United States Office of Emergency and
Environmental Protection Remedial Response
Agency Washington DC 20460
Superfund OSWER Directive 9380.0-6
v>EPA Guidance
Document for
Cleanup of Surface
Impoundment Sites
-------
OSWER Directive 9380.0-6
Guidance Document for Cleanup of
Surface Impoundment Sites
Prepared by
Camp Dresser & McKee Inc.
Woodward-Clyde Consultants
Roy F. Weston, Inc.
Project Team
R. Cote, E. Kunce, G. Smith, and W. Sydow
Camp Dresser & McKee
G. Deigan, S. Egnaczyk, E. Need, and J. Thorsen
Roy F. Weston
R. Coad and L. Penniman
Woodward-Clyde Consultants
Work Assignment Manager
Edwin Barth
U.S. Environmental Protection Agency
Office of Emergency and Remedial Response
401 M Street, S.W.
Washington, DC 20460
This document has been prepared for the U.S. Environmental Protection Agency
under Contract No. WA 68-01-6939
June 1986
U.S. Environmental Protection Agency
Region V, Library
230 South Dearborn Street
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OSWER Directive 9380.0-6
Foreword
The Comprehensive Environmental Response Compensation and Liability Act of
1980 (P.L. 96-510, commonly referred to as CERCLA or Superfund) established
a nationwide program for responding to releases of hazardous materials into the
environment as a result of past or present material production, storage,
transportation, treatment, or disposal. CERCLA allows EPA to respond rapidly to
potential threats to public health or the environment. The Superfund program is
implemented through the provisions of the National Contingency Plan (NCP), 40
CFR Part 300.
This guidance document was prepared to assist on-scene federal, state, and
local officials and private firms that may plan and implement remedial actions at
National Priorities List (NPL) sites having one or more surface impoundments
containing hazardous wastes. The primary purpose of this document is to
provide guidance on carrying out concurrent remedial action planning activities
and accelerating project implementation for the cleanup of surface impound-
ments containing hazardous wastes. This document is designed to be used in
conjunction with the EPA's guidance documents on conducting remedial
investigations and feasibility studies (EPA, 1985).
This guidance document will provide the user with a systematic approach to
remedial actions for surface impoundments. However, there are many unique
and potentially hazardous conditions on NPL sites which require very specialized
considerations. This manual does not substitute for the services of competent
professionals but is intended to serve as a planning and engineering guidance
tool.
U,S. Envlfonrntnul Protection Agency
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OSWER Directive 9380.0-6
Contents
Section Page
Foreword ii
1.0 Introduction 1-1
1.1 Purpose 1-1
1.2 Intended Use 1-1
1.3 Organization of Guide 1-1
1.4 Characteristics of Surface Impoundments 1-2
1.5 Operable Unit 1-2
2.0 Overview of Process for Conducting a Limited
RI/FS for a Surface Impoundment Operable Unit 2-1
2.1 General 2-1
2.2 Major Activities 2-1
3.0 Initial Scoping 3-1
3.1 Classification System for Determining
Applicability of Limited RI/FS 3-1
3.2 Decision Tree Analysis 3-3
3.2.1 Surface Impoundment Size 3-3
3.2.2 Waste Viscosity 3-3
3.2.3 Depth to Ground Water 3-5
3.2.4 Impoundment Leaking 3-5
3.2.5 Contaminated Soils 3-5
3.2.6 Permeability 3-5
3.2.7 Ground Water Controls 3-5
4.0 Limited Remedial Investigation
4.1 Develop Site Description and Data Base 4-1
4.1.1 Obtain Available Data 4-1
4.1.2 Review and Evaluate Available Data 4-1
4.2 Site Familiarization and Project Approach 4-5
4.2.1 Prepare Preliminary Base Map 4-5
4.2.2 Prepare Preliminary Soil/Geologic Cross
Section tl ,.. {. ^ v v 4-7
4.2.3 Prepare Initial Health and Safety Guidance...:.". 4-7
4.2.4 Prepare Community Relations Plan 4-9
4.2.5 Identify Potential Remedial Action
Technologies 4-9
4.3 Perform Initial Site Characterization 4-9
4.3.1 Conduct Initial Site Visit 4-10
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OSWER Directive 9380.0-6
Contents (continued)
Section Page
4.3.2 Determine if an Immediate Threat Exists 4-12
4.3.3 Conduct Preliminary Exposure Assessment 4-13
4.3.4 Determine Need for Continued Limited Activity 4-13
4.3.5 Define Data Needed to Conduct Limited
Feasibility Study 4-14
4.4 Conduct Detailed Field Investigation 4-15
4.4.1 Prepare Project Operations Plans 4-15
4.4.1.1 Sampling Plan 4-15
4.4.1.2 Health and Safety Plan 4-16
4.4.1.3 Quality Assurance/Quality Control Plan 4-17
4.4.2 Conduct Impoundment Investigation 4-17
4.4.3 Conduct Focused Ground Water Investigation 4-20
4.4.4 Conduct Surficial Soil Investigation 4-21
4.4.5 Conduct an Assessment of Soil/Waste System
Characteristics 4-22
4.4.6 Review Analytical Results for Conformance
with QA/QC Program 4-22
4.4.7 Evaluate All Data and Prepare Limited Remedial
Investigation Report 4-22
5.0 Limited Feasibility Study 5-1
5.1 Final Remedy 5-1
5.2 Interim Remedy 5-1
6.0 Reference Guide 6-1
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OSWER Directive 9380.0-6
List of Figures
Number Page
2-1 Overview of Limited RI/FS Process for
Surface Impoundment Operations 2-1
3-1 Classification of Impoundments 3-2
3-2 A process for selecting an operable unit and determining the
suitability of a surface impoundment for a limited RI/FS 3-4
4-1 Guidance Flow Diagram for Surface Impoundment Source
Control Limited Remedial Investigation 4-2
4-2 Existing Conditions Site Base Map 4-6
4-3 Typical Soil/Geologic Cross Section of Surface
Impoundment and Adjacent Area 4-8
4-4 Surface Impoundment Remedial Action
Logic Diagram 4-10
5-1 General Overview of Limited FS Process 5-2
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OSWER Directive 9380.0-6
List of Tables
Table Page
4-1 Example of a Completed Contaminated
Soil Target Area Inventory Form 4-11
4-2 Application of Geophysical Techniques
to Detection of Subsurface Hazards 4-12
4-3 Example of a Completed Matrix of
Exposure Assessment Activities 4-14
4-4 Examples of Data Needs for Evaluation of
Potential Remediation Activities 4-15
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OSWER Directive 9380.0-6
1.0 Introduction
1.1 Purpose
This guidance document addresses remedial ac-
tions for the cleanup of surface impoundments (de-
fined as a pit, pond, and/or lagoon) containing haz-
ardous wastes. Guidance is provided for the
scoping and performance of a limited remedial in-
vestigation (limited Rl) and limited feasibility study
(limited FS). These limited activities address one
"operable unit" at a site that, in the estimation of
the lead regulatory agency, can be investigated,
evaluated, and implemented in a relatively short
time period. An operable unit is one definable prob-
lem area or source of contamination at a site that
can basically be addressed independently of other
site issues and problems. It can typically be thought
of as one piece of the total remedial action at a site.
While the term "remedial action" is used, this doc-
ument may apply to either removal or remedial ac-
tions, since both require a similar decision process.
However, while the decision process may be simi-
lar, the level of detail required in planning will vary
widely between remedial and removal activities.
Limited RI/FSs are typically the first steps in the
remedial response at a National Priorities List (NPL)
site and should be consistent with the long term
remedy. Remedial actions, as defined by the Na-
tional Contingency Plan (NCP) in Section 300.68(a),
"... are those responses to releases on the NPL that
are consistent with a permanent remedy to prevent
or mitigate the migration of a release of hazardous
substances into the environment." Any remedial
action contemplated for implementation at a site
must be cost-effective, stabilize the situation, pre-
vent or limit the extent of contamination, and/or
provide temporary containment.
Depending on the urgency of response, removal
actions may be taken without the preparation of a
limited RI/FS, although the issues addressed in an
RI/FS will be assessed in an expedited manner.
Typically the Rl and the FS can be performed con-
currently, with the limited FS finished shortly after
the end of the limited Rl.
1.2 Intended Use
This guidance manual is intended to be used as an
aid to State and Federal staff and private firms for
the implementation of a remedial action for the
cleanup of hazardous wastes contained in surface
impoundments. The manual is informative rather
than prescriptive in nature. The basic objectives are
to provide a concise description of the necessary
steps to implement surface remedial actions for the
cleanup of surface impoundments within the provi-
sions of the NCP.
It must be emphasized that this guidance is not to
be used as an absolute reference. Its use should be
supplemented with other EPA guidance documents
and technical reports/references as appropriate.
Refer to Section 6.0 for references relevant to the
performance of a limited RI/FS for a surface im-
poundment operable unit. This manual should be
used under the direction of an engineer or scientist
experienced in hazardous waste remedial projects
or equivalent.
Revisions of this manual will be provided, as neces-
sary, to assure compliance with the NCP. Revisions
will be made available through EPA for intended
users.
1.3 Organization of Guide
This manual is organized into three major sections:
(1) initial scoping, (2) limited remedial investiga-
tion, and (3) limited feasibility study. These sections
represent the major activities to be conducted for
the cleanup of surface impoundments. Section 2.0
presents an overview of the process for performing
a limited RI/FS for a surface impoundment operable
unit. Section 3.0 presents a description of the initial
scoping procedure. A detailed review of the steps
necessary to conduct a remedial investigation to
estimate the characteristics and quantities of
wastes stored in impoundments is presented in
Section 4.0. An overview of the feasibility study
process is presented in Section 5.0; these steps
should lead to the evaluation and recommendation
of a cost-effective and environmentally sound re-
medial alternative for wastes in surface impound-
ments.
The guidance presented in this manual represents
a compilation of existing approaches derived from
similar remedial actions implemented at many sites
where surface impoundments were handled as a
single operable unit. However, it will be necessary
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OSWER Directive 9380.0-6
to tailor this approach to meet the user's particular
needs and the site specific characteristics.
Flow diagrams have been developed to present a
logical sequence of activities for the implementa-
tion of this type of remedial action. The flow dia-
grams present the detailed steps for a limited Rl
and limited FS. The diagrams are located at the
beginning of each major section. Each major activ-
ity on the flow diagrams is denoted by a rectangle.
Diamonds represent decision points and circles in-
dicate starting and ending points for each phase of
the entire project. These activities are cross refer-
enced by number to the text in this manual. The
user may start anywhere on the flow diagram as
long as the predecessor activity has been com-
pleted.
The execution of a limited RI/FS for a single opera-
ble unit is designed to be very flexible in practice.
While many of the component activities are similar
to a full RI/FS the user should tailor the approach
based upon site specific conditions and other previ-
ous and/or ongoing remedial action activities. A
limited RI/FS for a surface impoundment site could
be initiated during the execution of a full RI/FS or in
parallel with other limited RI/FSs (e.g., alternative
water supply activities).
1.4 Characteristics of Surface
Impoundments
"Surface impoundment" or "impoundment" may
be defined as a facility or part of a facility that is a
natural topographic depression, man-made exca-
vation, or diked area formed primarily of earthen
materials designed to hold an accumulation of liq-
uid wastes or wastes containing free liquids. How-
ever, impoundments may also be lined with
man-made materials. Examples of surface im-
poundments are holding, storage, settling, and aer-
ation pits, ponds, and lagoons. An injection well is
not an impoundment.
Exceptions to the above description include specif-
ically designed waste containers such as concrete-
lined basins, which should be considered to be
tanks. Tanks are stationary devices designed to
contain an accumulation of hazardous waste. They
are constructed primarily of nonearthen materials
(e.g., wood, reinforced concrete, steel, or plastic)
that provide structural support. A separate guid-
ance document is available for cleanup of surface
tank and drum sites (EPA, 1985).
Surface impoundments may range in surface area
from a few tenths of an acre to hundreds of acres.
Man-made impoundments typically range in depth
from 2 feet to as much as 30 feet or more below the
land surface. In many instances, impoundments are
built above the naturally occurring water table to
take advantage of impermeable surface or subsur-
face soils. In areas with high ground water tables,
some impoundments are constructed on the land
surface by using dikes or revetments to minimize
ground water contact.
Impoundments are typically used for the aeration,
oxidation, stabilization, settling, disposal, and stor-
age of wastes. Impoundments may be operated in-
dividually or be interconnected so that the flow
moves from one impoundment to another in series
or parallel. Many impoundments discharge, either
continuously or periodically, while others lose their
fluids by evaporation or infiltration into the soil.
Impoundments may be unlined, permitting seep-
age of fluids into the soil for the purpose of percola-
tion or infiltration. For certain wastes, impound-
ments are lined to prevent any seepage of fluid.
Typical liner materials include clay, asphalt, soil
sealants, and synthetic membranes.
1.5 Operable Unit
The operable unit concept allows phasing of the
response actions for a particular site. The primary
advantage of performing a separate limited RI/FS
for a surface impoundment operable unit is that
less time is required to address a contributing con-
taminant source than for the entire site to be evalu-
ated. This allows action to begin on selected por-
tions of the site, without the delay of waiting for
completion of the complete RI/FS for the entire site.
However, there are some risks involved when
implementing a remedial action for a surface im-
poundment operable unit if other contaminated
areas remain. These risks may include but not be
limited to:
• Higher unit cost for a technology that may also
be implemented for the other contaminated
areas (economies of scale or remobilization)
• Remedy for operable unit not consistent with
objectives of entire site
These risks can obviously be minimized by a careful
evaluation of site conditions by the lead agency
responsible for the site. An operable unit should
not be undertaken unless the ground water protec-
tion standard has been established or contami-
nated soil excavation can be undertaken without
conflicting with the potential final remedial actions.
1-2
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OSWER Directive9380.0-6
2.0 Overview of Process for Conducting a
Limited RI/FS for a Surface Impountment Operable Unit
2.1 General
The evaluation of whether a limited RI/FS can be
performed for a surface impoundment operable
unit should be based on an evaluation of the im-
poundment's hydrogeologic characteristics, deter-
mined during the initial scoping process. Figure 2-1
shows the overall process for performing a limited
RI/FS for a surface impoundment operable unit.
2.2 Major Activities
Initial Scoping. The initial scoping process should
be based on existing information regarding the hy-
drogeologic conditions of the surface impound-
ment. These conditions influence the amount of in-
formation, physical controls, evaluation, and time
required to ultimately evaluate and determine an
acceptable remedy for the impoundment. This
process is presented in Section 3.0.
Limited Rl. The limited Rl should begin once the
decision has been made to perform a limited Rl
based on the initial scoping process for a surface
impoundment operable unit. The primary purpose
of a limited Rl is to evaluate existing information
and conduct field and analytical studies to deter-
mine the extent of contamination and risk posed to
the public health and environment. The process for
the limited Rl is presented in Section 4.0.
Limited FS. The limited FS may be conducted con-
currently with the limited Rl. The limited RI/FS is
an interactive process. Data collected in the Rl
phase are fed into the FS process, where data gaps
may be identified, requiring additional Rl work, etc.
This process leads to a refinement of the remedial
alternatives under consideration. The major pur-
pose of a limited FS is to determine the appropriate
remedy for the problems posed by the impound-
ment. The nature of the remedy may be final or
temporary depending on several factors. A general
overview of the limited FS process is given in Sec-
tion 5.0.
Figure 2-1. Overview of limited RI/FS process for surface impoundment operations.
3.0
Initial
Scoping
Can a
Limited RI/FS
be
Performed
2-1
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OSWER Directive 9380.0-6
3.0 Initial Scoping
The initial scoping process for determining the ap-
plicability of an operable unit should be based on
existing information on the hydrogeologic condi-
tions of the surface impoundment. The hydrogeo-
logic conditions that would influence the decision
for a limited RI/FS may include, but not be limited
to:
• Size of surface impoundment
• Waste viscosity
• Depth to ground water
• Leakage of impoundment
• Amount of contaminated soils
• Soil permeability
• Amount of physical controls required for inves-
tigation
These conditions will be explained later in this sec-
tion.
As mentioned previously, there are always risks in-
volved when action is implemented for an operable
unit at a site that contains other contaminated
areas. Thus, the user is increasing such risk if a
limited RI/FS is initiated for a site whose hydrogeo-
logic conditions may favor a full RI/FS.
3.1 Classification System for
Determining Applicability of Limited
RI/FS
A classification scheme has been developed based
on the interconnection of impoundment contents
and ground water as a possible tool for evaluating
the relative complexity of surface impoundment
sites. The important feature of this approach is that
it is useful to determine the feasibility of perform-
ing limited activities for a surface impoundment
operable unit and to define the boundaries of the
operable unit.
Not all information required for classifying surface
impoundments may be available for scoping a lim-
ited Rl. In such a case it will be necessary to make
assumptions based on existing data. This classifica-
tion system may be reviewed at the end of each
major phase of the limited Rl as more data become
available.
There are four main scenarios that describe the in-
terconnection of surface impoundments and
ground water. These scenarios were developed
based primarily on the physical characteristics of a
site and describe the complexity of a surface im-
poundment. As the complexity of the site increases,
defining the extent of the operable unit becomes
less clear and the scope of the investigation in-
creases. These scenarios are illustrated in Fig-
ure 3-1 and are discussed in detail below.
Two of the scenarios have special cases that may
require a reassessment of the applicability of a lim-
ited RI/FS for a particular impoundment condition.
The general guidelines for defining special cases
relate to the amount of hazardous wastes and con-
taminated materials contained in the impound-
ment, as well as the amount of contaminated soil or
ground water that must be handled, treated and/or
disposed of in order to evaluate and implement a
remedial action for the impoundment.
A decision tree analysis procedure (Section 3.2) has
been developed for this classification system.
Under all scenarios, an operable unit should not be
undertaken unless the ground water protection
standard has been established or contaminated soil
excavation can be undertaken without conflicting
with the potential final remedial actions.
Scenario A
Scenario A includes those surface impoundments
that are situated above the ground water table and
are not leaking. The impoundment contents are
physically isolated from the ground water and are
not being hydraulically transferred from the im-
poundment to the ground water table. There is lim-
ited contaminated soil beneath the impoundment
and ground water dewatering is not necessary for
decanting liquids from the impoundment.
This scenario includes impoundments with engi-
neered liners or self-sealing impoundments. This
scenario, as presented, illustrates a clear division in
the extent of contamination and provides a single
definable operable unit for a limited RI/FS.
Scenario B
Scenario B includes those surface impoundments
3-1
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OSWER Directive 9380.0-6
that are situated above the water table and are leak-
ing. The impoundment contents are physically iso-
lated from the ground water but are being hydrauli-
cally transferred to the ground water table.
Although dewatering is not necessary, there is con-
taminated soil beneath the impoundment.
When estimating the volume of contaminated soil
that may be handled during the remedial action,
several considerations should be made. For exam-
ple, it may be very difficult to measure the concen-
trations of contaminants in the soil beneath the im-
poundment. In this situation, evaluation of
contaminant concentrations in the impoundment
and in ground water will provide indirect evidence
of levels in the soil. Finally, deep impoundments,
impoundments with deep soil contamination, and
impoundments with high dikes or containment
berms pose additional problems relating to side-
slope stability if excavation is being considered.
Large volumes of soil could generally be handled in
these situations, and it may be possible to segre-
gate clean soil excavated for geotechnical (slope
stability) reasons from contaminated soil exca-
vated for environmental reasons.
When there is significant soil contamination, good
engineering judgment should be used to determine
if a limited RI/FS is warranted. A significant short-
term threat may favor rapid remedial action. How-
ever, an extensive plume originating from the im-
poundment may favor a full RI/FS for the entire site.
Scenario C
Scenario C includes those surface impoundments
that extend below the water table and are situated
in relatively impermeable soils. The impoundment
contents are physically in contact with the ground
water and ground water contamination has (pre-
sumably) occurred. However, because the soils
have low permeability, substantial ground water
in-flows will not occur and dewatering of the soils
surrounding the impoundment will not be needed.
Figure 3-1. Classification of impoundments.
Scenario A
Clean Soils
Physically Isolated
Hydraulically Isolated
Scenario B
/i i i i i r\
Lightly Contaminated Soils
L\ n
Physically Isolated
Hydraulically Connected
Heavily Contaminated Soils
Special Case
Volume of Soil More Than
That of Waste
in Impoundment
Scenario C
Scenario D
Low-Permeability Soils jg
Physically Connected
Dewatering Not Needed
Physically Connected
Dewatering Needed
High-Permeability Soils
Special Case
Volume of Pumped Ground Water
More Than Waste Contained
in Impoundment
3-2
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OSWER Directive 9380.0-6
Excavations in such situations may not be impeded
by water or stability problems because the soils will
generally be cohesive.
Scenario D
Scenario D includes those surface impoundments
that extend below the water table and are situated
in relatively permeable soils. The impoundment
contents are in contact with the ground water and
ground water contamination has (presumably) oc-
curred. Dewatering of the soils surrounding the im-
poundment will be necessary in order to decant
liquids in the impoundment. If dewatering of soils
is not done, ground water in-flows to the impound-
ment will occur, prolonging the impoundment
cleanup activities. Contaminated ground water will
also require treatment prior to disposal. When the
volume of water pumped is more than the volume
of the liquids in the impoundment, the selection of
definable operable units for sludges or contami-
nated soils may be impractical.
Several factors need to be considered when evalu-
ating ground water in-flows to the impoundment
and consequent dewatering needs. A principal de-
terminant will be the permeability of the soils sur-
rounding the impoundment. Special cases are
more likely to occur when the soils are highly per-
meable (K> 1 x 10 3 cm/sec) and can occur even
for moderately permeable soils (1 x 10~6 cm/
sec > K > 1 x 10~3 cm/sec). Large in-flow area and/
or hydraulic gradients, both of which would apply
to deep impoundments, can compensate for mod-
erate permeabilities in causing special case situa-
tions. Finally, if the ground water is not contami-
nated or is not contaminated to a degree requiring
treatment before disposal, it might be possible to
dewater even highly permeable soils within the
scope of the limited RI/FS program.
3.2 Decision Tree Analysis
Identifying when site specific conditions of a sur-
face impoundment may present a situation beyond
the intended scope of a limited RI/FS is a key objec-
tive of the decision tree procedure. At various
stages in the limited Rl it is important to review the
key decision points of this evaluation process. As
more information is obtained and evaluated during
the limited Rl process it may become apparent by a
re-evaluation, within the structure of this recom-
mended decision tree process, that a particular sur-
face impoundment may be beyond the scope of an
expeditious action, even once the limited Rl is
under way. Even if it is found that it may not be
appropriate to address an impoundment within the
scope of a limited RI/FS, the evaluation and plan-
ning process should continue as part of a full RI/FS.
A "decision-tree" type procedure, presented be-
low, has been developed as a planning tool which
can be used in applying evaluation criteria to define
the complexity of a particular surface impound-
ment situation and determine the applicability of a
limited RI/FS. This review procedure is designed to
focus on the classification scheme developed to
generally distinguish different surface impound-
ment conditions. The specific steps of the decision
tree evaluation procedure are summarized in Fig-
ure 3-2.
3.2.1 Surface Impoundment Size
The size of an impoundment is a physical character-
istic that can affect the complexity of the remedial
planning activities.
In general, larger impoundments are associated
with larger industrial operations which may have
handled a more diverse waste stream. As a result,
there is a greater likelihood of multi-level phase
separation of waste types and differential settling
of sludge/solids across the bottom of the impound-
ment. In relative terms, as the size of the surface
impoundment increases, so does its complexity.
The following size restrictions can be used as a
guide:
• Less than one acre to five acres—this range
limit was selected based primarily on the phys-
ical restriction of access. Specifically, the reach
of the boom from a type of equipment such as
a "cherry picker" for sampling, or the boom of
a crane or similar equipment for excavation.
• Greater than five acres—a larger impoundment
may contain more varied waste types or phases
which require specific treatment trains and the
aqueous portion of the impoundment may be
of such large volume or dilute nature that its
treatment train or portion of it could overlap
with the ground water RI/FS, making the combi-
nation of the two the logical next step. Reme-
dial actions would be more difficult to imple-
ment in a short timeframe compared to smaller
impoundments. Larger lagoons are also more
difficult to excavate.
3.2.2 Waste Viscosity
The viscosity of the waste material is another phys-
ical characteristic that can be used in determining
the degree of complexity of a surface impound-
ment. The viscosity (resistance to flow) also indi-
cates the general extent of how far the actual waste
material has moved through soils.
• Highly Viscous Material—the denser or semi-
solid material will become more readily bound
up in the soil matrix under the impoundment,
restricting its movement through the soil. This
3-3
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OSWER Directive 9380.0-6
Figure 3-2. A process for selecting an operable unit and determining the suitability of a surface impoundmentfor a limited RI/FS.
^
> 5 Acres
Low
f
Larger
Scale
RI/FS
Probably
Required
A
b
Below
4
Excessive
4
High
High
Major
Controls
Required
Surface Impoundment
Size
Waste Viscosity
< t
Depth to Groundwater
V
Is the Impoundment
Leaking?
Determine the Amount
of Contaminated Soil
Site Soil
Permeability
s t
Determine the Level
of Groundwater
Controls
1 > Acres > 5
High
Above
Minor
Low
t
Limited RI/FS May
be Applicable
4
Low
Minor
Controls
3-4
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OSWER Directive 9380.0-6
does not refer to the material's leachability or
movement of contaminants, but indicates how
easily the impoundment can be defined, evalu-
ated, and remedied as an operable unit.
• Low Viscous Material—the more liquid mate-
rial indicates a higher degree of vertical and
horizontal flow, or dispersion, into the sur-
rounding soils.
3.2.3 Depth to Ground Water
The depth to ground water influences the amount
of ground water contamination from an impound-
ment.
• Waste Above Ground Water—In areas of low
ground water, distinction can be made between
the waste material itself, contaminated soil re-
sulting from leaching (or seasonal ground
water fluctuations), and contaminated ground
water. Remedial alternatives analyzed in the
feasibility study may address these threats sep-
arately or together.
• Waste Below Ground Water—In this case, at
least part of the waste material sets in the
ground water, basic contaminant dispersion
and the flow gradient through the waste will
expand the area and media of investigation re-
sulting in increased effort.
3.2.4 impoundment Leaking
The question of the presence or absence of a liner
and the integrity of the liner may indicate the rela-
tive complexity of the impoundment study due to
possible ground water contamination.
• Non-leaking Impoundments—A single opera-
ble unit can be delineated if the impoundment
is not leaking. Or, if the amount is so small that
very little is migrating from the impoundment,
then the limits of work can be defined.
• Leaking Impoundment—Depending on its rela-
tionship to the ground water and the extent of
contamination, the RI/FS may increase in levels
of complexity.
3.2.5 Contaminated Soils
Soils adjacent to the impoundment may be con-
taminated either due to seepage or the breach of
the containment berm. The impoundment volume
may be used as a relative guide to measure con-
taminated soils:
• Less than impoundment volume—This reflects
a relatively finite volume of associated con-
taminted soils which allows for these soils to be
handled within the operable unit impoundment
study.
• Greater than impoundment volume—The
greater volume and relative level of contamina-
tion of soils indicates handling the impound-
ment as a single operable unit may not be the
optimal approach for the site. Remedies for the
soils may be more practically evaluated with
other contaminated areas of the site.
3.2.6 Permeability
Physical data available from simple soil permeabil-
ity tests or other sources help quantify the decision
making process of the previous two steps. Soils
underlying the impoundment having a permeabil-
ity of less than 1 x 10~6 cm/sec may be considered
to be relatively tight, impeding migration of con-
taminants.
• Less than 1 x W~6—These soils may resist the
migration of contaminants either into the sur-
rounding ground water or of flow by ground
water across the site, suggesting that the sur-
face impoundment may be evaluated as an ap-
propriate operable unit.
• Greater than 1 x 10~6—As the permeability in-
creases the distinction of the waste, soil, and
ground water interfaces become less definable,
limiting the applicability of an operable unit ap-
proach.
3.2.7 Ground Water Controls
The need for physical ground water controls
(pumping, and possible treatment processes) dur-
ing evaluation and remedial action implementation
greatly increases with the permeability of the
underlying soils, to the point that there may be little
distinction between the probable treatment
schemes for the waste material and the ground
water.
The operable unit approach may be dependent on
the volume of ground water that must be pumped
which is either greater or less than the relative liq-
uid volume of the impoundment and whether a dif-
ferent waste handling/treatment scheme must be
applied.
• Less than—If the ground water volume is less
than the liquid volume of the impoundment,
then the operable unit approach may be appro-
priate.
• Greater than—If the ground water volume to be
handled greatly increases, then a broader
pumping and treatment scheme would be re-
quired, limiting the applicability of an operable
unit approach.
3-5
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OSWER Directive 9380.0-6
4.0 Limited Remedial Investigation
After a decision has been reached to evaluate a
surface impoundment operable unit, a limited re-
medial investigation (limited Rl) should be per-
formed to provide the information necessry to fur-
ther define the site, provide the basis to evaluate
conditions on the site, and to develop a remedial
program to mitigate potential adverse public health
and environmental impacts. The four main compo-
nents of a limited Rl are:
1. Develop site description and data base. (Sec-
tion 4.1)
2. Continue site familiarization and develop proj-
ect approach. (Section 4.2)
3. Perform initial site characterization. (Sec-
tion 4.3)
4. Conduct detailed field investigation. (Sec-
tion 4.4)
A description of these tasks and the associated de-
cision points are presented below. The logic flow
diagram for the Rl is presented on Figure 4-1.
4.1 Develop Site Description and Data
Base
The initial component of the limited Rl is to obtain
available data describing site conditions (e.g., the
nature, amount and character of wastes, the poten-
tial for migration from the site or exposure to haz-
ardous materials, and unique site features) and to
make an initial evaluation of these data relative to
cleanup activities for the site.
4.1.1 Obtain Available Data
Purpose
Data are collected for the following reasons:
• To better define site conditions so that a health
and safety plan and sampling plan can be pre-
pared (Section 4.4)
• To provide a basis for initial site evaluation and
identification of potential remedial alternatives
(Section 4.2.5 and 4.3.1)
• To perform an assessment of current on-site
hazards (Section 4.3.3)
• To identify and evaluate existing data base so
that future field activities can be planned to fill
data gaps (Section 4.3.5)
• To develop a data base for design of an ultimate
remedial program (contract documents, plans
and specifications)
• To provide data for evaluation of remedial alter-
natives
Techniques
There are many Federal, State, and local agencies
which may have pertinent information useful in
conducting a limited RI/FS at a surface impound-
ment site. Most of the available data may be gen-
eral in nature but possibly useful in establishing a
baseline. In addition to governmental sources,
other data sources that may be particularly useful
in obtaining more specific information on the con-
ditions of a site include:
• Site history, ownership, operation/disposal
practices (past and present, from past owners,
operators, and/or generators)
• Sensitive receptors in the vicinity of the site
• Initial planning documents, such as Remedial
Action Master Plan if available
• Preliminary assessment/site inspection data
• Aerial photos of the site
• Hazard Ranking System (MRS) documentation
Many other agencies and potential data sources
along with types of information that's generally
available from these sources are reviewed in Guid-
ance on Remedial Investigations Under CERCLA
(EPA, 1985).
Limitations
Effort should not be wasted on obtaining data that
are not applicable to the scope of the project or are
obviously generic or duplicative in nature.
4.1.2 Review and Evaluate Available Data
Purpose
The data should be evaluated and summarized in
formats that are easily reviewed by individuals not
4-1
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OSWER Directive 9380.0-6
involved in the collection process. By reviewing
and evaluating the available data, an understand-
ing of site conditions will be developed and evident
data gaps will be identified. During this activity, the
quality (i.e., accuracy and precision) of the data and
its conformance with the quality assurance/quality
control protocols under which it was collected
should be assessed.
Techniques
At this early stage it is important to focus on com-
piling as much information as possible on the char-
acteristics of the surface impoundments. This infor-
mation includes:
• Conditions of dikes with regard to stability,
seepage, and erosion
Figure 4-1. Guidance flow diagram for surface impoundment source control limited remedial investigation.
Obtain Available Data
• Background Data
— facility description
— site history
— past operation and
disposal practices
— physiography/
topography
—soils/geology
— climate/weather
— surface water
— ground water
—ecology/land use
— sensitive receptors
• Agency Data
—RAMP
—PA/SI
—health & safety plans
— chronology of agency
involvement
Review and Evaluate
Available Data
• Summary maps, tables,
matrices
• Executive Summary
• Evident data gaps
• Quality of data
4.1.2
4.1 1
Prepare Preliminary
Base Map
• Underground/overhead
utilities
• Availability of water and
electrical hookups
• Nearby structures and
residences
• Identify contaminated
soil target areas
• Location of known
potential hazards
• Property lines/
boundaries
• Access/security
• Topography/vegetation
• Drainage features
• Surface impoundment
location/size
• Buildings/structures/
piping
• Existing walls and
sampling locations
4.2
Prepare Preliminary Soil/
Geological Cross Section
• Ground surface features
• Soil horizons
• Major geological units
• Location of borings.
wells and test pits
• Sample locations/
analytical results
• Groundwater table
42
Prepare/Revise Health &
Safety Plan
Training
Medical screening
Protective and
monitoring equipment
Entry/exit procedures
On-site procedures
Emergency response
Site walkover
(if necessary)
4.2
Prepare Community
Relations Plan
•
2
3
F
Identify Potential Remedial
Actions
Conduct Initial Site Visit
• Verification of existing data
• Identification of unusual
features
—spills/stained soils
—evident environmental
stress/impact
—special wastes
(radioactive /explosive)
—other wastes (drums/
tanks, closed
impoundments)
• Examination of surface
impoundment
—dike erosion/instability/
seepage
—freeboard conditions
—construction details
—condition of piping
—accessibility for
equipment
• Characterization of wastes
—stratification/depth/
thickness
—nature (oily/aqueous)
—physical state (foam/
hquid/sludge/'solid)
—physical properties (color
/viscosity/texture)
—chemical properties
(organic/inorganic, pH)
—ambient vapor conditions
4.3 f
4.2.4
4-2
-------
OSWER Directive 9380.0-6
• Freeboard conditions and site features that
could result in changes to liquid levels
• Depth to ground water and seasonal fluctua-
tions in the vicinity of the surface impoundment
• Depth of surface impoundment(s)
• Surface area (individual and total when involv-
ing more than one impoundment)
• Evidence of phase separation in the vertical
profile of the surface impoundment
• Details of impoundment construction such as
dike composition or nature of liners
• Evidence of overflows, leakage, or other spread
of contamination
• Nature of soils around/under the surface im-
poundment (e.g., permeability, type, clay and
organics content, etc.)
• Nature and characteristics of material in surface
impoundment particularly chemical composi-
tion and physical features (e.g., viscosity)
Whenever possible, available data should be sum-
marized in graphic, tabular, or matrix formats.
These formats are compact and allow for efficient
presentation, comparison, and utilization of large
amounts of data. A written summary is also valu-
able for conveying data trends and general condi-
tions. All summaries, whether graphic, tabular or
written, should identify both what is known (condi-
tions at the site) and what is not known (evident
data gaps).
An important part of reviewing and evaluating the
available data is an assessment of its reliability, that
is, the extent to which the data represent site condi-
tions. The dates of maps, drawings, and plans
should be checked; sampling locations should be
evaluated for representativeness. Analytical data
should be checked against internal laboratory QA/
QC criteria (blanks, duplicates, spike/recovery); and
the methods of sample collection, preservation,
handling, and sampler decontamination should be
examined for potential irregularities. If more than
one laboratory tested samples from the same area
on site, the results should be assessed for consis-
tency and variations in methodology should be
identified.
Limitations
The data "pool" will be examined to see if the de-
sired information is available. Available data will be
evaluated and the need for additional data will be
re-evaluated. A balance must be maintained be-
tween the need to develop a detailed data base, the
need to concentrate on data essential to solving
environmental problems at the site, and the need to
arrive at the solution as soon as practicable. The
quality and accuracy of the data are principal con-
cerns along with the relative timeliness of various
data elements.
Figure 4-1. (Continued)
s There
an Immediate'
Public Health or
nvironmental
Threat?
Notify Agency and
National Response
Center
as Appropriate
Continue
Investigation
When Appropriate
Conduct Preliminary
Exposure Assessment
• Waste characteristics
• Migration pathways
• Potential receptors
4.33
etermme
Need for
Continued
Limited
RI/FS
Handle as
Part of Full or
Expanded RI/FS
Define Data
Needed to
Conduct Focused
Feasibility Study
4.3.5
Is
Exising
Data Base
Sufficient
for Focused
Feasibility
Study?
Prepare Project Operations Plan
• Sampling plan
• Health and safety plan
• QA/QCplan
4.4.1
Submit Plans for Agency
Review and Revisions
4-3
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OSWER Directive 9380.0-6
Figure 4-1. (Continued)
Prepare for Field Activities
• Indoctrination of field
personnel
— Stic conuiiionb
— sampling plan
— activities plan
— facilities layout
—health and safety plan
—emergency
contingency plan
— documentation/site
log procedures
— sample handling and
cham-of-custody
procedures
• Mobilization of field
facilities
— office and changing
trailers
— decontamination
stations (personnel
and equipment)
— materials and
equipment
— site security
— fixed air monitoring
station
t>
Conduct Impoundment
Investigation
• Quantification of waste
volumes
— measurement
— estimation
• Characterization of
impoundment structures
— number and location
of samples
—sampling methods
— physical properties
— geotechnical
properties
• Waste sampling and
characterization
— number and location
of samples
— sampling methods
— physical properties
— chemical properties
4.4.2
Conduct Focused
Groundwater and
Subsurface Investigation
1* Well network design
and installation
—number, location
and depth
— construction/
materials
— installation and
development
methods
• Field measurements
— water/fluid levels
— permeability
• Sampling methods
• Characterize
subsurface conditions
(physical and chemical)
4.4.3
Conduct Focused Surface
Soil/Water/Sediment
Investigation
• Sampling and
characterization
— number and location
of samples
— sampling methods
• Relationship/transition
to other Guidance
Documents
• Soil characterization:
field tests
• Soil characterization
lab tests
• Surface water and
sediment
characterization
• Sample classification.
disposition and
chain of custody
Review Analytical Results
f. for Compliance with
Quality Control Program
4.4.5 . Evaluate All Data and
V Conduct and Assess V Investigation Report
Characteristics of
Soil/Waste System 4 4.7
• Uncontammated vs.
contaminated
characteristics
L • Soil sorptive capacity
(attenuation)
• Potential chemical
reactions
• Potential rates of
volitalization
• Leaching potential
446
.
4.4.4
4-4
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OSWER Directive 9380.0-6
4.2 Site Familiarization and Project
Approach
The goal of the second major component of the
limited Rl is to develop the approach (scope) to be
followed in subsequent activities. This is accom-
plished through the preparation of preliminary
maps and plans, and the identification of potential
remedial technologies. The activities performed
during this component are to:
• Prepare a preliminary base map of the site (Sec-
tion 4.2.1)
• Prepare a preliminary soil/geological cross sec-
tion (Section 4.2.2)
• Prepare initial health and safety guidelines
(Section 4.2.3)
• Prepare a community relations plan (Section
4.2.4)
• Identify potential remedial technologies (Sec-
tion 4.2.5)
Identification of potential remedial actions that are
applicable to site conditions is a key step in the
limited Rl. By identifying these technologies early
in the overall limited RI/FS process, subsequent
data collection and analysis can be focused on the
development and evaluation of realistic and practi-
cable alternatives. Preparation of a base map, a
community relations plan, and an initial health and
safety guide will serve to better define site condi-
tions and data needs. The health and safety guide
should be prepared in conformance with EPA's
Standard Operating Safety Guides (EPA, 1984).
4.2.1 Prepare Preliminary Base Map
Purpose
The purpose of this activity is to develop an accu-
rate, detailed, up-to-date map of the site. The pre-
liminary site map is needed to effectively plan the
field activities of the initial site visit and is used to
record many of the observations made during that
visit. In most cases, the preliminary site map will be
updated to provide a completed site base map. The
base map will provide an accurate representation
of the site's impoundment, breaches in dike struc-
tures and contaminated soil areas in sufficient de-
tail to provide quantity take-offs, property
boundaries, and key physical features to meet all
limited RI/FS requirements.
Technique
The preliminary base map can be developed from
existing site maps, aerial photos or a site topo-
graphic survey. The EPA Environmental Monitoring
Systems Laboratory (EMSL) in Las Vegas, NV can
provide a wider range of information on a site.
EMSL may provide the following:
• Aerial photographs and analysis for a single
date
• Aerial photographs and analysis over time
either for the site itself or other wider area
• Topographic mapping at 1 foot to 5 foot inter-
vals
• Orthophotographic mapping—a rectified pho-
toimage with a topographic map superim-
posed.
These services can be obtained through the re-
gional EPA office.
A sample base map is included as Figure 4-2. Fea-
tures shown on the site map should include:
• Property lines, used to identify boundaries for
site access control and site security
• Location, size and pertinent features of all sur-
face impoundments including berms, area of
overflow, etc.
• Identified contaminated soil target areas
• Locations of known potential hazards
• Existing piping or interconnections between
surface impoundments
• Possible on-site staging/decontamination areas
for conductance of geophysical survey and per-
formance of activities during the site/surface
impoundment characterization
• Drainage patterns, wetlands, and other water
features
• Buildings and structures
• Utilities and other easements
• Wells
• Access/egress points
• Adjacent structures/residences
• Prior sampling locations (on and off site)
• Topography
• Vegetation and other environmental features
• Stained soils, pits, ponds, lagoons and other
waste disposal areas
• Site fencing and other security measures
Limitations
Old figures, photos and maps may be useful
sources of historic information but should not be
relied on for current site conditions. A fly-over of
the site to obtain aerial photos may be necessary.
4-5
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OSWER Directive 9380.0-6
Figure 4-2. Existing conditions site base map example.
USGS Disk Azimuth Mark
Elev = 299.55
X-Axis
Feet
0 20 40 80 \ 20
0 ^0 20
Meters
4-6
-------
OSWER Directive 9380.0-6
4.2.2 Prepare Preliminary Soil/Geologic Cross
Section
Purpose
In addition to the site base map, if possible, a pre-
liminary soil/geologic cross section should be de-
veloped to provide a three-dimensional overview of
soils/geology and the extent of soil contamination
at the site. The purpose of this effort is to identify
any characteristics, changes or correlation between
the type and movement of contamination and soil
types and structure. This information will be used
to:
• Estimate volume of site soil contamination
• Identify limits/depth of subsurface sampling
program
• Select appropriate soil sampling/drilling meth-
ods
• Evaluate and design remedial responses
Technique
The preliminary soil/geologic cross section can be
developed from existing site maps, soil and geo-
logic publications, any existing soil borings and
monitoring well installation reports and analytical
results of soil sampling and ground water sam-
pling, if available. A useful type of cross section
view is shown in Figure 4-3. Features shown on a
cross section of this type should include:
• Ground surface features (e.g., buildings, above-
ground tanks, roads)
• Soil horizons
• Major geologic units
• Location of existing borings, wells, test pits and
impoundments
• Sample locations and readings from field ana-
lyzers
• Ground water table
Limitations
If no soil borings, soil test pits or monitoring wells
have been installed at the site, it may not be possi-
ble to construct a detailed preliminary cross sec-
tion. However, geologic and soil publications
should be available to give an estimate of the thick-
ness of unconsolidated materials and the depth to
the ground water table.
4.2.3 Prepare Initial Health and Safety Guidance
Purpose
An adequate protocol to protect personnel during
the initial site visits, (Section 4.3.1) and later during
surface impoundment cleanup, is one of the most
important aspects of the remedial investigation
phase. This initial health and safety guide should be
prepared, (or revised, if available) and administered
by a trained professional.
Techniques
If an existing health and safety plan has been devel-
oped for prior site work, this plan may be adequate
for the initial site visit. This document should be
reviewed by a qualified professional using the ex-
isting site data base (see Appendix A of Guidance
Document for Cleanup of Surface Tank and Drum
Sites [EPA 1985] for an example of a site personnel
protection and safety evaluation form). If no plan
exists, guidance must be developed based on the
existing data. In either case, this guidance must
include:
• An objective evaluation of the goals both of the
site visit and the remedial action
• An evaluation of site specific hazards, including
airborne contaminants; potential radiological
exposure; dermal hazards; hazards due to falls,
electrical shock or other traumatic injury; haz-
ards from heavy equipment operation, en-
closed space entry, heat stress, etc.
• Medical monitoring of personnel going on site.
• Delineation of contaminated, decontaminated,
and clean zones
• If tanks are to be surveyed, specific protocol
must be included describing access proce-
dures, how personnel are to open and check
tanks, and how worker safety will be ensured if
tank structural integrity is uncertain.
• A description of site conditions including the
characteristics of the surface impoundment,
and the nature of wastes on-site
• Contingency plan for emergency action (e.g.,
include telephone numbers and locations of lo-
cal hospitals, fire departments, and police etc.)
• Training required.
The user is referred to the Occupational Safety and
Health Guidance Manual for Superfund Activities
(NIOSH, 1984), Guidance on Remedial Investiga-
tions Under CERCLA (EPA, 1985) and Standard Op-
erating Safety Guides (EPA, 1984) for additional in-
formation.
Limitations
If only limited data describing the potential hazard
level on site are available, the health and safety
guidance may be excessively conservative or inad-
equate to protect workers. Any existing data or past
4-7
-------
OSWER Directive 9380.0-6
Figure 4-3. Typical soil/geologic cross section of surface impoundment and adjacent area.
A-3
A-4
Oil and Light Hydrocarbons
( 1)—Loam, organic material with silt and clayey layers locally
(2)—Gray and brown silt and trace fine sand
f 3— Fine to coarse sand with gravel
—Glacial till, clay and weathered shale
5 )—Bedrock, refusal
Note: Number values represent total organic vapor content as
measured by OVA headspace analysis (ppm) as
influenced by soil structure and permeability.
4-8
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OSWER Directive9380.0-6
health and safety plans should be field verified
prior to adoption.
4.2.4 Prepare Community Relations Plan
Purpose
A community relations plan is a prerequisite for
remedial actions at NPL sites because of their high
public visibility and public interest. The purpose of
a community relations plan is to keep the public
aware of plans and activities related to the site and
to receive input from the community regarding the
site.
Techniques
This community relations plan includes: a site de-
scription; history of community relations activities;
discussion of key parties and their concerns; the
site specific community relations objectives; com-
munication methods; a staffing and budget plan; a
site mailing list; and work schedule. Further guid-
ance on these activities is provided in Community
Relations in Superfund: A Handbook, Interim Ver-
sion (EPA, 1983).
Limitations
Not applicable.
4.2.5 Identify Potential Remedial Action
Technologies
Purpose
This activity plays an important role in the develop-
ment of the remedial evaluation and provides the
basis to determine if existing data are adequate to
support proceeding directly to limited FS. A prelim-
inary list of applicable technologies is also pre-
pared so that during the initial site characterization,
any obvious limitations to a specific alternative can
be identified. While this step occurs in the Rl phase,
it is actually the initial activity of the limited FS
phase. This overlap in phases helps to expedite the
schedule, but more importantly, improves the use-
fulness of data generated in the limited Rl.
Techniques
Potential remedial technologies applicable to sur-
face impoundment sites can be identified by per-
forming the following three-step process:
1. Use existing references and documents con-
cerning remedial activities for surface im-
poundments and waste characteristics to
compile a list of remedial technologies that
could be applicable to the physical setting and
waste characteristics at the site.
2. Screen out technologies that are not likely to
be feasible on the basis of a broad-perspective
review of the constraints of implementation of
each technology for site conditions. This
screening should consider compatibility of
technologies, timing of implementation, envi-
ronmental impacts, regulatory requirements,
and relative costs. The analysis will require
substantial use of best engineering judgment.
3. The remedial technologies that may be imple-
mentable will serve as the basis for determin-
ing subsequent data needs. The limited Rl
should concentrate on obtaining the data
needed to adequately analyze the feasibility of
these technologies, alone and in combination
as remedial alternatives, during the limited FS.
An important part of the process of identifying po-
tential remedial technologies for surface impound-
ments is to review the logical steps involved in re-
medial action for a surface impoundment. A
diagram of these steps is shown in Figure 4-4. From
this logic diagram, and using available references
and documents concerning remedial activities for
surface impoundments, a matrix of potential tech-
nologies and waste categories can be developed.
Best engineering judgment may be necessary to
resolve issues for which there are insufficient exist-
ing data regarding the physical setting and waste
characteristics.
Sufficient existing data may be available to deter-
mine if some on-site alternatives, particularly re-
lated to disposal, can be eliminated. For example,
secure land burial, if the site is a wetland area or in
a floodplain, may not be a feasible or environmen-
tally sound alternative. The importance of begin-
ning the identification of technologies and initial
screening during the limited Rl is twofold. First,
technologies are reviewed and screened with re-
gard to the documented physical setting and waste
characteristics at the site. Secondly, it allows data
collection activities to include assembly of informa-
tion useful in the further evaluation of remedial
actions.
Limitations
Limited data may make selective identification of
potential remedial technologies difficult.
4.3 Perform Initial Site Characterization
The initial site characterization is an important tran-
sitional activity which is centered around an initial
site visit. The limited Rl progresses from activities
that are based upon existing data to activities and
decision points which use information developed
from initial field activities. The principal activities in
initial site characterization include:
• Performing an initial site visit (Section 4.3.1)
• Determining if conditions could result in an im-
4-9
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OSWER Directive 9380.0-6
Figure 4-4. Surface Impoundment Remedial Action Logic Diagram
Decision
to Implement
Remedial
Action
On-Site Liquid
Treatment
Off-Site Liquid
Treatment
Are
There
Free Liquids
in the
Sludge?
Yes
Remove Free Liquids
from Sludge
On-Site Sludge or Soil
Removal/Stabilization
Treatment/Isolation
Off-Site Sludge or Soil
Removal/Stabilization
Treatment/Isolation
mediate threat to human health and/or the en-
vironment (Section 4.3.2)
• Conducting a preliminary exposure assess-
ment so the scope of the limited RI/FS can be
evaluated (Section 4.3.3)
• Determining the need for continued limited ac-
tivity based upon review of additional informa-
tion (Section 4.3.4)
• Defining the data requirements for conducting
the limited FS (Section 4.3.5)
4.3.1 Conduct Initial Site Visit
Purpose
The purpose of this activity is to:
• Verify existing data (e.g., surface impoundment
conditions, freeboard conditions, extent of dike
erosion)
• Identify critical areas on-site (e.g., possible
equipment staging areas)
• Visually characterize wastes (e.g., stratification,
nature, physical state)
Gather additional data to support further site
evaluation (e.g., soils stains, areas where spills
have occurred)
Techniques
After all the preparatory activities described in Sec-
tion 4.2 have been completed, the user is ready to
enter the surface impoundment site for the initial
site visit. While on-site, the provisions of the initial
site health and safety guide must be strictly ob-
served. Furthermore, if anything unanticipated in
the health and safety guide happens, discontinue
on-site activities and re-evaluate the situation.
The potential hazards associated with volatilization
of some organic compounds will be assessed utiliz-
ing a portable organic vapor analyzer (OVA), com-
mercially available photoionizer, or photovac GC.
Indicator tube sampling can also be used to provide
qualitative information, which is important input to
the design of the site safety program. The sample
team monitors ambient air for the specific com-
pounds identified in preliminary information to de-
termine whether an imminent health hazard exists.
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The initial site visit may only involve limited sampling.
The following activities may be performed during
the initial site visit:
• Identification of unusual features, including
—spill areas and stained soils
—evidence of environmental stress to flora or
fauna
—presence of wastes requiring special han-
dling or precautions
—presence of wastes other than those in the
surface impoundments
• Examination of surface impoundments, includ-
ing
—amount of dike erosion, evidence of dike in-
stability, seepage through dikes
—freeboard conditions and site features that
could result in changes to liquid levels
—details of impoundment construction such as
dike composition or nature of liners
—condition of piping and other interconnec-
tions between impoundments
—factors affecting the accessibility of impound-
ments to heavy equipment such as moisture
content of soils and width of dike crest
• Field characterization of wastes, including
—presence of stratification in the impound-
ment, impoundment depth, and the thick-
nesses of various waste layers
—general nature of wastes—whether oily or
aqueous
—the physical state of the wastes—whether
scum/floating sludge, liquid, semi-solid
sludge, or solid
—physical properties of the wastes such as
color, viscosity, or texture
—chemical properties of the wastes such as
organic or inorganic
—ambient vapor conditions at various dis-
tances with respect to open impoundments
• Identify:
—Site utilities, facilities and structures
—Unusual wastes (lab pack, cylinder)
—Drainage
—Spills, seeps, etc.
—Divide site into zones to facilitate identifica-
tion of target areas and future remedial ac-
tions
• Make preliminary inventory of any waste sur-
face impoundments and drums/tanks that may
be on site
• Locate access, egress, and security points
• Note evident environmental stress
• Perform air quality monitoring
• Interview local residents
• Identify staging and access areas
• Identify and confirm features on the prelimi-
nary base map and soil/geologic cross section
• Photograph or videotape site features
It is not unusual for abandoned impoundments to
overflow, resulting in overland movement of
wastes. If contaminated soils are high in volume, or
are found at any substantial distance from the im-
poundment, the inclusion of a second operable unit
study or the move to a full RI/FS activities may be
required. If surface water bodies are involved in the
overflow event, observations of gross sediment
contamination or environmental stress should in-
clude these areas.
All contaminated soil target areas in the vicinity of
the surface impoundment should be located and
described. A typical contaminated soil target inven-
tory form is present in Table 4-1.
Table 4-1. Example of a Completed Contaminated Soil
Target Area Inventory Form
Target Area
A B
Approximate Extent of Area
Contamination .25 Acre .10 Acre
Field Instrument/Reading .250 ppm ND
Sludge Piles Yes No
Above Ground Tanks or
Drums
No
Barren (Sparsely Vege-
tated) Area Yes
Evidence of Soil Distur-
bance (Landfilling)
No
Seepage Basins/Lagoons No
No
Yes
No
No
Evidence of Dumping/Spills
(Tire markings or eroded Yes Yes
soil)
Evidence of Buried Drums
(Geophysical methods) No
No
Other Visible Evidence
(Explain)
None Near chemical transfer
facility some spillage
occurs during normal
operation
Possible Contaminants Solvents Acids, petroleum
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Detailed examination of the surface impoundments
is important for several reasons. Observation of
dike erosion, incipient instability, or seepage may
indicate the need for actions to mitigate an immedi-
ate hazard. Similarly, immediate hazards may be
posed by limited/inadequate freeboard conditions
or impoundments receiving stormwater runoff. De-
tails of impoundment construction (such as
whether the dikes are composed of on-site soils or
the presence and condition of a liner) will be useful
in estimating or measuring waste volumes and
may affect the feasibility of remedial technologies.
Severly deteriorated piping could become a path-
way for sudden releases of waste material. The fea-
sibility of remedial technologies that use heavy
equipment can be substantially affected by soft
ground or other conditions limiting access to the
impoundments.
Characterization of waste materials by visual obser-
vation and direct-reading instruments is also very
important. Identification of stratification within the
wastes is necessary for representative sampling,
while total impoundment depth and layer thick-
nesses are needed for determining waste volumes.
The physical and chemical characteristics of the
wastes are clearly key variables in defining alterna-
tive technologies for source control action and in
identifying the most cost-effective actions, if
needed.
A limited geophysical survey may be performed to
identify subsurface hazards such as buried drums,
tanks and semi-solid wastes. These hazards may
limit further field work such as drilling of soil bor-
ings for collection of subsurface samples until the
degree of hazard could be assessed and/or re-
moved. Geophysical methods that could be em-
ployed include ground penetrating radar, magnet-
ics, resistivity and electromagnetics (terrain
conductivity). The general applicability of each of
these techniques for detecting subsurface hazards
is shown in Table 4-2.
Special wastes (radioactive, gas, etc.) not associ-
ated with the surface impoundments may also be
present at the site and should be noted during the
site visit. Laboratory packs (drums, cans or boxes
containing laboratory wastes) may also hold haz-
ardous wastes. More commonly, however, lab
packs hold small containers of often incompatible
materials.
A higher level of health risk to the inspection team
is associated with the disturbance or handling of
special types of wastes. If any special wastes are
observed on-site, assistance from trained, experi-
enced personnel who are specialists in dealing with
these types of wastes should be obtained before
attempting to evaluate them.
Limitations
During the initial site visit, little sampling may be
performed and only preliminary on-site activities may
be performed, limiting the certainty of information.
4.3.2 Determine if an Immediate Threat Exists
Purpose
The primary purpose of this activity is to determine
if an immediate threat to human health or the envi-
ronment exists. The most common immediate
threat would be the release of hazardous wastes
due to the failure of a dike or a surface impound-
ment.
Technique
The following physical conditions justify special
and immediate attention:
• The absence of fencing or other measures to
prevent direct contact between the public and
hazardous materials in or around the surface
impoundments
• The presence of flammable or explosive mate-
rials in situations making fire or explosion pos-
sible or probable
Table 4-2. Application of Geophysical Techniques to Detection of Subsurface Hazards
Method Advantage
Disadvantage
Ground Penetrating Radar
Magnetics
Resistivity
Electromagnetics (terrain
conductivity)
Gives best depth estimate
Fast, inexpensive
Can sample discrete in-
crements of subsurface
materials
Fast, inexpensive
Depth penetration can be greatly reduced by
near surface clays, and other highly conduc-
tive mediums (e.g., scrap metals); most ex-
pensive method
Sensitive to cultural interference; e.g.,
powerlines, pipelines and buildings
Considerably slower than the other methods
listed and perhaps less sensitive to buried
drums
Sensitive to cultural interference, e.g.,
powerlines, buried pipelines and buildings
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• Severely degraded waste storage facilities,
such as excessively eroded or badly seeping
dikes, that would result in sudden and/or wide-
spread releases of large amounts of hazardous
materials
• Limited or inadequate freeboard conditions
with heavy rainfall likely or with surface
drainage directed into the surface impound-
ments
• Air releases above acceptable levels as meas-
ured by direct reading instruments or other air
quality monitoring devices
The presence of one or more of these conditions
does not necessarily mean there is a significant im-
mediate threat to human heath or environment.
Other factors should be considered, such as types
of waste materials in the impoundment, location
and exposure routes to sensitive/human receptors,
and existing topographic and physical features
near the site.
If an immediate threat is observed during the initial
site visit, after all factors have been considered, the
agency responsible for site activities and possibly
the National Response Center [Telephone (800)
424-8802] should be contacted.
Limitations
If uncertain of the nature and significance of the
threat, contact the agency responsible for site activ-
ities and evaluate the situation with them before
contacting the National Response Center. The focus
at this point is defining and reducing very eminent
and obviously dangerous conditions.
4.3.3 Conduct Preliminary Exposure Assessment
Purpose
The level of hazard posed by the site is assessed for
each of the identified receptors, and the need for
further action is determined. This assessment will
be used and further evaluated during the limited FS
to determine if a no action alternative is appropri-
ate.
Techniques
The following steps may be used to perform this
preliminary assessment:
• Identify and characterize each waste source
(type of waste in each impoundment).
• Identify and observe the conditions of dikes/
liners and freeboard.
• Identify the actual or potential pathways of
contaminant migration for each waste source
(surface water, ground water, air transport, or
combinations of the above which could result
in direct contact).
• Identify potential public and environmental re-
ceptors of the migrating contamination
(nearby residents, water wells, wetlands, en-
dangered species).
• Determine if a remedial action is necessary to
mitigate the threat to human health or the envi-
ronment.
An example of these steps is summarized in a ma-
trix in Table 4-3.
Evaluation of the actual or potential threat may in-
clude a qualitative or quantitative evaluation of
conditions such as the likelihood of migration,
amount of contaminant migration, and time frame
of the exposure.
(The user is referenced to Agency guidance on risk
assessment procedures such as the Draft Super-
fund Health Assessment Manual [EPA, 1985].)
Limitations
Data available at this stage of the investigation may
allow only a very cursory assessment of exposure
and threats to public health and the environment.
4.3.4 Determine Need for Continued Limited
Activity
Purpose
The decision to conduct a limited RI/FS for surface
impoundments should be re-evaluated in light of
the detailed review of data and the initial site visit.
While the basic objectives of a limited RI/FS may
still be valid, it may be more appropriate to expand
the scope to include other contaminated media
found on site (e.g., soils). The cost-effectiveness of
a focused fast-track surface impoundment project
must be compared with the value of integrating the
surface impoundment portion into the overall site
RI/FS.
Techniques
Criteria for making a decision on whether to con-
tinue a limited RI/FS for surface impoundments or
to expand the scope to include the entire site will
obviously vary depending upon site-specific condi-
tions. Some areas which should be focused upon
are summarized below:
Public Health and Environmental Risk. Would
fast-track handling of surface impoundment
waste significantly reduce potential public health
and environmental risk?
Cost-Effectiveness. Based upon new informa-
tion, is there a potential for implementing a reme-
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Table 4-3. Example of a Completed Matrix of Exposure As-
sessment Activities
Waste
Characteristics
Acid
Base
Inorganic
Organic
Solvents
PCB's
Sulfides
Cyanides
Halogenated
Pit 1
L/S
L
S
L/S
Pit 2
L/S
L/S
S
Sources
Pond 1
L/S
L/S
L/S
Lagoon 1
S
L/S
L
Integrity of Retaining Structures*
High
Medium
Low
Ground Water
Surface Water
Air
Direct Contact
Residents
Wells
Wetlands
X
X
Migration Pathways
p
A
P
A
P
A
P
P
P
A
P
Receptors
A
P
A
P
P
P
P
A
S = Applies to sludge phases; L = Applies to liquid phases
A = Actual pathway/receptor; P = Potential pathway/receptor
*This evaluation relates specifically to berm/dike stability avail-
able, free board and the presence of seeps or breaches.
dial program for the entire site on a more cost-
effective basis than a limited approach?
Schedule. Does new information show that the
schedule for implementing a limited remedial ac-
tion would not differ much from that of a larger
scale action?
Limitations
In deciding whether to expand the scope of the
limited Rl, the types of remedial technologies in-
volved with handling the different contaminated
areas on-site must be considered. In many cases,
the remedial technologies for buried wastes, waste
piles and waste spills (contaminated soil and water)
are different than those for surface impoundment
wastes. Where these different types of wastes are
present, the combination of remedial technologies
may be difficult and may not be cost effective. How-
ever, wastes contained in surface impoundments
may be similar or related to wastes in tanks and
drums on the same site. Previous operators of the
site may have used the surface impoundments to
hold certain waste residues removed from the
tanks and/or drums, or may have used impound-
ments as an intermediate step in a waste reclama-
tion process. In cases such as these, it may prove
cost effective to combine remedial technologies for
the similar types of wastes.
In very unique circumstances, it may be possible to
discontinue the limited RI/FS. Forexmple, if the pre-
liminary assessment indicates that migration and/
or significant exposure from hazardous materials
from surface impoundments cannot be reasonably
expected in the short term, the limited Rl may be
discontinued and the operable unit evaluated with
the other contaminated areas of the site. Another
reason for discontinuing evaluation would be if the
surface impoundment is reasonably determined to
be of no threat to public health and the environ-
ment in the short and long term.
4.3.5 Define Data Needed to Conduct Limited
Feasibility Study
Purpose
The data needed to evaluate the feasibility of poten-
tial remedial alternatives (identified previously) are
compared with the data collected up to this point in
the limited Rl. If the limited Rl data base is sufficient
to conduct the feasibility study, the final compo-
nent of the limited Rl can be omitted and the limited
FS initiated directly. If there are deficiencies in the
data base which would restrict the performance of
the limited FS, then additional data will be required.
Techniques
The types of data needed to evaluate remedial tech-
nologies are often described in existing reference
documents. A summary of data needs can be pre-
pared for techniques applicable to surface im-
poundment remedial actions. Table 4-4 presents a
list of data needs for evaluation of on-site disposal
and/or treatment of surface impoundment wastes.
This type of information would be useful for many
components of the limited FS (e.g., developing
costs and design evaluation criteria). If treatment
options are being considered, the applicability of
various technologies to the site-specific waste char-
acteristics should be reviewed.
Comparison of the data needs with the existing
data base will identify any data gaps. The data gaps
for each of the technologies should be consolidated
into a master list and then evaluated for signifi-
cance of the missing data. Although certain data
may not be directly available, it is often possible to
estimate certain parameters or quantities without
compromising the validity of a feasibility evalua-
tion.
Limitations
Not applicable.
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Table 4-4. Examples of Data Needs for Evaluation of Poten-
tial Remediation Activities
Is the site located in the 100-year floodplain?
Is the site located within 200 feet of a fault which has had
displacement in recent geologic history?
Does ground water under the site have a rapid rate of travel
(i.e. greater than 100 feet per 100 years)?
Is the site in a wetland?
Is the site in area with karst, subsidence, or landslide activity?
Is the depth to the seasonally high ground water elevation
beneath the site relatively shallow (i.e., less than 10 feet)?
Is the ground water beneath the site used for individual or
municipal water supply?
Is the site topography relatively steep (i.e., greater than 30
percent)?
Is the site located in the vicinity of a surface water body or a
ground water recharge area?
Have springs or seeps been identified in the area of the site?
Has underground mining previously been performed in the
vicinity of the site?
Is the site located in an area with weak and unstable soils?
Is the hydraulic conductivity of the bedrock beneath the site
relatively high (e.g., as would be expected within a sandstone
or fractured zone)?
Is the site located in close proximity to a residence, school,
hospital, commercial area, or other sensitive receptors?
Is an adequater buffer zone present around the site?
Is the site located in close proximity to a public water supply
(e.g., reservoirs, watersheds, or supply lines)?
Are there unique and protected land uses adjacent to the site
(e.g., parks, historic sites, etc.)?
4.4 Conduct Detailed Field Investigation
Once potential remedial technologies have been
developed and data gaps defined, a limited field
investigation is performed to gather the required
data to evaluate the technologies. The following
.steps can be followed for the final stage of the lim-
ited Rl.
4.4.1 Prepare Project Operations Plans
Purpose
Prior to beginning on-site elements of the limited
Rl, certain planning preparation must be com-
pleted. The development of project operations
plans will assist the user in initiating the limited Rl,
performing the limited Rl in a safe and effective
manner, and in being prepared for emergency situ-
ations, should they arise.
Techniques
The major components of a project operations plan
include a sampling plan and a health and safety
plan. In addition, a quality assurance/quality control
(QA/QC) plan may be included as part of the project
operations plan or as a separate document. Nor-
mally, a quality assurance plan is formulated out-
side of the project operations plan and quality con-
trol is addressed within the project operations plan.
4.4.1.1 Sampling Plan
A sampling plan is developed to describe what data
will be obtained, what sampling will be performed,
and how these tasks will be completed. The plan is
then reviewed by all involved parties to ensure that
data requirements will be met and that the data will
be collected in a proper and effective manner.
It is important to define specific objectives of the
sampling program in the plan. How data will be
used in the limited FS should be indicated. Also, the
waste categories to be analyzed will be clearly de-
fined with a description of the relationship of these
categories to the limited FS and project implemen-
tation activities.
Many guidance documents exist for preparing a
sampling plan (see Section 6.0), and sampling
plans used for completed projects are good mod-
els. A typical plan for a surface impoundment site
would address the following topics:
• Goals of sampling effort
• Use of sampling data (to select treatment or
disposal options)
• Types of surveys to be performed (geophysical
surveys, detailed site mapping, air monitoring,
etc.)
• Number and type of samples (supernatant,
sludge, ground water, surface water, soils,
dikes) and constituents for analysis
• Sample analyses/compatibility testing (or-
ganic/inorganic, reactivity, flash point, halogen
content, PCB, cyanide, sulfide, etc.)
• Methodology describing sampling procedures
The characterization of types of wastes on-site may
be used to prepare design reports, feasibility stud-
ies, cost estimates for cleanup, and contract
documents.
When developing a sampling plan, consideration
should be given to field screening techniques and
the use of composite samples. Both approaches
provide a means for obtaining needed data without
extensive laboratory analysis and its associated
costs. Field screening of samples, for example,
using organic vapor detectors to assess volatile or-
ganic compounds or pH papers/meters to assess
corrosivity, can be used in several ways. It can be
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used to identify those samples likely to have the
highest contaminant concentrations, which can
then be sent to the laboratory for quantitative con-
firmation. It can also be used to identify concentra-
tion gradients, the extent to which contaminants
are attenuated with distance from the source, both
horizontally and vertically. In this situation, sam-
ples from either side of the suspected boundary are
sent to the laboratory instead of sending all sam-
ples collected and determining the boundary later.
Composite samples can be used to obtain an over-
all indication of contaminant concentrations in situ-
ations where spatial variation is not likely, for ex-
ample, within liquid phase contained in an
impoundment. Because this approach averages
concentrations, it is not applicable to determining
maximum concentration gradients or detecting
contamination boundaries.
Methods of implementing components of the soil/
subsurface sampling and exploration plan, includ-
ing reconnaissance, sampling boring, logging and
handling of samples are discussed below. This in-
formation is intended as a brief overview of com-
monly used methods with respect to their appli-
cability to hazardous waste investigations, and is
not to be substituted for comprehensive proce-
dures.
• Reconnaissance methods
Site reconnaissance is useful in obtaining qual-
itative information about site facilities and
processes, topography, potential problems
pertaining to access of equipment and location
of monitoring wells, borings and sampling sta-
tions. This allows necessary modifications in
the sampling plan to be made before the con-
tractors and sampling personnel arrive on site.
Visual observations, hand sketches, and photo-
graphs comprise the primary means of record-
ing data. In addition, if a high hazard exists,
radio transmitters, blackboards and hand sig-
nals may be useful for communication be-
tween site personnel.
Elevation and boundary surveys may also be
useful in establishing control points for map-
ping locations of proposed site activities.
• Surficial soil sampling methodologies
Samples of surficial materials are collected for
analysis in order to provide data regarding the
extent of contaminant migration as a result of:
(1) transport of contaminated sediments and/
or (2) the absorption or reactivity (e.g., cation
exchange capacity) of contaminants with surfi-
cial materials, and/or (3) the general chemical
or physical nature of the surface sediments.
Analysis of surface soil and sediment samples
may serve to confirm or compliment data ob-
tained from analysis of surface waters.
Collection of surficial samples may not require
special sampling equipment other than prop-
erly cleaned hand-held tools (i.e., shovels,
trowels, plastic spoons) or may require back-
hoes and boring equipment. Samples may be
obtained on or in the vicinity of a hazardous
waste site and should be representative of the
nature of local surface soils or sediment.
Limitations
When sampling is not adequate to develop and
evaluate alternatives and cost estimates (+50/-30
percent), the selection of remedial activities may be
delayed.
Penetration of lined or sealed bottoms of surface
impoundments is an issue of concern when sam-
pling is needed to determine bottom sludge thick-
nesses and the extent of grossly contaminated
soils. If there is obvious leakage from the impound--
ment, penetration of the bottom layers during sam-
pling would probably not be a problem. In certain
cases, sampling may have to be planned to occur in
two phases, the second phase beginning after im-
poundment surface water removal.
The sampling plan would not be designed to collect
data for alternative actions that were determined to
be infeasible based on site conditions (see Section
4.2.5). Screening activities to this point would elim-
inate those remedial technologies which appear
least feasible and reasonable.
The user should be aware that field analysis of sam-
ples may not produce the litigation-quality docu-
mentation available through a laboratory. Instead,
field analysis can be used to develop information to
proceed with the project while a small percentage
(e.g., 25 percent) of the samples are sent to a labo-
ratory for analysis and verification. Additionally,
field screening techniques are of limited value in
complex samples (e.g., oily sludges) and are not
available for all contaminants. For example, few
field instruments measure inorganics; however,
some ion specific probes are available. Addition-
ally, because of the concentrated nature of these
samples, a laboratory equipped to handle such
high-hazard samples (such as EPA's hazard labora-
tory at NEIC) may be required.
4.4.1.2 Health and Safety Plan
A health and safety plan is developed to establish
the procedures that will be followed during the ex-
ecution of the detailed field investigation. This plan
is developed from earlier health and safety proto-
cols (See Section 4.2.3) and information assembled
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from activities such as the initial site visit (Section
4.3.1). EPA's detailed guidance on health and safety
can be found in Standard Operating Safety Guides
(EPA, 1984).
To confirm the basis for the site worker respiratory
protection protocol contained in the health and
safety plan, both on- and off-site air quality moni-
toring should be initiated at the onset of the project
mobilization and maintained during on-site activi-
ties. Additionally, due to the nature of waste mate-
rials often found in surface impoundments and
their ability to rapidly degrade ambient air quality,
it is important to continue air monitoring both on-
and off-site during the limited Rl so that potential
impacts from handling wastes can be evaluated.
A specific air monitoring program must be estab-
lished for each site based on the nature of the
wastes present on-site and site conditions. Sam-
pling may be performed for organics (volatile com-
pounds), inorganics (cyanide gas), or airborne par-
ticulate (asbestos). Methods currently used to
monitor air quality at surface impoundment sites
include:
• Direct reading methods
—Organic Vapor Analyzer (OVA)
—Photoionization detector
—Photovac GC
—Infrared gas monitors
—Explosive gas indicator
• Delayed quantification techniques
—Collection of samples using air sampling
pump and sorbent charcoal, glass filters, or
other media.
Other components of the health and safety plan
should include a training program (for surface im-
poundment sampling), contingency plan, and guid-
ance on area and access restrictions.
4.4.1.3 Quality Assurance/Quality Control Plan
A quality assurance plan is an assemblage of man-
agement policies, objectives, principles, and gen-
eral procedures to be followed in producing envi-
ronmental monitoring data of known and
acceptable quality. Quality control refers to the rou-
tine activities and checks, such as calibration and
duplicate analysis, conducted under the quality as-
surance program.
EPA's guidance on preparing quality assurance
plans is found in Interim Guidelines and Specifica-
tions for Preparing Quality Assurance Project Plans
(EPA, 1983). The sixteen components of a quality
assurance plan according to the EPA guidance are:
1. Title page with provision for approval signa-
tures
2. Table of contents
3. Project description
4. Project organization and responsibility
5. QA objectives for measurement data in terms
of precision, accuracy, completeness, repre-
sentativeness, and compatability
6. Sample procedures
7. Sample custody
8. Calibration procedures and frequency
9. Analytical procedures
10. Data reduction, validation and reporting
11. Internal quality control checks
12. Performance and system audits
13. Preventive maintenance
14. Specific routine procedures to assess data
precision, accuracy and completeness
15. Corrective action
16. Quality assurance reports to management
Some of these components of the quality assur-
ance plans are actually quality control procedures.
For example, the "Calibration Procedures and Fre-
quency" section of the QA plan may merely refer to
the applicable standard operating procedure (qual-
ity control) found in the sampling plan or health and
safety plan.
4.4.2 Conduct Impoundment Investigation
Purpose
The purpose of this investigation is to collect data
concerning the surface impoundments and the con-
tained wastes needed to conduct the limited FS.
The scope of this investigation may include further
assessment of impoundment stability and other
structures if potential problems were identified dur-
ing previous site visits. At a minimum, the investi-
gation must include measurement or estimation of
waste quantities, and sampling and characteriza-
tion, both physically and chemically, of all waste
phases.
Techniques
Dike Stability. Investigation of potential dike stabil-
ity should be done if it appears that failure could
occur before or during implementation of the reme-
dial action. The basis for identifying potential insta-
bility include ongoing seepage of liquid wastes
through the dikes, sagging along the crest of the
dike, or evidence of incipient failure such as
slumps, sags and tension cracks in the outer face of
the dike.
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Investigations should be undertaken using stand-
ard geotechnical techniques and analyses. These
include exploratory boring with Standard Penetra-
tion Tests and the collection of undisturbed sam-
ples; and laboratory testing of index properties
(moisture content, Atterberg limits, grain-size dis-
tribution) and engineering properties (unconfined
compression, consolidated-undrained triaxial, con-
solidation/settlement). Borings would be needed in
and/or adjacent to potential failure areas, prefer-
ably through the crest of the dike to a depth equal
to twice the height of the dike. (Note: Caution must
be used when boring at an uncontrolled site due to
activities that may cause excessive soil movement.)
The final determination of stability should be made
using generally accepted slope stability analytical
methods such as Bishop's method, or the method
of slices.
Measurement/Estimation of Waste Quanti-
ties. Measurement or estimation of waste quanti-
ties is clearly fundamental to the evaluation of ap-
plicable technology. In all cases, an attempt to
measure waste volumes should be made first, and
estimation used only when direct measurement is
not possible (the volume of contaminated soil be-
neath the impoundment, for example). In addition,
every effort should be made to quantify each phase
of waste separately.
It will first be necessary to establish some means of
accurately locating all measurements/samples
taken within the impoundment. If the area of the
impoundment is about one acre or less, due to ease
of access, it will generally be sufficient to divide the
impoundment into a grid system (50 ft. centers).
This can be accomplished with two orthogonal con-
trol lines, one parallel to the long axis of the im-
poundment, the other positioned to produce a grid
of roughly equal surface area. Control stakes are
recommended at each end of the control lines. If the
impoundment is relatively small, it may be possible
to mark the lines with string or light rope; otherwise
it will be necessary to determine locations along
the lines or within the grid with a compass and
range-finder. By measuring waste thicknesses
along the control lines, two profiles of the im-
poundment can be obtained and the waste vol-
umes calculated. It is recommended that 10 meas-
urement points be evenly distributed along the
lines, with spacing of not less than 5 feet and not
greater than 50 feet. If the area of the impoundment
is greater than one acre, the impoundment should
be divided into sections of not more than one quar-
ter acre.
Methods for measuring the thicknesses of liquid
waste phases can be grouped into two categories,
those allowing identification of multiple phases and
those providing only total thickness. Identification
of multiple phases is possible using thief samplers
(e.g., 3/8-inch to 5/8-inch diameter thick-walled
glass tubes). Bacon Bombs (used for bottom sam-
pling), and "strip rods", a measuring device devel-
oped by the oil and gas industry that uses special
sounding rods to indicate various chemicals colori-
metrically. The thief sampler has the advantage of
recovering samples from which the physical prop-
erties can be estimated. (Early identification of
waste properties may be important in selecting the
best device for obtaining representative samples.)
Methods that provide only total thickness measure-
ments include weighted sounding tapes and ordi-
nary, graduated sounding rods.
Measurement of sludge and solid phase thick-
nesses generally involves the use of rigid probes
that are pushed or driven through these phases to
refusal. Care must be exercised because these
methods could compromise the integrity of im-
poundment liners, particularly synthetic membrane
liners, or penetrate a gas pocket. At a site in Penn-
sylvania, remedial action implementation had to be
halted when it was found that what was thought to
be bedrock forming the bottom of a lagoon was
actually a bauxite crust layer. This layer was pene-
trated, releasing hydrogen sulfide gas. Sampling
may be extended as deep as possible in situations
where it is known that there is no liner and/or the
impoundment is leaking or that a gas pocket is un-
likely.
In general, probes should be pushed by hand first,
and the depth of initial refusal noted. However, the
point must be made that such a sampling proce-
dure requires the assurance that the probe may
also be removed. Then, if the probe is strong
enough, it should be driven (hydraulically, by vibra-
tion, or with a hammer) and the depth of final re-
fusal noted. Hollow pipes and conduits used as
probes have the advantage of allowing identifica-
tion of layering or multiple phase, and providing
samples for estimating physical properties. Ideally
these probes would have split barrels, but material
that could be readily cut with a hacksaw would
work just as well. However, such materials may not
have the strength to be driven into tarry sludges or
stiff solids. Solid probes, which would be better
able to withstand driving in difficult materials, can
be used to determine total thicknesses.
Although it will generally be possible to measure
the thickness of liquid phases in impoundments, it
may be more difficult to physically measure the
sludge and solid phases, particularly at the bottom
of the surface impoundment. In such cases, it may
be possible to quantify the volume of these phases
by estimating the total volume of the impoundment
and subtracting the volume of the liquid phases.
Methods for estimating total impoundment vol-
4-18
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OSWER Directive 9380.0-6
umes may also be applied in situations where the
health and safety hazards are significant. Total im-
poundment volumes can be estimated by several
methods:
• Projection of topographic trends—applicable
to situations where the impoundment was cre-
ated by closing off low spots, swales or valleys
• Identification of depth-limiting features—if
bedrock is relatively shallow; it may be reason-
able to assume that the bottom of the im-
poundment is not below the top of rock
• Evaluation of cut/fill balance—applicable to sit-
uations where the encircling dikes were proba-
bly constructed from material excavated to cre-
ate the impoundment
Whenever possible, direct measurement is the
preferable approach for developing volume esti-
mates and should be attempted before indirect
methods are used.
Sampling/Characterizing Waste Phases. Samples
for the purposes of physically and chemically char-
acterizing the waste phases present in an impound-
ment should be taken at the center of each quadrant
defined by the control lines established above,
from any operating inlets, and immediately adja-
cent to any inoperative inlets, outlets, and over-
flows. This will provide a general characterization
of the impoundment contents while allowing detec-
tion of spatial variations caused by differential set-
tlement of entering solids. Drill rigs are restricted to
solid ground, access to impoundment sampling lo-
cation can be accomplished by remote/on-shore
methods, such as "cherry pickers" (restricted by
25 ft reach) and platforms suspended from cranes,
(restricted by 100 ft reach) or by on-site/off-shore
methods, such as flat-bottomed boats and rafts. In
either case, the selection of sampling access should
consider both the safety of the workers and the
stability of the working area.
In general, sampling equipment should be dispos-
able or readily decontaminated. Whether a sam-
pling device is readily decontaminated will depend
in part on the characteristics of the wastes being
sampled. Sampling should proceed from "clean to
dirty", particularly when many samples will be
taken with the same piece of equipment; in practice
this generally means "from the surface down". The
sampling equipment selected for the various
phases will depend on the properties of the target
phase and the quantity needed for analysis. The
quantity needed for analysis will depend on the
kind of testing to be done.
Prior to actually obtaining samples at each sam-
pling location, the presence and thickness of the
waste phases should be verified. This can be ac-
complished using the methods and techniques de-
scribed above for measuring waste thicknesses.
Depending on the quantity of sample needed, it
may be possible to combine the verification of
phases with sample collection. For example, if the
quantities of liquids needed are relatively small, a
thief sampler could be used. The continuous sam-
ple obtained using a hollow conduit to identify
sludge and solid phases may provide enough mate-
rial for the required testing of these phases.
Floating scum and sludges can be efficiently sam-
pled using a common kitchen strainer, preferably
made of stainless steel. This sampler would be easy
to decontaminate and could be fitted with a tele-
scoping or extension handle as needed. Liquid
phases can be sampled with several devices. Sur-
face samples can be collected in open vessels
(beakers, bottles, etc.). Thief samplers, which are
disposable, provide samples of the entire liquid
column; but they do not work well for viscous or
tarry liquids, and the sampled volume is relatively
small. Depth-specific samples can be obtained with
double check-valve samplers such as Kemmerer
devices.
Sampling of sludge and solid phases can be done
with a variety of thin-walled tube samplers or with
auger devices. Examples of thin-walled tubes in-
clude standard Shelby tubes, piston corers, and
continuous conduit/casing. The Shelby tube is only
three feet long, and casing would be needed to
maintain an open hole if more than one depth inter-
val had to be sampled. Piston corers, which have
relatively better recovery in soft materials, are
available to lengths up to 10 feet, but these larger
devices may be unwieldly in some small boats.
Other methods for sediment sampling may include
the use of a dredge, gravity core sampler, small
drag line, alpha sampler, coliwassa sampler, con-
tinuous flight auger (hollow stem), or bucket auger.
Physical and chemical characterization of waste
phases should concentrate on parameters that will
have an operational impact on the handling, treat-
ment, and/or disposal of the waste. Physical charac-
terization of floating sludges and liquids should in-
clude density, viscosity, and suspended solids
content; and sludges and solids should be charac-
terized for free liquid content (paint filter test), bulk
density, percent solids, and slump angle. The ex-
tent of chemical characterization and sampling
should be discussed with the lead agency.
Limitations
The limitations of sampling methods and chemical
characterization methods is beyond the scope of
this document.
4-19
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OSWER Directive 9380 0-6
4.4.3 Conduct Focused Ground Water
Investigation
Purpose
The focus of a ground water investigation may vary
with site conditions and alternatives being consid-
ered and may include the following:
• Determining depth to water table and presence
of contamination from the impoundment
• Identifying local ground water flow direction
and rate
• Characterizing ground water flow systems
At a minimum, this investigation should address
the first purpose listed above. This will answer two
important questions—is the impoundment at or be-
low the water table? and is the impoundment leak-
ing? If the impoundment is in contact with the water
table and ground water control is part of the reme-
dial action being considered, the second purpose
listed above should be addressed. Finally, if on-site
alternatives appear to be feasible, the third purpose
listed above needs to be included in this investiga-
tion.
Techniques
Well Network Design. The number and location of
wells needed in the monitoring network will vary as
a function of the purpose of the investigation. De-
termining the depth to the water table requires only
one well, which should be located as close to the
impoundment as possible. The closest location
would be through the crest of the dike; and al-
though this would mean a deeper hole than a well
at the toe of the dike, a well located at the crest
would be less likely to miss ground water mound-
ing beneath the impoundment. Extremely elon-
gated impoundments might warrant a second hole
for this purpose. An additional advantage of posi-
tioning a well in close proximity to the lagoon is to
assure knowledge of underlying geologic forma-
tions.
Detecting the presence of ground water contamina-
tion from the impoundment could be done with
only one well if no other sources of contamination
were present. This well would have to be located
down-gradient of the impoundment or within the
ground water mound beneath the impoundment. If
other sources are present and a good estimate of
the ground water flow direction is available, confir-
mation of leaking could be verified with just two
wells—one down-gradient close to the impound-
ment and one up-gradient far enough away to
avoid encountering the ground water mound.
If the impoundment has a liner, especially a syn-
thetic membrane liner, the leak could be very local-
ized. In this situation, it will be easier to detect a
plume of contamination at relatively greater dis-
tances from the impoundment. The reason for this
is that a single well close to the impoundment may
be down gradient of the impoundment but not of
the leak, whereas a single well at a greater distance
has a better chance of being downgradient of both,
due to the tendency of plumes to expand in area as
they migrate. Thus, it may be necessary to define
the local ground water flow direction with on-site
well data and then place an additional well in the
confirmed down-gradient direction if needed to de-
tect the plume. This approach requires that site
soils be relatively permeable and that the impound-
ment have been in operation for several years;
otherwise, the plume will not have dispersed far
enough to be readily detected.
Identifying local ground water flow directions and
rates requires a minimum of three wells, which
should be located in a roughly triangular pattern
around the impoundment and far enough away to
avoid the ground water mound beneath the im-
poundment. Water level measurements in the three
wells define the slope and orientation of the local
water table. Ground water flow will be perpendicu-
lar to the equal-elevation contours (equipotentials)
on the water table surface. Ground water flow rates
are the product of the hydraulic gradient and the
permeability divided by the porosity of the soil. The
hydraulic gradient is equal to the slope of the water
table along a flow line. Permeability can be esti-
mated from grain-size data or the literature; poros-
ity is generally estimated from the literature. Identi-
fication of mounding beneath the impoundment
would require the addition of one more well to this
network. Having data on the vertical flow compo-
nent and mounding will be useful in any compari-
son of hydraulic gradients from before and after
any remedial activities at a surface impoundment.
Characterizing multi-aquifer ground water flow sys-
tems necessitates the use of well nests—two or
more adjacent wells with screened intervals at dif-
ferent and non-overlapping depths. A minimum of
one nest should be used. If the investigation in-
volves a near-surface (within 30 feet) confined aqui-
fer, the use of three nests is recommended. This
will allow the direction and rate of ground water
flow in the aquifer to be determined, if installed in
a triangular pattern so that hydraulic gradients can
be measured.
Well Network Installation. The monitoring well net-
work designed above should be installed in a man-
ner that minimizes the potential for unrepresenta-
tive water level readings and samples. Thus, the
drilling methods used to create boreholes for the
wells should minimize both the disturbance of sub-
surface materials and the addition of fluids to the
4-20
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OSWER Directive 9380.0-6
subsurface. Commonly used drilling methods that
meet these criteria include hollow-stem augers and
wash-rotary with casing advanced ahead of the
hole. In either case, it will generally be worthwhile
to sample the subsurface materials encountered in
the borehole. Sampling of these soil (and rock) ma-
terials will provide a basis for estimating or mea-
suring permeabilities and will allow the well design
to be "fine-tuned" in the field to meet site-specific
conditions. This sampling should make use of both
standard split-barrel and thin-walled tube sam-
plers, at a sampling interval of not more than five
feet.
The materials used to construct the well should
also be chosen so as to minimize unrepresentative
data. The well screen and riser casing should be
compatible with known contaminants and not in-
troduce any contaminants. For example, no
solvent-based cements should be used for PVC cas-
ings, nor should galvanized materials be used if
dissolved metals are of concern. Two-inch diameter
wells will generally be sufficient. After placement of
the well itself, careful backfilling of the annular
space in the borehole is important. The concern
here is to provide for the integrity of the well by
completely sealing it off from the surface, or in case
of nested wells, from overlying aquifers. In general,
there should be a granular media around the
screen, an initial seal of bentonite pellets above
this, and a cement-bentonite grout placed by tremie
pipe from the initial seal to the ground surface. A
lockable protective casing should be installed to
deter vandalism.
The final part of any well installation is the develop-
ment of the well. This involves pumping or surging
the well in order to create a good hydraulic connec-
tion between the subsurface materials and the well.
Development is needed for representative samples,
especially if a drilling fluid has been used. In this
situation, development also has the purpose of
purging as much of the drilling fluid from the aqui-
fer as possible. Development can also be used to
perform simple field tests, such as rising head or
recovery tests, that allow calculation of permeabil-
ity.
Ground Water Sampling. There are two parts to
obtaining ground water samples that have an im-
pact on the representativeness of the resulting
data. The first is the purging of standing water from
the well. This water generally has a different water
quality than the water in the pores of the subsurface
materials and it must be removed from the well
prior to sampling. As a rule of thumb, between
three and five times the volume of water in the well
should be purged. Periodic measurement of pH,
temperature and specific conductance during purg-
ing provides a direct means of verifying that repre-
sentative ground water is present in the well. Sam-
ple collection should utilize methods and
equipment that will preserve the integrity of the
samples. For example, direct air-lift pumping
should not be used if the sample is to be tested for
volatile organic compounds, and pumps and bail-
ers should be constructed out of inert materials
such as stainless steel or Teflon.
Limitations
The limitations of a ground water investigation are
beyond the scope of this document.
4.4.4 Conduct Surficial Soil Investigation
Purpose
This is an investigation that may be undertaken if
there is evidence that substantially contaminated
soil and sediment are present in the immediate
vicinity of an impoundment. The investigation is
undertaken to determine if the distribution and con-
centration of the contaminated materials warrant
their inclusion in source control actions taken for
the impoundment. Grossly contaminated soils in
the immediate vicinity of the impoundment may be
included as part of the remedial activities for the
surface impoundment operable unit. Any remain-
ing contaminated soils would be addressed under a
full RI/FS for the entire site.
Techniques
Basis for initiating study
• Evidence of past or existing dike overtopping,
failure or seepage
• Stained soils adjacent to impoundment
• Environmental stress adjacent to impound-
ment
Scope of study
• Area within close proximity of impoundment
(e.g., 50 feet)
• If suspect areas are small, include all in this
study
Number and location of samples
• Appropriate number and extent of areas sam-
pled; at least one from each different area/me-
dia; even spatial distribution within areas
• If field screening is being used (OVA or pH me-
ter) more samples can be taken
• Composite samples can also be used to reduce
number of analyses required
Sampling methods
• Standard methods for surface materials
4-21
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OSWER Directive 9380.0-6
—Stainless steel trowels and shovels
—Glass and plastic bottles
• Vertical profiling
—Sediment; short piston or thin walled tubes
—Soil; bucket augers and soil probes, test pits
Parameters that may be evaluated as part of the soil
characterization field tests include the following:
• Soils slope
• Surface drainage
• Extent of highly contaminated soils
• Field contaminant instrumentation
Determining the extent of soil contamination can
be a very time consuming and costly process. It is
important to keep the principal focus for conduct-
ing any soil sampling in the proper perspective,
that is, defining grossly contaminated soil that will
be included as part of the surface impoundment
operable unit. Waste characteristics, impoundment
design and condition, and soil features such as at-
tenuation capacity all have to be considered when
selecting parameters useful in defining grossly con-
taminated soils.
Limitations
The use of field techniques to evaluate the degree
of contamination of soil/water systems may be a
very difficult task. If volatile organics are present in
the system, the use of an OVA or photoionization
meter may give an indication of the presence of
volatiles. However, the "head space" reading from
a sample will be dependent upon time delay after
sampling, temperature, seal of lid on sample con-
tainer, and wind. The results of the "head space"
reading are indicative of the presence of contami-
nation by volatiles, but usually do not produce
quantitative results.
The use of a field gas chromotograph requires the
availability of a power supply with a "clean area,"
which allows the analysis of samples for particular
contaminants rather than a total contaminant level,
as with the use of the OVA or photoionization me-
ter.
PCBs in the soils can be detected in the field with a
turnaround of approximately one day. However,
this requires the use of a field lab set up at the site
and generally is a large expense for timely
turnaround.
The detection of acids or bases in the soil/waste
system can generally be accomplished in the field
by the use of litmus paper or phenolphthalein (pH
8.3 to 10) and methylorange (pH 3.1 to 4.4).
The use of conductivity of the soil/waste system as
4-22
compared to background could give an indication
of contamination, although the degree of contami-
nation will probably not be a direct correlation.
4.4.5 Conduct an Assessment of Soil-Waste
System Characteristics
Purpose
The data generated from soil and subsurface explo-
ration and sampling is used to characterize the soil-
waste system so that remedial alternatives which
involve the grossly contaminated soils associated
with the impoundment can be properly evaluated.
Soil properties influence volatilization, leaching po-
tential and attenuation of contaminants. These
processes, along with the chemical structure of the
compound involved are major considerations in the
assessment of impact to receptors (i.e., ground
water and air).
Techniques
A discussion of analysis methods for determining
attenuation and volatilization of a given contaminant
in a soil system is beyond the scope of this document.
Limitations
Due to the complex nature of the soil-waste rela-
tionships, an in-depth assessment of soil-waste
system characteristics is quite complex and time
consuming. Typically the limit of grossly contami-
nated soils included as part of the impoundment
operable unit may not extend much more than
three feet beyond the waste material and/or liner of
an impoundment.
4.4.5 Review Analytical Results for Conformance
with QA/QC Program
Purpose
EPA has developed QA/QC protocol and evaluation
methodology to verify the accuracy and reliability
of analytical data. The analytical data generated
during the limited Rl must be examined in accord-
ance with these methods to assure their reliability
and subsequent usefulness.
Techniques
Step-by-step QA/QC validation protocol have been
developed by EPA (Section 4.4.1).
Limitations
Not applicable
4.4.7 Evaluate All Data and Prepare Limited
Remedial Investigation Report
Purpose
The evaluation of data is an ongoing process
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OSWER Directive 9380 0-6
throughout the limited Rl. However, once all field
work has been completed and the data base is es-
sentially complete, a final analysis is conducted.
The activities of the limited Rl and the results of the
data evaluation are then presented in a remedial
investigation report. During this final analysis the
scope of the limited RI/FS is again reviewed.
Techniques
This evaluation of data should focus on the needs
to perform a limited FS. The objectives of various
data collection activities are reviewed and then
compared to the actual results of the limited Rl. It is
important to ensure that the data obtained satisfies
the earlier defined objectives. If the objectives have
been adequately met, the quality of the limited FS,
which is based upon data obtained during the lim-
ited Rl, will be enhanced.
A remedial investigation report on the surface im-
poundment operable unit should integrate and
present a discussion of activities and observations
made during the limited Rl, and include an evalua-
tion of these data. Detailed discussion of the con-
tents of a full Rl report are presented in EPA guid-
ance documents referenced in Section 6.0. A typical
report for a surface impoundment site could con-
tain, but is not limited to, the following major ele-
ments:
• Site Background Information
• Nature and Extent of Problem
• Limited Remedial Investigation Summary
• Overview of Report
• Demography
• Land Use
• Natural Resources
• Climatology
• Updated Base Map
• Hydrogeologic Features
• Surface Features
• Soil Features
• Surface Impoundment(s) Features
• Site Health and Safety Features
• Bench and Pilot Tests (if applicable)
• Potential Receptors
• Public Health Issues
• Environmental Issues
• References
• Appendices
Evaluations of the expanded data base could indi-
cate that the magnitude and/or complexity of the
hazardous waste and environmental problems at
the site are too great to remain within the scope of
the limited RI/FS approach. If this is the case, a
full-scale, comprehensive RI/FS may need to be
considered in lieu of a limited single operable unit
approach.
Limitations
Not applicable.
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OSWER Directive 9380.0-6
5.0 Limited Feasibility Study
As previously discussed, the activities of the limited
Rl are used to determine the extent of contamina-
tion and the threat of these contaminants to the
public health and enviroment. The limited FS proc-
ess involves the evaluation and selection of an ap-
propriate remedy to prevent and/or minimize the
threat these contaminants pose.
The remedy for the surface impoundment operable
unit may be final ortemporary in nature, depending
on the site characteristics and other circumstances
such as the level of analysis conducted. This flexi-
bility is due to the fact that other remedial actions
may be required for other contaminated areas on
the site; therefore, a safety outlet to address all site
contamination is provided beyond any interim rem-
edy that is implemented for a surface impound-
ment operable unit.
The FS process may be thought of as consisting of
two phases. The first phase involves determining
the appropriate level of cleanup. The second phase
involves determining the appropriate alternative to
achieve these selected cleanup levels.
Figure 5-1 is a general overview of the feasibility
study evaluation process through remedial action.
A detailed discussion of the remedy evaluation and
selection procedures of the limited FS process can
be found in the Guidance Document for Cleanup of
Surface Tank and Drum Sites (EPA, 1985). A de-
tailed explanation of general contracting proce-
dures can also be found in this referenced docu-
ment.
5.1 Final Remedy
The final remedy for the surface impoundment op-
erable unit should be a permanent remedy that pro-
vides adequate protection to the public health and
environment in the short and long term. Final reme-
dies must have well defined objectives. For exam-
ple, the ground water response actions must be
known for the site. Typically this would involve the
removal of any aqueous material in the impound-
ment and removal, stabilization, treatment, and/or
isolation (individually or in combination) of soils or
sludges down to sufficient levels to protect the pub-
lic health and environment. Backfilling and/or ac-
tual cover may also be necessary. Corrective action
or long-term monitoring may be necessary for con-
taminated ground water.
5.2 Interim Remedy
The selection of an interim remedy would be based
on the fact that definable objectives have not been
set for the surface impoundment (after the limited
RI/FS activities) but source reduction is desired be-
fore addressing all other contaminated areas of the
site. For example, ground water response actions
may not be finalized. Future actions will therefore
determine the ultimate level of cleanup for the op-
erable unit. Obstacles to clearly defined objectives
may be modeling and data uncertainty, and uncer-
tainty of health based cleanup levels.
An interim remedy would be similar to a final rem-
edy involving the removal of any aqueous material
and removal, stabilization, treatment, and/or isola-
tion (individually or in combination) of soils/
sludges down to levels that would reduce contami-
nant migration. This level may not be to the extent
that is ultimately necessary to protect the public
health and the environment in the long term. This
approach is generally not appropriate if capping or
backfilling of the residual is necessary. The risks
associated with the operable unit concept dis-
cussed previously are inherent with selecting an
interim remedy over a final remedy. In these situa-
tions, removal levels for interim remedies may be
based on engineering criteria that make sense from
a technical viewpoint.
Engineering criteria are short-term remedial ac-
tions; therefore, the impoundment must also be left
in an environmentally sound condition. Diking and
drainage improvement measures may be neces-
sary to prevent or minimize any remaining contam-
inant movement and exposure.
Verification monitoring may also be necessary to
determine the adequacy of the interim cleanup
levels.
The ultimate cleanup level and remedy for the im-
poundment may be delayed until a remedy for the
entire site is selected. The site may be deleted from
the NPL when the implemented action meets envi-
ronmental and public health protection goals.
5-7
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OSWER Directive 9380.0-6
Figure 5-1. General overview of limited FS pr
./Determine Type\. Temporary 5.2 ^
\ ot Hemedy / *
ocess.
Implement
Remedial
Action
Further
Evaluation
Implement
Further
Remedial Action
If Necessary
Final (5.1)
Implement
Remedial
Action
5-2
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OSWER Directive 9380.0-6
6.0 Reference Guide
The references included in this section are orga-
nized according to the section titles of this guidance
manual. Some entries are cross-referenced when
they apply to more than one area. The list, which
includes sources of information beyond those cited
in the text of the document, is intended as a bibliog-
raphy of resources but is not all inclusive.
Foreword
U.S. Environmental Protection Agency (EPA).
Draft Survey and Case Studies of Remedial Ac-
tions at Hazardous Waste Sites. JRB Associates,
McLean, Virginia and Environmental Law Insti-
tute, Washington, D.C. for EPA Municipal Envi-
ronmental Research Laboratory, Cincinnati,
Ohio, 1983.
EPA. Guidance on Remedial Investigations Under
CERCLA. EPA 540/G-85/002. June 1985a.
EPA. Guidance on Feasibility Studies Under
CERCLA. EPA 40/G-85/003. June 1985b.
1.0 Introduction
EPA. Guidance Document for Cleanup of Surface
Tank and Drum Sites. Office of Emergency and
Remedial Response. Prepared by Camp Dresser
& McKee Inc. May 1985.
4.0 Limited Remedial Investigation
4.1 Develop Site Description and Data
Base
4.1.1 Obtain Available Data
EPA. Characterization of Hazardous Waste
Sites—A Methods Manual, Volume 1—Inte-
grated Approach to Hazardous Waste Site Char-
acterization. EPA. Las Vegas, Nevada. 1983.
See EPA 1985a under Foreword.
4.7,2 Review and Evaluate Available Data
Neely, N. et al. Survey of On-Going and Com-
pleted Remedial Action Projects. EPA 600/2-81-
246. Cincinnati, Ohio. September 1981.
4.2 Site Familiarization and Project
Approach
See EPA 1984 under Section 4.2.3.
4.2.2 Prepare Preliminary Soil/Geologic Cross
Section
Dennison, John M. Analysis of Geologic Struc-
tures. W.W. Marten & Company, Inc. New York.
1968.
4.2.3 Prepare Initial Health and Safety Guidance
Bareis, Donna Lynn, Ph.D., Larry R. Cook and
Gene A. Parks. Safety Plan for Construction of
Remedial Actions. In Proc. National Conference
on Management of Uncontrolled Hazardous
Waste Sites Washington, DC. October 31-
November 2, 1983.
Buecker, D.A. and M.L. Bradford. Safety and Air
Monitoring Considerations at the Clean Up of a
Hazardous Waste Site. In Management of Uncon-
trolled Hazardous Waste Sites National Sympo-
sium, EPA et al. Washington, DC. November 29-
December 1, 1982.
Herrick, R. Dangerous Properties of Industrial Ma-
terials. Sax, N.I., Ed; Van Nostrand: New York.
1979.
International Technical Information Institute.
Toxic and Hazardous Industrial Chemicals Safety
Manual for Handling and Disposal with Toxicity
and Hazardous Data. Tokyo, Japan. 1975
Merck & Co. Merck Index, An Encyclopedia of
Chemicals and Drugs. 9th Ed. Rahway. 1976.
Meyer, E. Chemistry of Hazardous Materials.
Prentice-Hall, Inc. Englewood Cliffs, New Jersey.
1977.
NIOSH. Occupational Safety and Health Guid-
ance Manual for Superfund Activities. 1984.
Roos, Kathleen S. and Patrician A. Scofield.
Health and Safety Considerations: Superfund
Hazardous Waste Sites. In Proc. National Confer-
ence on Management of Uncontrolled Hazardous
Waste Sites. Washington, DC. October 31-
November 2, 1983.
U.S. Army Corps of Engineers. Safety and Health
Requirements Manual. EM-385-1-1. Washington,
DC. 1982.
U.S. Environmental Protection Agency (EPA).
6-1
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OSWER Directive 9380.0-6
Safety Manual for Hazardous Waste Site Investi-
gations (Draft). Office of Occupational Health and
Safety, and the National Enforcement Investiga-
tion Center. Denver, Colorado, 1979.
EPA. Standard Operating Safety Guides. Office of
Emergency and Remedial Response. Washing-
ton, DC. November 1984.
Wallace, Lynn P., Ph.D. and William F. Martin.
Hazardous Wastes Worker Health and Safety
Guidelines. In Proc. National Conference on Man-
agement of Uncontrolled Hazardous Waste Sites.
Washington, DC. October 31-November 2, 1983.
See also EPA 1985a under Foreword.
4.2.4 Prepare Community Relations Plan
EPA. Community Relations in Superfund: A
Handbook (Interim Version). EPA OERR. 'Wash-
ington, DC. September 1983.
4.2.5 Identify Potential Remedial Action
Technologies
Anonymous. Bugs Tame Hazardous Spills and
Dumpsites. Chemical Week, May 5, 1982. p. 49.
Bracker, Brian D. and Hilary M. Theisen. Cleanup
and Containment of PCB's—A Success Story.
Presented at EPA et al. Management of Un-
controlled Hazardous Waste Sites National Sym-
posium. Washington, DC. November 29-
December 1, 1982.
Fuller, Wallace H. Soil Modification to Minimize
Movement Of Pollutants from Solid Waste Oper-
ations. In Critical Reviews in Environmental Con-
trol. March 1980 V9, N3, p. 213(58).
Griffin, Robert A., and Sheng-Fu J. Chou. Dis-
posal and Removal of Halogenated Hydrocar-
bons in Soils. Presented at EPA Disposal of Haz-
ardous Waste 6th Research Symposium.
Chicago. March 17-20, 1980.
Kastman, Kenneth H. Remdial Actions for Waste
Disposal Sites. Presented at Applied Research
and Practice on Municipal and Industrial Waste,
4th Conf. Madison, Wisconsin. September 28-30,
1981.
Neely, N., et al. Survey of On-Going and Com-
pleted Remedial Action Projects. EPA 600/2-81-
246. Cincinnati. September 1981.
EPA. Handbook for Remedial Action at Waste Dis-
posal Sites (Revised). EPA-625/6-82-006, EPA,
Cincinnati, Ohio. October 1985.
EPA. Protection of Groundwater Resources from
the Effects of Accidental Spills of Hydrocarbons
and Other Hazardous Substances (Guidance Doc-
ument). EPA-570/9-79-017. Washington, DC. July
1979.
See also EPA 1985a under Foreword and Pro-
ceedings of EPA et al. Management of Uncon-
trolled Hazardous Waste Sites National Sympo-
sium, November 29-December 1, 1982.
4.3 Perform Initial Site Characterization
Barbara, Michael A., Thomas J. Morahan and
Robert W. Teets. Site Security and Waste Re-
moval Activities at an Abandoned Hazardous
Waste Site. In Proc. National Conference on Man-
agement of Uncontrolled Hazardous Waste Sites.
Washington, DC. October 31-November 2, 1983.
4.3.3 Conduct Preliminary Exposure Assessment
Heer, John and D.J. Hagerty. Environmental As-
sessment and Statements. Van Nostrand Press.
1977.
EPA. Draft Superfund Health Assessment Man-
ual. May 1985.
See EPA 1985a under Foreword.
4.3.5 Define Data Needed to Conduct Limited
Feasibility Study
Hillenbrand, E. and B. Burgher. Spill Incidents at
Hazardous Material Storage Facilities: An Analy-
sis of Historical Data From the PIRS and SPCC
Data Bases. In Management of Uncontrolled Haz-
ardous Waste Sites National Symposium. EPA et
al. Washington, DC. November 29-December 1,
1982.
See also EPA 1985, in references for Section
2.3.3.
4.4 Conduct Detailed Field Investigation
4.4.1 Prepare Project Operations Plan
Acker, W.L III. Basic Procedures for Soil Sam-
pling and Core Drilling. Acker Drill Co., Inc. Scran-
ton, Pennsylvania. 1974.
Barbara, Michael A., Thomas J. Morahan and
Robert W. Teets. Site Security and Waste Re-
moval Activities at an Abandoned Hazardous
Waste Site. In Proc. National Conference on Man-
agement of Uncontrolled Hazardous Waste Sites.
Washington, DC. October 31-November 2, 1983.
Dahn, C.J. Chemical Compatibility and Storage
Considerations for Process Systems Hazards
Analysis. Journal of Hazardous Materials, 4, 121-
127. 1980.
de Vera, E.R., B.P. Simmons, R.D. Stephens, and
D.L. Storm. Samples and Sampling Procedures
6-2
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OSWER Directive 9380.0-6
for Hazardous Waste Streams. EPA-600/2-80-018.
Cincinnati, Ohio. January 1980.
Fuller, Wallace H. Methods for Conducting Soil
Column Tests to Predict Pollutant Migration. Pre-
sented at EPA et al. Land Disposal of Hazardous
Wastes 8th Annual Symposium. Ft. Mitchell, Ken-
tucky. March 8-10, 1981.
Garret, B.C., J.S. Warner, M.P. Miller, and LG.
Taft. Laboratory and Field Studies of Factors in
Predicting Site Specific Concentrations of Haz-
ardous Waste Leachate. Presented at EPA et al.
Land Disposal of Hazardous Wastes 8th Annual
Symposium. Ft. Mitchell, Kentucky. March 8-10,
1981.
GCA Corporation. Characterization of Hazardous
Waste Sites—A Methods Manual Volume II—
Available Sampling Methods. EPA-600/4-83-040.
Las Vegas, Nevada, September 1983.
Hina, Charles E., Al B. Garlauskas, and Timothy D.
Carter. Techniques for Identification and Neutral-
ization of Unknown Hazardous Materials. In Proc.
National Conference on Management of Uncon-
trolled Hazardous Waste Sites. Washington, DC.
October 31-November 2, 1983.
King, M.V., P.M. Eller, and R.J. Costello. A Quali-
tative Sampling Device for Use at Hazardous
Waste Sites. Proc. of The American Industrial Hy-
giene Association and American Conference of
Governmental Industrial Hygienists Hazardous
Waste Symposium. Philadelphia, Pennsylvania.
May 1983.
Lynn, J.P. and H.E. Rossow. Classification of
Chemical Reactivity Hazards. National Technical
Information Center. Alexandria, Virginia. 1970.
Mason, Benjamin J. Preparation of Soil Sampling
Protocol: Techniques and Strategies—Final Re-
port. EPA-600/4-83-020. EPA. Las Vegas, Nevada.
May 1983.
McNeil, Donald G. Barrels of Chemicals Rot as
Disposal Fails. New York Times. July 5, 1979.
Meyers, L.C. The Chemical Reactivity Test-A
Compatibility Screening Test for Explosives. J. of
Hazardous Materials. 4, 77-87. 1980.
Simmons, B.P., I. Tan, T.H. Li, R.D. Stephens, and
D.L. Strom. A Method For Determining the Reac-
tivity of Hazardous Wastes (Preliminary). EPA.
Cincinatti, Ohio. 1982.
Tewhey, John D., Josh E. Sevee, and Richard L.
Fortin. Silresim: A Hazardous Waste Case Study.
In Management of Uncontrolled Hazardous
Waste Sites National Symposium. EPA et al.
Washington, DC. November 29-December 1,
1982.
Turpin, R.D. Oxidation/Reduction Potential Field
Test Kit for Use at Hazardous Material Spills.
Proc. Hazardous Material Spills Conference. April
1982.
Vecera, M. and Gasparic, J. Detection and Identi-
fication of Organic Compounds. Plenum Press.
New York. 1971.
Wolbach, C.D., Ph.D. Protocol for Identifiction of
Reactivities of Unknown Wastes. In Proc. Na-
tional Conference on Management of Uncon-
trolled Hazardous Waste Sites. Washington, DC.
October 31-November 2, 1983.
U.S. Environmental Protection Agency (EPA). In-
terim Guidelines and Specifications for Preparing
Quality Assurance Project Plans. Office of Moni-
toring Systems and Quality Assurance, Office of
Research and Development. QAMS-005/80.
PB83-170514(NTIS). EPA-600/4-83-004. February
1983.
See also EPA 1985 in references for Foreword
and EPA 1984 from Section 4.2.3.
4.4.3 Conduct Focused Ground Water
Investigation
Geraghty and Miller, Inc. Procedures Manual for
Groundwater Monitoring at Solid Waste Disposal
Facilities. EPA/53C/3W-611. EPA. Cincinnati,
Ohio. 1977.
Johnson Division, UOP Inc. Groundwater and
Wells. Johnson Division, UOP Inc. Saint Paul,
Minnesota. 1966.
See also GCA Coroporation, 1983, in references
for Section 2.4.1.
4.4.4 Conduct Surficial Soil Investigation
ASTM, 1984 Annual Book of ASTM Standards
Volume 04.08 Soil and Rock; Building Stones.
ASTM. Philadelphia, Pennsylvania. 1984.
Black, C.A., Editor. Methods of Soil Analysis, Part
1, Physical and Mineralogical Properties Includ-
ing Statistics of Measurement and Sampling.
A.S.A., Inc. Madison, Wisconsin. 1965.
Black, C.A., Editor. Methods of Soil Analysis,
Chemical and Microbiological Properties. A.S.A.,
Inc. Madison, Wisconsin. 1965.
USDA. Soil Survey Manual. USDA. Washington,
DC. 1951.
U.S. Dept. of the Interior. Earth Manual—A Water
Resources Technical Publication. U.S. Depart-
ment of the Interior, Water and Power Resources
Service. Washington, DC. 1974.
6-3
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OSWER Directive 9380.0-6
U.S. Environmental Protection Agency (EPA).
Test Methods for Evaluating Solid Waste. EPA,
Office of Solid Waste and Emergency Response.
Washington, DC. July 1982.
4.4.5 Conduct an Assessment of Soil/Waste
System Characteristics
American Society of Agronomy and Soil Science
of America, Inc. Chemistry in the Soil Environ-
ment. ASA Special Publication Number 40.
Madison, Wisconsin. 1981.
Copenhaver, Emily D. and Benita K. Wilkinson.
Movement of Hazardous Substances in Soil: A
Bibliography, Volume I Selected Metals. EPA-
600/9-79-024a. Cincinnati, Ohio. August 1979.
4.4.6 Review Analytical Results for Compliance
with QA/QC Control Program
Houle, Martin J. and Duane E. Long. Interpreting
Results from Serial Batch Extraction Tests of
Wastes and Soils. Presented at EPA Disposal of
Hazardous Waste 6th Research Symposium.
Chicago. March 17-20, 1980.
Copenhaver, Emily D. and Benita K. Wilkinson.
Movement of Hazardous Substances in Soil: A
Bibliography, Volume 2 Pesticides. EPA-600/9-79-
024b. EPA. Cincinnati, Ohio. August 1979.
Davidson, J.M., P.S.C. Rao, and Ri-Tse Ou. Move-
ment and Biological Degradation of Large Con-
centrations of Selected Pesticides in Soils. Pre-
sented at EPA Disposal of Hazardous Waste 6th
Research Symposium. Chicago. March 17-20,
1980.
Freeze, R. Allan and John A. Cherry. Ground-
water. Prentice-Hall, Inc. Englewood Cliffs, New
Jersey. 1979.
Josephson, Julian. Immobilization and Leach-
ability of Hazardous Wastes. Env. Science &
Technology. April 1982. V16, N4, p. 219A.
Lindsay, Willard L. Chemical Equilibria in Soils.
John Wiley & Sons. New York. 1979.
Merrill, L.G., B.C. Mahilum, and S.H. Mohiuddin.
Organic Compounds in Soils: Sorption, Degrada-
tion and Persistence. Ann Arbor Science. Ann
Arbor, Michigan. 1982.
Overcash, Michael R. Decomposition of Toxic
and Nontoxic Organic Compounds in Soils. Ann
Arbor Science. Ann Arbor, Michigan. 1981.
5.0 Limited Feasibility Study
See EPA 1985 under Section 1.0.
6-4 ft US GOVERNMENT PRINTING OFFICE 1986 - 646-116/40610
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U.S. Environmental Protection Agency,
Region V, Library
230 South Dearborn Street
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