develops
Federal Water Quality Criteria (FWQCs), including criteria for
protection of aquatic life. In 1987, EPA's Office of Water Regu-
lations and Standards revised and published its Quality criteria
for Water. 1986. For each of more than 120 inorganic and organic
compounds, this publication contains numerical Ambient Water Qua-
lity Criteria for the protection of fresh and salt water plants
and animals and their habitats, covering both acute and chronic
exposure. The proposed NCP describes the FWQCs as:
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OSWER Directive 9285.7-01
. . . non-enforceable guidelines used by the States to
set Water Quality Standards (WQS) for surface water.
. . . States designate the use of a given water body
based on its current and potential use and apply the
FWQC to set pollutant levels that are protective of
that use. ... If a State has promulgated a numerical
WQS that applies to the contaminant and the designated
use of the surface water at a site, the WQS will gener-
ally be applicable or relevant and appropriate for de-
termining cleanup levels, rather than a fwqc.
The proposed NCP discusses the difference between use of a
FWQC when the water will be used for drinking and when the prin-
cipal human exposure is expected through consumption of fish.
Separate FWQC exist for protection of aquatic life. According to
the proposed NCP:
A FWQC for protection of aquatic life may be relevant
and appropriate for a remedy involving surface waters
(or groundwater discharges to surface water) when the
designated use requires protection of aquatic life or
when environmental concerns exist at the site. If
protection of human health and aquatic life are both a
concern, the more stringent standard should generally
be applied.
The proposed NCP sets several criteria for determining the
relevance and appropriateness of a FWQC. The FWQC should be "in-
tended to protect the uses designated for the water body at the
site, or . . . the exposures for which the FWQC are protective
are likely to occur." The FWQC "must also reflect current scien-
tific information." Finally, the relevance and appropriateness
"depends on the availability of standards, such as an MCL [Maxi-
mum Contaminant Level] or WQS, specific for the constituent and
use. "
It is important to stress that the above list of statutes is
not intended to be exhaustive. In particular, the preceding dis-
cussion focused only on potentially applicable Federal laws and
regulations. State, local, and other Federal requirements may
also be applicable or relevant and appropriate. For a specific
site, specific requirements will apply, depending on the contami-
nants of concern, the location of the site, and the potentially
exposed receptors. Some, all, or none of the potential ARARs
discussed in this Section may apply. The RPM or OSC should con-
fer with appropriate State regulatory authorities, officials in
other EPA programs, and representatives of other Federal agencies
in the event of uncertainty on possible ARARs.
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3. BASIC CONCEPTS FOR ECOLOGICAL ASSESSMENT
This chapter has three purposes. First, the chapter intro-
duces and defines ideas and terms commonly used in ecology. Our
intent is to make the RPM or OSC aware of the general meaning of
these concepts, so as to facilitate discussion with the technical
specialists providing consultation on ecological assessment.
Second, the chapter discusses the nature of contaminants' ecolog-
ical effects. Although a contaminant may cause illness or death
to individual organisms, its effects on the structure and func-
tion of ecological assemblages may be measured in terms quite
different from those used to describe individual effects. Third,
the chapter describes some of the biological, chemical, and envi-
ronmental factors that influence the ecological effects of conta-
minants .
Readers who are familiar with these topics may wish to skim
this chapter. Those who are well versed in ecology and environ-
mental chemistry may want to skip it entirely.
3.1 Objects of Study in Ecology
Ecologists generally study three levels of organization:
populations, communities, and ecosystems. (See Figure 3.1.)
Each level has its characteristic measures of extent, structure,
and change.
A population is a group of organisms of the same species,
generally occupying a contiguous area, and capable of interbreed-
ing. The size and extent of populations are most often described
in terms of density, the number of organisms per unit area. Such
terms as standing crop or standing stock may be used to indicate
population size at a particular time interval, with the unit area
specified or implied. The structure of populations is often ex-
pressed in terms of the numbers of organisms in different age
classes, such as eggs, juveniles, and adults. Population growth
and decline are determined by characteristic rates of birth,
death, immigration, and emigration, all of which are subject to
change with environmental conditions, including interaction with
populations of other organisms.
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INTERIM FINAL March 1989 OSWER Directive 9285.7-01
Figure 3.1
Levels of Organization of Matter
Ecosphere
Ecosystems
Realm
Communities
of
Populations
Ecology
Organisms
HU.
r;i
7k"//' ,'*< zz— —-.
•
^eoiy«a«n»Ai
Source: Living in the Environment. 3/E, by G. Tyler Miller, Jr.
Copyright (C) 1982 by Wadsworth, Inc. Reprinted by per-
mission of the publisher.
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OSWER Directive 9285.7-01
No species in nature exists in isolation from all others.
Populations of different species live together in complex associ-
ations called communities. The interactions among populations
and the chemical and physical constraints of the environment to-
gether determine a community's structure and geographical extent.
The structure of a community is defined by what species are pre-
sent , in what numbers, and in what proportion to each other. It
is also described by the food web, or trophic structure: that is,
which species eat which other species, or who produces and con-
sumes how much.
Most communities change seasonally or over longer cycles as
some species increase or decrease in abundance in response to en-
vironmental changes such as temperature or rainfall cycles. Com-
munities also can evolve over longer periods of time in a process
known as succession. In successional change, some species are
displaced by others and new environmental conditions are created
that support more species. For example, when a meadow "grows"
¦into a forest, annual plants are gradually replaced by peren-
nials, shrubs/ and trees. Each plant type modifies the environ-
ment in ways that tend to favor the succeeding type. Eventually,
tree canopies shade much of the area that was once exposed to
sunlight, and a leaf-litter layer covers soil that was once bare.
Species diversity—expressed as the number of species or the rel-
ative abundance of the various species in a given area—is often
used to characterize and compare the structure and evolutionary
"maturity" of communities. Communities are in constant flux as
organisms are born, eat and get eaten, immigrate and emigrate,
die and decompose. These fluxes are described as energy and nu-
trient flows through food webs, and are determined by rates of
primary production (photosynthesis) by plants and rates of con-
sumption by herbivores, carnivores, and decomposers.
Just as populations exist only in association with others in
communities, so too do communities interact continuously with the
nonliving components of the environment in an ecosystem: "A func-
tional system of complementary relationships, and transfer and
circulation of energy and matter."1 The ecosystem comprises all
the living organisms, their remains, and the minerals, chemicals,
water, and atmosphere on which they depend for sustenance and
shelter. Living and nonliving components are closely linked,
each affecting the other. For example:
Eugene P. Odum, Fundamentals of Ecology. Third Edition
(Philadelphia: W.B. Saunders Company, 1971).
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OSWER Directive 923S.7-01
- Soil composition and structure is often highly influenced
by the organisms that inhabit it, and by the decomposi-
tion products of organisms after they die.
- Geological formations such as coral reefs and chalk
cliffs are the result of calcium deposition by plants and
animals over eons; they in turn affect: the flow of wind
and water, and provide habitat for countless other organ-
isms.
Ecosystems are characterized by many of the same measures as
communities: species composition and diversity, nutrient and en-
ergy flows, and rates of production, consumption, and decomposi-
tion. Unlike community measures, however, ecosystem structure
and function includes nonliving stores of materials and energy
along with the animals, plants, and microbes that make up the bi-
otic portion of the environment. Because it encompasses all of
the relevant physical and biological relationships governing
organisms, populations, and communities, the ecosystem is gener-
ally considered the fundamental unit of ecology.
Energy and matter flow through ecosystems by means of com-
plex systems known as food chains and food webs. (See Figures
3.2a and 3.2b.) A food chain describes the transfer of material
and energy from one organism to another organism as one eats or
decomposes the other. Food chains are hierarchically arranged
into trophic levels:
Primary producers—green plants (including algae and
microscopic aquatic plants called phytoplankton)—capture
solar energy through photosynthesis which converts carbon
dioxide and water into carbohydrates, a form of energy
storage suitable for use by other organisms;
Primary consumers (herbivores) eat plants;
Secondary consumers (carnivores) eat herbivores;
Tertiary consumers (top carnivores) feed on other car-
nivores; and
Decomposers—including certain fungi, and bacteria—feed
on dead and decaying organisms, liberating simple organic
chemicals and mineral nutrients for recycling in the eco-
system.
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OSWER Directive 9285.7-01
?igura 3.2a
Examples of Typical Food Chains
Type of Food Chain
Primary Secondary Tertiary Quaternary
Producer Consumer Consumer Consumer Consumer
Terrestrial
grazing
rioe humans
=> ^
grain steer humans
Terrestrial
decomposer
leaves bacteria
Terresmai
grazing
decomposer
leaves lungi squirrel hawfc
Aquatic
grazing
=> ^ =>
pftytopJanfcton zooplankton pereft bass humans
T errestnal-aquatic
grazing
§ =>% ^ fjf
grain grasshopper Irog trout human3
Source: Living in the Environment. 3/E, by G. Tyler Miller, Jr.
Copyright (C) 1982 by Wadsworth, Inc. Reprinted by per-
mission of the publisher.
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OSWER Directive 9285.7-01
Figure 3.2b
A Greatly Simplified Terrestrial Food Web
mountain Uons
Tarttary
Conaumera
(top carnivores)
Secondary
Con tumors
(carnivores)
0«co
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OSWER Directive 9285-7-01
Food veba are interconnecting food chains. These more real-
istically describe the complex system of pathways by which the
flow of matter and energy takes place in nature. Such pathways
do not always follow a strict progression of producer to herbi-
vore to carnivore. Some plants die and are decomposed without
first being eaten by herbivores. Many species have mixed diets
of plant and animal material; others change their feeding habits
seasonally or have different food requirements at different life
stages. For example, many bird species that feed primarily on
seeds during most of the year switch to insects and other inver-
tebrates when raising young, because the higher protein content
of the animal prey increases the likelihood that the young birds
will survive.
3.2 Types of Ecosystems
The' types of ecosystems vary with climatic, topographical,
geological, chemical, and biotic factors. On land, they range
from Arctic tundras to tropical rain forests, sand dunes to moun-
tain tops, deserts to forests, pure stands of evergreens to mixed
stands of hardwoods. Freshwater ecosystems include ponds, lakes,
streams and rivers. In the transition zones between land and
water, wetlands include fresh-water and salt marshes, wet mead-
ows, bogs, and swamps. Marine ecosystems range from estuaries
and intertidal zones to the open sea and deep ocean trenches.
Each ecosystem type has unique combinations of physical, chemi-
cal, and biological characteristics, and thus may respond to con-
tamination in its own unique way. Not only does the environment
influence the activities of organisms, but organisms also influ-
ence the environment.
The physical and chemical structure of an ecosystem may de-
termine how contaminants affect its resident species, and the
biological interactions may determine where and how the contami-
nants move in the environment and which species are exposed to
particular concentrations. For example, contaminants in a fores-
ted area may be subject to less degradation due to sunlight than
the same chemicals in grassland soils. Chemicals adhering to
soil particles are less likely to be washed into streams if the
soil is well covered with vegetation or decomposing leaf litter
than if the area is sparsely vegetated or bare.
Terrestrial ecosystems are generally categorized according
to the vegetation types that dominate the plant community. These
are the species upon which the rest of the community's structure
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is based—the herbivores which feed on the vegetation, the carni-
vores which feed on the herbivores and on each other, and the de-
composers which feed on the dead plant and animal material and
return mineral nutrients to the soil for recycling through the
food web. The vegetation found at a particular site is deter-
mined by a wide variety of factors, including climate, soil type,
altitude and slope of the land, and current and former uses of
the land by people. Two very common ecosystem types in the tem-
perate zone are deciduous forests and grasslands.
Temperate deciduous (leaf-shedding) forests are found in
eastern North America. They have plentiful, evenly dispersed
rainfall, moderate temperatures, and contrasting seasons. The
annual leaf fall provides habitat for large numbers of insects
and fungi that feed on the leaf litter, eventually breaking it
down into organic materials and minerals that build up the soil.
Temperate grasslands cover the interior of North America and
Eurasia, southern South America, and Australia. They receive
moderate amounts of rainfall. Tall grasses tend to grow in soil
having a high moisture content, while shorter grasses occur in
more arid areas. Numerous grass species have developed adapta-
tions to take advantage of seasonal variations in climate. One
group grows in the cooler temperatures of the spring and fall,
while another group thrives in the warmer temperatures- of summer.
These seasonal shifts in species' growth results in a high annual
productivity in grasslands, as the growing season for the commu-
nity as a whole is effectively extended to three seasons. This
productivity has allowed grasslands to support large herds of
grazing animals, such as bison, but the comparatively simple veg-
etation structure tends to support fewer animal species than a
forest of similar size. The high volume of plant material avail-
able for decomposition in grasslands creates very different soil
compositions from those created by forest leaf litter. Occasion-
al fires contribute to the stability of grasslands, as they hin-
der the growth of competitive woody plants.
Wetlands are areas m which topography and hydrology create
a zone of transition between terrestrial and aquatic environ-
ments. The combined characteristics of each create conditions of
great productivity and biological diversity. Because of these
unique conditions, both fresh-water and marine wetlands perform
several important ecological functions and provide benefits that
can be adversely affected by contamination. These include:
Hydrologic benefits such as flood attenuation and ground-
water recharge;
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OSWER Directive 9285.7-01
- Water-quality benefits such as (a) removal and cycling of
sediments, organic materials, and nutrients, and (b) sta-
bilization of banks and shorelines and control of ero-
sion; and
- Wildlife benefits such as providing habitat and food
sources for fish, shellfish, waterfowl and other birds,
mammals and other wildlife.
Contamination may adversely affect wetland functions in many
ways, depending on the wetland type, geographic location, loca-
tion within a watershed, and other factors. For example, a con-
taminated wetland may occur close to a National or State park or
wildlife management area, or may be of a type and in an area that
contains endangered species. (According to the U.S. Fish and
Wildlife Service, most endangered species in the United States
are dependent on wetlands.) Ecological impacts to wetlands may
be either direct, where a contaminant has been deposited into a
wetland, or indirect, where a wetland is in close proximity to a
contaminant source.
The type of wetland may by itself be important in determin-
ing the ecological effects of contamination. For example, heavy-
metal contaminants are more likely to impair ecological functions
when released into an acidic bog than a similar release into the
relatively well buffered waters of a salt marsh. Hence, the
classification of wetlands can be used as a starting point for
the evaluation of ecological impacts.1 General wetland types
include freshwater deciduous wetlands (dominated by red maple in
the Northeastern U.S.), wet meadows (transitional stage to
terrestrial systems), bogs (acidic peat rich soils prevalent in
the Northeastern U.S.), bottomland hardwood wetlands (dominant in
the Southeastern U.S.), and coastal salt marshes.
Fresh-water ecosystems, though comparatively smaller in area
than marine and terrestrial habitats, are of great significance
because they are:
For more information, see U.S. Fish and Wildlife Service,
An Overview of Major Wetland Functions and Values
(FWS/QBS-84/18), September 1984.
For a more complete reference on classification of
wetland types, see Cowardin, Carter, Golet and LaRoe,
Classification of Wetlands and Deepwater Habitats of the
United States. (FWS/OBS-79/31) U.S. Fish and Wildlife
Service, December 1979.
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OSWER Directive 9285.7-01
- A major component in the hydrological cycle (rivers and
streams drain a large percentage of the earth's land
surface) ,
- A breeding and rearing habit for wildlife species of
value to people,
- A readily accessible and low-cost source of water for do-
mestic and industrial use, and
A valued recreational and aesthetic resource.
In fresh-water environments, the dynamics of water tempera-
ture and movement can significantly affect the availability and
toxicity of contaminants.
The waters in lakes and ponds have relatively long residence
times. For example, consider the Niagara River as it flows into
Lake Ontariq. The Niagara's strong- currents move a given mol-
ecule of water along the 37-mile length of the river in about one
day. However, the same molecule will remain in the lake for sev-
eral years before it flows into the St. Lawrence River. A simi-
lar molecule will remain in Lake Michigan for nearly a century,
while another one would remain in Lake Superior for 191 years.
In addition, temperate lake ecosystems exhibit strong sea-
sonal cycles. In summer, surface waters warm up and become
thermally stratified—that is, they do not mix with the colder
bottom waters. (See Figure 3.3.) As a result, nutrients re-
leased through decomposition of animal.and plant material tend to
accumulate in the bottom waters. In the fall and spring, when
these temperature differentials disappear, the waters in the lake
are able to mix, allowing circulation of accumulated nutrients.
As nutrients are brought up into water that receives sunlight,
they become available to aquatic plants, which can use the nutri-
ents to support photosynthesis. These plants provide energy that
sustains growth of most other organisms in the lake system. At
each of these seasonal shifts, the biotic communities in the up-
per waters exhibit clear successional changes in their planktonic
communities. (Plankton are small plants and animals that float
passively, or can swim weakly, in the water column.) These annu-
al cycles can also greatly influence the availability of contam-
inants that may reside in the lake sediments for part of the year
and be dissolved or suspended in the water column at other times.
Such contaminants may become available to upper-water organisms
during periods of mixing.
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Figure 3.3
Thermal Stratification of a North Temperate LaJce.
i 1 1 M l>8
¦I I I I
1
Li ' ¦ i1 11 H II ¦> Ss.ii I'd il :i :i ni-:l-;i.'
KWK SCCC-'il^fii.i! .i; ii ihiMKI! I
; •|,i .ii •. - 'j •: i| ;'.:t t»< i: u «l* "*i.
« • * «i
Summer conditions are shown on the right, winter condi-
tions on the left. Note that in summer a warm oxygen-
rich circulating layer of water, the epilimnion, is
separated from the cold oxygen-poor hypolimnion
waters by a broad zone, called the thermocline, which
is characterized by a rapid change in temperature and
oxygen with increasing depth.
Source: Figure 11-9 from Fundamentals of Ecology, Third Edition,
by E.P. Odum. Copyright (C) 1971 W.B. Saunders Company,
A Division of Harcourt, Brace, Jovanovich, Inc. Reprin-
ted by permission of the publishers.
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OSWER Directive 928S.7-01
Rivers and streams are substantially different from lakes
and ponds not only in their obvious physical conditions (e.g.,
moving vs. standing water, low vs. high degree of thermal strati-
fication) but also in the types of organisms that they can sup-
port, especially in the numbers of smaller organisms and in the
types of larger plants and animals. For example, a racing brook
will have low numbers of plankton (regardless of the concentra-
tions of nutrients present) because the current rapidly moves
them downstream. In the same brook, large plants must be firmly
attached to rocks or rooted in the sediment, and fish must be
strong swimmers. In contrast, a lake or pond can accumulate high
densities of plankton, and lily pads and slow-swimming fish can
thrive. As a broad generality, food chains and food webs in
flowing waters will have fewer links or trophic levels than those
in still waters.
Marine ecosystems are of primary importance because of their
vast size and critical ecological functions, which maintain much
of the global environment's capacity to sustain life. The sea
accounts for some 70 percent of the earth's surface and supports
a wide variety of life forms at all depths, especially in the
areas bordering continents and islands. Oceans are constantly in
motion and always circulating, which is critical for replenishing
nutrients and dissolved oxygen vital for marine life. The
world's oceans have pH values around 8 and average salinity of
about 3 5 parts per 1,000. (Fresh water averages less than 0.005
parts per 1,000.)
The continental shelf comprises the submerged margins of the
land mass. The high concentration and diversity of marine life
found here is due to a high level of nutrients deriving from both
land and sea bottom. Most of the world's marine fishing grounds
are on the continental shelf. The characteristics of different
types of ecosystems in this area can affect the nature and magni-
tude of the ecological risk associated with contaminants. Inter-
tidal environments, with their continuous cycles of exposure and
re-immersion, provide unique physical conditions for resident or-
ganisms and for flow and availability of contaminants. For in-
stance, a volatile compound introduced into a rocky intertidal
zone with considerable wave and tidal action will volatilize into
the air much more rapidly than the same chemical released into a
marsh with few waves and little tidal action. As another ex-
ample, crude oil spilled onto the rocky, wave-swept coast of
France in the early 1970s is now difficult if not impossible to
detect; similar oil spilled about the same time along a marsh in
Buzzards Bay, Massachusetts, is still detectable. Hence, tidal
and subtidal ecosystems may range from relatively sheltered estu-
aries, where sediment deposition is the major physical condition,
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OSWER Directive 9285.7-01
to open coasts, where wind and wave exposure are the dominant
forces governing the fate of chemicals.
Estuaries are partly open bodies of water closely associated
with the sea in coastal zones, including river mouths, bays, tid-
al marshes, or waters behind barrier beaches. The mechanics of
estuarine systems are unique since they are strongly influenced
by the salt water of tides and the drainage of fresh water from
land. Tides play an important role in removing wastes and pro-
viding food. With a continual flow of nutrients from upstream
and from nearby marine environments, estuaries-support a multi-
tude of diverse communities, and are more productive than their
marine or freshwater sources. They are also especially important
as breeding grounds for numerous fish, shellfish, and species of
birds.
3.3 Effects of Contaminants on Ecosystems
The introduction of contaminants into an ecosystem can cause
direct harm to organisms, or may indirectly affect their ability
to survive and reproduce. The results of contamination may be
immediately apparent or may become noticeable only after con-
siderable delay. The effects of contaminants on ecosystems are
due in part to the physical and chemical properties of the
chemicals themselves, but are also mediated by the unique com-
bination of physical, chemical, and biological processes occurr-
ing m each ecosystem. In addition, populations of exposed
organisms can differ in their response to contaminants depending
on their natural tolerance to the chemical, their behavioral and
life-history characteristics, the dose to which they are exposed,
and the exposure time. Furthermore, responses may be transient
(and therefore reversible) or permanent (irreversible).
Ecological assessment seeks to determine the nature, magni-
tude, and transience or permanence of observed or expected ef-
fects. This must be accomplished in an environment that is it-
self changing and causing change in the organisms and systems un-
der study. Hence, one critical goal of ecological assessment is
to reduce the uncertainty associated with predicting and measur-
ing adverse effects of a site's contaminants.
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OSWER Directive 9285.7-01
3.3.1 Reduction in Population Size
Populations change in size through births, deaths, immigra-
tion, and emigration. Contaminants can cause reductions in popu-
lations of organisms through numerous mechanisms affecting one or
more of these four processes. Most obvious are increases in mor-
tality due to the exposure of some organisms to lethal doses, or
decreases in birth rates caused by sublethal doses. Mortality
may also increase because a food source (e.g., a key prey spe-
cies) has been depleted, perhaps by exposure to the contaminant,
or because the contaminant allows tolerant organisms to outcom-
pete other species for scarce resources. Birth rates can decline
not only due to toxic effects but also through reduction of suit-
able breeding habitat or changes in the availability of high-
quality food for breeding females. Populations may also be re-
duced through increased emigration; or decreased immigration if
organisms can sense and avoid contaminants in the environment, or
if the contaminants' sublethal effects cause a change in migra-
tory behavior.
-3.3.2 Changes in Community Structure
Many communities are constantly changing. Populations may
increase and decrease with the seasons or over longer periods.
Predation and competition among species may bring about changes
in the relative abundance of various species. Chance eventsr
such as severe storms, may cause sudden increases in mortality of
some species and open up habitat for others to colonize. Under-
lying all of this change, however, is a certain range of possi-
bilities that help to define a given community. In the absence
of a major disruption, species composition and relative abundance
in a community can be expected to vary within definable bounda-
ries, perhaps cyclically or perhaps randomly.
Contaminants introduced into such systems create new bounda-
ries, changing the range of possibilities in ways that are not
always predictable. Because most contaminants of concern exhibit
toxic effects, they often reduce the number and kinds of species
that can survive in the habitat. This may result in a community
dominated by large numbers of a few species that are tolerant of
the contaminant, or a community in which no species predominate
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OSWER Directive 9285.7-01
but most of the component populations contain fewer organisms. A
contaminant need not be directly toxic to affect community struc-
ture. If, for example, a change occurs in the salinity or dis-
solved oxygen content of an aquatic system, the new environmental
conditions may eliminate some species and favor others, creating
an entirely new species mix and food web. For example, salinity
changes in Lake Michigan are changing the species composition of
the primary producer component of the lake community from one
dominated by green algae and diatoms to one composed principally
of blue-green algae. Because many fish species currently in the
lake are unable to feed on the blue-green algae, this species
change portends significant shifts in other segments of the lake
community.
Contaminants may cause or induce changes in the composition
and structure of a biotic community as a secondary effect of- the
changes in the size of particular populations. These species may
be a major source of food or shelter for the rest of the commu-
nity, such as the large marine plants that give their name to
California's kelp forests;. Others may be crucial in maintaining
a balance of species in a habitat. If, for example, a key preda-
tory species is reduced or eliminated, the relative abundance of
prey species may change significantly. In studies where preda-
tory starfish were removed from an interti-dal community, the num-
ber of species of prey animals (barnacles and shellfish) dropped
from fifteen to eight. The starfish was preventing some species
from outcompeting others because it preyed on whatever species
was most abundant. In agricultural insect pest control, the phe-
nomena of pest resurgence and secondary pest outbreaks are well
known. When an insecticide kills off predatory insects along
with the target pest, the pest population sometimes rebounds to
much higher numbers than before because few predators remain to
keep it in check. Destruction of the predators may also allow
populations of other plant-feeding insects to increase beyond the
limits imposed by the predators, thus creating new pest problems.
3.3.3 Changes in Ecosystem Structure and Function
As contaminants modify the species composition and relative
abundance of populations in a community, the often complex pat-
terns of matter and energy flow within the ecosystem may also
change. If certain key species are reduced or eliminated, this
may interrupt the flow of energy and nutrients to other species
not directly experiencing a toxic effect. If plant life is ad-
versely affected by a contaminant, the ecosystem as a whole may
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OSWER Directive 928 5.7-01
capture less solar energy and thus support less animal life. If
microbial or invertebrate populations are disrupted, decomposi-
tion of dead plants and animals may not occur rapidly enough to
supply sufficient mineral nutrients to sustain the plant commu-
nity.
3.4 Factors Influencing the Ecological Effects of Contaminants
A contaminant entering the environment will cause adverse
effects if:
It exists in a form and concentration sufficient to cause
harm ,
- It comes in contact with organisms or environmental media
with which it can interact, and
- The interaction that takes place is detrimental to life
functions.
Adverse effects may also occur if a contaminant interacts with
other chemicals already present such as to raise the overall tox-
icity of the contaminated environment. The likelihood of harm is
thus a combined function of chemical, physical, and biological
factors, depending both on the nature of the contaminant and the
nature of the environment into which it is released.
3.4.1 Nature of Contamination
Classification of Chemicals
Chemical contaminants typically found at hazardous waste
sites are classified into groups based on the analytical methods
used to analyze for the chemicals in question. The CLP User's
Guide divides the contaminants commonly found at Superfund sites
into two major classifications: inorganic and organic compounds
(substances containing the element carbon).
User's Guide to the Contract Laboratory Program, EPA
Office of [ADD] (1988).
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The CLP routine inorganic analytical group is subdivided
into two categories: heavy metals (lead, mercury, etc.) and
cyanide. For the metal analysis, the OSC or RPM will need to
determine whether they need "total" metal analysis (sample as
collected in the field) or "dissolved" metal analysis (sample
filtered to remove particulate matter).5 A large amount of par-
ticulates in the sample matrix can produce large differences in
the analytical results between the two analyses. The choice of
analytical method also may depend on the expected route of
exposure and the biotic species of concern at a particular site.
The routine organic analyses are subdivided into three cat-
egories: volatiles (benzene, vinyl chloride, etc.), semivolatiles
(phenol, naphthalene, etc.), and pesticides (DOT, arochlors,
etc.). For compounds not routinely analyzed for, or for unusual
matrices, special analytical methods may be requested from the
CLP. The OSC or RPM should consult the CLP User's Guide regard-
ing the availability of special services. New procedures are
also being developed in response to special requirements at some
sites.
When requesting analytical services, the OSC or RPM should
take note of any special conditions on the site that may make
results of routine analyses insufficient for assessment needs.
For example, it may not be possible to detect very low concen-
trations of certain contaminants in a sample matrix that contains
(a) high concentrations of other contaminants or (b) chemicals
(interferents) that coextract with the contaminants of concern.
Physical and Chemical Properties
Measurement of key physical/chemical properties of con-
taminants is useful in ecological assessment for two main rea-
sons. First, these properties generally govern the transport and
fate of chemicals in a particular environment- Second, for chem-
icals about which little is known, these characteristics can help
the analyst identify chemical analogues among other commonly ob-
served compounds that may serve as initial predictors of the nov-
el compound's transport and fate.
The Superfund Exposure Assessment Manual (EPA, 1988) , or
SEAM, provides a comprehensive discussion of the environmental
fate of contaminants by medium. Chapter 3 of the SEAM, "Contami-
5 "Filtered" is operationally defined as that which passes
through a 0.45 um filter.
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OSWER Directive 9285.7-01
nant Fate Analysis," includes both screening criteria and quanti-
tative methods. Intermedia transfers and transformation are in-
cluded in sections covering atmospheric, surface-water, and
groundwater fate, as well as biotic exposure pathways. In ad-
dition, the Ecological Information Resources Directory (EPA,
1989) will contain updated references for some parameters, such
as bioconcentration factors.
Frequency of Release
The ecological effects of a single or occasional release are
likely to be considerably different from those associated with a
continuous release. Frequent release of a non-persistent com-
pound may have a long-term effect equivalent to a single release
of a very persistent chemical. Occasional release may temporari-
ly depress an invertebrate population, but continuous release may
trigger drastic shifts in the species composition of an ecosys-
tem. These effects should be carefully considered when perform-
ing quantitative exposure analyses as described in the SEAM.
Toxic chemicals may enter the environment, or move among
compartments of the environment, on several possible time scales.
For example, toxic discharges from a Superfund site to a waterway
may occur:
Only once (e.g., from an accidental spill),
Intermittently (e.g., from storms causing nonpomt-source
runoff of contaminated soils),
Seasonally (e.g., from snowmelt in the spring),
Regularly (e.g., from daily activities at the site), or
- Continuously (e.g., from ground-water discharge to the
waterway).
Some or all of these types of release may .happen at a particular
site, and each type of release may cause a different concentra-
tion and mass to enter the waterway.
Different species of plants and animals may have different
abilities to withstand or resist intermittent or continuous re-
leases of toxic chemicals, so it is important to characterize the
sources in terms of the kind of release that is occurring. For
example, adults of a species may withstand a short-term discharge
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that kills all the juveniles, but be severely affected by a regu-
lar or continuous release. If such a differential effect were
suspected, knowing the nature of the discharge might lead to mon-
itoring strategies that emphasize one life stage or the other.
Similarly, chronic discharges that allow bioaccumulation of cer-
tain toxicants may cause more lasting damage to certain species
than to others. Such releases might be especially harmful to
relatively immobile species.
Toxicity
Exogenous chemicals in an ecosystem can greatly increase the
mortality rate of component populations, or can change the orga-
nisms* ability to survive and reproduce in less direct ways, such
as:
Altering developmental rates, metabolic processes, physi-
ologic function, or behavior patterns;
Increasing susceptibility to disease, parasitism, or pre-
dation;
Disrupting reproductive functions; and
Causing mutations or otherwise reducing the viability of
offspring.
In assessing toxicity, the analyst is concerned about t-o
aspects. The hazard posed by a contaminant is the effect (or
endpoint), such as those mentioned above, that the chemical (or
mixture of chemicals) can cause in the organism. The dose-
response relationship describes the amount of chemical necessary
to produce the observed effect. A broad array of toxicity tests
are available for evaluating the effects of contaminants and
their dose-response relationships. These are summarized in the
companion volume to this manual and related references.6
The toxicity of a substance is generally described by the
duration of exposure or the reactions it elicits.
Ecological Assessments of Hazardous Waste Sites: A Ref-
erence Document (EPA/500/3-89/013). EPA Office of
Research and Development, 1989.
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- Acuta toxicity causes death or extreme physiological dis-
orders to organisms immediately or shortly following ex-
posure to the contaminant.
- Chronic toxicity involves long-term effects of small
doses of a contaminant and their cumulative effects over
time. These effects may lead to death of the organism or
disruption of such vital functions as reproduction.
Acute or chronic exposure can have lethal or sublethal effects.
- Lethal doses cause death directly through disruption of
key physiological function. Population levels are af-
fected by the contaminant if the overall mortality rate
is increased.
- Sublethal toxicity entails symptoms other than death or
severe disorder, but may have long-term effects on a pop-
ulation. For example, some toxicants at low concentra-
tions cause a change in the behavior of migratory fish(
interrupting their natural habit of returning to fresh-
water streams to spawn.
Evaluating the toxicity of a particular substance requires
careful specification of the endpoints of concern, which entails
describing:
- The
organism tested or observed,
- The
nature of the effect,
- The
concentration or dose needed to produce the effect,
- The
duration of exposure needed to produce the effect,
and
- The
environmental conditions under which the effects were
observed.
Ecologists will often use professional judgment to select a
particular organism as an "indicator species," that is, a species
thought to be representative of the well-being and reproductive
success of other species in a particular habitat. The indicator
species may also be chosen because it is known to be particularly
sensitive to pollutants or other environmental changes. In addi-
tion, ecologists will often study some life stage of interest in
the indicator species, such as:
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Reproductive success as measured by the survival of gam-
etes, larvae, or embryos;
Survival of juveniles or molts;
Longevity of adults; or
Incidence of disease, including physiological and be-
havioral abnormalities.
In studies of toxicity, certain measures are commonly used:
LDjq or LC50—the administered dose or environmental
concentration at which 50 percent of the experimental
organisms die in a specified period of exposure time
(often 96 hours).
EDjq or ECS0—the dose or concentration at wnich 50 per-
cent of the experimental organisms exhibit a certain
nonlethal physiological or behavioral response in a
specified time period (often 96 hours).
No Observed Effects Level (NOEL) or No Observed Adverse
Effects Level (NOAEL)—these measures, which are not
tine-dependent, describe the threshold below which pre-
defined effects are not observed. When this threshold
has not been determined, the Lowest Observed Effects
Level (LOEL) or Lowest Observed Adverse Effects Level
(LOAEL) describes the lowest recorded dosace at which
effects were observed.
3.4.2 Physical/Chemical Characteristics of the Environment
A wide variety of environmental variables can influence both
"he nature and extent of effects of a contaminant on living sys-
tems. These factors—interacting with each other, with contami-
nants, and ^ith organisms—can affect the outcome of a contamina-
tion by:
Cheaically changing the contaminant to make it more or
less toxic,
Making the contaminant more or less available in the en-
vironment, or
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- Making the organisms more or less tolerant of the chemi-
cal.
Among the many factors that can affect the outcome of con-
tamination in the environment are temperature, pH, salinity,
water hardness, and soil composition.
Temperature affects the chemical activity of contaminants
and biological activities of organisms in the environment. Low
temperatures may be advantageous in certain contamination epi-
sodes, since both chemical and biological activity may be low.
For example, low winter temperatures can reduce the toxicity of
mining effluent to macroinvertebrates1 found in streams. But the
same low temperatures can be detrimental in other circumstances.
In a study of susceptibility of seabirds to oil contamination,
researchers found that an amount of oil on the feathers too low
to cause death under normal environmental conditions was much
more stressful at colder temperatures.
The pH of the environmental medium may affect a contami-
nant's chemical form, solubility, and toxicity. This is especi-
ally true in the case of toxic metals. A one-unit decrease in pH
can cause a more than twofold increase in lead concentrations in
the blood of exposed rainbow trout. Studies have also shown
that, in general, as environmental pH decreases, the toxicity of
contaminants tends to increase.
Salinity, the amount of dissolved salts in a volume of
water, is an environmental variable to which many marine and
estuarine species are very sensitive. Some contaminants reduce
these organisms' tolerance of normal changes in salinity, de-
creasing their ability to adjust to salinity fluctuations. For
instance, one species of yearling salmon demonstrated reduced
tolerance of increases in salinity after long-term exposure to
copper.
Hardness, the amount of calcium, magnesium, and ferric car-
bonate in fresh water, can affect the toxicity of inorganic con-
taminants. Several Federal and State water quality criteria and
standards are dependent on specific hardness ranges.
Soil composition can greatly affect the nature and extent of
movement and toxicity of contaminants. Soils with a high clay-
humus colloid content can absorb high levels of certain ions and
neutral organics. The organic content of some wetland soils can
bind large amounts of heavy metals, rendering them unavailable to
the biota. Some water-insoluble pesticides are known to adsorb
to soil particles that can then transport the chemical to surface
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water when erosion occurs. Light, sandy soils readily permit
percolation of chemicals to groundwater, which may in turn con-
taminate surface waters.
3.4.3 Biological Factors
Susceptibility of Species
Species differ in the ways that they take in, accumulate,
metabolize, distribute, and expel contaminants. Taken together,
these traits result in marked differences among species in their
sensitivity to contamination. For example, over 400 species of
insects and mites have developed resistance to pesticides used to
control them, while hundreds of other species exposed to the same
chemicals remain susceptible1.
Usually, the major consideration as to how species will re-
act to a potential toxicant is the dose. Generally speaking, the
higher the dose, the greater is the likelihood that biological
effects will occur. However, response to a particular dose may
also depend on the duration of exposure. Some organisms can take
in higher doses of a toxic material if exposure is spread out
over time in smaller doses. For example, in one experiment, hens
were fed leptophos (an organophosphate insecticide) in a single
high dose or a series of lower doses. At the lower but multiple
doses, the hens developed ataxia (paralysis of the legs) later
than with the single high dose, but the total dosage over time
was greater in the multiple feeding than the single amount that
caused immediate ataxia.
Susceptibility of an organism varies with the mechanism
through which contaminants are taken up from the environment. A
given environmental concentration may result in different actual
dosages for different species. For instance, some fish not only
take in certain chemicals through their gills as they breathe,
but can also absorb the chemicals through their skin. Species
also differ in the way in which their bodies metabolize, accumu-
late, and/or store contaminants. For example, an organism that
commonly holds energy in reserve in the form of body fat may ex-
perience little effect from the accumulation of fat-soluble
chlorinated hydrocarbons such as DDT. However, in a time of
scarce food supplies, the animal might then metabolize large
amounts of fat, receiving a high dose of chemical as it does so.
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In general, the susceptibility of a species to a particular
contaminant will depend primarily on:
- The rapidity with which the contaminant is absorbed from
the environment,
- The resultant dosage actually incurred at the physiologi-
cal site where toxic effects occur within the organism
(the "site of action"),
The sensitivity of the site of action to the dosage in-
curred,
- The relationship between the site of action and the ex-
pression of symptoms of toxic injury, and
The rapidity of repair or accommodation to the toxic in-
jury.
Chaxacteristics Governing Population Abundance
and Distribution
For a given set of environmental conditions, species have
characteristic attributes such as birth rates, age and sex dis-
tributions, migration patterns, and mortality rates. The spe-
cies' habitat preferences, food preferences, and other behavioral
characteristics (e.g., nesting, foraging, rearing young) also may
determine population size and distribution in an area, and may
also significantly affect the potential for exposure.
Differences in responses to contamination due to such char-
acteristics- may be manifest immediately. For instance, a species
with a high proportion of juveniles in its age distribution might
suffer a more precipitous decline after a release than another
species that has a higher proportion of adults, simply because
adults of a species can often sustain higher doses of a toxicant
before succumbing than can juveniles.
Alternatively, the effects of species attributes governing
population abundance and distribution may become apparent only
when the stress is removed from the environment. Some species
are very successful at colonizing new habitats. They typically
have high rates of reproduction and short generation times, and
are able to disperse widely in search of suitable habitat. For
example, annual weeds, often the first plants to occupy disturbed
environments, usually produce large numbers of seeds that are
easily dispersed by wind or other means. In well established,
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more stable habitats, such "pioneer" species are often poor com-
petitors against other species for limited resources. The spe-
cies thriving in stable environments use the resources effici-
ently in the areas where they become established, and typically
have low reproductive rates, long generation times, and often,
longer life spams. They also tend to be better competitors in
the territories they occupy. These are the species that are more
likely to recolonize a disturbed habitat only after some consid-
erable delay.
Species often combine characteristics of both of these
idealized types. They may exhibit high reproductive rates and
dispersal capability, along with other traits that allow them—
under the right conditions—to outcompete later invaders. For
example, in the southern United States, the imported fire ant. has
become a serious nuisance due in part to its ability to recolon-
ize areas where insecticides were applied to control it. If the
chemicals kill off other ant species, the fire ant is better able
than its competitors to immigrate quickly and become entrenched
in the newly opened habitat.
Temporal Variability in Communities
The effects of a contaminant discharge into a particular
habitat may vary with seasonal or longer cycles governing com-
munity structure and function. Effects may be apparent immedi-
ately at one point of the cycle (e.g., in spring), whereas at
another point the effects would be delayed. Contaminants may
also elicit different effects at different stages of a commun-
ity's development.
Seasonal changes entail relatively predictable, ordered
changes associated with organisms' life histories, and are driven
principally by cyclical changes in weather and other physical in-
fluences. Examples include:
The spring blooms of plankton in estuaries and lakes,
The change throughout the summer in the relative abun-
dance of species of stream insects,
- The appearance of successive species of annual plants
from spring to fall, and
The concentration and dispersal of various animal species
for breeding, nesting, and foraging.
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When conducting an ecological assessment at a Superfund
site, the analyst must consider these kinds of temporal varia-
tions when determining the probability of exposure. Depending on
the time of year or the point in some longer cycle, a potentially
exposed species may or may not be present or in a vulnerable life
stage at the time of a chemical release.
Successional time scales are less regular and hence less
predictable. Biological interactions or physical changes medi-
ated by biological activity are usually important in the evolu-
tion of communities. The classic example of succession is the
gradual change of a meadow to a forest. v This series of events is
measured in scores of years in undisturbed environments, and is
not likely to be important in assessment of Superfund sites.
Other successional change may be brought about by natural distur-
bance or human intervention and occur more rapidly. For example,
intensive herbicide use in agricultural production sometimes re-
sults in preferential survival of weed species that are naturally
tolerant to the chemicals used on the site. As the herbicides
continue to kill off sensitive species, the herbicide-tolerant
weeds come to dominate the non-crop plant community, and may in
turn determine which species of insects, small mammals, and birds
inhabit the area.
Movement of Chemicals in Food Chains
Food-chain transfer of contaminants represents a potential
exposure route that should be addressed in assessing the ecologi-
cal effects of a site. The processes involved in accumulation
and transfer of chemicals via food webs are complex. Nonethe-
less, an understanding of a few basic aspects may be helpful in
evaluating the importance of this phenomenon at a given site:
Elevated concentrations of contaminants in organisms
compared to environmental concentrations may not always
signal food-chain transfer. Animals and plants can ac-
cumulate chemicals directly from the medium in which they
live. Bioaccumulation7 of chemicals in this manner is
especially important for aquatic organisms and for ter-
restrial plants and animals (e.g., earthworms) in direct
contact with soils. Elevated levels of a chemical found
in most fresh-water fish and aquatic and soil inverte-
The process that results in increased concentrations of
contaminants in organisms with increasing trophic
levels in the food chain.
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brates occur by direct concentration of the contaminant
from the water, sail, or sediment rather than through the
food chain.
Certain species are more likely to be exposed due to
food-chain transfer of bioaccumulating chemicals than
others. Predators and other species near the tops of
food chains are among the most vulnerable. Long-lived,
fattier, and larger species have a greater opportunity to
accumulate compounds in their tissues. Species that are
more sensitive to the chemicals than the animals on which
they are preying may be at particular risk of exposure
(e.g., osprey feeding on contaminated fish).
Certain chemicals are more likely to be transferred via
food webs than others. Organochlorines and other per-
sistent organic compounds (either parent materials or
metabolites resistant to further degradation) are more
likely to be transferred than are non-chlorinated hydro-
carbons and metals. Organic compounds with higher mo-
lecular weights are more likely to be transferred than
those with lower molecular weights. Compounds with high
Log Pa values are most likely to be accumulated.
Plants may take up chemicals with low Log P values by way
of their roots, but cannot transport significant amounts
of compounds with high molecular weights and high Log P
values in the same manner. However, foliage can become
contaminated from soil or water by sorption of volatil-
ized chemical on the leaves or by deposits of dust, aero-
sols, and vapors.
Longer food chains increase the time needed to reach
equilibrium levels of contaminants in the predators at
the top of the chain. The maximum value of bioaccumu-
lation in the top species is also lower in longer food
chains, but there is a greater certainty that a toxic
chemical will have time to exert its effects on the popu-
lation. Table 2.2 illustrates this for DDT applied to
forest foliage. The table also shows the shift from DDT
at the low end of the food chain to the more stable and
toxic metabolite, DDE, at the high end.
The logarithm of the octanol-water coefficient (K ) .
Predictor of bioaccumulation in the oils of fish and
the fat of animals.
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Bioaccumulation may be less than predicted for a variety
of reasons. For example, organisms may avoid the chemi-
cal. or prey that have consumed it, or exposure time may
be insufficient to achieve equilibrium in living tissues.
Furthermore, not all food chain transfers lead to bionxag-
nification. Field monitoring should be used wherever
possible to determine actual tissue concentrations.
For terrestrial species, bioconcentration factors
(BCFa)10 of as little as 0.03 can be significant if the
residue is toxic. For aquatic species, BCFs greater than
300 are generally considered significant.
Table 3.2
Forest Food Chain for DDT
Years to
Receptor
Chemical
Maximum
Foliage
DDT
0
Forest litter
DDT/DDE
1
Litter invertebrates
DDT/DDE
2
Ground-feeding birds
DDE
4-5
Canopy-feeding birds
DDE
5-7
Bird-eating hawks and
owls DDE 7-10
Source: James W. Gillett, Cornell University
Higher concentration in the consumer than in the con-
taminated source.
10 The BCF is the ratio of the concentration of a contami-
nant in the organism to the concentration in the imme-
diate environment (soil, water, and sediments).
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4. THE ROLE OF TECHNICAL SPECIALISTS
IN ECOLOGICAL ASSESSMENT
"Every site is unique."
This is probably the most common generalization on which
ecologists who have worked on hazardous waste sites will agree.
It is also only partly true.
What makes every site unique is its particular combination
of characteristics—the contaminants of concern, the topography
of the site, the presence or absence of surface water, the vege-
tation, other species present, soil types, proximity to other im-
portant habitats, etc. Taken together, these factors present an
almost infinite array of potential ecological risk scenarios—the
populations at risk, the nature of the contaminants, their toxi-
city to different species, routes and probabilities of exposure,
environmental factors contributing to or inhibiting toxicity,
short- and long-term shifts in the structure of biotic communi-
ties, and the effects of remediation on the habitats at or near
the site.
Nonetheless, ecologists are able to find common elements in
their study of populations, communities, and ecosystems, some of
which were discussed in Chapter 3. These common elements form
the basis for designing a strategy for characterizing any indi-
vidual site and defining its specific properties. Thus, although
every site is unique, the methods for assessing each site are
not. Deciding which factors are important, and which methods to
use to assess those factors, is a complex task requiring the ex-
pertise of ecologists who are familiar with the organisms, eco-
logical processes, and environmental parameters that characterize
a site. This chapter outlines how such specialists can help the
RPM or OSC specify, obtain, and evaluate information needed to
assess ecological effects at Superfund sites.
This guidance manual presumes Chat the RPM or OSC will ob-
tain the assistance of ecologists and other environmental spe-
cialists. In some Regions, informal or formally constituted
technical assistance groups already exist. In other Regions,
advice may be obtained from various sources, including:
EPA Regional Environmental Services Divisions,
The EPA Environmental Response Team,
EPA Regional NEPA coordinators.
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Ecosystem-specific EPA programs, such as the Great Lakes
National Program Office in Chicago, or the Chesapeake Bay
Program Office in Annapolis, Maryland;
Laboratories of EPA's Office of Research and Development;
and
- Regional and field offices of the U.S. Fish and Wildlife
Service, the National Oceanic and Atmospheric Administra-
tion {especially NOAA's Coastal Resource Coordinators),
and other Federal and State environmental and resource-
management agencies.
Generally, technical specialists serve an advisory role.
Their function is to assist the RPM or OSC with information col-
lection and evaluation, and to help ensure that ecological ef-
fects are properly considered in investigations and decisions.
In specific cases, it may be possible to make arrangements (such
as interagency- agreements in the case of non-EPA staff) for them
to be involved directly in conducting the work.
In the following sections, we describe how ecological speci-
alists can contribute to the RI/FS and Removal processes. We
have divided the discussion into five major aspects:
Site characterization,
Site screening and identification of information gaps,
Work plan development,
Data review and interpretation, and
Enforcement.
These divisions are made for convenience of discussion only. Not
all sites will reguire all five types of activity, and some ac-
tivities may proceed in parallel rather than sequentially.
4.1 Site Characterization
RPMs and OSCs are encouraged to consult with ecologists as
early as possible to obtain their help in conducting an effective
ecological assessment. This assessment should begin with an eco-
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logical characterization of the site. In the RI/FS process, this
stage corresponds with the early phases of developing a site man-
agement strategy.
An initial site description will be necessary to orient the
technical specialists. This description should be assembled by
the RPM or OSC from existing sources of information, without con-
ducting formal field studies. Its primary purpose is to allow
the specialists to:
Identify issues that should be addressed in the ecologi-
cal assessment to follow, and
Develop data-collection strategies.
The description should include information on the location of the
site, its history, likely contaminants of concern, and the envi-
ronmental setting of the proposed actions. Although primary re-
sponsibility for preparing the site description lies with the RPM
or OSC, the technical specialists should provide guidance, when
requested, on what information they need in the initial site de-
scription to allow them to understand the scope of the problem.
Much of the information needed at this stage is commonly used ma-
terial, available from published sources or from previous assess-
ments of the site. For example, studies in support of a removal
action may be useful in planning for a Remedial Investigation.
Site location. The technical specialists should be provided
with maps and descriptions of the site, indicating, where pos-
sible:
The geographical area (town, county, quadrant, or other
appropriate unit) around the site;
The locations of streams or other surface waters on or
near the site;
Locations of other ecological habitats such as forested
areas, grasslands, floodplains, and wetlands on or near
the site;
Locations of soil types and current or projected uses;
and
Locations of contaminant sources at or near the site.
Topographical maps published by the U.S. Geological Survey
should be provided. For areas that are predominantly privately
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owned, floodplains are delineated on the Flood Insurance Rate
Maps and the Flood Hazard Boundary Maps published by the Federal
Emergency Management Agency. For areas that are predominantly
owned by States or the Federal government, the controlling agency
can usually provide floodplain information.
Documentation of the fact that a site exists in or near wet-
lands is an important first step in the ecological assessment.
Several sources of information are available to RPMs and OSCs to
determine if a contaminated area is in or near a wetland. Maps
of wetlands are available from a variety of sources, including
the U.S. Fish and Wildlife Service, local and State planning
agencies, and the Section 404 staffs in the EPA Regions. The
National Wetlands Inventory maps (NWI) developed by the Fish and
Wildlife Service, or other more specific information at the State
level should be consulted as early as possible. If more exact
locations and/or boundaries are required, the Federal Manual for
Identifying and Delineating Jurisdictional Wetlands (March 1989)
should be consulted. This manual was developed to identify jur-
isdictional wetlands subject to Section 404 of the Clean Water
Act and the "Swampbusters" provision in the Food Securities Act,
as well as to identify vegetated wetlands for the NWI.
The OSC or RPM should contact the State Geographical Infor-
mation System, Information Management Office, and Land Management
Offices for additional maps of environmental resources. Aerial
and satellite photographs that include the site and its surround-
ings should also be sought out and provided to the specialists if
appropriate.
Site history and contaminants of concern. The initial site
description should include a history of the site drawn from ex-
isting sources. Topics that should be addressed include avail-
able information on chemical-handling activities, storage loca-
tions, and known or potential contaminants. If a health effects
assessment has already been performed on the site, standard in-
formation on contaminants—chemical composition, amounts, and lo-
cations—will also be useful for ecological assessment. Where
available, the descriptions of chemicals should also include in-
formation on:
Decomposition rates and products,
Bioaccumulation potential,
Known toxic effects, and
Fate and transport.
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Environmental setting. The initial site description should
include any available information on geology, hydrogeology, and
ecological habitats at or adjacent to the site. Geological in-
formation may be obtainable from existing publications of the
U.S. Geological Survey or similar sources. Precipitation records
for nearby weather stations (often located at the nearest air-
port) can be obtained from the National Weather Service. Previ-
ous environmental analyses may be available for some sites, which
could help identify important habitats or species for the assess-
ment to consider. These might include, for example, an Environ-
mental Impact Statement for a nearby facility (e.g., highway,
power plant), a State Remedial Action Plan for a designated Area
of Concern, or a National Pollutant Discharge Elimination System
permit for wastewater discharge into a nearby waterway.
Obtaining information about local ecological resources may
require consultations with local experts on the subject, includ-
ing State pollution-control officials, State or Federal fisheries
and wildlife-management specialists, State or Federal foresters,
agricultural extension agents or Soil Conservation Service offi-
cials, and others familiar with the terrain and biology of the
region. These individuals may also provide important details re-
garding past, present, and likely future uses of land and water
resources in the area. The RPM or OSC may want to consult the
tecnnical assistance group or individual specialists for help in
identifying people to contact for this information. These con-
tacts may also provide assistance in identifying potential ARARs
for the site.
Using this information, the technical specialists should be
able to begin identifying the habitats potentially affected by
contaminants at the site. Key to this activity will be a prelim-
inary definition of the likely pathways for exposure to the con-
taminants. Once these habitats are identified, the relevant Fed-
eral and State Natural Resource Trustees should be notified and
invited to participate in planning the ecological assessment, if
they are not already serving as technical specialists.
If possible, one or more technical specialists should accom-
pany the RPM or OSC to the site for an initial field reconnais-
sance. This visit can help clarify for the assistance group the
kinds and amounts of data that may be needed to characterize the
site and its contaminants, keeping in mind that seasonal changes
may alter the nature and quantity of releases or affected organ-
isms .
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4.2 Site Screening and Identification of Information Gaps
Following collection of existing data, the technical assist-
ance group should be in a position to determine the nature and
extent of ecological assessment that will be necessary for the
site. If no ecological exposure pathways have been revealed in
this initial review, little or no additional work may be needed.
Alternatively, certain exposure pathways might be eliminated from
further study while others might require more data. For in-
stance, if there is no surface water on the site and no oppor-
tunity for contaminants to reach surface waters off the site,
further data on aquatic effects would very likely be pointless,
even though concern about exposure to terrestrial organisms might
warrant extensive sampling and testing.
Examination of preliminary data could point up important
gaps in the information concerning characterization of the site.
Site visits, aerial or satellite photographs, or information from
local experts may reveal habitats subject to exposure that were
not part of the original data-gathering effort. For instance,
careful examination of the site might result in the discovery of
a previously unreported stream running through the property that
could raise questions about contaminants' reaching an off-site
wetland.
Review of the data from initial studies may also indicate
that potential exposure pathways or receptors were either over-
looked or previously unknown to the site investigators. For ex-
ample, evidence might be found that small mammals are burrowing
and foraging near storage facilities. This information would
probably raise concern about direct exposure of these animals to
contamination. Depending on the persistence and bioaccumulation
potential of the contaminants, the observation of these mammals
might also suggest additional risk to predatory birds and mammals
both on and off the site through the food chain. These concerns
might then lead to a new study plan to trap some of the mammals
and test their tissues for contaminants.
The technical specialists might also conclude from informa-
tion developed during the early stages that the contaminants
identified at the site are causing unexpected toxic effects. For
instance, biotic surveys might show an absence of certain fish
species that occur in otherwise similar, but uncontammated,
streams. If there is reason to suspect that the absence of these
fish may be caused by toxic effects, field or laboratory toxicity
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tests might be appropriate to determine the toxicological poten-
tial of the contaminants.
4.3 Advice on Work Plans
Where applicable, ecological assessment is an integral part
of the RI/FS Work Plan. Technical specialists should be consul-
ted as early as possible in the development of the Work Plan and
the Sampling and Analysis Plan, to ensure that the plans for eco-
logical assessment are well designed and capable of answering the
necessary questions about the ecological effects of the contami-
nants at a site.
Effective ecological assessment will require a design that
is tailored to each site's specific characteristics and the spe-
cific concerns to be addressed. Choosing which of the many pos-
sible variables to investigate in the study will depend on the
nature of the site, the types of habitats present, and the objec-
tives of the study. The technical specialists should therefore
assist the RPM in specifying technical objectives for the inves-
tigation. Such objectives might include:
Determination of the extent or likelihood of impact,
Interim mitigation strategies and tactics,
Development of remedies, or
Remediation criteria.
The technical specialists can then help the RPM develop data qua-
lity objectives to support these technical objectives.
Although each assessment is in some way unique, it is pos-
sible to outline the general types of data that may be required.
For terrestrial habitats, the technical specialists may specify
such data needs as:
Survey information on soil types, vegetation cover, and
resident and migratory wildlife;
Chemical analyses to be conducted in addition to any pre-
vious work done as part of a Preliminary Assessment or
Site Investigation; and
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Site-specific toxicity assessments to be conducted.
For fresh-water and marine habitats, the information needed
will most likely include:
- Survey data on kinds, distribution, and abundance of pop-
ulations of plants (phytoplankton, algae, and higher
plant forms) and animals (fish, macro- and micro-inverte-
brates) living in the water column and in or on the bot-
tom;
Chemical analyses of samples of water, sediments, leach-
ates, and biological tissue;
Sediment composition and quality, grain sizes, and total
organic carbon; and
- Toxicity tests designed to detect and measure the effects
of contaminated environmental media on indicator species,
or on a representative sample of species, such as water
fleas (Daphnia or Ceriodaphnia), amphipods, chironamid
nidge larvae, tubificiid worms, mysid shrimp, and fathead
minnows.
Where specialists have reason to believe that contaminants
may move from one type of habitat to another, such as chemicals
washing into a stream in runoff water, data from each potentially
exposed habitat will be needed. The Superfund Exposure Assess-
ment Manual contains much valuable information on predicting
movement of contaminants from one medium to another.
The technical specialists should also provide guidance on
such quality assurance and quality control (QA/QC) issues as:
The area to be covered in biotic and chemical sampling
programs,
The number and distribution of samples and replicates to
be drawn from each habitat,
The preferred biological analysis techniques to be used,
Adherence to the assumptions of predictive models used in
the analysis,
The physical and chemical measurements (e.g., dissolved
oxygen in a water sample, pH of water or soil, ambient
temperature) to be taken at the time of the survey, and
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- Any special handling, preservation methods, or other
precautions to be applied to the samples.
Technical specialists may make specific recommendations on
sampling and analytical methods, or they may review plans and
offer comments or suggestions for improvement of the assessment
methodology. Ideally, the sampling and assessment process should
be a phased approach, where preliminary results are reviewed by
technical specialists, who may find reason to suggest changes in
the scope of the project or in the methods used during subsequent
stages of the study.
4.4 Data Review and Interpretation
The technical assistance group should also be called upon to
review data and provide comments on the interpretation of data.
In most situations, extensive and long-term ecological studies
are unlikely to be undertaken, and informed professional judgment
will be required Co determine if the weight of evidence supports
a particular decision regarding the site.
Specialists should be closely involved in reviewing interim
and draft assessments as these documents are completed. The ap-
propriate specialists should be consulted to ensure that the as-
sessments :
Address all important habitats and contaminants of con-
cern,
Identify all significant receptor populations,
Portray all relevant routes of exposure,
Characterize all significant ecological threats, and
Describe uncertainties in the assessment process.
The specialists may also provide advice on how to present the
results to decision makers who are not trained in environmental
science.
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4.5 Advice on Remedial Alternatives
Remediation measures can also pose environmental threats.
For instance, channeling a stream may deprive a wetland of its
primary water source; earthmoving and construction operations may
increase siltation of nearby streams due to increased soil run-
off. In such situations, compliance with appropriate laws and
regulations may require that the remediation plan include pro-
visions for minimizing environmental damage. Ecologists should
therefore be involved as early as possible in the selection and
review of remedial alternatives so that ecological as well as
public health concerns are addressed in the Feasibility Study.
Technical specialists should also be involved in designing
monitoring programs to evaluate the success of a removal or re-
medial project. Biological monitoring plans should be developed
to evaluate the effects of remedial actions on local populations
of various forms of wildlife. In addition, toxicity tests can be
used as sensitive indicators of the presence- or absence of con-'
taminants following remediation. Such tests may be useful in
defining cleanup levels.
4.6 Enforcement Considerations
If ecological effects of contaminants are a factor in en-
forcement actions, technical specialists may be a valuable re-
source both in crafting the decision documents and in providing
support for the decision. Proposed decisions that incorporate
ecological criteria for cleanup or remedial action should be re-
viewed by appropriate ecological experts to ensure that the cri-
teria (1) are accurately described and (2) can be effectively im-
plemented. Technical specialists may serve as expert witnesses
in court or administrative hearings in support of enforcement ac-
tions. Finally, as discussed above, ecologists may be consulted
on the design and implementation of monitoring programs to help
ensure that remedial actions achieve their objectives.
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5. PLANNING AN ECOLOGICAL ASSESSMENT
Because ecological assessments will vary widely from site to
site, no standard design is appropriate. The scope, level of
detail, and design of the assessment should be determined in
close consultation with ecologists who understand both the tech-
nical issues involved and the requirements of the Superfund pro-
gram. Some of the factors that should enter into the planning
stage are:
- The objectives of the assessment, as determined by the
management decisions required at the site;
The programmatic goals, mandated schedules, and budgetary
restrictions associated with the site's remediation;
- The kinds, forms, and quantities of contaminants at the
site;
The means of potential or actual release of contaminants
into the environment;
- The topography, hydrology, and other physical and spatial
features of the site;
The habitats potentially affected by the site;
The populations potentially exposed to contaminants;
The exposure pathways to potentially sensitive popula-
tions ; and
The possible or actual ecological effects of the con-
taminants or of remedial actions.
This phase of the assessment process is concerned with de-
termining what information should be collected for an ecological
assessment. It consists primarily of identifying characteristics
of the contaminants and the potentially affected environments,
to:
Determine if enough evidence exists to warrant further
investigation of ecological effects at the site;
Establish the scope of the ecological assessment (if one
is judged necessary) in terms of spatial and temporal ex-
tent, tests to be conducted, time and resources needed,
and level of detail required; and
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Define study goals and data quality objectives if collec-
tion of new data is deemed necessary.
If new data axe collected, it is essential that data quality ob-
jectives reflect specific programmatic goals and management ob-
jectives, to ensure that time and funds spent to gather and ana-
lyze data are used efficiently and effectively.
This chapter discusses the principal components of defining
the scope and design:
- Determination of the objectives and level of effort ap-
propriate to the site and its contaminants,
Evaluation of site characteristics,
- Evaluation of the contaminants of concern,
Identification of exposure pathways, and
- Selection of assessment endpoints.
These are logically distinct activities, but they are not neces-
sarily undertaken sequentially. All may be underway simultane-
ously, or one activity may await the outcome of data from other
activities. The outcome of this process is the Sampling and Ana-
lysis Plan (SAP), which specifies the methods for data collection
and analysis, and the procedures for quality assurance and con-
trol (QA/QC).
5.1 Determination of Need, Objectives, and Level of Effort for
Ecological Assessment
Defining the scope and design of an assessment is initially
based on available information and data from previous studies.
Using this material, the RPM or OSC should consult with technical
specialists, who can be expected to use good professional judg-
ment to provide advice on how to evaluate a specific site. The
outcome of this phase should be an assessment design that will
ensure scientific defensibility of data and decisions based on
those data, while remaining cognizant of the CERCLA-mandated
schedules and budget constraints faced by decision makers.
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An ecological assessment may be conducted to:
- Document actual or potential threat of damage to the en-
vironment, in support of a proposed removal action;
Define the extent of contamination;
Determine the actual or potential effects of contaminants
on protected wildlife species, habitats, or special en-
vironments;
- Document actual or potential adverse ecological effects
of contaminants, as part of a Remedial Investigation;
Develop remediation criteria; and
- Evaluate the ecological effects of remedial alternatives,
as part of a Feasibility Study.
A given assessment may entail one or more of these objec-
tives as the primary reason(s) for the study. Specification of
assessment objectives should in turn allow clear definition of
the ecological endpoints of concern, the study methods to be em-
ployed, and the data quality objectives for the study.
The RPM or OSC should confer with technical specialists to
determine appropriate levels of detail for ecological assessment
of a site based on available information. This should be under-
taken as an iterative process. Data from the field may warrant
further investigation and greater detail. Conversely, such data
may indicate that little or no additional work is necessary co
characterize ecological effects. The definition phase should be
used to identify the criteria needed to make these judgments.
Each assessment will vary in the extent to which resources,
exposure concentrations, effects, and other variables are iden-
tified and quantified- The more serious effects found may not
relate absolutely to the amount of detail required in the assess-
ment. The need for detailed, quantitative information will be
driven by the difficulty in adequately characterizing the parame-
ters that comprise the assessment. For instance, a fish kill
might be readily traced to a high concentration of a contaminant
from a point source. On the other hand, considerable effort
might be needed to evaluate the causes of unusually low popula-
tions of fish in a stream that contains low levels of diverse and
dispersed contaminants.
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5.2 Evaluation of Site Characteristics
5.2.1 Nature and Extent of Contaminated Area
In defining the scope and design for an ecological assess-
ment, it is important to determine the full spatial extent of the
contamination through sampling and measurement. The sampling
plan should be designed with a broad enough radius to find the
"edge of the plume," the farthest extent of the contamination in
soils or other environmental media.
Haps and aerial photographs should be used whenever possible
to define the general habitats at or adjacent to the site. Small
wetlands, intermittent streams, and other potentially important
areas that might have been missed during a preliminary site visit
may be seen from aerial photographs or maps. Significant off-
site information may also be derived from good maps and photo-
graphs (e.g., discharges from surrounding areas that may affect
the site). This type of information may provide significant in-
sight into the conduct of the site investigation. Ground verifi-
cation of all habitat locations should be conducted before devel-
oping any sampling plans.
At this stage, it is also important to determine which
transport processes are likely to be at work with respect to each
contaminant. From this information, analysts should be able to
discern likely off-site exposure routes and the habitats threat-
ened or potentially threatened by that exposure. The RPM or OSC
should consult the Superfund Exposure Assessment Manual (SEAM)
for detailed information on predicting chemical fate and trans-
port in the environment.
In characterizing a site and determining how contaminants
may move through the environment associated with the site, the
RPM or OSC should examine trend data such as variations in clima-
tic conditions that may affect population levels of resident spe-
cies. These data may indicate conditions, such as periods of
high rainfall or drought, that place additional stress on local
ecosystems and may affect the fate and effects of contaminants.
Based on all of this information, and in close consultation
with technical specialists, the RPM or OSC should set site-speci-
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fic objectives for investigation of each potentially contaminated
habitat, including:
- Environmental media to be sampled and analyzed for con-
taminant levels,
Detection limits for contaminants,
- Toxicity tests to be performed and species to be tested,
and
Ecological (population, community, or ecosystem) effects
to be measured or predicted.
Data quality objectives arising from these study objectives
should then be developed to determine what level of effort will
be necessary to obtain scientifically defensible answers. It is
important to emphasize that the extent of delineation of exposed
habitats should be determined by the potential for exposure, not
by arbitrary distances or boundaries that lack a biological just-
ification.
5.2.2 Sensitive Environments
For a particular site, the project team should prepare a
list of habitats requiring special attention in the assessment.
Although ecological judgment is necessary to define some priori-
ties, State and Federal laws and regulations designate certain
types of environments, such as wetlands, as requiring special
consideration or protection. Critical habitats for species
listed as threatened or endangered also may require protection.
Consultation with natural resource trustees and other technical
specialists will be invaluable in ensuring identification of
these key areas.
In addition to identifying habitats that meet specific State
or Federal criteria, the project team should also consider if any
other habitats on the site are:
Unique or unusual, or
Necessary for continued propagation of key species (e.g.,
rare or endangered species, essential food sources or
nesting sites for other species, spawning and rearing
habitats, etc.).
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The importance of habitats on or near a hazardous waste site will
vary from area to area, depending on such factors as:
- The species native to the area and their significance
(e.g., regionally important sport fish),
- The availability and quality of substitute habitats,
The land use and management patterns in the area, and
- The value (economic, recreational, aesthetic, etc.)
placed on such habitats by local residents and others.
The project team should define and identify sensitive environ-
ments based on a site- and area-specific analysis, keeping in
mind the ecological connections between the site and nearby habi-
tats.
5.3 Contaminant Evaluation
5.3.1 Identification and Characterization
Along vith site characterization, a parallel prime objective
in defining the scope and design of an assessment is to charac-
terize the contaminants of concern (and their transformation pro-
ducts) in terms of their knowi or suspected potential to cause
ecological harm. Besides identifying and classifying the con-
taminants of concern, the RPM or OSC should make sure that
characteristics of the chemicals are measured that will help to
determine the site's likely ecological effects. Based on mea-
sured or calculated physical/chemical properties and other pub-
lished data, the contaminants' likely persistence in the envi-
ronment should be estimated. The RPM or OSC should also obtain
information to describe the frequency, intensity, and route(s) of
chemical release to the environment.
Preliminary information on the physical/chemical properties,
bioaccumulation potential, and other characteristics of contami-
nants can be used to define the parameters of studies to be con-
ducted for an ecological assessment. For example:
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If chemicals are known or suspected to be water-soluble,
analysts should be prepared to investigate potential ex-
posure routes to aquatic habitats. Water-soluble com-
pounds may also be expected to move readily within the
aqueous phase of some soils, increasing the likelihood of
exposure for soil-inhabiting organisms.
For chemicals with low solubility in water, the RPM or
OSC should investigate the potential for the compound to
adsorb to soil particles. Should this occur, the chemi-
cal could be transported through erosive soil runoff to
surface waters or other terrestrial environments near the
site. Contaminated soil particles may also be ingested
by organisms living on or in the ground.
If a contaminant is judged to be persistent, or if envi-
ronmental release is frequent or continuous, the ecologi-
cal assessment may (where time permits) include chronic
as well as acute toxicity tests on potentially exposed
organisms. The RPM or OSC may also need to consider
studies and/or use of appropriate predictive models to
assess long-term population effects.
If compounds are known or suspected to bioaccumulate,
studies may be needed to determine the extent of bio-
accumulation in potentially exposed organisms. This will
probably entail a close look at transport and exposure
pathways and collecting data on contaminant concentra-
tions in tissues of likely bioaccumulators such as fish.
5.3.2 Biological and Environmental Concentrations
Based on the preliminary information about the nature the
contaminants, a sampling and analysis plan can be devised to de-
termine contaminant concentrations in all relevant media. As in
all other assessments, the best measures are those that are accu-
rate, precise, and representative of the situation in space and
time. The best way to achieve this is to plan sampling programs
with ecological assessment as a clearly specified objective. As
a general principle, sampling, monitoring, and measurement should
be designed by taking account of exposure pathways to habitats
and organisms on or near the site.
A brief field reconnaissance of the site, combined with ac-
curate maps or aerial photographs, should be sufficient to iden-
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tify important habitats that may require sampling- Consultation
with ecologists familiar with the area will probably indicate the
kinds of organisms to be expected on the site and the probable
exposure pathways that should be investigated. This in turn
should lead to study designs for measuring contaminants in media
appropriate to those exposure pathways. For instance, if a com-
pound is known or suspected to be volatile, air sampling in po-
tentially exposed habitats may be appropriate. If the chemicals
are believed to have reached surface waters, stream sediments and
biota may need to be analyzed to determine the full extent of
contamination. If biological transport of the contaminants is
considered possible, the sampling plan may need to include test-
ing for the presence or effects of low levels of chemical at some
distance from the source.
If contaminants are suspected of bioaccumulation or are con-
sidered fairly persistent, the RPM or OSC may need to require
studies to determine if the chemicals are being transferred from
organism to organism through the food web. Food-chain linkages
can be evaluated using information on the trophic relationships
of the species at a site. Direct measurements of chemical resi-
dues in animal tissues provide the most direct approach for as-
sessing the extent to which food-chain transfer of chemicals may
be occurring. If such biological transfer of contaminants is
suspected, the RPM or OSC should consult with technical special-
ists on the proper design of studies to evaluate the extent and
effects of the phenomenon.
Estimating chemical fate and transport is a key first step
in quantifying exposure. Having identified the exposure path-
ways, the analyst should plan on sampling pertinent media to de-
termine the concentrations of the contaminants of concern. As
discussed in detail in the SEAM, predictive models can help in
estimating fate and transport of contaminants. For Superfund
sites, the analyst should consult the SEAM and specialists to
determine the applicability of any particular model to the speci-
fic site. Among the considerations will be the assumptions un-
derlying the model, the quantity and quality of input data need-
ed, and the degree of confidence in the model's results. The
decision on what model(s) to use may determine sampling and ana-
lytical design, including analyses required, sample sizes, samp-
ling method, and sampling frequency.
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5.3.3 Toxicity of Contaminants
A key objective of the definition phase of the assessment
process is to develop a sampling and analysis plan to assess the
toxicity of site contaminants to potentially exposed populations
of plants and animals. Evaluating the toxicity of a substance at
a particular site requires careful specification of the effects
of concern, such as mortality or reproductive failure, and the
duration of exposure (i.e., acute or chronic). At the planning
stage, literature reviews are the most likely sources of informa-
tion on the toxicity of contaminants. Literature searches can
help guide an investigation, especially in identifying the likely
mechanisms of toxicity. However, the user of a literature review
must fully understand the restricted character of the informa-
tion. Its value in characterizing actual or probable hazards at
a specific site is extremely limited, for several reasons:
Toxicologists generally study a population of one species
because the effects on a community or ecosystem are too
difficult for standard practice. If the species chosen
for the study is not a good indicator species for habi-
tats found at the site, the study's findings may be a
poor predictor of the site's actual hazards.
Toxicologists generally study the effects of a single
toxicant at a tine. This practice is rarely representa-
tive of field conditions where organisms may be stressed
simultaneously by several toxicants, fluctuations in the
availability and quality of nutrients, and variations in
weather and climate. When organisms are exposed to two
toxicants at the same time, the effects may be directly
additive, more than additive (synergistic) , or less than
additive (antagonistic), depending on the toxicants in
question, the organisms exposed, and the environmental
conditions.
Published research may use death or a subacute effect,
such as behavioral change, as the endpoint. Incorporat-
ing statistics into their analyses, scientists may select
the median (50 percent) response of a population, or they
may choose some other percentile of response as appropri-
ate, perhaps the 10 percent or the 90 percent response.
Unless the measures used in the research correspond well
to the objectives of the ecological assessment, the re-
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suits may be difficult to apply to the specific site or
contaminants at issue.
- Researchers usually report a fixed time for an experi-
ment. For example, for aquatic tests, toxicologists
often study the response over 48 or 96 hours, depending
on the species and the toxicant. Occasionally, research-
ers will study a complete generation of organisms or a
complete cycle of reproduction and recruitment, but rare-
ly do they have the resources or time to study several
generations.
A vide array of experimental protocols and results exists in
the literature, in which every variation from study to study can
be found—different organisms, toxicants, laboratory conditions,
endpoints, concentrations, statistical summaries, and durations.
Although all of these studies may be informative for some pur-
poses, they are difficult to compare and contrast, and judging
the validity of extrapolation to a specific site and its contami-
nants should be left to qualified specialists.
Despite the vide diversity of experimental designs, ecolo-
gists have settled on a few widely recognized organisms and pro-
tocols for study. For example:
To study effects on terrestrial invertebrates, research-
ers commonly use one or more species of earthworms to
represent soil organisms, generally using two- or four-
week test protocols.
Toxicology studies of birds often use bobwhite quail,
ring-necked pheasants, or mallard ducks.
Because of their widespread use for human health assess-
ment, there exists a large data base of toxicity studies
on laboratory rats, mice, and rabbits. Therefore, these
are also commonly used as surrogate species for estima-
tion of toxicity to other mammals.
For equivalent studies of aquatic organisms, scientists
have long used species of Daphnia or Ceriodaphnia (water
fleas) to represent freshwater invertebrates in 48- or
96-hour test protocols, while freshwater fish have been
represented by the fathead minnow, rainbow trout, and
bluegill.
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The Microtox* test, dissolved oxygen depletion test, or
reazurin reduction test are sometimes used to indicate
toxic effects on microbial populations.
- Commonly studied marine and estuarine species include my-
sid shrimp, Oungeness and blue crabs, oysters, mussels,
and sheepshead minnows.
For studies of effects on plants, domesticated species
are often used, such as lettuce seeds in germination
tests.
It is often possible to select one or more of these commonly
tested species as surrogates for species found at a site if toxi-
city testing is warranted. To develop a proper understanding of
conditions at the site, data on surrogate species need to be
interpreted by wildlife/fishery toxicologists and ecologists
experienced in evaluating contaminants. Differences in physio-
logy between closely related species or apparently minor dif-
ferences in physical or biological conditions at the site can
often complicate such interpretations.
Literature surveys can help identify possible targets for
investigation if toxic effects are reported, but they are un-
likely to eliminate chemicals from further consideration if nega-
tive results are reported. Positive findings in a laboratory
research study of toxic effects may indicate the mode of action
of the chemical. They may also help the investigator determine
the endpomt for toxicity tests conducted with materials from the
site. Laboratory tests indicating low toxicity may or may not
mean low toxicity in the field, since even the best laboratory
simulation cannot mirror field conditions.
Generally speaking, field data, monitoring information, and
toxicity testing of contaminated media are more useful and reli-
able than literature estimates. Wherever possible, the assess-
ment should be based on data collected from the field.
In those circumstances where exposure appears likely, toxi-
city testing will be needed to determine the effects of contami-
nants—in the concentrations found or expected at the site—on
potentially exposed plant and animal populations. Results from
published studies can serve as a useful guide for deciding:
What toxicity tests (e.g., acute, chronic) should be
conducted with field-collected samples,
What kinds of organisms should be tested,
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- What effects should be anticipated, and
- How the tests should be interpreted.
From these decisions, a specific set of data quality objectives
should be formulated, including:
- The number and type of tests to be run,
- The environmental conditions to be monitored,
- The detection limits for contaminants,
- The number of samples to be taken, and
The acceptable margin of error in analyzing results.
Site-specific information on sensitivity to contaminants
should be gathered wherever necessary and feasible. Studies to
collect such data should be designed carefully, in close consul-
tation with technical specialists. The general categories of
studies that might be conducted include the following:
In-situ (in-field) toxicity tests. Methods for in-situ
studies are available for aquatic toxicology and, to a
more limited extent, terrestrial toxicology. Such meth-
ods usually involve exposing animals in the field to
existing aquatic or soil conditions. Generally, these
methods involve the use of enclosures to hold the animals
at a specific location for the designated exposure period
(e.g., caged fish studies).
Field observations. Correlation of the abundance and
distribution of animals and plants with measurements of
chemical concentrations may not prove the existence of
toxic effects, but may offer some insights as to likely
sensitivities and add to the "weight of evidence" con-
cerning the site.
Toxicity tests of contaminated water, soil, sediments, or
elutriates in the laboratory. These can be used to eval-
uate the lethal or sublethal effects of chemicals as they
occur in environmental media. They can also be used to
test for toxicity of mixtures as they actually occur m
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the environment. Some methods for these tests have been
published by EPA.1
5.3.4 Potential ARARs and Criteria
Once the contaminants at a site have been identified, the
RPM or OSC should identify those for which criteria have been
established, and determine whether1any such criteria apply as
potential ARARs at the site in question. (See Chapter 2.) If
usable and applicable criteria exist, the assessment should in-
clude sampling and monitoring plans to determine the extent to
which those criteria are exceeded by environmental concentrations
at the site. If criteria do not exist for the contaminants in
question, analysis of known toxic effects and possible threshold
levels may be used to develop site-specific criteria against
which to compare field data. The RPM or OSC may also wish to
consult with technical specialists to determine if any chemicals
for which criteria have been established might be appropriate
analogues for the contaminants of concern at the site. EPA's
Office of Toxic Substances has published a volume describing the
use of analogues for estimating toxicity to aquatic organisms.2
5.4 Potential for Exposure
Before the effects of a contaminant on an organism can be
evaluated, it is necessary to )cnow how much of the chemical is
actually or potentially reaching the point of exposure (the loca-
tion where effects can occur). This depends on characteristics
1 Ecological Assessments of Hazardous Waste Sites: A Field
and Laboratory Reference Document (EPA/600/3-89/013) , EPA
Office of Research and Development, 1989; J.C. Greene,
S.A. Peterson, C.L. Bartels, and W.E. Miller, Bioassav
Protocols for Assessing Acute and Chronic Toxicity at
Hazardous Waste Sites. EPA Office of Research and Devel-
opment, January 1988.
2 Estimating Toxicity of Industrial Chemicals to Acruatic
Organisms Using Structure Activity Relationships. Office
of Toxic Substances (EPA/560/6-88/001), July 1988.
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of the contaminant, the organism, and the environment. Exposure
assessment seeks to answer the following questions:
- What organisms are actually or potentially exposed to
contaminants from the site?
- What are the significant routes of exposure?
- To what amounts of each contaminant are organisms actual-
ly or potentially exposed?
- How long is each exposure?
- How often does or will exposure take place?
What seasonal and climatic variations in conditions are
likely to affect exposure?
What are the site-specific geophysical, physical, and
chemical conditions affecting exposure?
Analysis of contaminant concentrations in tissues of exposed
organisms can help provide a link between environmental con-
centrations and the amount of contaminant likely to reach the
site of action. For many contaminants and organisms, time delays
may need to be considered when attempting to correlate environ-
mental and biotiic concentrations. This will allow for the time
that may elapse before a chemical is taken up into living tissue.
Some of the factors that may influence uptake include:
- The environmental concentration of the contaminant in the
media to which the organism is most often exposed;
- The metabolic rata of the organism, which in turn may be
a function of such environmental parameters as tempera-
ture, availability of sunlight, water, nutrients, oxygen,
etc. ;
Species-specific metabolic processes, such as food
absorption rates and the ability to degrade, accumulate,
store, and/or excrete the contaminant;
Behavioral characteristics such as food preferences and
feeding rates (both of which may vary with the time of
year and the age of the organism], and the ability to
detect and avoid contaminated media or food;
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Other characteristics of the organism, such as gill sur-
face area, lipid content, and metabolic ability to liber-
ate a "bound" residue; and
- The bioavailability of the contaminant, i.e., its ten-
dency to partition into a form conducive to uptake; this
will vary among chemicals and organisms. Bioavailability
will be influenced by such environmental factors as tem-
perature, salinity, pH, redox potential, particle size
distribution, and organic carbon concentrations.
Because individuals and species accumulate contaminants dif-
ferentially in their tissues, environmental concentrations and
uptake rates will not necessarily predict biotic concentrations.
Pharmacokinetic distribution following bioaccumulation determines
the concentration of contaminant that actually reaches the physi-
ological site of action within an organism, and thus the likeli-
hood of adverse effects. Whether or not bioaccumulation is sus-
pected, analysts should try to determine contaminant concentra-
tions in environmental media and biotic tissues simultaneously.
Based on these data, site-specific bioconcentration factors
(BCFs) can be estimated. One must make sure, however, that the
measured environmental concentrations are relatively stable and
not short-term aberrations. If site-specific BCFs cannot be
derived from monitoring data, the analyst nay need to use pub-
lished BCF values or predicted BCFs.
To be meaningful, chemical analyses of biota should use
sample sizes large enough to obtain variance estimates. Extrap-
olating contaminant concentrations from a sample of organisms to
an average for the population may be a complex process. Such
factors as the time of year of the sample, the life stage or age
of the organisms, and the spatial distribution of the population
may need to be considered. For highly mobile animals, estimates
of exposure may need to be adjusted to account for the likelihood
that not all of the animal's food will be obtained from the af-
fected area. In the wildlife refuge study noted above, for
example, the analysts calculated exposures for mink and mallard
ducks based on the assumption that the contaminated area repre-
sented ten percent of their home ranges. When such adjustments
are made, the analyst should clearly state the justification for
the assumptions and estimates used.
The SEAM provides detailed guidance on estimating or pre-
dicting environmental concentrations in media and intermedia
transfers of contaminants. In addition, it offers a brief dis-
cussion on evaluating biotic exposure pathways to human popula-
tions. However, the SEAM is specifically intended for estimation
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of human exposure. Since human and environmental receptors do
not share all exposure routes, the analyst will need to go beyond
the decision models provided in the SEAM to consider exposure of
environmental receptors. For example, in the exposure assessment
for contaminated soil, the analyst will need to determine if the
soil is sterile or if it is inhabited by plants and animals. If
the soil is inhabited, the analyst will need to determine if
organisms are contaminated and, if so, what the potential is for
off-site movement of animals or food-chain transfer of contamin-
ants.
5.5 Selection of Assessment and Measurement Endpoints
Based on the available information concerning the site, the
contaminants, and the likely exposure pathways, the analyst
should identify and select appropriate endpoints for the assess-
ment. The companion volume to this manual discusses in detail
the distinction between assessment and measurement endpoints.3
Assessment endpoints are those describing the effects that drive
decision making, such as reduction of key populations or dis-
ruption of community structure. Measurement endpoints are those
used in the field to approximate, represent, or lead to the as-
sessment endpoint. If new data are to be collected to evaluate
these endpoints, EPA's guidance on data quality objectives should
be followed (see Section 5.6).
5.5.1 Ecological Endpoints
Toxicity of contaminants to individual organisms can have
consequences for populations, communities, and ecosystems. As
discussed in Chapter 3, changes in rates of mortality, birth,
immigration, and emigration can cause population sizes in an
affected area to increase or decrease. These changes can also
lead to shifts in the spatial distribution of populations in the
environment. Such population-level effects may in turn determine
the nature of changes in community structure and function, such
as reduction in species diversity, simplification of food webs,
Ecological Assessments of Hazardous Waste Sites: A Ref-
erence Document. EPA Office of Research and Development,
1989.
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and shifts in competitive advantages among species sharing a
limited resource. Finally, ecosystem functions may be affected
by contaminants, which can cause changes in productivity or
disruption of key processes. For example, at a Superfund site
contaminated with creosote and related compounds, the analysts
noted;
The presence of beds of detritus in the stream and
layers of contaminated undecomposed leaves in the soil
indicates that litter degradation is not occurring, at
least not at a natural rate.
Contaminants can disturb ecosystems in ways other than di-
rect toxicity. For example, a chemical that decreases available
oxygen in aquatic systems can have catastrophic effects, whether
or not it is toxic to the organisms there. Contamination leading
to destruction of terrestrial vegetation can result in increased
sedimentation of streams, which can adversely affect benthic pop-
ulations that never come in contact with the chemical. Remedial
actions that reduce water flow to a wetland or that replace in-
digenous vegetation with introduced plant species can remove an
essential resource for one or more species in the community. In
assessing the ecological effects of a site or its remediation,
the analyst should consider use of appropriate measures of com-
munity and ecosystem function to determine if the weight of evi-
dence indicates that effects other than toxicity are significant.
To characterize the effects of contaminants on populations,
communities, and ecosystems, the analyst may choose one or more
measures depending on the objectives of the study.
Use of these measures will usually require comparison of the
site to a carefully selected reference area. To allow proper
comparison, it is important that reference areas be chosen that:
Are in close proximity to the contaminated area(s);
Closely resemble the area(s) of concern in terms of to-
pography, soil composition, water chemistry, etc.; and
Have no apparent exposure pathways from the site in ques-
tion or from other sources of contamination.
The RPM or OSC should consult closely with technical specialists
on specific criteria for selecting an appropriate reference area.
The following are examples of measures that might be used to
compare contaminated and reference areas:
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- Population abundance — the number of individuals of a
species in a given area, usually measured over a period
of tine or at a specified time;
- Age structure — the number of individuals in the popula-
tion in each of several age classes or life history
stages, which can be an indicator as to whether the
population is increasing, decreasing, or stable;
- Reproductive potential and fecundity — expressed as the
proportion of females of reproductive age, the number of
gravid females, the number of eggs or viable offspring
per female, or the percentage of females surviving to
reproductive age;
- Species diversity — the number of species in an area
(species richness), the distribution of abundance among
species (evenness), or an index combining the two;
Food web or trophic diversity — calculated in the same
way as species diversity, but classifying organisms
according to their place in the food web;
Nutrient retention or loss — the amount of undecomposed
litter or, conversely, the amounts of nutrients lost to
ground or surface waters;
Standing crop or standing stock — total biomass in an
area; and
Productivity — sometimes determined indirectly by mea-
suring oxygen production by the plant community per unit
time; ecologists also sometimes gauge respiration rates
by measuring carbon dioxide output per unit time, and
calculate the ratio of production to respiration (P/R
ratio) as a measure of the efficiency of the ecosystem.
From measures such as these, specific assessment endpoints can be
established, such as "reduction in population abundance" or "re-
duced fecundity." These would then be quantified to develop
site-specific measurement endpoints, such as "significant differ-
ence between contaminated and reference areas with respect to
numbers of organisms or numbers of young per female."
The analyst should use these measures with a great deal of
caution. If differences appear in the above measures between
contaminated and uncontaminated areas, it is a complex task to
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demonstrate that the effect observed is the result of contami-
nation rather than some other factor.
In planning an ecological assessment, the OSC or RPM will be
concerned with potentially affected habitats and, through them,
potentially affected populations. Within each of these catego-
ries, a set of characteristic endpoints will need to be consid-
ered, and special types will elicit particular attention.
5.5.2 Evaluation of Potentially Affected Habitats
Habitats in the vicinity of a Superfund site can be affected
by:
Direct or indirect exposure to the site's contaminants
due to transport from the source;
Physical disruption of the habitat due to the site's de-
sign or operation;
Chemical disruption of ecosystem processes due to the
contaminants' interference with natural biochemical,
physiological, and behavioral processes;
Physical or chemical disturbance or destruction due to
cleanup or remedial activities; and/or
Other stresses not related to the site or its contami-
nants, such as extreme weather conditions or air pollu-
tion.
Each of these types of effects will be manifested different-
ly in different ecosystems, depending on the magnitude of the
disturbance and the nature of the habitat receiving the disturb-
ance. The various types of terrestrial, aquatic, and marine eco-
systems each have their own particular structures, dynamics, en-
ergy flows, and transport mechanisms that determine how they are
affected by chemical or physical insult such as might occur at a
Superfund site.
Structure and Dynamics
Planning an ecological assessment should consider collection
of qualitative and (where feasible) quantitative information
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about the structure and dynamics of biotic communities that are
potentially threatened, with sufficient detail to:
- Decide whether a detailed ecological assessment is neces-
sary,
- Develop a defensible professional judgment as to the
likelihood of contamination and adverse effects, and
- Define study goals and data quality objectives for an
ecological assessment if it is justified by the prelim-
inary evidence.
When considering study objectives for an ecological assess-
ment, the RPM or OSC may wish to specify that data be collected
to support calculation of certain measures of community structure
and function. These include determining species diversity and
community productivity. It is important to recognize that such
measures were not designed for the purpose of estimating or dem-
onstrating environmental harm, and they may be inappropriate for
many sites. When these measures are used, they should not be re-
lied upon to the exclusion of other information? rather, they may
add to the weight of evidence supporting a particular conclusion
about a site and its contaminants. Used properly, in close con-
sultation with technical specialists, these measures may help to:
Delineate the extent of contamination at a site, and/or
Document the ecological effects of contamination.
Measures of biotic diversity have often been used to aid in
characterizing community structure. The use of these measures in
the context of hazardous waste sites rests on the premise that a
disturbed or stressed area will exhibit changes in the composi-
tion and relative abundance of species as compared to a reference
area that appears not to be contaminated. When using diversity
indices or measures of community structure, the analyst should
choose for study those segments of the ecosystem that are likely
to:
Be exposed to the contaminants of concern, and/or
Contain organisms suspected of being vulnerable or sensi-
tive to those contaminants or the effects of remediation.
Thus, for example, if the chemicals are present in surface soils,
it would probably be useful to apply diversity comparisons to the
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soil or leaf litter organisms at a potentially affected site and
a reference area.
The Office of Research and Development volume, Ecological
Assessments of Hazardous Waste Sites: A Reference Document, con-
tains detailed discussions of assessment and measurement end-
points for evaluating community- and ecosystem-level effects.
Significance and Uniqueness
The significance or uniqueness of an environment is often a
subjective judgment, that may be determined by social, aesthetic,
or economic considerations. Some environments, such as critical
habitats for endangered species, are defined by law. To the ex-
tent that these concerns can be spelled out in the definition
phase, they should be articulated with regard to any such habi-
tats, Generally speaking, environments may be considered signi-
ficant because, in the professional opinion of technical speci-
alists, they:
- Are unusually large or small,
Contain an unusually large number of species,
- Are extremely productive (such as an important fishery),
Contain species considered rare in the area, or
Are especially sensitive to disturbance.
In defining the scope of an ecological assessment, consid-
eration of such environments should be similar to that given to
rare and endangered species (see below). These areas may have
unusual underlying physical and chemical characteristics that may
affect removal and remediation decisions. The existence, loca-
tion, and sensitivity of such environments should be noted, and
study objectives may need to be developed to reflect the poten-
tial exposure of these special areas to contamination.
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5.5.3 Evaluation of Potentially Affected Populations
Productivity and Abundance
Ecologists use the word "productivity" to mean the rate at
which new biomass is produced per unit time. Plant stress may be
a useful indicator of reduced productivity in an affected area.
Visual inspection of the site during an initial visit may be
sufficient to identify probable stress on terrestrial vegetation
(such as yellowing, leaf drop, or other symptoms), but it is im-
portant to bear in mind that the cause could be something other
than toxic effects of the contaminants. Reduction in the growth
of plants in terrestrial or aquatic habitats will not be as easi-
ly observed and may require a detailed botanical survey in com-
parison to a reference area to be verified. Bioassays may need
to be conducted to determine if the productivity of the plant
community is being affected, and whether or not contaminants froc
the site are implicated. Toxic effects may be determined in
tests using algae or easily grown terrestrial plants as test spe-
cies. Seed germination, root elongation and morphology, and
plant growth assays can be used to evaluate contaminated soils'
effects on plant development.
Toxic chemicals may exhibit a wide range of effects that can
ultimately influence productivity and abundance of animals.
Effects of contaminants on animal productivity can be assessed
through the use of field ecological studies, on-site toxicity
tests, and laboratory tests. Study designs and data quality
objectives for field and laboratory studies should be developed
to determine exposure concentrations and their likely relation to
observed or suspected effects.
The RPM or OSC should seek out trend data such as population
fluctuations of key species over time. Such information may be
available from State and Federal fish and game personnel, or fron
previous environmental analyses (such as an Environmental Impact
Statement) conducted in the vicinity of the site. These data can
assist analysts in distinguishing between normal fluctuations and
changes that may be attributable to the effects of contamination.
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Raxa, Threatened, and Endangerad Species
By definition, endangered and threatened species are already
at risk of extinction: the loss of only a few individuals from
the population may have significant consequences for the contin-
ued existence of the species. In the definition phase of the as-
sessment process, the presence of threatened or endangered spe-
cies, and/or habitats critical to their survival, should be docu-
mented. If information is available on these or related species'
sensitivity to contaminants of concern, this should also be indi-
cated. The RPM or OSC should consult with Federal and State nat-
ural resource trustees or other specialists to determine the lo-
cation of such species and their potential for exposure to the
contaminants.
Rare species may present a more difficult problem for eco-
logical assessment. A species may be rare in a given locale be-
cause :
- The area is at the edge of the species' principal geo-
graphical range,
- The natural habitats available in the area are only mar-
ginally able to support the species,
The species may be prevented from attaining high numbers
by competition from other species or by predation, or
The species depends upon rare habitats or food sources
for its continued existence.
If a species is rare, but not legally designated as either
threatened or endangered, the RPM or OSC will have to depend on
consultation with local ecologists and other experts to determine
the importance of the species in the context of the site.
The major sources of information on rare, threatened, and
endangered species are field offices of the Fish and Wildlife
Service (U.S. Department of Interior) and the National Oceanic
and Atmospheric Administration (U.S. Department of Commerce), of-
ficials of State fish and game departments and natural heritage
programs, and local conservation officials and private organiza-
tions .
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Potentially Affected Sport or Commercial Species
In planning an ecological assessment, the analyst should
note potential effects on species that are of recreational and
commercial importance. In addition, species such as food sources
that directly support these important species, and habitats es-
sential for their reproduction and survival, should be considered
in the planning and assessment process.
Information on which species are of recreational or commer-
cial importance in an area can be gathered from State environmen-
tal or fish and wildlife agencies. Federal agencies such as NOAA
and the U.S. Fish and Wildlife Service, and local conservation
and fish and game personnel. Commercial fishermen's and trap-
pers' associations may also be valuable sources of data.
Most States maintain fish stocking programs for sport or
commercial fisheries. The agencies running these programs can
provide information on where fish are stocked and released, and
the areas to which they migrate. Many States also gather creel
survey data for stream reaches or other bodies of water, and col-
lect harvest data for management of deer, game birds, and other
animals.
5.6 Sampling and Analysis Plan
The planning stage of the ecological assessment process
culminates in the Sampling and Analysis Plan (SAP), which con-
sists of a Field Sampling Plan and a Quality Assurance Project
Plan (QAPP). In directing the preparation of the SAP, the QSC or
RPM should be satisfied that the following questions are an-
swered:
What are the specific objectives of the sampling effort?
How will the proposed data collection meet those objec-
tives?
Will the sampling plan (types, number, distribution, and
timing of samples) provide sufficient information to meet
the objectives?
Does the sampling plan address all important exposure
pathways and environmental receptors?
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Does the sampling plan make the best use of pre-existing
data and sampling locations?
Is the sampling of the various media associated with the
site coordinated to allow maximum integration of the data
(e.g., to measure or predict intermedia transfer of con-
taminants) ?
5.6.1 Field Sampling Plan
To address all of these issues effectively, a Sampling and
Analysis Plan should be developed that takes account of:
Actual or potential sources of contaminant release,
The media to which contaminants can be or are being re-
leased,
The organisms that can come into contact with the con-
taminants, and
The environmental conditions under which transport and/or
exposure may be taking place.
Identification of exposure routes and media should lead m
turn to a selection of the most appropriate plant and animal
species to be sampled for analysis of contaminant concentration,
toxicity testing, or other measures of potential effects. If
food-chain transfer of contaminants is suspected, information on
the trophic structures of affected ecosystems will be needed to
determine which species should be examined for chemical residues.
Biological data to be collected in conjunction with these
analyses may include such parameters as dry weight of tissues or
organisms, percent moisture, lipid content, and the size and age
or life stage of the organism. Contaminant concentrations may
need to be expressed relative to the whole-body weight (sometimes
minus the intestines) or weight of the edible portion (for input
to human health studies).
Depending on the media to be sampled, the contaminants of
concern, and the organisms under study, the sampling plan will
also require collection of data on environmental conditions at
the time of the study. For aquatic systems, these include:
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- Hater quality parameters such as hardness, pH, dissolved
oxygen, salinity (for marine ecosystems), temperature,
presence or absence of thennocline, color, dissolved or-
ganic carbon, conductivity, and total suspended solids;
• Hydxologic characteristics such as flow rate, ground-
water discharge/recharge rates, aquifer thickness and
hydraulic conductivity, depth, velocity and direction of
current, tidal cycle and heights, and surface water in-
puts and outflows; and
- Sediment parameters such as grain size distribution,
permeability and porosity, bulk density, organic carbon
content, pH, color, general mineral composition, benthic
oxygen conditions, and water content.
For studies of potentially contaminated soil, information
will be needed on such parameters as particle size, permeability
and porosity, fraction and total organic carbon, pH, redox poten-
tial, water content, color, odor, and soil type.
The OSC or RPM should consult the SEAM and technical speci-
alists to determine the specific set of environmental parameters
that should be measured to permit effective analysis of contami-
nant fate, transport, exposure, and effects.
5.6.2 Quality Assurance
EPA policy requires that all Regional Offices, program of-
fices, laboratories, and States participate in a centrally-man-
aged quality assurance (QA) program. This requirement applies to
all environmental sampling, monitoring, and measurement efforts
mandated or supported by EPA through regulations, grants, con-
tracts, or other formal means. Each program office or laboratory
that generates data must implement minimum procedures to ensure
that the precision, accuracy, completeness, and representative-
ness of the data are known and documented.
To ensure that these responsibilities are met uniformly
across the Agency, each EPA program office or laboratory must
have a written Quality Assurance Project Plan (QAPP) covering
each monitoring or measurement activity within its purview.
These Quality Assurance and Quality Control (QA/QC) requirements
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apply for all monitoring at all Superfund sites or at any loca-
tion where toxic substances have been released to the environ-
ment.
QAPPs are written documents for all planned sampling or mon-
itoring at a named location, including ecological assessments of
Superfund sites. The program office, Regional Office, contrac-
tor, grantee, State, or other organization must prepare and re-
ceive written approval for the QAPP for the specific sampling and
measurement program before the field or laboratory work can be-
gin.
The QAPP presents, in specific terms, the policies, organi-
zation, objectives, functional activities, and specific QA/QC ac-
tivities designed to achieve the data quality goals for single or
continuing activities. The QAPP must cover all environmentally
related measurements, including but not limited to:
- The measurement of physical, chemical, or biological
variables in air, water, soil, or other environmental
media;
The determination of the presence or absence of pollu-
tants or contaminants in waste streams or site media;
The assessment of ecological effects studies;
The study of laboratory simulation of environmental
events; and
The study or measurement of pollutant transport and fate,
including diffusion (i.e., dispersion and transport)
models.
The QAPP serves two important functions. First, it seeks to
ensure that as much as possible is done at the beginning of a
study to achieve the QA objectives for the data. Second, it al-
lows for analysis of the study to determine what improvements can
be made if QA objectives are not met. The plan cannot guarantee
results, but it requires the analyst to justify a particular ap-
proach before proceeding.
For each major measurement variable, the QAPP must state
specific data quality objectives. This is usually accomplished
by preparing a table listing the variable, the sampling method,
the measurement method, the experimental conditions, the target
precision (measured in relative standard deviation), the target
accuracy (measured in acceptable relative deviation from the true
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value), and the completeness (measured in terms of percent cover-
age) . The RPM or OSC should also require project analysts to
specify clearly:
- What tests are to be performed,
- What measurements are to be taken, and
- How the results will be used (e.g., estimate exposure,
correlate diversity or abundance with a chemical gradi-
ent, predict population response to ambient contaminant
levels).
Consultation with a technical assistance group to define
data needs and study goals is essential for the successful speci-
fication of data quality objectives. The ecological assessment
is not a research project and thus should not be expected to en-
tail long-term field studies. With the guidance of technical
specialists who understand both the scientific questions at issue
and the exigencies of the Superfund program, it is possible to
define carefully delineated studies to collect the data needed
for making reasoned judgments on Superfund sites.
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6. ORGANIZATION AND PRESENTATION
OF AN ECOLOGICAL ASSESSMENT
This chapter provides a checklist of the basic questions
that should be asked in an ecological assessment. It is intended
to ensure completeness and consistency in the reporting of as-
sessment results. The amount of detail required in a given re-
port will depend upon the scope of the study, as determined in
the iterative planning process discussed in Chapter 5, and the
amount of data collected in the investigation. Regardless of the
level of detail, the assessment report should be clear and con-
cise, to ensure that the results are readily understood and prop-
erly interpreted.
To aid Agency review of assessments, metric units should be
used throughout. These include specification of appropriate
units in chemical quantification such as ug/1, ug/g, etc., in-
stead of mixing ratios such as ppb or ppm.
Some information, such as characterization of the site or
the contaminants of concern, may have been given in other sec-
tions of a report such as an RI or Action Memorandum. If so, the
information can be referenced; however, the analyst may wish to
summarize such information in the ecological assessment section.
6.1 Specify the Objectives of the Assessment
As discussed in Section 5.1, an ecological assessment may be
undertaken for a variety of reasons, from evaluating the threat
posed by a site to examining the effects of remedial alterna-
tives. For example, for two sites evaluated by EPA's Environ-
mental Response Team, the assessment objectives were stated as
follows:
The main objective of this . . . investigation was to
generate data that could be utilized for the determina-
tion of site cleanup criteria for the creosote contami-
nated soils and sediments in the floodplain of the
Creek.
The objective of this study was to determine if the ar-
senic compounds present in the water and sediments of
the River watershed are resulting in an adverse
ecological impact. The data collected [were] utilized
in conjunction with existing data to determine the bio-
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availability and toxicity of arsenic contamination to
the resident aquatic biological communities, and [to]
quantitatively assess impacts.
6.2 Define the Scope of the Investigation
This section of the report should describe the kind and
amount of information that was collected in the study. The ana-
lyst should describe the data in terms of the physical, biologi-
cal, and chemical parameters measured, estimated, or calculated
in the assessment. It is also important to specify the time
frame of the study:
Over what time period(s) and in what season(s) were the
data collected?
At what time intervals were samples taken?
Were the data used to assess current effects or past dam-
age, or to predict future scenarios?
The discussion gives the reader a clear indication of the
nature, depth, and boundaries of the investigation. Was the as-
sessment, or the data used in the assessment, based on long-term
studies of the site and its surroundings or do the data provide a
"snapshot:" of the site in a restricted time period? Was the
sampling extensive or limited to specific areas? Are the analy-
ses reasonably straightforward or are considerable inferences and
professional judgments involved?
6.3 Describe the Site and Study Area
In this section, the analyst should provide a physical de-
scription of the site at a level of detail appropriate to the
scope of the assessment. The study area for an ecological as-
sessment may extend well beyond the boundaries of the area in
which hazardous wastes have been stored or released. For ex-
ample, depending on the available pathways for exposure and the
habitats potentially exposed to contamination, the area under
investigation might; include portions of several tributaries of a
potentially affected river, a wetland downhill or downstream from
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INTERIM FINAL March 1989
OSWER Directive 9285.7-01
a release source, or a wildlife refuge within the same drainage
basin as a waste site.
The description should include the size of the area (in
metric units) within the physical boundaries defined for the
assessment and the size of physical features such as stream
reaches, roads, wetlands, or forested areas- The report should
provide a map of the area, showing all physical features at a
minimum resolution equivalent to a 7.5 USGS quadrangle map,
marked to show any changes to the topography up to the present
time. This map should include all potentially affected areas
linked to the contaminated zone by pathways of concern through
any media, sampling locations, and any reference areas selected
for the investigation. An example of such a map is given in
Figure 6.1.
A brief description of the contamination that led to listing
of the site, or a reference to such a description should be in-
cluded, giving dates where possible.
The description of the site and study area should provide a
full accounting of the ecosystems and populations potentially
exposed to contamination. This may be accomplished with a narra-
tive description of each habitat (e.g., oak-hickory forest, Soar-
tina salt marsh, etc.), accompanied by lists or tables of species
collected or observed there. The resident and transient flora
and fauna should be described, or if catalogued, the table can be
referenced. Where relevant, it should be noted if a cited spe-
cies is:
Resident, breeding, or a rare or frequent transient
(e.g., migratory waterfowl),
Endangered or threatened, or
A natural resource trustee concern.
The significance, uniqueness, or protected status of potentially
exposed ecosystems (as discussed in Chapter 5) should also be
noted and documented.
Other information with possible bearing upon the ecological
characteristics of the site should be provided, such as current
or projected land uses; proximity to population centers, indus-
try, agriculture, or hunting areas; and special climatic condi-
tions affecting movement, availability, or effects of contami-
nants .
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INTERIM FINAL March 1989
OSWER Directive 9285.7-01
Figure 6.1
Example of Study Area Map
CRQUnO COnTQuh
r - '
X SURFACE WAT6H AMO
IWftOOt SCQlMfiNT SAM*llNG4.0CAtt0N
' «w smCAM
^ ST«VCTU«<
— — — — — AWMOKIMArf CQjMOAflV
a r°°o O 4
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INTERIM FINAL March 1989
OSWER Directive 9 285.7-01
Einally, the site description should include narrative char-
acterizations of:
Likely or presumed exposure pathways, such as surface
vater, air, soils, sediments, or vegetation; and
- Any readily observed effects potentially attributable to
the site, such as stressed or dead vegetation, fish
kills, or unusual changes in species composition or dis-
tribution in a habitat.
6.4 Describe Contaminants of Concern
The ecological assessment should specify which contaminants
at a site are of particular concern from an ecological perspec-
tive. • This list may differ somewhat from those contaminants that
raise questions about human health risks. For example, a given
chemical may exhibit low toxicity toward mammals but be highly
toxic to fish, invertebrates, or plants. The fate of a contami-
nant in the environment may make it unavailable for human expo-
sure while increasing exposure for other organisms. For in-
stance, a chemical that is found to be adsorbing to soil and
sediment particles may pose little risk to humans, but may cause
considerable disruption of terrestrial vegetation or benthic
invertebrates.
Results of chemical analyses should be presented in tabular
form, identifying compounds and the media in which they were
found. If tables of data from the human health evaluation are
used by reference, it is important to report measurements of pa-
rameters affecting the toxicity to biota, such as alkalinity or
total organic carbon. It is important to note the source of all
analytical data, including laboratory, CLP certification, sam-
pling and analytical method, and date of analysis. Data may be
summarized, but both the mean and range should be included, along
with an explanation of how and why calculations were made. The
report should explain how non-detects, replicates, duplicates,
etc. were treated in the statistical analysis. All sample data
should be accounted for: infrequency of detection (rarity) is an
unacceptable explanation for culling a particular data item from
the sample. The report should describe both laboratory and field
analysis of contaminants, along with variances from detection
limits that affect the applicability of the data to the study.
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OSWER Directive 9285.7-01
6.5 Characterize Exposure
This section should identify actual and potential exposure
pathways, taking into account environmental fate and transport
through both physical and biological means. The analyst should
consult the Suoerfund Exposure Assessment Manual and technical
specialists to make sure that all likely exposure pathways have
been considered. In discussing the investigation of exposure
pathways, the report should describe each pathway by chemical(s)
and media involved, and identify the pathway in space and time
with respect to the site and the period of investigation. If
contaminant concentrations and effects data (such as toxicity
tests or population studies) correspond to identified pathways by
spatial or temporal gradient, their presentation should demon-
strate the correlation.
If sampling stations have been selected to measure concen-
trations of contaminants along likely exposure pathways, the
sampling data should be presented in such a way as to allow the
reader to see quickly the relationship between a sample's loca-
tion and its contaminant levels. For instance, stations can be
numbered in a sequence that indicates their relative distance
from the source of contamination, as shown on a map of the study-
area. Another method is to present the data on a scatter dia-
gram, in which sampling locations are shown as points on a graph
with distance from the source given on the X-axis and concentra-
tions an the f-axis. Ideally, concentrations at key contaminants
should be displayed in graph form with geographic locations indi-
cated (see Figure 6.2) or on a map (see Figure 6.3).
Results of toxicity tests may also be effectively displayed
using maps. For example, in a study of the effects of pcBs and
other contaminants at a Northeastern site, the researchers showed
the results of toxicity testing on a map of the affected area
(Figure 5.4). This type of presentation makes readily apparent
the relarive hazard associated with different locations.
If such gradients are not apparent, or are contradicted by
other data, the analyst should discuss the possible reasons for
the discrepancy in the report. If exposure pathways are modeled,
the report should clearly state the limiting assumptions of the
model(s) used. A full reference for every model used in the as-
sessment should be included. The analyst should characterize the
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INTERIM FINAL March 1989
OSWER Directive 9 2 85.7-01
Figure 6.2
Graphic Display of Contaminant Concentrations
soo
400
300
200
100
Arsenic Concentrations in Various
Fractions at Water Sampling Sites
Arsenic Concentration (ag/1)
ERT-2 ERT-4 ERT-5
Branch
Total Arsenic
5S2J _Dl"Olv«d Arsaolc
I I Particulate Arsenic
— Detection Limit
(10 ua/1)
¦—-r-lBh-
SRT-6 ERT-0
River
ERT-9 ERT-10 EI?T
Lake
-u
6-7
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INTERIM FINAL March 1989 OSWER Directive 9285.7-01
Figure 6.4a
Map Display of Toxicity Test Results
0
ioo-«. uoatautv a*rE n aou.ts.
on. momtautt ¦ ecc3
(X4oo pom roxAt pcb«."j
' zax MOW TAUT Y . AOULT
•«r% «*0«TAuTr m pooCCnv
( HATCKfl )
• 3K. MORTALITY M EGGS
(220 PPM TOTAL PCO« •)
' COCCCShac ST.
MX MCWTAUTY • EGG3
(17 pom TOTAL PCBO- •
UEGEfO
A SED««MT 3AWVC LOCATXX
« TOSPOMOCft fTATXX LOCATION
REFERENCE;
in, mohtauty m pnoccjcr
11% MO«TAUTY m CGG3
(0.03 pom TOTA1. rCB«. •)
• M6AH PCS COMCZKnRATXX
sum * r xx o. i • cx io
SCalC
TOXICITY Of-
SEDIMENTS TO TH€ FISH
CYPfltNAOON VARI6GATUS
4 0OO T
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INTERIM FINAL March 1989 OSWER Directive 9 285.7-01
Figure 6.4b
Map Display of Toxicity Teat Results
0
100%
(2.000 MM TOTAL PCS**)
92-2%
(320 mtm TOTAL PC3«
85-5 X
(37 PO" TOTAL
46.7%
(17 ppna TOTAi. PC3«-.|
LEGghO
A SEOMtKT SJLMPTJ1 LOOkTKX
• TRJSPOf«efl STATKX LOCATKX
REFEFtGNCc;
(txj* o.aa pom total rca«- )
- M(AN PC3 CONCEKTRAnOM
sciMAnoH a. 1 - a. to.
CORNELL
DUQILIER
PERCENT MORTALITY
OF
SEDIMENTS TO THE AMPHIPOO
AMPEUSCA AQOITA
&.000 FEET
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OSWER Directive 9285.7-01
uncertainty associated with all parameters that are measured or
modeled, and specify statistical significance levels for quanti-
tative results.
If the analysis uses data from toxicity tests, population
studies, or other effects-related investigations, to demonstrate
that exposure has occurred, the report should carefully explain
the limitations of the data. For instance, the site and refer-
ence area might differ in terms of the degree of physical distur-
bance, which may account for some of the observed effects. If
toxicity test results are presented in the form of LDsos or
ED50s, they should be shown graphically on a log probit scale.
6.6 Characterize Risk or Threat
In characterizing risks or threats to environmental recep-
tors associated with Superfund sites, the analyst should try to
answer the following questions:
What is the probability that an adverse effect will
occur?
What is the magnitude of each effect?
What is the temporal character of each effect (transient,
reversible, or irremediable)?
What receptor populations or habitats will be affected?
Depending on the assessment objectives and the quality of
the data collected, the answers to these questions will be ex-
pressed quantitatively, qualitatively, or a combination of the
two.
If water quality or other criteria have been exceeded at a
site, this may be sufficient in some cases to justify remedia-
tion. In presenting the data, the analyst should document the
number and location of sampling results that exceed the acute
and/or chronic criteria for the protection of the species and
habitat of concern at a site. The number of exceedences can be
compared to the number of total measurements for each contaminant
in a table. In addition, the locations of all exceedences and
the locations of all measurements can be shown with different
symbols on a map. Use of a map can be especially helpful if
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OSWER Directive 9285.7-01
contaminant concentrations form a reasonably clear gradient
leading away from the source.
Beyond criteria exceedences, however, risk characterization
is most likely to be a weight-of-evidence judgment. The analyst
should present a summary of the risk-related data concerning the
site, including:
Environmental contaminant concentrations,
Contaminant concentrations in biota,
Toxicity test results,
Literature values of toxicity,
Field surveys of receptor populations, and
Measures of. community structure and ecosystem function.
If the contaminants at the site are exerting a clear effect, the
data from all of these studies will, on balance, support the con-
clusion that an effect is occurring. If the data are ambiguous,
the analyst should try to discern the reasons for conflicting re-
sults and present those reasons along with the rationale for the
conclusion reached.
Ecological risk characterization entails both temporal ana
spatial components. In describing the nature and probabi lity of
adverse effects, the analyst should also consider such questions
as:
How long will the effects last if the contaminants are
removed? How long will it take for receptor populations
to recover from the effects of the contaminants? Will
there be intergenerational effects?
Will the contaminants move beyond the current area of
study through biotic transport? What effect will re-
mediation have on this movement?
If there are community and ecosystem effects of the con-
tamination, is removal of the contaminants sufficient to
restore community structure and ecosystem function? If
not, what else will be needed?
How do the data on exposure and observed or predicted
effects relate to the rapidity of response required?
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OSWER Directive 9235.7-01
Which responses are required immediately? Which can or
should be undertaken later?
- What limits will proposed remediation or mitigation ac-
tions place on future options for further remediation,
follow-up assessment, and resource use?
Questions like these will most likely be answerable only in
narrative fora, as an expression of best professional judgment by
a qualified ecologist. Nonetheless, they lie at the heart of
ecological assessment. Many populations and ecosystems exhibit
considerable resilience in the face of disturbance; in fact,
change is more common in ecosystems than stability. Populations
are continually increasing and decreasing due to natural cycles
and chance occurrences. In many situations, when a source of
contamination is removed, natural systems will rapidly recover
their former appearance. Hence, for the same amount of chemical
released, the risk associated with an acutely toxic but short-
lived chemical may be considered important but less so than a
moderately toxic chemical that is highly persistent.
6.7 Describe the Derivation of Remediation Criteria or Other
Uses of Quantitative Risk Information
If water quality or other criteria are available for com-
parison to observed concentrations of contaminants, the analyst
should try to show the data along with applicable criteria so
that exceedences are easily apparent. Table 6.1 is an example of
this kind of presentation. If criteria exceedences occur along a
clearly identified gradient, the data may best be presented in a
map.
Remediation criteria may also be derived from risk informa-
tion developed for use under other environmental statutes, sxich
as the Toxic Substances Control Act or the Federal Insecticide,
Fungicide and Rodenticide Act- If the report recommends remedi-
ation criteria based on such information, the analyst should give
a full reference citation for the source of reference doses,
standards, or risk assessments use in calculating the criteria.
In addition, the analyst should provide an explanation of, or
reference for, the calculation method used to develop the cri-
teria. Equations and parameters (such as exposure factors) used
in the calculations should be provided in the text or referenced.
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OSWER Directive 9 285.7-0L
Table 6.1.
Example of Presentation of Criteria Exceedences
Mean and Maximum Surface Water Concentrations (ug/1)
In On-Site Lakes at a Landfill
Chemical
Observed
Concentrations
Mean Maximum
Water Quality
Criteria3
Acute Chronic
Ammonia
150*
6,800*
20
20
Copper
16
•
o
in
48
29
Cyanide
NE
•^P
O
O
ND
ND
Iron
125
1,300*
300
300
Zinc
20
L50*
30
30
Phenol
ME
2.1*
1
1
Federal, State, or county criteria used as available
KEY: ME = Mot evaluated
ND = No detectable amount permitted
* = Criteria exceeded
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OSWER Directive 9285.7-01
6.8 Describe Conclusions and Limitations of Analysis
Assessment of Superfund sites will depend primarily on the
weight of evidence supporting particular conclusions, since eco-
logical effects seldom occur in isolation from other stresses.
To accomplish this, it may be necessary to use a variety of mea-
surements in an effort to establish that a trend is likely in the
data.
For example, in a study of an arsenic-contaminated site and
a nearby river system, the analysts compared several different
indices of species diversity for benthic invertebrates (Figure
6.5) and examined differences in the trophic structure at the
various sampling locations (Figure 6.6). Analysts next combined
these data with information on contaminant concentrations and
toxicity tests. They concluded that arsenic concentrations in
the stream sediments were significantly effecting benthic inver-
tebrates downstream from the contamination source.
In presenting conclusions from an ecological assessment, the
analyst should address the degree of success in meeting the
objectives of the evaluation. The report should present each
conclusion, along with the items of evidence that support and
fail to support the conclusion, and the uncertainty accompanying
the conclusion. Analysts should also describe factors that
limited or prevented development of definitive conclusions.
The process of assessing ecological effects is one of esti-
mation under conditions of uncertainty. To address this neces-
sary reality, the analyst should provide information that indi-
cates the degree of confidence in the data used to assess the
site and its contaminants. In summarizing assessment data, the
RPM or OSC should specify sources of uncertainty, including:
Variance estimates for all statistics;
Assumptions underlying use of statistics, indices, and
models;
The range of conditions under which models or indices are
applicable, and
6-15
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SAMPLE LOCATION
COMPARISON OF VARIOUS DIVERSITY INDICES CALCULATED
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INTERIM FINAL March 1989 OSWER Directive 9285.7-01
Figure 6.6
Graphic Display of Trophic Structure
Composition oi Functional Feeding Groups
At Benthic Invertebrate Sampling Sites
Percent Composition
SO
40
30
20
10
0
ERT-2 ERT-4 ERT-5 EI?T-
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INTERIM FINAL March 1989
OSWER Directive 9285.7-01
- Narrative explanations of other sources of potential er-
ror in the data (e.g., unexpected weather conditions, un-
expected sources of contamination).
Ecological assessment is, and will continue to be, a process
combining careful observation, data collection, testing, and pro-
fessional judgment. By carefully describing the sources of un-
certainty, the analyst will strengthen the confidence in the con-
clusions that are drawn from the analysis.
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