EPA450/l-39-001a
AEPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/1-89-001 a
(replaces EPA-450/1-89-001)
November 1992
Air/Superfund
AIR/SUPERFUND
NATIONAL TECHNICAL
GUIDANCE STUDY SERIES
Volume I - Overview of
Air Pathway Assessments
for Superfund Sites (Revised)
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SECTION 1
INTRODUCTION
1.1 BACKGROUND
The U.S. EPA's Office of Air Quality Planning and Standards (OAQPS)
directs a national Air/Superfund Coordination Program to help EPA Headquarters and
the regional Superfund offices evaluate National Priority List (NPL) sites and determine
appropriate remedial actions to mitigate their effects on air quality. Each regional air
program office has an Air/Superfund Coordinator who coordinates activities at the
Regional level.
OAQPS has a number of responsibilities related to the Air/Superfund
program including preparation of national technical guidance (NTG) documents. Since
the Air/Superfund program began in 1987, a number of guidance documents have been
prepared. Among these are a four-volume series on air pathway analysis1"4, which have
been distributed to federal, state, and local agencies, as well as to consultants and
industrial users, and which have been widely used. Six national workshops have also
been held to train users in air pathway analysis techniques.
EPA has recognized the need to periodically update the information
contained in the NTG study series. Given the large amount of information and guidance
that has become available in recent years, one need is to keep an overview document
current. Therefore, this revision to Volume I is one of the first revisions to the NTG
study series to be made.
12 OBJECTIVE
This document introduces and gives an overview of air pathway
assessments for Superfund (i.e., NPL) sites. The specific objectives of this document are
to:
• Introduce the basic elements of air pathway assessments (APA) for
Superfund sites;
• Identify and discuss the key issues related to APA work; and
• Identify the best sources of published information and guidance for
each typical component of APA work.
1.3 DEFINITION OF APA
An air pathway assessment (APA) is a systematic evaluation of the
potential or actual effects on air quality of an emission source such as a Superfund site.
The APA may involve modeling or monitoring to estimate these effects. The primary
components of an APA are:
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• Characterization of air emission sources;
• Determination of the effects of atmospheric processes such as
transport and dilution; and
• Evaluation of the exposure potential at receptors of interest.
The terms "air pathway assessment" and "air pathway analysis" are frequently used
interchangeably.
1.4 WHY ARE APAs NECESSARY?
CERCLA and SARA mandate the characterization of all contaminant
migration pathways from the waste or hazardous material to the environment and
evaluation of the resulting environmental impacts. However, air pathway analyses are
often overlooked because many sites have little or no perceptible air emissions in their
baseline or undisturbed state. Even low-level emissions, however, may be significant if
toxic or carcinogenic compounds are present. Also, emissions during cleanup may be
much higher than baseline emissions. From a health-risk perspective, the dominant
exposure pathway over the lifetime of a site will, in many cases, be due to air exposure
during remediation. Failure to perform an adequate air pathway assessment may result
in an underestimate of the risk posed by the site and, in some cases, can ultimately result
in work stoppages, added costs, and public relation problems.
All pathways of potential exposure are of concern at Superfund sites,
including groundwater, surface water, direct contact, and air. The air pathway, however,
has several unique characteristics. Most pathways require extended time periods for
exposure to first occur, and exposure can be minimized by limiting site access (e.g., by
putting a fence around the site) or by getting local residents to forgo use of
contaminated resources (e.g., replacing the source of drinking water). With the air
pathway, however, any on-site releases of emissions can have an almost immediate
downwind impact. The point(s) of impact can change relatively quickly as the wind
direction and wind speed shift; therefore, the effects of atmospheric plumes may cover a
wider area than those of groundwater plumes. If local residents are within an air
emission plume, they have little choice but to breathe the air. The exposure rate,
however, may vary greatly from receptor to receptor. The factors cited above cause, in
many cases, exposure via the air pathway to be harder to predict than exposure via other
pathways.
The potential for air releases from a site can be difficult to determine in
some cases. If unplanned-for air releases occur during remediation activities (e.g., the
release of subsurface pockets of toxic gases); it may be necessary to suspend remediation
activities until further site investigation or remedial design work can be completed to
address air emission concerns. Such delays can be costly and also may affect the public's
confidence in the selected remediation approach.
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The exposure via the air pathway can be harder to control than exposure
via other pathways, especially during remediation. If a significant emission source exists
on site, the only ways to decrease air exposure are to reduce the strength of the emission
source, restrict the activities of the surrounding populace (e.g., keep children indoors), or
to temporarily relocate the surrounding populace. The latter two options have obvious
negative impacts. Reducing the magnitude of emissions, however, may not always be
straightforward. For example, excavation of contaminated soils can release VOCs and
other contaminants to the air, but controls for area sources of fugitive emissions such as
excavation may be costly to implement and be less effective than traditional point source
controls.
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SECTION 2
OVERVIEW OF THE CLEAN-UP PROCESS AT SUPERFUND SITES
The U.S. Environmental Protection Agency (EPA) under the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
and the Superfund Amendments and Reauthorization Act (SARA), is required to
develop and implement measures to clean up hazardous or uncontrolled waste sites.
Under CERCLA and SARA, the U.S. EPA is also responsible for ranking these sites
according to their relative risk to the public health and the environment to determine the
order of site cleanup. The Superfund process consists of three phases: pre-remedial,
remedial and post-remedial. Figure 2-1 displays the phases and the associated actions.
The following sections describe the actions that make up each of these phases.
Activities in support of an air pathway assessment, such as ambient air
monitoring and emission measurements, may be needed during a number of the steps in
the overall Superfund remediation process. Therefore, to understand APAs, one must
understand the data needs for each step of the Superfund remediation process. An
overview of this process as it relates to air pathway assessments is given below.
The U.S. EPA has taken steps to streamline the cleanup of Superfund sites,
with an emphasis on speeding up the process of studying the site in the pre-remedial
phase and more quickly moving the site into the remedial phase. This streamlined
process is known as the Superfund accelerated cleanup model (SACM). One possibility
is to merge the removal and remedial programs and eliminate any redundant data
collection steps. If so, the poisitions of RPM and OSC will become essentially identical.
Nonetheless, the general objectives and data needs of each phase discussed below will
remain the same even if individual steps are expedited or consolidated.
2.1 PRE-REMEDIATION PHASE
The pre-remedial phase is concerned with evaluating the potential risk to
public health and the environment posed by the site. The pre-remedial phase begins
with site discovery. From there, a Preliminary Assessment (PA) is conducted to collect
as much information as possible about the pollutants present and their physical state.
This is meant to be a relatively quick and inexpensive undertaking that involves the
collection of all relevant documentation about the site. EPA uses the information
gathered in the PA to determine whether further investigation or action is warranted.
If further investigation is warranted, a Site Inspection (SI) is conducted.
The SI is the first action that involves some form of sample collection. It is concerned
with determining the immediacy of the health risk posed by the site. Samples are
collected from the various media present and analyzed, and the results are used to rank
the site within the Hazard Ranking System (HRS) model. The HRS model ranks the
relative contamination the site poses over five pathways: air, direct contact,
groundwater, surface water, and fire/explosion (the direct contact and fire/explosion
pathways are evaluated but not currently included in the ranking). If the site scores
higher than a predetermined amount, it is placed on the National Priorities List (NPL).
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Site Discovery
Preliminary Assessment
Site Inspection
Ranking
National Priorities List
Remedial Investigation/
Feasibility Study
Record of Decision
Remedial Design
Remedial Action
Operation and Maintenance
Pre-Remediation
Emergency Removal
Remediation
Post Remediation
Figure 2-1. Phases of the Superfund Process.
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Once on the NPL, the necessity of an Emergency Removal (ER) is
evaluated via a site inspection by personnel from the Removal Program. This site
inspection may take place during the RI (see below). If the site is believed to pose an
immediate and significant health risk, actions are taken to ameliorate the problem. This
may entail removing or covering exposed surface wastes, removing compressed gas
cylinders, fencing the site to reduce public access, etc. Following the SI and emergency
removal actions, if any, the remediation phase begins.
22 REMEDIATION PHASE
The remediation phase consists of the Remedial Investigation (RI) and
Feasibility Study (FS), production of a Record of Decision (ROD), Remedial Design
(RD), and Remedial Action (RA). This phase lasts longer than the pre-remediation
phase and is designed to take the site from a known health risk to a clean site in a
controlled fashion.
The RI and FS are separate steps but are typically conducted
simultaneously and interactively. During the RI, data are collected to determine more
precisely the types of compounds present at the site and the location and extent of
contamination. The data gathered during the RI are used for any risk assessment that is
performed. The data also are used to help identify appropriate cleanup procedures and
remedial alternatives. The FS is concerned with identifying the preferred cleanup
alternative. In making this identification, several alternative cleanup methods are
considered and, when warranted, developed. Once the FS is completed, a ROD is
issued, which serves as the official EPA decision about the preferred course of
subsequent action.
The next actions are the design and implementation of the remediation
alternative. The RD is a detailed plan for site remediation and the RA can take a
variety of forms -- from short-term activities to long-term activities that can take several
years to complete.
2.3 POST-REMEDIATION PHASE
Once the remedial activity has ended, a brief monitoring period takes place
during which the effectiveness of the cleanup is determined. This is called the post-
remediation phase; it may also be referred to as the Operation & Maintenance (O&M)
phase. If the monitoring shows that the site no longer poses a health or environmental
threat, the site may be removed from the NPL.
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SECTION 3
OVERVIEW OF APA FOR SUPERFUND APPLICATIONS
The typical goals of air pathway assessments performed for Superfund sites
are discussed below, followed by a discussion of the typical air pathway assessment
activities associated with each step of the Superfund cleanup process.
3.1 GOALS OF AIR PATHWAY ASSESSMENTS
The overall goal of an air pathway assessment (APA) is to evaluate a given
site's actual or potential effects on air quality. The specific goal typically is to evaluate
the exposure of on-site workers, the exposure of the off-site populace, or to evaluate
environmental impacts.
3.1.1 Evaluate Exposure of On-Site Workers
On-site workers at Superfund sites may be exposed to significant amounts
of air pollutants in the course of performing their jobs. Any source of emissions at a site
will result in an emissions plume. Fugitive air emission releases at Superfund sites
usually occur at ground level and are not thermally buoyant; therefore, the maximum
ambient air concentrations for such sources occur immediately downwind of the source
and at ground level. Point sources such as air strippers may have relatively short stacks
and non-buoyant plumes; the maximum ambient air concentrations resulting from such
sources often may occur within the site boundaries' It frequently is necessary for on-site
workers to operate equipment or otherwise work in contact with such emission plumes.
As a consequence, on-site workers must undergo training to recognize and respond to
such potentially adverse exposures as part of their OSHA-mandated safety training.
On-site workers may employ varying degrees of personal protective
equipment (PPE) (e.g., levels A, B, C, or D) to ensure their safety . One major function
of the PPE is to minimize the exposure of the workers to vapors and wind-blown
particulate matter. There is a trade-off between safety and cost, since increasing the
degree of worker protection generally reduces the amount of time workers can actively
work per hour and also reduces worker productivity during active periods. This is
especially true when safety concerns dictate that breathing air be supplied (level A or B).
There is also a trade-off between minimizing the exposure to airborne contaminants and
maximizing overall worker safety. Safety gear that offers protection from airborne
contaminants (e.g., fully-encapsulated suits with SCBA gear) may otherwise decrease
worker safety by increasing worker heat stress, decreasing peripheral vision, decreasing
hearing, and increasing the likelihood of falls and other accidents because of the
worker's increased bulk and weight.
On-site personnel may work close to emission sources and they tend to
move around over time. These factors make it very difficult to accurately predict worker
exposure using a modeling approach. Instead, monitoring is usually performed to
determine worker exposure. This monitoring may entail the use of both portable
monitoring instruments (e.g., THC or TNMHC hand-held analyzers) to provide
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immediate feedback on surrogate indicators such as total hydrocarbons, and industrial
hygiene (IH) type of sampling to provide information on exposure to specific compounds.
The IH type of sampling involves placing dosimeters or low-volume sampling pumps with
sorbent tubes, filters, etc. on the workers and measuring the average concentration of
selected contaminants in the breathing zone over a given time period (e.g., 8- to 10-hour
worker shift). The IH type of sampling yields more detailed information than portable
monitoring instruments, but data turnaround time is usually at least 24 hours. For either
type of sampling, the measured values can be compared with occupational exposure
limits to determine whether worker exposure is within safe levels. In general, short-term
acute exposure is more of a concern for on-site workers than is long-term chronic
exposure. A series of action levels is often established that relate the level of required
PPE to specific ambient air concentrations. For example, workers may be required to
put on respirators if the total hydrocarbon (THC) concentration in the breathing zone at
the work area exceeds some level for a specified period of time (e.g., if the THC
concentration exceeds 10 ppmv for 1 minute).
In many cases, the site health & safety plan requires a conservative (i.e.,
restrictive) approach. At the start of the project, on-site workers are required to wear
adequate PPE to safely work under assumed worst-case levels of emissions. The PPE
requirements are gradually reduced if the air monitoring data collected in and near the
work zones indicate that no problems have been encountered, i.e., that no action levels
have been exceeded. The larger the database of on-site ambient air monitoring data, the
greater confidence there is in extrapolating these data forward in time.
3.1.2 Evaluate Exposure of Off-Site Populace
A major concern at Superfund sites is the potential exposure via the air
pathway of residents and workers in the areas surrounding the site. The degree of
concern varies from site to site, as discussed below, depending on the nature of the
contamination, the proposed remedy, and the proximity of the off-site populace
(receptors). The exposure of off-site receptors typically is evaluated at several steps of
the Superfund process and both modeling and monitoring approaches may be employed
as part of the exposure assessment.
Superfund sites often contain a complex mixture of contaminants. The
potential adverse health effects vary from compound to compound, and the health-based
action levels may vary by orders of magnitude between compounds with relatively similar
structures and physical properties. For example, 1,2-dichloroethane is considered to be a
much more potent carcinogen than 1,1-dichloroethane, and benzene is considered to
pose a much more significant risk than equal amounts of toluene or xylenes. Therefore,
the most significant compounds at the site from a health risk standpoint may not
necessarily be those compounds present in the highest concentrations in the soil or water
at the site.
Certain compounds typically are considered to "drive" the risk assessment
at Superfund sites, i.e., they pose the most significant risk. Air monitoring or modeling
studies, therefore, typically will focus on those compounds thought to pose the most
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significant risk at a site, rather than include an evaluation of every possible compound
found at the site. The selected analytes are usually referred to as target compounds or
compounds of potential concern. Compounds of frequent concern at Superfund sites
include:
1) Volatile organic compounds (VOCs), especially benzene and
chlorinated solvents such as vinyl chloride, methylene chloride,
chloroform, etc.;
2) Semi-volatile organic compounds (SVOCs), such as polychlorinated
biphenyls (PCBs), polynuclear aromatics (PNAs), and pesticides;
3) Semi-volatile inorganic compounds such as mercury; and
4) Non-volatile compounds, such as asbestos and cyanides; and heavy
metals, such as lead, chromium, cadmium, zinc, beryllium, copper,
and arsenic.
The non-volatile compounds may be transported as windblown paniculate matter (PM).
Of course, not every compound listed above is present in significant quantities at every
Superfund site.
The proposed remedy will greatly influence the potential emissions from a
site. In general, in-situ remediation methods result in lower levels of air emissions than
ex-situ remediation methods. Any activity that moves or disturbs the waste present at
the site can potentially result in emissions of VOCs and PM. Public concern historically
has focused on point sources of air emissions such as incinerator stacks, but fugitive
sources of emissions such as materials handling operations may result in greater air
emissions at many sites.
The proximity of off-site receptors to Superfund sites influences the results
of the air pathway assessment. Diffusion and dilution in the atmosphere will reduce
ambient concentrations of pollutants, and the greater the distance the emissions travel,
the more diluted they become. Superfund sites vary from the best case — a site in a
remote, rural area with few or no persons living and working within several miles of the
site, to the worst case -- a site in an urban area with housing on all sides and a minimal
distance between the areas of contamination and the site fenceline.
• The evaluation of exposure using a modeling approach generally involves
atmospheric dispersion modeling using an EPA-approved model such as the Industrial
Source Complex (ISC) model. The source term (i.e., emission rate) can be estimated
from emission models or derived from field measurements. The dispersion model
requires meteorological data from an on-site or local monitoring station to calculate
(annual) average downwind ambient air concentrations for receptors of interest.
Maximum short-term (hourly) downwind ambient air concentrations can be estimated
using worst-case source term and meteorological conditions. There are atmospheric
dispersion models (e.g., SCREEN) that automatically run through various combinations
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of wind speed and stability class and identify the maximum short-term ambient air
concentrations for a given source.
The evaluation of human exposure (due to inhalation) using a monitoring
approach generally involves measuring the concentrations of target analytes at the
fenceline of the site for ground-level emission sources and at the areas of maximum
estimated ground-level impacts for elevated emission sources (e.g., thermal treatment
unit smokestacks). Additional ambient air monitoring (AAM) may take place at selected
receptor locations in the surrounding community (e.g., at nearby schools) or on site, if
there is public access. Data are collected at locations both upwind and downwind of the
site. The data are compared with action levels to determine if there is cause for concern
at downwind locations. The difference in the concentrations measured downwind and
upwind of the site yields an adjusted concentration considered to represent the
contribution of the site emissions to the local air quality. The risk is based on the
incremental increase in total risk posed by site emissions; therefore, increases in
downwind concentrations that are of interest may represent only a small increase over
background levels. For example, background levels of benzene in the air may be several
parts-per-billion on a volume basis (ppbv), but the selected action level may be an
increase in downwind benzene concentrations versus upwind concentrations of only 0.04
ppbv (based on a IxlO"6 acceptable risk and a 70-year exposure). In such cases, the
precision of the sampling and analytical methods may not be adequate to permit an
evaluation of whether action levels have been exceeded.
Usually, a fixed network of point samplers is located around the perimeter
of the site, samples are collected continuously during on-site activities, and all samples
are analyzed. Additional samplers may be located near the working areas. The number
of sampling locations will depend on the size of the site, among other factors. For large
sites surrounded by nearby residences, a twelve-station network may be used to provide
nearly complete coverage of the fenceline (i.e., a station every 15 degrees). In some
cases, only samples from stations located directly upwind or downwind of the site for a
given sampling period will be analyzed; samples collected at locations perpendicular to
the emission plume(s) are not analyzed to save time and money. Alternatively, a smaller
number of AAM stations may be used and these stations moved from day to day
according to predicted wind patterns. If the predictions are wrong, however, the
monitoring stations may not be in the emission plume as needed.
An emerging AAM method is the use of open path monitors (OPMs) that
rely on spectroscopic methods to nondestructively determine ambient air concentrations.
Typically, a light beam is directed along a path and the absorbance of various
compounds in the infrared or ultraviolet regions is measured. The systems offer several
important advantages over conventional point samplers: 1) It is possible to continuously
monitor the entire fenceline of the site; 2) No samples have to be collected (therefore,
no sample custody procedures are necessary); 3) There are no associated unit analytical
costs (therefore, the collection of additional data does not greatly increase the cost of the
monitoring); and 4) Turnaround of preliminary data can occur within minutes of
measurement. The principal drawbacks of the method are that only a relatively limited
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number of compounds can be monitored in real time and the detection limits of OPM
methods are often higher than those of conventional AAM methods.
A target list of analytes is usually developed to limit the scope to the most
significant compounds present from a risk standpoint. Single AAM methods may be
appropriate for one or more classes of compounds, but multiple AAM methods may be
needed to detect all the target analytes. For example, at a given site, evacuated canisters
or sorbent tubes may be used for VOCs, filters or polyurethane foam (PUF) plugs may
be used for pesticides and PCBs, and a separate filter may be used to collect samples for
PM10 and metals. Samples will usually be collected over 8-hr, 12-hr, or 24-hr periods,
depending on the degree of temporal resolution needed to determine any impacts on the
air quality. The temporal resolution that is needed will depend on the specific ARAR or
action level that is used. The sample collection period should match the time period of
the applicable ARAR or action level to the extent that is feasible. If the ARAR or
action level is based upon an extended period (e.g., one year), then multiple samples
typically are collected and the results averaged to obtain an estimated concentration over
the time period of interest. The specific AAM method used will greatly influence the
minimum and maximum allowable sampling durations, the sampling flow rate, and the
achievable detection limits.
3.1.3 Evaluate Environmental Impacts
The procedures used to evaluate adverse environmental impacts are
generally the same as those described above to evaluate the exposure of the off-site
populace. Potential environmental impacts may be evaluated at several stages of the
Superfund process, and both modeling and monitoring approaches may be employed as
part of the evaluation.
For most sites, the evaluation of environmental impacts will have a
somewhat lower priority than the evaluation of the exposure of the off-site populace, and
the design of any air monitoring network will be based primarily on determining the
exposure of the off-site populace. In general, however, the same data used to evaluate
the exposure of the off-site populace can also be used to evaluate any adverse effects on
the environment. To fully address potential environmental impacts, it may be necessary
to add additional receptor locations of interest (e.g., near surface waters) and add to the
target analyte list compounds that typically have a greater effect on nonhuman receptors
than on humans. For example, copper may kill fish when present in water at levels that
are not of great concern for human health. The action levels for evaluating
environmental impacts may be based on total deposition rates over a given area or on
biological uptake rates rather than on human health data. General environmental
impacts, such as effects on visibility, should also be considered.
3.2 TYPICAL APA ACTIVITIES FOR SUPERFUND SITES
The cleanup of a contaminated site under the Superfund program proceeds
via a series of actions designed to remove or stabilize the contaminated material in a
controlled way. Activities related to an air pathway assessment for a Superfund site may
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be necessary during the Site Inspection (SI), the Remedial Investigation (RI), the
Feasibility Study (FS), the Remedial Design (RD), the Remedial Action (RA) and the
Post Remediation (often called Operation and Maintenance (O&M) ). Typical APA
activities associated with each action are summarized in Table 3-1 and discussed below.
Typical APA activities at Superfund sites can be divided into the following
four categories:
1) Screening evaluation of site emissions and impacts or air quality
under baseline or undisturbed conditions;
2) Refined evaluation of site emissions and their effect on air quality
under baseline or undisturbed conditions;
3) Refined evaluation of emissions and their effect on air quality from
pilot-scale remediation activities; and
4) Refined evaluation of the effects on air quality of full-scale
remediation activities.
Other APA activities may be appropriate for specific site applications. Screening studies
are performed to better define the nature and extent of a problem (i.e., to limit the
number of questions to be considered for a site), while refined studies are performed to
find definitive answers to one or more air-related questions. While screening studies are
less time- and resource-intensive than refined studies, they do not necessarily use
different monitoring methods or approaches. Screening studies should not be thought of
as being necessarily inexpensive, "quick-and-dirty", or qualitative in nature. Screening
studies have more associated uncertainty than refined studies, so their experimental
design should be more conservative. For example, if only a few days of monitoring data
are to be collected, then it should be collected during periods of worst-case conditions.
With regards to air monitoring, the goal for categories one through four
listed above may be to measure ambient concentrations at the site fenceline. The goal
for categories two and three may also be to measure ambient concentrations immediately
downwind of the emission source to generate emission rate estimates. These data can be
combined with tracer gas measurements or an atmospheric dispersion model to back-
calculate an emission rate from the source. This emission rate can then be used with an
atmospheric dispersion model to estimate ambient concentrations at various receptor
locations under various meteorological conditions.
Category 1 APA activities are most likely to occur during the SI, early RI,
or O&M steps of the Superfund process. Category 2, 3, and 4 APA activities are most
likely to occur during the RI and O&M, FS, and RA, respectively.
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3.2.1 Pre-Remediation Phase
The only action during Pre-Remediation that is likely to require ambient
air monitoring or modeling is the SI. Data collected during the PA, however, may also
be useful as input to the APA process. The goals of the SI (with regard to the air
pathway) are to demonstrate what emissions, if any, are coming from the site in question
and what areas may be affected by these emissions. Also, all data needed to conduct
HRS scoring of the air pathway should be obtained. During the SI, the site is in an
undisturbed or baseline state and typically will have low levels of emissions. This is
especially true if the waste is covered by layers of clean soil or if volatile compounds
have become dissipated from wastes on the surface.
Monitoring during the SI, if any is performed, will generally involve surveys
of site emissions using handheld analyzers to: 1) Determine worker exposure;
2) Determine the general levels of pollutants present in the ambient air; and 3) Identify
any emission "hot spots". Monitoring upwind and downwind of the site may also be
performed, and the difference in the identified species and concentration levels of
downwind and upwind samples can be used to determine the existence and general
magnitude of site emissions. The concentration levels at the fenceline may be only in
the 1-10 ppbv range, and at the time of the SI there will usually be little prior knowledge
of the type of compounds being emitted, the magnitude of the emissions, or the location
of the emission sources. Therefore, ideally, the monitoring system should: 1) be capable
of detecting a broad range of compounds; and 2) be sensitive enough to detect the level
of compounds present and to distinguish between on-site and off-site emission sources.
Modeling during the SI, if any is performed, will generally involve
modeling unit emission rates (i.e., a nominal 1 g/sec source) along with historical
meteorological data from the nearest National Weather Service (NWS) station to
determine the areas of maximum impact from site emissions. The point of least dilution,
and therefore of greatest downwind concentrations, is usually referred to as the
maximum exposed individual (MEI), regardless of whether or not an actual person
resides at this point. For sites in their baseline state, the MEI will be at the site
boundary opposite the prevailing average wind direction. The results of the modeling
performed during the SI will generally be used to aid in the design of an AAM network
for subsequent phases of the site cleanup. The results may also be used to help
determine whether an emergency response action is warranted.
3.2.2 Emergency Removal
Emergency removal (ER) actions are taken only when a site is believed to
pose an immediate and significant health threat. These actions tend to be limited in
scope and duration, and the associate APA work also tends to be limited. At a
minimum, air monitoring generally will be performed to determine the exposure of on-
site workers. In some cases, the ER action will temporarily increase the emissions from
the site (e.g., when explosive material is detonated on-site). In such cases, air modeling
prior to the ER action may be needed to determine whether, and to what extent,.the
local populace should be evacuated. During the actual ER action, additional air
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modeling may be needed to update the earlier predictions as new information becomes
available. In addition, fenceline AAM may be needed to determine the exposure of the
off-site populace to the increased levels of emissions. Monitoring results also may be
compared to short-term trigger levels and, if exceedances occur, pre-identified actions
undertaken such as emission suppression.
3.2.3 Remediation Phase
The activities during the remediation phase that may require APA
activities are the Remedial Investigation (RI), the Feasibility Study (FS), the Remedial
Design (RD), and Remedial Action (RA). Two types of air monitoring are of interest:
1) fenceline ambient air monitoring, and 2) ambient air monitoring just downwind of the
emission source under prescribed conditions to develop emission rate or flux estimates.
Air monitoring will also generally be conducted during the RI/FS and RA to determine
the exposure of on-site workers. Air modeling may be performed during the FS or RD
as part of an overall site risk assessment study or as an aid in siting an AAM network.
The goal of the RI, which is generally an undisturbed site investigation, is
to obtain a more detailed knowledge of the potential air contaminants that are present.
Certain activities during the RI, however, such as drilling or trenching may increase the
emissions from the site over baseline levels. The monitoring needs are similar to those of
the SI, but the speciation of compounds and the location of emission sources are studied
in greater detail.
Air monitoring may also be performed during the RI to determine the risk
potential of the site. This monitoring may be performed directly at specific downwind
receptor locations or indirectly by estimating emission rates that will subsequently be
used with a dispersion model to estimate the concentrations at downwind receptor
locations. The determination of emission fluxes during the RI will require identification
of the compounds present in the contaminant plume and determination of the average
concentration of each contaminant of interest. The temporal variability in the emission
flux will also generally be of interest. This information can then be used to determine
the emissions potential of the site. Therefore, the air monitoring approach used must be
capable of providing: 1) data of a sufficient temporal resolution to determine the
emissions rate; and 2) sensitivity and selectivity equivalent to those required during the
SI.
The air monitoring goal during the FS is to determine the emission rates
that will probably be encountered during the RA as the possible remediation alternatives
are developed and evaluated. The FS may involve testing some options on a pilot-scale
basis as well as evaluating possible control technologies. Air monitoring during the FS
may be performed to investigate the emission rates as a function of site, waste, and
operational variables. Pilot-scale activities during the FS may result in substantially
larger amounts of emissions from the site than was the case during earlier steps. The
primary use of AAM during the FS is to measure emission rates close to the pilot-scale
unit. The measurements are generally performed as close to the emission source as is
feasible so that the measured ambient concentrations will be as high as possible. These
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concentrations may be in the range of 100 to 200 ppb per compound. Farther downwind,
of course, the concentrations will decrease because of dispersion. The total mass of
contaminants released from pilot-scale activities is likely to be small, so the effects at the
fenceline can be expected to be minimal.
Compared with the baseline emissions seen during the SI or RI, activities
undertaken during the FS will significantly change both the amount and type of
emissions present. Earlier investigatory activities should have determined most of the
compounds present in the waste at the site; therefore, the monitoring system will not
need the broad species identification capability of the systems used in the SI and RI
steps. The air monitoring system used during the FS, however, must still have:
1) Detection limits at or below the concentration levels of the compounds of interest;
2) Sufficient temporal resolution to determine the time variability of the emissions; and
3) Ample flexibility in the range of compounds that can be detected.
A site risk determination involving air modeling will usually be performed
as part of the FS or RD for the site. The air modeling results should be more accurate
than any similar work performed during the SI, because the number, location, and
magnitude of the source terms should be better known at this time. Also, historical on-
site meteorological data will often be available for the time the RI/FS was performed.
Compared with the modeling performed for any ER actions, there is more time to plan
and perform the modeling, including time to acquire and validate data, establish a
modeling grid, perform a sensitivity analysis for the variables, develop site-specific action
levels, etc.
Air modeling may also be performed during the RD to support the
development of an air emissions control strategy. The air modeling would be used to
predict the downwind effects for a number of scenarios based on the use of various types
of controls and various application rates. The goal is to find the optimum point of
maximum emission reductions without undue increases in the cost or duration of
remediation.
The RA is the full implementation of the chosen remedial alternative and
can proceed over several years. Air monitoring during the RA step is usually concerned
with the risk the site emissions pose to downwind receptors. These emissions are likely
to be significantly higher during the RA than during any other step in the Superfund
process, since, at least for ex-situ remediation processes, greater volumes of
contaminated material are being exposed and handled. Depending on the air emissions
controls used, the concentrations at the fenceline may also be higher during this step
than during any previous steps.
The primary goal of air monitoring during the RA is to protect human
health and the environment. This monitoring is therefore employed at the downwind
fenceline or point of plume impact (if elevated sources such as air strippers are being
used). One key requirement of any monitoring system being used during the RA is that
it provide rapid feedback to site personnel so that they can halt or modify the
remediation activities if fenceline action levels are exceeded.
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In most cases however, it is not the fenceline concentration that is
important but the concentration at the receptor. Dispersion models play an important
role in extrapolating these fenceline concentrations to receptor concentrations.
Therefore, it is only necessary to know the upper limit (i.e., the system detection limit)
concentration at the fenceline. If this upper limit is known, it can be used to ascertain a
source term for use as input to a dispersion model for cases where the compound is not
detected at the fenceline. The dispersion model can then be used to calculate the
maximum impact at the receptor. A software package can be set up for a given site to
quickly perform these calculations and provide on-site decision makers with timely
information.
The air monitoring system used during the RA must have detection limits
sufficiently low that (estimated or measured) ambient concentrations at receptors of
interest can be compared with action levels regardless of the placement of the
monitoring system. It is also useful if the system can determine both short-term and
long-term exceedances of the health-based action levels. There must be a reasonable
certainty that the monitoring system will intercept the emission plume downwind of the
site. One important consideration is meteorological conditions, such as stability, that
affect the dispersion of the plume. Thus the sensitivity of the system to deviations in
wind direction must be considered.
3.2.4 Post Remediation (O&M)
Air monitoring, after the remedial phase is completed, is conducted to
ensure that the site is clean and that it does not emit compounds at hazardous levels.
This monitoring is conducted under undisturbed conditions and close to the area of the
remedial activity. If the remedial option did in fact clean up or isolate the vast majority
of the contaminants, the emissions will be low; therefore, the monitoring system must be
able to monitor the emitted compounds at very low concentrations.
The previous air monitoring activities at the site should have revealed a
wealth of knowledge about the amounts, location, and types of compounds present. This
knowledge should make identification of the type of system capable of monitoring these
compounds straightforward. Time response is not as critical an issue as during earlier
phases, nor is determining variability in the emissions. The primary question, therefore,
is one of sensitivity for determining risk.
Air modeling may be performed as part of the O&M if a post-remediation
risk assessment is required. If so, this effort can usually be based on previous risk
assessment studies for the site and should not involve a great deal of time or effort.
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SECTION 4
KEY ISSUES RELATED TO APA FOR SUPERFUND SITES
The key issues related to air pathway assessments performed for Superfund
sites are discussed below. For these issues, there is on-going debate as to what
procedures should be followed, or they are issues that are commonly not given adequate
attention. Key issues are considered to be action levels, data turnaround time for
ambient air monitoring (AAM) methods, detection levels for AAM methods, ARARs,
data uncertainty, often overlooked emission sources, modeling of area and volume
sources, and monitoring and modeling during emergency removal.
4.1 ACTION LEVELS
Ambient concentrations at the fenceline of a Superfund site or at specified
receptor locations can be measured directly or estimated using a modeling approach.
These data are typically compared to action levels based on health or environmental risk
values to determine whether any significant air pathway exposure has occurred or is
likely to in the future. Several frequently encountered questions related to actions levels
are:
i) At what locations should action levels be established?
ii) What time averaging periods should the action levels cover?
iii) What compounds should be addressed?
iv) What are the bases for the action levels?
v) What monitoring methods should be used to check compliance?
vi) What response or corrective action should be required?
The two areas for which action levels are usually established are the
immediate working area within the site and the fenceline (i.e., property boundary) of the
site. The action levels associated with the working area are designed to protect the
health of the on-site workers. During the RI or FS, the working area of the site is
typically limited in size, but during full-scale remediation a large portion of the site may
be of interest. The action levels associated with the fenceline are designed to protect the
surrounding populace and environment. The fenceline is assumed to represent the
worst-case exposure for persons in nearby homes, businesses, or public-access areas. In
some cases, monitoring will occur at the fenceline and a dilution factor will be used to
estimate the concentration at receptors downwind of the site.
Several time-averaging periods may be of interest including instantaneous
values and 15-minute, one-hour, 24-hour, one-month, and one-year averages. As
previously discussed, the time-averaging period needed will depend on the time period of
the applicable action level or ARAR. The choice of time periods also will depend on
the specific compounds present and their health effects, as well as on the capabilities of
the air monitoring equipment used to check for compliance with the action levels. In
many cases, instantaneous measurements are used for comparison with short-term action
levels, and 8-, 12-, or 24-hour composite samples are used for comparison with long-term
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action levels. These latter data may be used to generate daily, monthly, and annual
averages.
The compounds addressed by the action levels will typically be a subset of
the contaminants present at the site, since it is often prohibitively expensive to generate
data for all contaminants present. Risk assessments for the air pathway usually indicate
that a relatively few compounds account for the great majority of the risk. The
compounds requiring action levels are those compounds present at the site in significant
quantities that have high toxicity or degree of hazard and that are capable of being
released to the atmosphere. Compounds that, if present at a site, frequently dominate
the risk assessment include benzene and chlorinated solvents such as 1,1,2-
trichloroethane, 1,2-dicloroethane, methylene chloride, chloroform, and vinyl chloride.
SVOCs and non-volatile compounds such as heavy metals, pesticides, and PCBs also may
be important if present in wind-blown dust or process emissions from the site.
Several categories of action levels may be necessary, depending on the
compounds of interest, the operating life of the source, the type of emission sources, and
the potentially exposed population. Categories of action levels used most often are long-
term action levels for carcinogens, long-term action levels for non-carcinogens, and short-
term action levels. No universally recognized basis exists for establishing action levels,
especially for short-term action levels. A fourth category, action levels for odors, may be
needed at some sites.
Long-term action levels for human carcinogens should be based, whenever
possible, on inhalation unit risk (IUR) values published by EPA (see Section 5.6). The
IUR values are based on assumptions of typical body weight, inhalation volume, and so
forth for the receptors of interest. The duration of exposure is generally assumed to be
the expected operating life of the source or 30 years, whichever is less. Receptors are
assumed to be continuously present at the location unless there is a plausible basis for
estimating the aggregate duration of intermittent exposures. The level of risk that is
acceptable is subject to debate, but values of 10^ to 10"6 aggregate cancer risk for the
lifetime of the remediation are generally considered to be appropriate upper limits.
Long-term action levels for human non-cancer effects can be derived by
using chronic reference concentrations (RfCs). An inhalation RfC is the estimate (with
uncertainty spanning perhaps an order of magnitude) of continuous exposure to the
human population that is likely to be without risk of deleterious effects during a person's
lifetime. If inhalation RfCs are not available, then chronic oral reference dose (RfD)
data can be used to derive an action level, but the appropriateness of any extrapolation
of oral data to ambient air action levels should be assessed on a compound-by-compound
basis. Important factors for such route-to-route extrapolations include the absorption,
distribution, metabolism and excretion of the compound; portal of entry effects; acute
and chronic toxicities, and other information. If the duration of exposure is expected to
be less than seven years, the action level should be derived using subchronic reference
concentrations.
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If no IUR, RfC, or RfD values for a given compound are available, then
the justification of a long-term action level for that compound becomes more tenuous.
One approach is to base the action levels on occupational exposure levels (OELs)
established by the Occupational Safety and Health Administration (OSHA) and the
American Conference of Governmental Industrial Hygienists (ACGIH). Action levels
may be derived using the lower of the OSHA Permissible Exposure Limit-Time
Weighted Average (PEL-TWA) level (or ceiling value) or the ACGIH Threshold Limit
Value - Time Weighted Average (TLV-TWA) level (or ceiling value) divided by a factor
to compensate for differences between occupational and residential exposures. This
approach is not necessarily endorsed by either OSHA or ACGIH. A value of OEL/1000
for long-term exposure has been suggested in some guidance documents5'6'7.
Short-term (e.g., one hour) action levels for human exposure can also be
obtained by dividing the lower of the OSHA PEL-TWA or the ACGIH TLV-TWA (or
ceiling limits if 8-hour averages are not available) by a factor to account for variations in
human sensitivity (occupational levels are designed to protect healthy adult workers) and
for uncertainties in using occupational exposure levels to derive ambient air action levels.
The dividing factor used at various sites in the past has ranged from 4.2 to 1000. A
factor of 4.2 is used to convert from a 40-hour worker exposure per week to a 168-hour
continuous exposure per week. A value of OEL/100 has been suggested in some
guidance documents5'6'7. The user of the short-term action levels, however, should
consider that no EPA-accepted method exists to determine the short-term concentrations
of airborne chemicals acceptable for community exposure.
The occupational exposure levels on which the short-term action levels are
based are subject to change, as are the IUR, RfC, and RfD values for a given compound.
It is strongly recommended that an experienced toxicologist or risk assessment expert be
consulted when establishing action levels.
In some cases, the exposure of the environment to chemicals in the air will
be of concern in addition to, or instead of, human exposure. Examples of such exposure
include the long-term deposition of contaminants onto surface waters, or emissions
affecting the habitat of endangered species. Site-specific action levels would need to be
developed in such cases, though guidance may be limited. Procedures for evaluating
environmental exposure may also apply to the evaluation of contaminant deposition onto
cropland, which may present a potential human exposure pathway.
The appropriate monitoring methods used to check compliance with
established action levels will vary from target compound to target compound and from
site situation to site situation. Compliance monitoring for long-term action levels tends
to involve the continuous collection of time-integrated samples at fixed locations, while
compliance monitoring for short-term action levels tends to involve the periodic
collection of nearly instantaneous samples at various locations of interest. Long-term
monitoring is intended more to document actual exposure than to provide feedback to
on-site operations. Short-term monitoring is intended to provide information to on-site
decision makers to help them select operating rates and decide whether emission control
measures are needed.
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In general, compliance with long-term action levels is based on daily
samples collected at each location within an AAM network. Broad-based collection
methods such as evacuated canisters, Tenax tubes, or charcoal tubes are usually selected
for VOCs so that all the target analytes can be measured using only one or two sampling
and analysis approaches. Alternatively, dedicated gas chromatographs (GCs) used as
point samplers or open path monitors (OPMs) may be used in some cases to minimize
unit analytical costs. Standard methods are available for PM10, metals, and some
SVOCs.
The selection of monitoring methods to document compliance with short-
term action levels often is more difficult than for long-term action levels. Dedicated
GCs or OPMs are the only realistic options for the cost-effective continuous or semi-
continuous monitoring of individual volatile organic compounds. These methods require
a relatively large capital investment and they may not be a viable option for certain
compounds or mixtures of compounds. Several methods are commonly used for periodic
compliance monitoring for short-term action levels. Fixed or portable broad-band
analyzers for total hydrocarbons (THC) or total non-methane hydrocarbons (TNMHC)
can be used if it is assumed that the instrument response (or some fixed fraction thereof)
is wholly due to the most hazardous compound present. Colorimetric tubes that are
compound-specific are available for many compounds, though usually only for relatively
high concentration ranges (e.g., ppm levels). Short-term monitoring for SVOCs and
metals cannot be performed directly. Instead, portable monitors for particulate matter
monitors can be used to measure total suspended particulate (TSP). An action level can
be established if the average fraction of SVOCs or metals associated with the TSP is
assumed.
Generalized EPA guidance does not yet exist for the response or corrective
action called for when action levels are approached or exceeded, although guidance has
been developed on a site-by-site basis. In general, a flexible set of actions is
recommended. If one or several days monitoring data showed an exceedance of long-
term action levels, the corrective actions would not necessarily require immediate or
drastic action. Instead, the site activities could be adjusted fairly gradually to ensure that
monthly or annual averages continue to meet the long-term action levels.
For short-term action levels, several levels of response may be the best
option8. For example, when ambient concentrations of compounds of interest are below
a given level (Level I), site operations are unimpeded. If the ambient concentration(s)
reaches some pre-determined Level II, the site is placed on "warning" status and
measures are taken to reduce the emission levels by reducing operating rates or applying
emission controls. If Level III is reached, the site is place on "alert" status and
operations are reduced and emission controls are applied. If Level IV is reached,
operations are halted and emission controls are applied as required. All of these levels
are based on time-averaged data (e.g., one- to eight-hour averages). A Level V based on
instantaneous readings would require operations to be halted and emission controls
applied as required. The associated ambient concentration would increase from level to
level, with Level I being the lowest concentration and Level V being the highest.
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42 DATA TURNAROUND TIME FOR AAM
The above discussion of action levels should make obvious the need for a
timely turnaround of data. Typical turnaround times for AAM data for non-Superfund
applications are several weeks in most cases. For Superfund sites, such dated
information would serve to document exposures but would otherwise be of little use to
site decision makers.
Data turnaround times for samples collected from long-term monitoring
networks are usually limited to 24 to 48 hours for Superfund sites. This may require the
use of a dedicated, on-site laboratory or stringent performance clauses if an off-site
contract laboratory is used. In many cases, samples will be collected 365 days per year
for several years. This unrelenting need for consistent, rapid data turnaround puts an
added burden on the laboratory equipment and staff.
The most critical need for timely information is to compare AAM data
with short-term action levels during remediation. As previously discussed, the most
common solution is to use broad-band THC or TNMHC analyzers or to use colorimetric
tubes. For sites where the concentration of specific analytes must be measured,
dedicated gas chromatographs (GCs) used as point samplers have until recently been the
only realistic option. GCs can provide updated values every 30 minutes or so. The main
drawbacks of the use of GCs as short-term monitors have been the cost of the
equipment (e.g., $30,000 per station), the complexity of installing and controlling the
monitoring network, maintenance requirements, and the labor required for data
reduction and data management.
A promising monitoring approach for Superfund remedial actions is the use
of open path monitors9. OPMs are spectroscopic instruments configured to monitor the
open air over extended paths of hundreds of meters or more. They rely on the
interaction of light with matter to obtain information about that matter. The potential
advantages of OPMs compared with more conventional air monitoring approaches
include: 1) there is rapid, essentially real-time data analysis; 2) no sample collection is
required in the normal sense of the term; 3) no additional analytical costs are associated
with each additional sampling episode; and 4) data are path-weighted concentrations
rather than concentrations for specific sampling points. The first advantage implies that
information is available to site decision makers within minutes and short-term
fluctuations in ambient concentrations can be detected. The last advantage listed implies
that it is less likely that an emission plume will evade the monitoring network and that
source terms can be directly determined. Data management software is available for
handling the very large quantities of data that are generated. The main disadvantages of
OPMs at this time are the lack of standard operating procedures, the lack of qualified
equipment operators, the lack of standardized procedures for dealing with spectral
interferences, the lack of reference spectra for some compounds of interest, and
detection limits that, for some compounds (e.g., benzene), are higher than those for
conventional methods.
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43 ANALYTICAL DETECTION LIMITS AND CAPABILITIES
The issue of detection limits is closely tied to the previous discussions of
action levels and data turnaround time. Compliance monitoring for action levels
generally requires that the detection limit of the sampling and analytical approach be
lower than the action level concentration. For example, the one-in-a-million (i.e., 10"6)
risk level, assuming a 70 year exposure, for benzene is only 0.12 ug/m3 or 0.040 ppbv.
This is well below the detection limit of all measurement methods. In addition, it is the
incremental risk that is typically of interest for Superfund sites, i.e., the increase in
ambient concentration, downwind minus upwind, is compared to the action level. For
urban areas, this may require that increases of only a few percent of ambient levels be
detected. Such increases must be distinguished from the sample-to-sample variability
that is always present. Therefore, the precision of the measurement method is critical,
but of course the precision of analytical methods tends to deteriorate as the detection
limit is approached.
There often is a trade-off between analytical data turnaround time and
detection limit. Measurement methods that provide rapid data turnaround often are
screening methods that provide rapid feedback for parts-per-million concentration levels
rather than for parts-per-billion or lower concentration levels. The data accuracy and
precision of such screening methods also tend to be less desirable that those for non-
screening methods. For example, portable THC analyzers may exhibit a large daily zero
and upscale drift, especially if they are exposed to very high concentration levels or if the
internal batteries are allowed to fully discharge. As previously mentioned, dedicated
GCs or OPMs may be the best options to meet data turnaround and detection limit
requirements for sites where potential adverse air impacts are a major concern.
At some sites it may be possible to monitor for action levels that are one
or two orders of magnitude below the detection level of the sampling and analysis
methods, though this is only feasible if the receptors are some distance downwind of the
emission source. The AAM collection device is placed between the emission source and
the receptor of interest, and the measured concentrations are multiplied by a dilution
factor based on the predicted dilution from the collection point to the receptor due to
atmospheric diffusion and dispersion. The actual dilution factor varies with the wind
speed and atmospheric stability, so either the actual amount of dilution should be
routinely modeled or a single worst-case dilution factor should be used to be
conservative.
4.4 ARARs
The National Oil and Hazardous Substances Pollution Contingency Plan10
(NCP) specifies that human health and the environment must be protected from
exposure via all pathways, including the air pathway. This protection includes
compliance with federal and state applicable or relevant and appropriate requirements
(ARARs) and other nonbinding criteria to be considered (TBCs), as well as risk
assessment studies to demonstrate that potential exposures are within the acceptable risk
range for carcinogens and are at or below established risk levels for noncarcinogens.
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Compliance with ARARs/TBCs and risk-based criteria are not necessarily
one and the same. ARARs and TBCs may not be based on actual exposure but instead
.are often based on mass emission rates or on the best available control technology.
Furthermore, ARARs and TBCs may be based on occupational exposure limits and are
not as protective of human health as the criteria defined in the NCP. While compliance
with ARARs and TBCs should occur, such compliance does not negate the need to
comply with Superfund risk assessment criteria.
Most ARARs specify that compliance with the applicable standard occur at
the point of public access. This will be the site fenceline for ground-level nonbouyant
sources, even if the site fenceline is not considered to be the maximum exposed
individual (MEI) for dispersion modeling purposes.
Two problems have been noted with ARARs and TBCs. One, the need for
compliance is not always known by RPMs and other site decision makers. Two, it can be
difficult to find out which specific ARARs and TBCs apply to a given site. To address
this need, the EPA has established compilations of ARARs11'12 and has assigned an
ARARs coordinator within each Regional office.
4.5 UNCERTAINTY OF DATA
Air pathway assessments are frequently limited by the uncertainty
associated with the input data or the complete lack of information about certain input
parameters. In many cases, RI/FS work is done to characterize the hydrogeology of the
site, but little or no work is done to address the air pathway beyond a limited amount of
air monitoring. Air monitoring data collected during the RI/FS generally will be of little
use in predicting potential ambient concentrations during remediation activities. More
generally, ambient concentration data are much less useful for predicting future ambient
concentrations that are emission rate (source term) data.
The RI/FS will usually provide some key information that is needed for
APAs, including a knowledge of what contaminants are present in the soil, waste, or
groundwater; what is the average and maximum concentrations of these contaminants,
what volume of soil or water is contaminated, and what is the spatial distribution of the
contamination at the site. Most sites are highly heterogeneous, so this information is
rarely known with much certainty. Other information needed for APAs is often lacking.
For example, the air-filled porosity of the soil is a key variable for estimating diffusion-
controlled VOC emissions from landfills, excavation, etc., but the information needed to
calculate air-filled porosity (i.e., bulk density, moisture content, and particle density) are
not collected. Information needed for determining baseline air quality can often be
especially difficult to obtain. Even if there is detailed information about the
contamination of subsurface soils, wastes, and sludges, there may be little or no
information about the concentration of contaminants in surface waters and soils. These
data gaps can be minimized by having review and oversight by the Air/Superfund
coordinator or other air staff during the early stages of, and throughout, the Superfund
process.
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Not all APA-related data are of equal quality. The data quality objectives
(DQOs) associated with the measurement or modeling should be considered. Certain
basic considerations are that quantitative measurement approaches are capable of
providing more accurate data than screening approaches and actual field measurements
generally are much preferable to model estimates.
Finally, air pathway assessment procedures themselves have a significant
degree of uncertainty. Published emission models, emission factors, dispersion models,
and health-risk data all may have order of magnitude or greater uncertainties. When
combined in an air pathway assessment, these individual data biases and uncertainties
may result in a very large overall bias or uncertainty. Section 5 presents information on
recent and on-going efforts to improve APA guidance, but there may always be processes
or contaminants that are not addressed by existing guidance.
4.6
FREQUENTLY OVERLOOKED POTENTIAL EMISSION SOURCES
Process stacks and vents are obvious point sources of emissions and are
usually considered during an APA. Area sources of emissions, however, may be
overlooked or underestimated. Potential area sources of VOC emissions that are
sometimes overlooked are listed below.
Sometimes Overlooked Area VOC Sources
• Materials Handling Operations:
Excavation
Grading
Site preparation/clearing
• Short-Term Storage Piles
• Bioremediation Units
• Solidification and Stabilization Processes
The excavation and removal of soils contaminated with VOCs is a common
practice at Superfund sites. Excavation and removal may be the selected remediation
approach or it may be a necessary step in a remediation approach involving treatment.
If removal is the preferred approach, the excavated soil is typically transported off-site
for subsequent disposal at a landfill. Excavation activities also are typically part of on-
site treatment processes such as incineration, thermal desorption, batch biotreatment,
and certain chemical and physical treatment methods. The soil is excavated and
transported to the process unit and the treated soil typically is put back into place on the
site.
The clearing of vegetation, grading, and other site construction activities
may also expose fresh waste material or otherwise increase VOC emissions. The
disturbance of contaminated soil and waste material has the potential to release a large
fraction of the VOCs present in the material. The handling of dry soil with low ppb
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levels of VOCs may result in all or most of the mass of VOCs being lost to the
atmosphere. The handling of wet soil with higher levels of contamination will strip a
smaller percentage of the VOCs from the soil.
VOC emissions from handling operations result from the exchange of
contaminant-laden soil-pore gas with the atmosphere when soil is disturbed and from the
diffusion of contaminants through the soil. The magnitude of VOC emissions depends
on a number of factors, including the type of compounds present in the waste, the
concentration and distribution of the compounds, and the porosity and moisture content
of the soil13. The key operational parameters are the duration and vigorousness of the
handling, and the size of equipment used. The longer or more energetic the moving and
handling, the greater the likelihood that organic compounds will be volatilized.
Storage piles of excavated or dredged material are another potential source
of VOC emissions. Long-term storage piles at Superfund sites may be placed in
enclosures and the emissions vented to a control device. Short-term storage piles,
however, are more often overlooked as an emission source. During excavation, it is
rarely feasible to remove the soil and place it directly into transport vehicles or process
units. More likely, the excavated material will be placed onto a short-term storage pile
directly adjacent to the excavation pit. The material may then be moved to a second
short-term storage pile at a staging area. Each of these storage piles and each of these
material transfer steps are potential emission sources.
Stabilization and solidification are generally employed to immobilize
metals or other nonvolatile contaminants and are not appropriate for wastes with a large
VOC content. They may be used, however, on wastes that contain some VOCs as a
secondary class of contaminants. The mixing steps required to blend the contaminated
material with the stabilizing agents will enhance VOC emission rates, as will the heating
of the material from any exothermic reactions. Measurements have indicated that most
or all of the VOCs originally present in the waste material are lost to the atmosphere by
the end of the curing period .
Bioremediation is another remediation process that may result in
unexpectedly large VOC emissions. For ex-situ bioremediation processes, any steps to
excavate, prepare, and transfer the contaminated material to the process unit have much
the same emission potential as other materials handling operations. The bioremediation
process typically will involve some type of liquid slurry (except for the special case of
bioventing). Biodegradation and volatilization will be among several competing
mechanisms for removal of the VOCs that are present. Biodegradation rates are difficult
to measure directly and removal rates are often measured as a surrogate for
biodegradation rates. Many studies, however, have assumed that all the removal is due
solely to biodegradation without considering losses due to volatilization. Therefore,
quoted biodegradation rates may be overly optimistic. Also, any activities to keep the
biosluny mixed or the addition of air to maintain the dissolved oxygen content will also
tend to increase the volatilization rate.
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Particulate matter emissions are readily visible and therefore are less
frequently overlooked than VOC emissions. Sources of PM emissions that are
potentially significant include all material handling operations, stabilization and
solidification, and on-site vehicular traffic.
4.7 MODELING OF AREA AND VOLUME SOURCES
The estimation of air quality impacts for fugitive sources of emissions is
less definitive than it is for point sources of emissions. This is because it usually is more
difficult to accurately specify the magnitude of these emissions and to characterize their
spatial and temporal variabilities. Field measurements of emission rates from fugitive
sources are possible2, but are not routinely performed as part of the RI/FS. Estimates
of source terms based on emission models usually suffer from large uncertainties in the
input values, as described in Section 4.5. Furthermore, current treatment of fugitive
emissions in air quality dispersion models has inherent limitations for estimating ambient
concentrations, particularly for locations close to the source of emissions. The exact
distance at which model estimates are unreliable depends on many factors, including the
distance between the source and receptor and the spatial extent of the source.
Fugitive emissions are represented as area or volume sources in air
dispersion models routinely used for regulatory applications. Each approach requires
definition of the height at which emissions are released and each approach is based on
modeling emissions from square areas. Individual area or volume source inputs to the
models require that the north-south and east-west dimensions of the source be the same;
irregularly shaped fugitive source areas are simulated by dividing the area into multiple
squares that approximate the geometry of the total emission source. In addition to
defining the release height, area sources require that the length of the side of the square
be defined. Volume sources require estimation of the initial lateral and vertical
dimensions of the source.
Based on the uncertainties in fugitive emission rates and how these
emissions are characterized in dispersion modeling, it is evident that concentration
estimates from these sources may be less accurate than concentrations predicted from
point source emissions. To achieve greater reliability in concentration estimates, it is
preferable to use on-site meteorological measurements and as accurate a
characterization of the emissions as possible. Furthermore, it may be necessary to use
multiple area or volume sources to best represent what may be considered a single
fugitive source.
4.8 MONITORING AND MODELING DURING ER ACTIONS
Emergency removal (ER) actions present a special group of APA
considerations because ER actions usually have severe time constraints. Prior to the ER,
there may be neither sufficient time nor adequate information to accurately estimate
potential air impacts or to select air monitoring methods for specific compounds. Once
the ER is underway, there will seldom be time to wait for off-site analytical results or
modeling studies.
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Emergency removal actions also may present unique challenges from an air
monitoring and emissions estimation standpoint. ER actions often involve the removal
or capping of surface contamination, but also may involve the removal, detonation, or
destruction of compressed gas cylinders, explosives, unstable chemicals, or containers of
questionable integrity (or content).
Because of the above considerations, it is necessary to have somewhat
generic contingency plans in place before the ER and to have maximum on-site flexibility
to address air concerns. As indicated in Section 5, EPA has developed guidance for
contingency dispersion modeling and air monitoring for Superfund emergency removal
actions. On-site flexibility may require that broadband monitoring methods be employed
to minimize the chances of emissions going undetected. Screening models for dispersion
(e.g., SCREEN and TSCREEN) may be required to make rapid assessments of plume
impacts and of areas to be evacuated. The need for emission control strategies and
equipment during ER actions should be obvious. There will also be a need to have
redundant capabilities, as well as for people, monitoring equipment, safety equipment,
etc. to be in reserve for use under worst-case scenarios.
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SECTION 5
SOURCES OF INFORMATION AND GUIDANCE FOR APA WORK
A tremendous amount of information related to air pathway assessments
(APA) for Superfund sites is available. Air monitoring and hazardous waste remediation
technologies have both undergone rapid development in recent years, however, and
information on these topics may become quickly dated. Also, there may be significant
amounts of overlap between existing sources of information.
Recommended sources of current information and guidance for APA work
are identified in this section. A listing of general information sources is presented first,
followed by listings for specific topics. The specific topics covered are ambient air
monitoring, emission rate measurements, emission rate estimates, atmospheric dispersion
modeling, and risk assessment.
5.1 GENERAL SOURCES OF INFORMATION
A number of staff positions within the U.S. EPA exist, in part, to provide
guidance and assistance on APA-related issues, including Regional Air/Superfund
Coordinators and Regional ARARs Coordinators. EPA also maintains a number of
organizational units for information transfer, such as the Center for Environmental
Research Information (CERI) and the Control Technology Center (CTC). In addition,
automated information systems are available, such as the OAQPS Technology Transfer
Network (TTN), the OSWER Electronic Bulletin Board, the Records of Decision
(RODs) Database, and the Integrated Risk Information System (IRIS). The OAQPS
TTN includes several bulletin boards, such as the Ambient Monitoring Technology
Information Center (AMTIC), the Support Center for Regulatory Air Models (SCRAM),
and the Clearinghouse for Inventories and Emission Factors (CHIEF). All of the
information sources listed above, along with other useful contacts and the associated
phone numbers are given as Appendices A and B to this document. Similar information
is also contained in EPA's directory of technical support services for Superfund site
remediation15 and in a recent journal feature16.
The EPA Superfund program maintains a compendium of program
publications17 available through the National Technical Information Service (NTIS).
This compendium identifies by topic area, several hundred documents that cover all
facets of Superfund. Included in this compendium is a partial listing of documents
prepared under the Air/Superfund program; a complete, current listing of Air/Superfund
documents appears in Appendix C.
The four-volume National Technical Guidance (NTG) study series was
prepared by the Air/Superfund program in 1987 through 1989. The information
contained in these documents has been superseded in some cases, but they still contain
much useful information. An index to Volumes II, III, and IV of the NTG study series
appears in Appendix D.
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A number of new technologies are under consideration for possible use at
Superfund sites. The U.S. EPA, through its Superfund Innovative Technology Evaluation
(SITE) program, works with technology developers to refine innovative technologies at
bench-scale and pilot-scale and demonstrate these technologies at hazardous waste sites.
The SITE demonstrations include an evaluation of the cost-effectiveness of the
remediation process. A compendium of profiles of the technologies covered by the SITE
program is available, along with contacts for further information . In addition, reports
are available for individual process demonstrations. Listings of these reports are
available17'18.
5.2 AMBIENT AIR MONITORING
The discussion of ambient air monitoring (AAM) is divided into industrial
hygiene-type monitoring, fenceline AAM using conventional methods, open path
monitoring, and meteorological monitoring. Currently, no single document adequately
addresses all of these topics, but a document of this scope is being prepared under the
Air/Superfund program as a revision of Volume IV of the NTG series4.
5.2.1 IH-Tvpe Monitoring
No comprehensive guidance is known for the selection and use of industrial
hygiene (IH) monitoring methods for Superfund applications. The occupational exposure
for workers in hazardous waste and industrial facilities is regulated by the Occupational
Safety and Health Administration (OSHA). OSHA regulates workplace exposures by
means of a system of Permissible Exposure Limits (PELs). A PEL has the sense of a
time-averaged workplace exposure that the majority of workers can encounter for 8
hours per day, 40 hours per week for a working lifetime without experiencing an adverse
health result such as injury, disability, illness, or death.
PELs have been established for over 500 chemicals, noise, radiation, heat
and cold. The PELs for individual chemicals are expressed in terms of a time-averaged
air concentration in the worker's breathing zone. Only two averaging times are
addressed in the PELs: 15 min for the Short-Term Exposure Limit (STEL) concentration
and 8 hours for the daily Time-Weighted Average (TWA) concentrations. These
standards are published in the Federal Register .
OSHA and NIOSH (National Institute for Occupational Safety and Health)
have developed sampling and analytical methods to measure chemical concentrations in
the breathing zone of workers. Many of these methods have been published20'21.
5.2.2 Conventional Ambient Air Monitoring
The U.S. EPA is the accepted authority on the monitoring of atmospheric
pollutants. The EPA has developed guidance documents and reference methods for the
monitoring and analysis of various pollutants to facilitate accurate and representative
measurement. These pollutants include criteria pollutants, volatile organic pollutants,
semi-volatile organic compounds (SVOCs), and particulate matter. Criteria pollutants
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are sulfur dioxide, carbon monoxide, ozone, nitrogen dioxide, lead, and paniculate
matter of less than 10 microns diameter (PM10). Guidance for concurrent meteorological
monitoring is also provided in some of these documents (see Section 5.2.4).
General guidelines for monitoring programs have been established by the
EPA22. The following aspects of monitoring programs are discussed in this source:
• Monitoring objectives, data rationale, and data uses;
• Duration of monitoring;
• Sampling methods, procedures, and frequency;
• Monitoring plan;
• Network design;
• Probe siting criteria and design requirements;
• Quality control and quality assurance requirements;
• Meteorological monitoring requirements; and
• Data reporting requirements.
Additional guidance on these topics is identified below.
Selection of Target Analytes - Superfund sites often have an extensive
number of potential contaminants that could be released to the atmosphere. The
limitations of measurement methods and cost considerations make it necessary to select
a subset of target compounds to be measured in any AAM program. Guidance in
selecting target analytes is given in Section 3.4.2 of Volume IV of the NTGS series4; a
list of the compounds in the Hazardous Substances List (HSL) developed by EPA for the
Superfund program is included as Table 9 of that document. Volume II of the NTGS
series2 also contains information in Section 3.1.4 for selecting indicator species and
information in Section 2.4 on specific compounds frequently encountered at Superfund
sites.
Network Design - This topic addresses the number, spacing, and location of
ambient air monitors and the frequency of sampling. Network design tends to be very
site and situation specific, so no mandatory network design criteria exist. A discussion of
the key issues related to network design may be found in Section 3.4.4 of Volume IV of
the NTGS series4. Guidance in probe siting is given in EPA's PSD guidance document22.
In general, AAM networks at Superfund sites are usually more complete
than AAM networks for any other application. This is especially true during full-scale
remediation. It is not uncommon for samples to be continuously collected, as opposed to
the once every sixth- or twelfth-day schedules common with long-term ambient air
monitoring networks. Measurements may be made at up to six to twelve fixed locations
ringing the site, as opposed to the one upwind and three downwind locations that are
common with non-Superfund AAM networks.
Method Selection For Criteria Pollutants - The EPA promulgates
Reference or Equivalent methods for monitoring criteria air pollutants that have passed
rigorous testing protocols to ensure that the method is accurate and representative. The
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Reference methods are described in the Code of Federal Regulations23 and in the
AMTIC bulletin board (see Appendix B). A list of designated continuous Reference or
Equivalent Methods can also be obtained by writing Environmental Monitoring Systems
Laboratory, Department E (MD-76), U.S. Environmental Protection Agency, Research
Triangle Park, NC 27711.
Method Selection For Non-Criteria Pollutants - Sampling and analytical
guidance related to toxic organic (TO) monitoring efforts is available as a set of fourteen
procedures24. The methods address volatile, semi-volatile, and nonvolatile organic
compounds, halogenated hydrocarbons, volatile oxygenates, semi-volatile phenolics, semi-
volatile base/neutral extracts, and semi-volatile pesticides/PCBs. Both sampling and
analytical methods are covered in each TO method.
Section 3.4.4 of Volume IV of the NTGS series4 provides guidance for
selecting monitoring methods that includes a discussion of the fourteen TO methods.
Detailed guidance and recommended procedures for monitoring toxic compounds in
ambient air have been prepared for EPA for short-term canister sampling, long-term
canister sampling, PUF plug sampling for SVOCs, and high-volume sampling for heavy
metals25.
Sampling and analysis methods for toxic organic compounds is an area of
active research. Good sources of information about the current capabilities of these
methods can be found in the proceedings of the annual EPA/AWMA Symposium on
Measurement of Toxic and Related Air Pollutants and the proceedings of AWMA's
Annual Meeting and Exhibition. These are available through the Air & Waste
Management Association (AWMA); see Appendix B for contact information. One
commonly used method for monitoring of VOCs is TO-14, which is a canister-based
method. Research on the use of evacuated, stainless steel canisters has recently been
summarized26.
A list of acceptable measurement methods for noncriteria pollutants is
available through the AMTIC bulletin board (see Appendix B) and is also available by
writing Environmental Monitoring Systems Laboratory, Quality Assurance Division (MD-
77), USEPA, Research Triangle Park, NC 27711. This list is reviewed at least annually.
A recent compendium of air sampling methods27 gives methods for the
following:
• Halogen and halogen compounds;
• Metals;
• Inorganic nitrogen compounds and oxidants;
• Radioactive species; and
• Sulfur compounds.
Many other compendiums of air monitoring methods are available.
Sampling and analytical methods for toxic organic compounds have undergone great
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improvements in recent years and methods more than about five years old may be
suspect.
5.2.3 AAM During Emergency Removal Actions
A guidance document is currently being prepared for air sampling during
emergency removal actions28.
5.2.4 Open Path Monitoring
As previously discussed, open path monitoring (OPM) using optical remote
sensing methods is an emerging option for AAM at Superfund sites. A recent
publication provides an introduction to the topic of OPM and contains discussions of
where in the Superfund process OPM may be applicable9. Several shorter articles are
also available that introduce the topic of OPM ' .
OPM systems have been applied to fenceline monitoring at petrochemical
facilities and hazardous waste sites, work place monitoring, and mobile source
monitoring. The use of various spectroscopic methods with a closed cell also show
promise for source sampling applications. The most commonly used OPM methods, in
decreasing order of use, are the Fourier Transform Infrared (FT-IR), the Ultraviolet-
Differential Optical Absorbance Spectrometer (UV-DOAS) and the Gas Filter
Correlation (GFC).
Remote sensing technologies are expected to see increased use over the
next several years as more of their potential applications are demonstrated. Efforts are
underway to lower their detection limits and increase their stability, reliability, and stand-
alone capacities. Work is currently underway to develop standard operating procedures
for the use of JHT1R systems for hazardous waste applications.
5.2.5 Meteorological Monitoring
Site-specific meteorological (met) measurements including wind speed,
wind direction, ambient temperature, and precipitation typically are needed for emission
modeling and atmospheric dispersion modeling. These data typically are collected using
a continuously operating, on-site met station. If on-site data are unavailable, met data
can be obtained for the nearest National Weather Service (NWS) station.
Several good sources of guidance on met system design and operation are
available. Sections 5, 6, and 7 of EPA's ambient monitoring guidelines for PSD22 address
met monitoring, met instrumentation, and quality assurance for met data, respectively.
This information should be augmented with other sources of guidance available from
EPA31'32'33.
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5.2.6 OA/OC for AAM
Quality assurance (QA) and quality control (QC) procedures for ambient
air monitoring programs for criteria pollutants are well established. QA/QC procedures
for non-criteria pollutants are much less well established. Furthermore, sampling and
analytical methods often are modified to meet specific project needs. Therefore, it is
important to incorporate specific QA/QC procedures into the AAM program so that
measurement data of known quality are generated.
QA/QC procedures for monitoring networks are summarized in Volume
IV of the NTG series4 that are largely taken from previous EPA publications22'32. QC
procedures for specific measurement methods are included in the method
writeups20'21'23'24'25. QA/QC procedures for meteorological monitoring are given in EPA's
on-site meteorological program guidance30.
5.2.7 Case Studies of AAM at Superfund Sites
Ten case studies of ambient air monitoring at Superfund sites are included
in a recent document on contingency plans at Superfund sites . Several additional case
studies are contained in Section 4 of Volume IV of the NTGS series4. Also, examples of
the application of data quality objectives (DQOs) for AAM at Superfund sites are
available35'36.
5.3 EMISSION RATE MEASUREMENTS
Emission rate measurement approaches may be divided into those suitable
for point sources of emissions and those for area sources.
5.3.1 Emission Rate Measurements for Point Sources
Measurement methods for emissions from point sources such as stacks,
vents, and ducts are well documented. Information on stack sampling methods for
stationary sources is available through the EMTIC bulletin board (see Appendix B).
Reference methods are published in the Code of Federal Regulations37.
5.3.2 Emission Rate Measurements for Area Sources
Emission flux measurements provide an estimate of the amount of a single
species or multiple species being emitted from a given surface area per unit time. These
data then can be used to develop emission rates for a given source for the purposes of
predictive modeling for population exposure assessments and for development of
emission factors. These measurements may be made either directly or indirectly. The
measurement of emission fluxes or rates from area sources is more difficult than from
point sources, and the procedures are less well established. The basic approaches for
these types of measurements are presented in Section 4 of Volume II of the NTG
series2. That document was prepared before the initial use of open path monitors for
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making emission rate measurements; the applicability of OPMs for emission rate
measurements is discussed in another EPA guidance document9.
Perhaps the most well-known direct techniques for measuring emission
fluxes are the flux chamber and soil vapor (ground) probe techniques. Flux chambers
have been widely used to measure emission fluxes of volatile organic compounds (VOCs)
and inorganic gaseous pollutants from a wide variety of sources, including landfills,
lagoons, storage piles, and spill sites. A user's guide summarizes guidance on the design,
construction and operation of EPA's recommended flux chamber for use on land
surfaces38. A more recent publication summarizes the effect of key design and
operational factors on the precision and accuracy of the measurements39. A database of
emission flux measurement data is available40. A modified version of the flux chamber
can be used inside of hollow-stem augers to estimate the emissions potential of
subsurface wastes41.
Guidance is available for making soil vapor measurements42, although some
of the sample collection and analysis discussion is dated. Soil vapor measurements
frequently are made by driving a series of ground probes into the ground and
withdrawing soil gas for on-site analysis. These data may be perfectly adequate for
mapping subsurface vapor plumes and identifying good locations for placing groundwater
monitoring wells. In most cases, the data should be considered to be relative
concentrations and, as such, they are not suitable for use with diffusion models to predict
exposure. The collection of absolute soil vapor concentration data would require that
the soil-gas equilibrium be allowed to become re-established after the placement of the
ground probes and that the sample collection method not greatly alter the soil-gas
equilibrium as happens when large volumes of gas are rapidly withdrawn.
Emission fluxes also can be measured by a variety of indirect methods that
generally involve the collection of ambient air concentration data upwind and downwind
of the emission source and the collection of meteorological data for estimation of local
dispersion characteristics.
Measurements typically are made at a series of downwind locations to
determine the average concentration in the emission plume. The upwind monitor(s)
serves as a blank or background sampling location. Concentration data are converted to
the mass of pollutants in the emission plume using information about the volume of air
passing over the sampling array during a given time period. This generally is
accomplished using an atmospheric dispersion model to "backcalculate" an emission rate
(i.e., source term) from the concentration data. The average emission rate is equal to
the increase in mass (downwind minus upwind) divided by the transit time across the
source. The various approaches for making these estimates using conventional ambient
air monitoring (AAM) methods include the upwind/downwind and transect methods2.
Remote sensing methods also can be used to develop emission flux/rate
information from upwind/downwind concentration measurements . These types of
measurements have been compared to flux chamber measurements and emission model
predictions44. In some cases, gaseous tracers can be used to mimic the emission source.
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When the tracer gas is released at a known rate, the emission rate of compounds of
interest can then be determined by comparing the measured concentration (using either
conventional or remote sensing methods) to the concentration of the tracer species
measured at the same downwind location43.
5.4 EMISSION RATE ESTIMATES
A great deal of information has been made available over the last few
years related to emission rate estimates for Super-fund sites. Sources of information are
given below for typical characteristics and emission levels for uncontrolled emission
sources, typical characteristics and emission levels for remedial action emission sources,
emission models, emission factors, and control technologies.
5.4.1 Background Information For Uncontrolled Emission Sources
Section 2.1 of Volume II of the NTGS series2 contains descriptions of
uncontrolled emission sources such as landfills and lagoons, and a discussion of the key
factors controlling the emissions from these sources. These types of sources tend to vary
greatly in size, types of contaminants, and concentration levels from site-to-site and
among sources at the same site. Therefore, the levels of potential emissions from these
sources may also vary greatly. In many cases, the contaminatants are covered by several
feet of relatively clean soil or are trapped in sediments under relatively clean water. In
these cases, emission levels will be quite low until the contaminated material is
uncovered and exposed to the air. Field measurements of air emissions from lagoons
and landfills have been compiled40; most of the compiled data are from non-Superfund
sites.
5.4.2 Background Information For Remedial Action Sources
Recommended sources of information for design and operating conditions
and typical levels of emissions for various emission sources at Superfund sites are
summarized in Table 5-1.
The best single source of information is a recent EPA-CTC report13.
Further references for specific emission sources are given in the EPA-CTC report and a
recent EPA-CERI report56. Other good sources of information for specific remediation
techniques are individual EPA SITE program reports (see SITE Technology Profiles18)
and the several dozen Engineering Bulletins that are available through CERI (See
Appendix B)
5.4.3 Emission Models
Recommended models for estimating emission rates are summarized in
Table 5-2. The source of information on models for estimating air emission rates for
Superfund sites has just been published57. This is the most user-friendly general source
of emission estimation procedures since default values are given for most all necessary
input parameters. The emission estimation procedures shown in Table 5-2 have
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Table 5-1.
Recommended Sources of Emission Information
Emission Source
Covered Landfills
Lagoons
Spills, Leaks, Open Pits
Storage Piles
Air Strippers
Soil Vapor Extraction
Thermal Destruction
Thermal Desorption
Excavation
Dredging
Materials Handling
Vehicular Traffic
Solidification/Stabilization
Bioremediation
Soil Washing/Solvent Extraction
References
Process Information
NA
NA
NA
NA
5,45
6, 13, 47
13,48
13,49
7, 13, 50, 51
50,52
50
53
54
13
13
Typical Levels of Emissions
40
40
40
40
5, 45, 46
6, 13
13
13
7,13
—
—
~
14, 55, 56
13
~
Notes: 1. "NA" - Not applicable
2. "--" - No suitable reference
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Table 5-2.
Recommended Emission Rate Models
Emission Source
Covered Landfills
Lagoons
Spills, Leaks, Open Pits
Storage Piles
Air Strippers
Soil Vapor Extraction
Thermal Destruction
Thermal Desorption
Excavation
Dredging
Materials Handling
Vehicular Traffic
Solidification/Stabilization
Bioremediation
Soil Washing/Solvent Extraction
Reference for Models
VOCs
57,60
57,60
57,60
57
5,57
6,57
57,61
57
7,57
57
53,57
53,57
57
57
~
PM
NA
NA
NA
53,57
NA
NA
57,61
~
—
NA
53,57
53,57
53,57
NA
NA
Metals, SVOCs
NA
NA
NA
53,57
NA
NA
57,61
~
--
NA
53,57
~
53,57
NA
NA
Notes: 1. "NA" - Not Applicable
2. "--" - No suitable reference
3. Where two references are given for a given scenario, the references
contain the same basic equations.
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superseded the procedures given in Volume III of the NTG series3 and summarized in
JAWMA58. The models given in Table 5-2, along with those presented in a recent
guidance document59, supersede the models for estimating baseline emissions presented
in Volume II of the NTG series2.
The compilation of models for Superfund applications57 contains the same
emission estimation procedures previously published for individual remediation
processes: air stripping5, soil vapor extraction6, and excavation7. Work currently is
underway to develop similar documents for solidification and stabilization, bioventing,
thermal desorption, and materials handling.
Other good compilations of emission models for lagoons and landfills
include compilations developed for bioremediation processes62 and TSDF facilities63'64.
A recent publication presents a model for estimating emission rates into basements and
other subsurface structures65.
The emission models cited above require both site-specific input data such
as soil or water concentrations, and physical property data such as vapor pressure,
Henry's Law constant, diffusivity in air, etc. There are several good sources of physical
property data available. Reference 44 provides all necessary physical property data for
the models in that document for 168 compounds. Another good database is found in
two places: Appendix D of Reference 48 and Appendix F of Reference 2. Superfund has
published a database of chemical, physical, and biological properties66. Physical property
data are available from chemistry reference books67'68 and estimation procedures are
available for cases when input data cannot be found69.
5.4.4 Emission Factors
Emission factors have been published70 for controlled and uncontrolled
emissions of VOCs, PM, metals, and inorganic gases from the following remediation
technologies:
• Thermal destruction (incineration);
• Air stripping;
• Soil vapor extraction;
• Solidification and stabilization;
• Physical and chemical treatment; and
• Biotreatment and land treatment.
Emission factors for these and other remediation technologies could also be calculated
using the recent compilation of emission models for Superfund sources57 and the default
values given in that document.
Emission factors for paniculate matter from vehicular traffic, dry lagoons,
storage piles, etc. are widely published53157'60. A good general source of emission factors
is EPA's AP-42 document71, although it should be noted that AP-42 is voluminous and
contains only limited information that may be germane to Superfund applications.
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5.4.5 Control Technologies
The recommended source of information on control technologies is the
recent CERI report on the control of air emissions from Superfund sites56. The
discussion in this manual covers the process description, applicability for remediation
technologies, range of effectiveness, sizing criteria, and cost information for the following
control techniques:
• Point Source Controls for VOCs and SVOCs
Carbon Adsorption
Thermal Incineration
Catalytic Incineration
Condensers
Internal Combustion Engines
Soil Beds/Biofilters
Operational Controls
Membranes
Emerging/Miscellaneous Controls
• Point Source Controls for PM. Metals. Acid Gases, and Dioxins
Fabric Filters
Wet and Dry Electrostatic Precipitators
Operational Controls
Wet Scrubbers
Dry Scrubbers
Miscellaneous Controls
• Area Source Controls
Covers and Physical Barriers
Foams
Wind Screens
Water Sprays
Water Sprays with Additives
Operational Controls
Enclosures
Collection Hoods
Miscellaneous Controls
Other good general sources of information about point source controls include EPA's
handbook of control technologies for hazardous air pollutants (HAPs)72, the recently
revised Air Pollution Engineering Manual73, and a recent text by Hesketh74. References
for detailed information about specific control technologies are available56'72. Good
sources of information about the costs of control options for point sources have been
recently been published75'76.
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5.5 ATMOSPHERIC DISPERSION MODELING
Regulatory procedures for atmospheric dispersion modeling are described
in the Guideline on Air Quality Models (Revised).33 This document is the principal
source of information on the proper selection and regulatory application of air dispersion
models. The Guideline is periodically updated to reflect clarifications and
interpretations of modeling procedures and to reflect advances in the field of air
dispersion modeling. A copy of the Guideline may be downloaded from the SCRAM
electronic bulletin board (see Appendix B). Dispersion model codes and documentation
are also available from SCRAM.
Aside from the Guideline, a conceptual framework for performing a
detailed modeling study for a Supecfund site is provided in Section 2 of Volume IV of
the NTGS series.4 This document also provides lists of air dispersion models that are
suitable for various applications and references for further information. The
Air/Superfund program has produced other useful documents related to dispersion
modeling, including a review of area source dispersion algorithms.77 Further, a report
providing guidance on contingency response modeling is currently being completed.78
This latter report presents the possible range of different kinds of accidental releases
that might take place at a Superfund site and illustrates how air dispersion models,
including dense gas models, should be applied.
Air pollutant concentrations can be based on either screening-level or
refined dispersion modeling. The major distinction between screening-level and refined
dispersion modeling is that the screening-level approach incorporates generic
meteorological data, in the form of standard combinations of atmospheric stability class
and wind speed, and predicts the maximum impacts creditable from a single source (e.g.,
one stack or area source) with each model execution. The screening level approach is
more readily implemented than the refined approach and is typically most useful for
single source applications. Refined dispersion modeling incorporates actual
meteorological data representative of the site to yield "best" (unbiased) concentration
estimates. Refined models can also readily accommodate multiple source impacts.
Various screening-level techniques have been established. Two interactive
EPA screening models that can be used to predict maximum short-term pollutant
impacts are the SCREEN79 and TSCREEN80 models. TSCREEN differs from SCREEN
in that it contains algorithms for calculating source terms (including some typical
Superfund scenarios) and can handle noncontinuous releases. A workbook for use with
TSCREEN has been developed.81 As screening techniques, these models assume that
maximum impacts can be predicted in any direction from the source. Therefore,
receptors (locations where impacts are predicted) are simply expressed in terms of
distances considered to be downwind of the source. At a minimum, the user must
specify the nearest and farthest distances at which air pollutant concentrations are to be
predicted. The models will then automatically calculate impacts at distances within that
range and will interpolate to find the maximum value. Terrain heights should be input
for each receptor distance if the facility is located in an area of rolling or complex
terrain.
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Aside from estimating impacts in both complex and noncomplex terrain,
these models are capable of estimating impacts under different downwash conditions.
Impacts within the cavity region that develops on the immediate downwind side of
structures or terrain obstacles can be estimated with these models. Because air flow
within the cavity region is generally recirculating, pollutant concentrations in this region
tend to be greater than those outside the cavity.
Application of refined air dispersion modeling requires more extensive
input than screening-level air dispersion modeling and should be performed in
consultation with the EPA Regional Meteorologist or Regional Air/Superfund
Coordinator. The benefit derived from the refined modeling approach is that by
considering the specific characteristics of each source, and accounting for the variability
in actual meteorological conditions, site-specific estimates of plume dispersion are
obtained. The basic components of a refined dispersion modeling analysis to consider
include:
• model selection;
• terrain type;
• urban/rural classification;
• source parameters;
• meteorological data;
• receptor grids; and
• downwash.
Each of these topics is addressed in detail in Reference 33.
Several dispersion models are available and each may be appropriate for
certain situations encountered at Superfund sites. One of the commonly used models for
simple terrain application is the Industrial Source Complex Model (ISC2).82 With
respect to area source modeling, recent studies have shown that the integrated line
source algorithm is the best available technique.77 The Point, Area, and Line Source
(PAL) model and the Fugitive Dust Model (FDM)83 incorporate this algorithm. Because
these models have limitations for regulatory application, the Industrial Source Complex
model is commonly used for modeling of area sources.
Building downwash and the potential for cavity impacts should be included
in the modeling analysis for all stacks with heights less than good engineering practice
(GEP) stack height.84 The ISC2 models contain algorithms for determining pollutant
impacts influenced by building downwash. Methods and procedures for determining the
appropriate inputs to account for downwash are discussed in the ISC2 user's guide8 and
in Reference 84.
Atmospheric dispersion modeling can be a complex undertaking and the
validity of modeling results is dependent on the modeling technique that is used.
Determination of the proper modeling technique to be used for a specific application
should be made in consultation with the EPA Regional Meteorologist or Regional
Air/Superfund Coordinator.
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5.6 RISK ASSESSMENT
References are given below for sources of information on ambient air
quality standards, inhalation exposure standards and guidelines, and guidance on
estimating human and environmental exposures.
5.6.1. Information Sources For Ambient Air Quality and Emission Standards
Ambient air quality standards are potential ARARs for Superfund sites.
These standards are designed, in part, to protect human health from air pathway
exposure. Therefore, they provide some guidance for setting acceptable limits for human
and environmental exposure.
The Clean Air Act (CAA) and its Amendments (CAAA) require the EPA
to develop and promulgate National Ambient Air Quality Standards (NAAQS) for
certain pollutants; i.e. criteria pollutants. The NAAQS's are enforceable standards that
take economic and technical feasibility into consideration. Only seven substances
currently have a NAAQS, however, and they are: sulfur dioxide, carbon monoxide,
nitrogen dioxide, hydrocarbons, ozone, particulate matter (PM10), and lead.
Since the development of a NAAQS is a slow process, states have been
encouraged to develop their own air toxics programs and ambient air levels (AALs).
The AALs have not necessarily been used as strict ambient standards, but rather are
used as guidelines in most states. If the AAL is exceeded, the industry or regulatory
agency step in to develop a mutually acceptable plan85. AALs tend to vary from state to
state because of the number of methods used to develop them. One method is to apply
safety factors to occupational exposure limits (OELs) developed by the National Institute
of Occupational Safety and Health (NIOSH), the Occupational Safety and Health
Administration (OSHA) and the American Conference of Governmental Industrial
Hygienists (ACGIH). These OELs are discussed later in this section.
Also developed pursuant to the CAA are the National Emissions Standards
for Hazardous Air Pollutants (NESHAPs) and New Source Performance Standards
(NSPSs). NESHAPs and NSPSs are promulgated for emissions of particular air
pollutants from specific sources as specified in Title 40 of the Code of Federal
Regulations. NESHAPs are generally not applicable to Superfund remedial activities
because CERCLA sites do not usually contain one of the specific source categories
regulated. Moreover, they are generally not relevant and appropriate because the
standards of control are intended for the specific type of source regulated and not for all
sources of that pollutant. Applicability should be examined on a site-by-site basis.
NSPSs are generally not applicable to Superfund cleanup actions; however, this also
should be determined on a site-by-site basis12.
5.6.2 Inhalation Standards and Guidelines
This section lists air standards and some of the guidelines currently
available.
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Enforceable Standards - The NAAQS list is contained in the 40 CFR part
50. These are enforceable criteria for ambient air. The Occupational Safety and Health
Administration (OSHA) derives permissible exposure limits (PELs) for workplace air
that are time-weighted averages for a 40-hour work-week86. They also derive 15-minute
STELs, and ceiling concentrations that are not to be exceeded during any part of the
workday. The OSHA limits are legally enforceable limits for occupational exposure.
Recommended Levels For Ambient Air - As discussed in Section 4.1,
several sources of information can be used to develop recommended levels or action
levels for ambient air. IRIS lists verified inhalation Reference Concentrations (RfCs)
and the inhalation slope factors when they are available. The RfCs may be derived by
following EPA's Interim Methods for Development of Inhalation Reference Doses87.
The American Conference of Governmental Industrial Hygienists (ACGIH) has
developed threshold limit values for use in industrial hygiene programs88. These values
are time-weighted averages, generally for an 8-hour workday. The National Institute for
Occupational Safety and Health (NIOSH) also derives exposure values for occupational
health professionals89. NIOSH values (recommended exposure limits or RELs) are 10-
hour time-weighted averages and Short-Term Exposure Limits (STELs).
Example calculations for action levels are given in the Federal Register90.
These calculations use Reference Doses (RfDs) and slope factors, which are found in the
IRIS database. Examples of possible long-term and short-term action levels for
Superfund sites have been published5'6'7.
5.6.3 Sources of Risk Information
Sources are identified below for information for toxic air pollutants and
guidance for evaluating human and environmental risk. Contact information is contained
in Appendices A and B for the various hotlines and databases cited.
The Air Risk Information Support Center (AIR RISC) is a primary source
of health, exposure, and risk assessment information for toxic air pollutants. Another
important source of toxicity information is the Integrated Risk Information System
(IRIS). IRIS is an EPA database containing up-to-date health risk and EPA regulatory
information for a number of chemicals. Information in IRIS is verified and supersedes
all other sources. Inhalation Reference Concentrations and inhalation slope factors are
among the types of information found in IRIS. For information on accessing this
database, call IRIS User Support, or see the Federal Register notice about the
availability of IRIS91.
The EPA Environmental Criteria and Assessment Office (ECAO) provides
information on toxicology and technical guidance concerning route-to-route
extrapolations, and the evaluation of chemicals without toxicity values. The ECAO
should be contacted when alternate sources of toxicity information are used, to establish
whether the source is relevant and accurate.
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The Agency for Toxic Substances and Disease Registry (ATSDR) publishes
lexicological profiles for hazardous substances found at Superfund sites92. Information
on health effects in animals and humans is discussed by exposure route and duration. In
addition, physiochemical properties, environmental fate, the potential for human
exposure, analytical methods, and regulatory and advisory status are given.
The National Air Toxics Information Clearing House (NATICH) helps
federal, state, and local agencies exchange information about air toxics and the
development of air toxics programs. The Resource Conservation and Recovery Act
(RCRA)/Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) Hotline is available to answer regulatory and technical questions and to
provide documents on RCRA, CERCLA, and UST programs. Lastly, the Toxic
Chemical Release Inventory Data Base (TRI) makes toxic emissions data available to
the public through the TRI database.
EPA criteria documents, such as the Air Quality Criteria Documents, are
useful if IRIS does not contain the needed information. Criteria documents may be
obtained through the NTIS. Open literature may be searched for new information or
information on chemicals not included in IRIS or criteria documents and profiles. The
NTIS lists a variety of sources on air toxics, along with telephone numbers and
addresses93.
As previously discussed, action levels for odor may be needed at some sites
in addition to action levels for health or environmental risk. Information about odor
threshold values is available94'95.
5.6.4 Sources of Guidance For Determining Risk
Guidance on determining exposure and health risk is contained in Risk
Assessment Guidance for Superfund Volume I. Human Health Evaluation Manual (Part
A). Interim Final or RAGS Part A, as it is often called96. Air concentrations in mg/m3
are converted to intakes mg/kg-day. The algorithm requires the inhalation rate (20
m3/day for an adult), exposure time (hours/day), exposure duration (years), body weight
(70 kg for an adult), and an averaging time (period in days over which exposure is
averaged).
Guidance is also available for developing risk-based preliminary
remediation goals in RAGS, Part B97, and for evaluating the risk from remedial
alternatives in RAGS, Part C98. The Superfund Exposure Assessment Manual60, or
SEAMS, provides guidance for estimating exposure from the air pathway.
Limited guidance is also available for setting short-term and continuous
exposure levels for exposures due to releases during emergency actions99.
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Indoor air emissions may be the result of outdoor dust and vapors moving
indoors, or from the volatilization of chemicals from indoor water sources (i.e., showers,
baths, sinks). There are not many sources available to model exposure from indoor
emissions from outdoor sources. Dust concentrations are generally assumed to be lower
indoors than outdoors and vapor concentrations are assumed to be equal in most cases,
however vapors indoors can exceed those outside. Models for evaluating volatilization of
chemicals from the indoor use of water are discussed in the Exposure Assessment
Methods Handbook100.
Superfund has published guidance for determining the environmental risk
posed by Superfund sites101. This document presents the statutory and regulatory basis
for ecological assessments, addresses the basis concepts of ecological assessments, and
presents guidance for planning, organizing, and presenting such assessments. Other
useful guidance documents also are available102.
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SECTION 6
EPA'S AIR/SUPERFUND PROGRAM
6.1 DESCRIPTION OF PROGRAM
The Office of Air Quality Planning and Standards (OAQPS) directs a national
Air/Superfund Coordination Program to help EPA Headquarters and the Regional
Superfund Offices evaluate Superfund sites and determine appropriate remedial actions
to mitigate their effects on air quality. Each Regional Air Program Office has an
Air/Superfund Coordinator who coordinates activities at the Regional level.
The regional Air/Superfund Coordinators are responsible for ensuring that air
program support is provided to Superfund. Air offices provide routine site support
services, such as a review of proposals, plans, and reports, as well as consulting on
technical issues. The coordinators participate in decisions relating to preremedial,
remedial, and removal actions that may have significant effects on air quality. They help
ensure that decisions on air pollution issues at Superfund sites are consistent with
federal, state, and local air regulations and policies. The coordinators may also perform
special field evaluations and help Superfund contractors by providing technical assistance
in areas such as air modeling, monitoring, and the development of air pollution control
strategies. Appendix A contains a list of contact information for the Air/Superfund
coordinators.
OAQPS has established four types of activities as the primary components of the
Air/Superfund program:
• Coordination;
• Training;
• Technical assistance; and
• National Technical Guidance Studies.
The scope of each of these activities is briefly described below.
OAQPS provides overall coordination to facilitate the exchange of information
among Regional Air Offices and between Regions and EPA Headquarters offices on
Air/Superfund issues, procedures, and data. Coordination meetings are held several
times a year to bring together the ten Air/Superfund coordinators and outside experts to
exchange information, identify technical and policy issues requiring resolution, and to
provide feedback about on-going research projects. Regular mailings are also distributed
that summarize recent activities at specific Superfund sites and that update technical
information and guidance.
Workshops and training courses are held several times a year to instruct EPA
staff, other regulatory people, and EPA contractors on the key issues, priorities, methods,
and procedures related to air pathway work at Superfund sites. This training includes
both Vi-day courses for specific EPA regional offices and 2-day courses open to a
nationwide audience.
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Technical assistance is offered to Regional Air offices to help them evaluate air
issues for individual Superfund sites and review documents prepared by contractors. The
technical assistance also may take the form of analyzing candidate remedial actions and
making recommendations about how to minimize effects on air quality.
The fourth activity of OAQPS is the preparation of national technical guidance
series (NTGS) documents. Since the Air/Superfund program began in 1987, a number
of NTGS documents have been prepared. Among these documents are a four-volume
series on air pathway analysis1"4. These have been distributed to federal, state, and local
agencies, as well as to consultants and industrial users, and have been widely used. A
number of documents have also been prepared that focus on specific air pathway issues
or applications. A full listing of NTGS series documents prepared to date appears in
Appendix C.
62 ACCOMPLISHMENTS TO DATE
In its first years, the Superfund program was principally concerned with
groundwater contamination and the subsurface migration of contaminants. The
Air/Superfund program has been successful in alerting RPMs and others to the need to
give equal consideration to the air pathway of contaminant exposure, along with all other
exposure pathways. The Air/Superfund program also has been successful at providing
EPA staff and their contractors with the technical guidance and training necessary to
perform air pathway assessments (APAs). To a large extent, this support has been
provided through the distribution of technical reports prepared under the direction of the
Air/Superfund program. The accomplishments to date of the program are summarized
in Table 6-1. The technical studies and related reports prepared through the
Air/Superfund program, or with its active support, are summarized in Table 6-2.
6.3 FRAMEWORK FOR FUTURE WORK
The long-term goal of the Air/Superfund program is to lead and support the
regional EPA offices in addressing the potential air effects of Superfund sites on air
quality. To meet this goal, feedback is regularly solicited about how the program is
doing, what data gaps/guidance needs exist, and what projects should be undertaken to
meet these needs.
The coordination, training, and technical assistance activities of the Air/Superfund
program are expected to continue in their current form. Two recent trends will probably
continue: 1) There will be a greater need for technical assistance on specific problems
or concerns at individual sites than for generalized guidance; and 2) Guidance
documents produced will cover limited topics but in great detail. These trends are the
result of a growing awareness of air pathway issues. As a result, there is less of a need
to provide general background information to EPA staff and contractors who are
performing APAs and more of a need to provide prescriptive (i.e., step-by-step, how-to)
technical guidance.
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Table 6-1.
Summary of Air/Superfund Program Accomplishments To Date.
Program Component
Example Activities
1. Coordination
la. Program coordination w/OSWER
Ib. Quarterly summaries of regional activities
Ic. Distribution of reports
Id. Semi-annual meetings of Air/Superfund coordinators
National APA workshop co-sponsored by AWMA
Regional one-day workshops
APA training module for RPM/OSC academy
Instructional programs for regional staff
2. Training
2a.
2b.
2c.
2d.
3. Technical
Assistance
3a. Review of air impacts for specific sites
3b. Review of state regulations for specific cleanup options
3c. Review of ARARs for specific sites
3d. Summary of health-based action levels for metals
3e. Glossary of health and exposure terminology
4. National
Technical
Guidance Studies
4a. Site emissions
Emission rate estimates
Emission rate measurements
Ambient air monitoring
Air emission controls
4b. Dispersion modeling
4c. Health effects
4d. Other topics [see Appendix C for a complete list of reports]
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Table 6-2.
Overview of Air/Superfund Reports to Date
Topic Area
Site Emissions
* Emission Rate Estimates
* Emission Rate Measurements
* Ambient Air Monitoring
* Controls
Dispersion Modeling
Health Effects
Other Topics
Applicable Reports
Baseline
NTGS Series Volume II: Estimation of Baseline Air Emissions at Supcrfund Sites. Aug. 1990.
Guideline For Predictive Baseline Emissions Estimation Procedures For Supcrfund Sites. January 1992.
During Remediation
NTGS Series Volume III: Estimation of Air Emissions from Clean-up Activities at Superfund Sites.
January 1989.
Comparison of Air Stripper Simulations and Field Data. March 1990.
Air Stripper Design Manual. May 1990.
Development of Example Procedures for Evaluating the Air Impacts of Soil Excavation Associated With
Superfund Remedial Actions. July 1990.
Emission Factors For Superfund Remediation Technologies. March 1991.
Estimation of Air Impacts for Air Stripping of Contaminated Water. August 1991.
Estimation of Air Impacts for Soil Vapor Extraction (SVE) Systems. January 1992.
Screening Procedures For Estimating the Air Impacts of Incineration at Superfund Sites. February 1992.
Estimation of Air Impacts for the Excavation of Contaminated Soil. March 1992.
NTGS Series Volume II: Estimation of Baseline Air Emissions at Superfund Sites. Aug 1990.
Field Measurement of VOC Emissions From Soil Handling Operations at Superfund Sites. September
1990.
Database of Emission Rate Measurement Projects - Draft Technical Note. May 1991.
NTGS Series Volume W: Procedures for Dispersion Modeling and Air Monitoring for Superfund Air
Pathway Analyses. July 1989.
Guidance on Applying the Data Quality Objectives Process for Ambient Air Monitoring Around Superfund
Sites (Stages I & II). August 1989.
Guidance on Applying the Data Quality Objectives Process for Ambient Air Monitoring Around Superfund
Sites (Stage III). March 1990.
Contingency Plans at Superfund Sites Using Air Monitoring. September 1990.
Applicability of Open Path Monitors For Superfund Site Clean-Up. May 1992.
Soil Vapor Extraction VOC Control Technology Assessment. September 1989.
Control of Air Emissions From Superfund Sites (sponsored by EPA-CERI). July 1992.
A Workbook of Screening Techniques for Assessing Impacts of Toxic Air Pollutants. September 1988.
NTGS Series Volume IV: Procedures for Dispersion Modeling and Air Monitoring for Superfund Air
Pathway Analyses. July 1989.
Review and Evaluation of Area Source Dispersion Algorithms for Emission Sources at Superfund Sites.
November 1989.
Users Guide for the Fugitive Dust Model. May 1990.
Estimation of Air Impacts for Air Stripping of Contaminated Water. August 1991.
Estimation of Air Impacts for Soil Vapor Extraction (SVE) Systems. January 1992.
Screening Procedures For Estimating the Air Impacts of Incineration at Superfund Sites. February 1992.
Estimation of Air Impacts for the Excavation of Contaminated Soil. March 1992.
Guideline For Predictive Baseline Emissions Estimation Procedures For Superfund Sites. January 1992.
Estimation of Air Impacts for Air Stripping of Contaminated Water. August 1991.
Estimation of Air Impacts for Soil Vapor Extraction (SVE) Systems. January 1992.
Screening Procedures For Estimating the Air Impacts of Incineration at Superfund Sites. February 1992.
Estimation of Air Impacts for the Excavation of Contaminated Soil. March 1992.
Superfund Air Pathway Analysis Review Criteria Checklists. January 1990.
Indoor Air Impacts from Superfund Sites.
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An annual review is performed to determine what projects should be
funded as part of the Air/Superfund program. Staff from each region and OAQPS
suggest study topics and vote on which projects are most needed. As part of this review,
about every two years the currently available documents will be reviewed to determine if
they should be revised. This document (Volume I of the NTGS series) will continue to
serve as an overview of Air/Superfund issues and will be updated every two years or as
needed. There are no plans to completely revise the three remaining volumes of the
NTGS series2'3'4; they will gradually be superseded by various reports that address
individual topics. Volume I of the NTGS series will direct readers to the latest or best
information available on each topic of interest.
For several reasons, the types of technical information and reports needed
by the scientific community performing APA work will change with time. First, some
past needs will cease to exist when specific technical guidance becomes available. For
example, several years ago there was a lack of procedures and tools for estimating
emissions from remediation technologies such as air slippers and, therefore, a number of
guidance documents have been prepared that address that need.
Second, some new needs will become more pressing as an increasing
percentage of NPL sites move into the remediation phase. The emphasis on predicting
potential future emissions will decrease and the emphasis on designing air emission
control strategies will increase. The design and operation of air monitoring networks to
detect any adverse effects on local air quality will also be of greater interest. Third,
changing technology will create a need for new information and guidance. A large
number of technologies are being evaluated by EPA for possible use at Superfund sites,
such as novel biodegradation and stabilization processes. The potential air impacts of
these processes will be of concern to regulatory staff. Fourth, changing regulations will
create the need for information and guidance about cost-effective compliance. Remedial
actions at Superfund sites must comply with all Applicable or Relevant and Appropriate
Regulations (ARARs) such as the Clean Air Act Amendments (CAAA).
Several key issues to be addressed by the Air/Superfund program over the
next several years are:
1. Guidance about air monitoring methods to use for specific
compounds to provide rapid feedback to on-site decision makers;
2. Guidance on establishing appropriate risk-based action levels for
removal and remedial actions; and
3. Guidance about how air issues will be affected by EPA's program to
accelerate the Superfund clean-up process.
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In the short term, a number of documents are currently under development
by the Air/Superfund program and should be available within the next year, including:
• Guidance on Appropriate Short-Term Health-Based Action Levels
for Ambient Air Monitoring Networks at Superfund Sites;
• Models for Estimating Air Emissions From Superfund Remedial
Actions;
• Estimation of Air Impacts for the Treatment of Contaminated Soil
by Thermal Desorption;
• Estimation of Air Impacts for Stabilization/Solidification;
• Estimation of Air Impacts for Bioventing;
• Estimation of Air Impacts from Particulate Matter Emissions From
Materials Handling Operations;
• Evaluation of Real-Time Air Monitoring Equipment; and
• Guidance for Performing Ambient Air Monitoring at Superfund
Sites (supercedes parts of Volume IV of the NTGS series).
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SECTION 7
REFERENCES
1. Stoner, R., et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 1 - Application of
Air Pathway Analyses for Superfund Activities. EPA-450/1-89-001 (NTIS
PB90-113374/AS). July 1989.
2. Schmidt, G, et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 2 - Estimation of
Baseline Air Emissions at Superfund Sites. EPA-450/l-89-002a (NTIS
PB90-270588). August 1990.
3. Eklund, B., et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 3 - Estimation of
Air Emissions From Clean-up Activities at Superfund Sites. EPA-450/1-
89-003 (NTIS PB89-180061/AS). January 1989.
4. Stoner, R., et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 4 - Procedures for
Dispersion Modeling and Air Monitoring for Superfund Air Pathway
Analyses. EPA-450/1-89-004 (NTIS PB90-113382/AS). July 1989.
5. Eklund, B., S. Smith, and M. Hunt. Estimation of Air Impacts For Air
Stripping of Contaminated Water. EPA-450/1-91-002 (NTIS PB91-
211888), May 1991 (Revised August 1991).
6. Eklund, B., S. Smith, P. Thompson, and A. Malik. Estimation of Air
Impacts For Soil Vapor Extraction (SVE) Systems. EPA 450/1-92-001
(NTIS PB92-143676), January 1992.
7. Eklund, B., S. Smith, and A. Hendler. Estimation of Air Impacts For the
Excavation of Contaminated Soil. EPA 450/1-92-004 (NTIS PB92-171925),
March 1992.
8. Konz, JJ. of EPA's Toxics Integration Branch. Memorandum on Air
Action Levels to Regional Air/Superfund Coordinators. March 12, 1992.
9. Draves, J. and B. Eklund. Applicability of Open Path Monitors for
Superfund Site Clean-Up. EPA-451/R-92-001. May 1992.
10. U.S. EPA. National Oil and Hazardous Substances Pollution Contingency
Plan (NCP). 40 CFR Part 300, Volume 55, No. 46. March 8, 1990.
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11. U.S. EPA. Superfund Removal Procedures: Guidance on the
Consideration of ARARs During Removal Actions. OERR/ERD. NTIS
PB92-963401. August 1991.
12. U.S. EPA. CERCLA Compliance With Other Laws Manual Parts I and II.
OSWER Directives 9234.1-01 and 9234.1-02. Office of Emergency and
Remedial Response, Washington, D.C. EPA-540/G-89/006, August 1988
and EPA-540/G-89/009, August 1989.
13. Eklund, B., P. Thompson, A. Inglis, and W. Dulaney. Air Emissions From
the Treatment of Soils Contaminated With Petroleum Fuels and Other
Substances. EPA-600/R-92-124. U.S. EPA, Control Technology Center,
My 1992.
14. Sykjes, A, W. Preston, and D. Grosse. Volatile Emissions from
Stabilization/Solidification of Hazardous Waste. Presented at the 85th
Annual AWMA Meeting in Kansas City, MO (Paper No. 92-98.07). June
21-26, 1992.
15. U.S. EPA. Technical Support Services for Superfund Site Remediation:
Interim Directory. EPA/540/8-90/001. February 1990.
16. Anonymous. The Search For Air Pollution Information - Where To Go,
Who To Ask. The Air Pollution Consultant. pp4.1-4.20. July/August
1992.
17. U.S. EPA, Compendium of Superfund Program Publications. EPA/540/8-
91/014. November 1991.
18. U.S. EPA. The Superfund Innovative Technology Evaluation Program:
Technology Profiles - 4th Edition. EPA/540/5-91/008. November 1991.
19. Code of Federal Regulations, Title 29, Subtitle B, Chapter XVII, Part
1910.1000, USGPO, 1991, July 1, 1990.
20. OSHA Manual of Analytical Methods, 2nd Edition, Part 1 - Organic
Substances, Methods 1-80, USDOL, OSHA, Salt Lake City Analytical
Laboratory, Salt Lake City, Utah, January 1990. Part 2 - Inorganic
Substances, May 1991.
21. NIOSH Manual of Analytical Methods, 3rd Edition, P.M. Eller, Editor.
U.S. Department of Health and Human Services, National Institute of
Occupational Safety and Health, Cincinnati, Ohio. February 1984.
22. U.S. EPA. Ambient Monitoring Guidelines for Prevention of Significant
Deterioration (PSD). EPA-450/4-87-007. May 1987.
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23. Code of Federal Regulations. Title 40, Part 50, Appendices A-G, and J.
USGPO. 1987.
24. U.S. EPA. Compendium of Methods for Determination of Toxic Organic
Compounds in Air. EPA/600/4-89-017, June 1988.
25. Anderson, E., S. Jenkins, and A. Hendler. Guidance and Recommended
Procedures For Monitoring of Toxic Compounds in Ambient Air. EPA
Contract No. 68-02-4392, WA85. Report to Mary Kemp, U.S. EPA,
Region VI. September 26, 1990.
26. McClenny, W., J. Pleil, G. Evans, K. Oliver, M. Holdren, and W. Winberry.
Canister-Based Method for Monitoring Toxic VOCs in Ambient Air. J.
Air Waste Manage. Assoc., Vol. 41, No. 10, pp!308-1318. October 1991.
27. Lodge, James P. - Editor. Methods of Air Sampling and Analysis, 3rd
Edition. ISBN 0-87371-141-6. 1989.
28. U.S. EPA. Removal Program Representative Sampling Guidance - Air.
Draft Report. EPA/ERB/ERD/OERR/OSWER. December 1991.
29. Grant, W.B., R.H. Kagann, and W.A. McClenny. Optical Remote
Measurement of Toxic Gases. J. Air Waste Manage Assoc., Vol. 42, No.
18, ppl8-30. January 1992.
30. Spellicy, R.L., W.L. Crow, J.A. Draves, W.F. Buchholtz, and W.F. Herget.
Spectroscopic Remote Sensing Addressing Requirements of the Clean Air
Act. Spectroscopy, Vol. 6, No. 9, pp24-34. Nov/Dec 1991.
31. U.S. EPA. On-Site Meteorological Program Guidance for Regulatory
Modeling Applications. EPA-450/4-87-013. June 1987.
32. U.S. EPA. Quality Assurance Handbook for Air Pollution Measurements
Systems: Volume IV, Meteorological Measurements. EPA-600/4-82-060.
February 1983.
33. U.S. EPA. Guideline on Air Quality Models (Revised). EPA-450/2-78-
027R (NTIS PB86-245248). Office of Air Quality Planning and Standards,
Research Triangle Park, NC. July 1987.
34. Paul, R. Contingency Plans at Superfund Sites Using Air Monitoring.
EPA-450/1-90-005. September 1990.
35. Salmons, C, F. Smith, and M. Messner. Guidance on Applying the Data
Quality Objectives For Ambient Air Monitoring Around Superfund Sites
(Stages I & II). EPA-450/4-89-015. August 1989.
7-3
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36. Smith, F., C. Salmons, M. Messner, and R. Shores. Guidance on Applying
the Data Quality Objectives For Ambient Air Monitoring Around
Superfund Sites (Stages III). EPA-450/4-90-005. March 1990.
37. Code of Federal Regulations. Volume 45, Number 9, Appendix A.
January USGPO. 1980.
38. Kienbusch, M. Measurement of Gaseous Emission Rates from Land
Surfaces Using an Emission Isolation Flux Chamber - User's Guide. EPA
600/8-86-008 (NTIS PB86-223161). February 1986.
39. Eklund, B. Practical Guidance for Flux Chamber Measurements of
Fugitive Volatile Organic Emission Rates. (Paper No. 92-66.07). Journal
of the Air and Waste Management Association (in press). 1992.
40. Eklund, B., C. Petrinec, D. Ranum, and L. Hewlett. Database of Emission
Rate Measurement Projects -Draft Technical Note. EPA-450/1-91-003
(NTIS# PB91-222059LDL). June 1991.
41. Eklund, B. User's Guide for the Measurement of Gaseous Emissions
From Subsurface Wastes Using a Downhole Flux Chamber. EPA Contract
No. 68-CO-0003, WA 0-13, Task 3. Report to Michelle Simon of U.S.
EPA, Cincinnati, OH. May 1, 1991.
42. Devitt, D.A., R.B. Evans, W.A. Jury, T.H. Starks, B. Eklund, and A.
Gholson. Soil Gas Sensing for Detection and Mapping of Volatile
Organics. (EPA/600/S8-87/036) National Water Well Association, Dublin,
OH. 1987.
43. Scotto, R.L., et al. "VOC Emission Rate Determination Using Open-Path
FTIR Spectroscopy During Pilot Scale Site Disturbance and Remediation
Activities: A Case Study Using the Ratio Technique" (Paper No. 92-83.04).
Presented at the 85th Annual Meeting of the Air and Waste Management
Association, Kansas City, MO, June 21-26, 1992.
44. Eklund, B. Estimation of VOC Emissions From Excavation Activities at
the Gulf Coast Vacuum Site - Revised Summary Report. EPA Contract
No. 68-CO-0003, WA 1-13, Task 7. Report to Michelle Simon of U.S.
EPA, Cincinnati, OH. June 15, 1992.
45. Vancit, M., R. Howie, D. Herndon, and S. Shareef. Air Stripping of
Contaminated Water Sources - Air Emissions and Controls. EPA-450/3-
87-017. August 1987.
46. Damle, A.S., and T.N. Rogers. Air/Superfund National Technical
Guidance Study Series: Air Stripper Design Manual. EPA-450/1-90-003.
May 1990.
7-4
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47. Pederson, T. and J. Curtis. Soil Vapor Extraction Technology: Reference
Handbook. EPA/540/2-91/003. 1991.
48. Oppelt, E.T. Incineration of Hazardous Waste - A Critical Review.
JAPCA, Vol. 37, No. 5, pp558-586, May 1987.
49. Troxler, W.L., JJ. Cudahy, R.P. Zink, and S.I. Rosenthal. Thermal
Desorption Guidance Document For Treating Petroleum Contaminated
Soils. Draft Report to James Yezzi, EPA-Edison, NJ. 1992.
50. Dosani, M. and J. Miller. Survey of Materials-Handling Technologies Used
at Hazardous Waste Sites. EPA/540/2-91-010. June 1991.
51. Church, H. Excavation Handbook. McGraw-Hill, NY, NY. 1981.
52. Radian Corp. Preliminary Assesment of Potential Organic Emissions from
Dredging Operations. Report to Dennis Timberlake, U.S. EPA, Cincinnati,
OH. September 1991.
53. Cowherd, G, P. Englehart, G. Muleski, and J. Kinsey. Hazardous Waste
TSDF Fugitive Paniculate Matter Air Emissions Guidance Document.
EPA 450/3-89-019. May 1989.
54. U.S. EPA Handbook for Stablilization/Solidification of Hazardous
Wastes. Report No. EPA-540/2-86/001. U.S. EPA, Cincinnati, OH, June
1986.
55. Ponder, T.C. and D. Schmitt. Field Assessment of Air Emissions from
Hazardous Waste Stabilization Operations. In: Proceedings of the 17th
Annual HWERL Conference, pp532-542. EPA/600/9-91/002. April 1991.
56. Eklund, B., et al. Control of Air Emissions From Superfund Sites. EPA
report in press. U.S. EPA, Center for Environmental Research
Information, June 1992.
57. Eklund, B. and C. Albert. Models For Estimating Air Emission Rates
From Superfund Remedial Actions. EPA Contract No. 68-DO-0125, WA75.
Draft Report to James Durham, U.S. EPA, RTP, NC. July 31, 1992.
58. Eklund, B. and J. Summerhays. Procedures for Estimating Emissions From
the Cleanup of Superfund Sites. J. Air Waste Manage. Assoc., Vol. 40, No.
1, pp 17-23. January 1990.
59. Mann, C. and J. Carroll. Guideline For Predictive Baseline Emissions
Estimation Procedures For Superfund Sites. EPA-450/1-92-002. January
1992.
7-5
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60. Schultz, H.L, et al. Superfund Exposure Assessment Manual (SEAMs).
EPA/540/1-88/001. April 1988.
61. Carroll, J. Screening Procedures For Estimating the Air Impacts of
Incineration at Superfund Sites. EPA-450/1-92-003. February 1992.
62. Sharp-Hansen, S. Available Models for Estimating Emissions Resulting
from Bioremediation Processes: A Review. EPA/600/3-90/031. March
1990.
63. U.S. EPA. Hazardous Waste Treatment, Storage, and Disposal Facilities
(TSDF) - Air Emission Models. EPA-450/3-87-026. November 1989.
64. Breton, M., T. Nunno, P. Spawn, W. Farino, and R. Mclnnes. Evaluation
and Selection of Models for Estimating Air Emissions From Hazardous
Waste Treatment, Storage, and Disposal Facilities. EPA-450/3-84-020.
December 1984.
65. Johnson, P.C. and R. A. Ettinger. Heuristic Model for Predicting the
Intrusion Rate of Contaminant Vapors Into Buildings. EST Vol. 25, No. 8,
pp!445-1452, 1991.
66. U.S. EPA. Chemical, Physical, and Biological Properties of Compounds
Properties Present at Hazardous Waste Sites. OSWER Directive No.
9850.3 (NTTS# PB89-132203). September 27, 1985.
67. The Merck Index, llth Ed. Merck & Co. Rahway, NJ. 1989.
68. CRC Handbook of Chemistry and Physics, 61st Edition. CRC Press. Boca
Raton, Florida. 1980.
69. Lyman, W.F., F.W. Reehl, and D.H. Rosenblatt. Handbook of Chemical
Property Estimation Methods. McGraw-Hill, NY. 1990.
70. Thompson, P., A. Ingles, and B. Eklund. Emission Factors For Superfund
Remediation Technologies. EPA-450/1-91-001 (NTIS# PB91-190-975),
March 1991.
71. U.S. EPA. AP-42: Compilation of Air Pollutant Emission Factors, Fourth
Edition. U.S. EPA, Office of Air Quality Planning and Standards,
Research Triangle Park, NC. September 1985.
72. U.S. EPA Handbook: Control Technologies for Hazardous Air Pollutants.
EPA/625/6-91/014. June 1991.
7-6
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73. Buonicore, A., W. Davis - Editors. Air Pollution Engineering Manual.
(AP-40). Published by the Air & Waste Management Association and Van
Nostrand Reinhold, NY, NY. 1992.
74. Hesketh, H.E. Air Pollution Control: Traditional and Hazardous
Pollutants. Technomic Publishing Co., Lancaster, PA. 1991.
75. U.S. EPA OAQPS Control Cost Manual - 4th Edition. EPA 450/3-90-
006. January 1990.
76. Vatavuk, W. Estimating Costs of Air Pollution Control Equipment. Lewis
Publishers (ISBN 0-87371-142-4). 1990.
77. TRC Environmental Consultants. Review and Evaluation of Area Source
Dispersion Alogrithms for Emission Sources at Superfund Sites. EPA-
450/4-89-020. November 1989.
78. U.S. EPA. Contingency Response Modeling Guidance. In press.
79. U.S. EPA. Screening Procedures for Estimating the Air Quality Impacts of
Stationary Sources. EPA-450/4-88-010. August 1988.
80. U.S. EPA. User's Guide to TSCREEN - A Model for Screening Toxic Air
Pollutant Concentrations. EPA-450/4-90-013. 1990.
81. U.S. EPA A Workbook of Screening Techniques for Assessing Impacts of
Toxic Air Pollutants. EPA-450/4-88-009. September 1989.
82. U.S. EPA. User's Guide for the Industrial Source Complex (ISC2)
Dispersion Models, Volume I - User Instructions. EPA 450/4-92-008a.
Office of Air Quality Planning and Standards, Research Triangle Park, NC.
March 1992.
83. U.S. EPA. User's Guide for the Fugitive Dust Model (FDM)(Revised),
User's Instructions. EPA-910/9-88-202R (NTIS PB90-215203, PB90-
502410). January 1991.
84. U.S. EPA. Guideline for Determination of Good Engineering Practice
Stack Height (Technical Support Document for Stack Height Regulations
(Revised). EPA 450/4-80-023R. Office of Air Quality Planning and
Standards, Research Triangle Park, NC. June 1985.
85. Calabrese, Edward J., and Elaina M. Kenyon. Air Toxics and Risk
Assessment Lewis Publishers, Chelsea, Michigan. 1991.
86. Code of Federal Regulations. Title 29, Part 1910.1000 - OSHA General
Industry Air Contaminants Standard. USGPO.
7-7
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87. U.S. EPA. Interim Methods for Development of Inhalation References
Doses. Environmental Criteria and Assessment Office. APE/600/8-
88/066F. 1989.
88. American Conference of Governmental Industrial Hygienists (ACGIH).
Threshold Limit Values for Chemical Substances and Physical Agents and
Biological Exposure Indices. ACGIH Cincinnati, OH, 1992.
89. National Institute for Occupational Safety and Health (NIOSH). NIOSH
Pocket Guide to Chemical Hazards. U.S. Department of Health and
Human Services, Washington, DC, 1990.
90. Federal Register. Volume 55, No. 145. USGPO. Friday, July 27, 1990.
91. Federal Register. Availability of the Integrated Risk information System
(IRIS). 53 Federal Register 20162. June 2, 1988.
92. U.S. EPA First Priority List of Hazardous Substances that will be the
Subject of Toxicological Profiles. 52 Federal Register 12866. April 17,
1987.
93. U.S. EPA. Directory of Information Resources Related to Health,
Exposure, and Risk Assessment of Air Toxics. Air Risk Information
Support Center (Air RISC). EPA/450/3-88-015. August 1989.
94. American Society for Testing and Materials, F.A. Fazzalari-Editor.
Compilation of Odor and Taste Threshold Values Data. ASTM Data
Series DS 48A, ASTM, PHiladelphia, PA.
95. American Industrial Hygiene Association. Odor Thresholds for Chemicals
with Established Occupational Health Standards. AIHA, Akron, OH.
1989.
96. U.S. EPA. Risk Assessment Guidance for Superfund Volume I, Human
Health Evaluation Manual (Part A). EPA/540/1-89/002. Office of
Emergency and Remedial Response, Washington DC, 1989.
97. U.S. EPA. Risk Assessment Guidance for Superfund Volume I, Human
Health Evaluation Manual (Part B, Development of Risk-based
Preliminary Remediation Goals) - Interim. Publication 9285.7-01B. Office
of Emergency and Remedial Response, Washington DC. October 1991.
98. U.S. EPA. Risk Assessment Guidance for Superfund Volume I, Human
Health Evaluation Manual (Part C, Risk Evaluation of Remedial
Alternatives) - Interim. Publication 9285.7-01C. Office of Emergency and
Remedial Response, Washington DC. October 1991.
7-8
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99. Committee on Toxicology, National Research Council. Criteria and
Methods for Preparing Emergency Exposure Guidance Level (EEGL),
Short-Term Public Emergency Guidance Level (SPEGL), and Continuous
Exposure Guidance Level (CEGL) Documents. National Academy Press,
Washington, DC. 1986.
100. U.S. EPA. Exposure Assessment Methods Handbook. Draft. Office of
Health and Environmental Assessment. 1989.
101. U.S. EPA Risk Assessment Guidance for Superfund, Volume II,
Environmental Evaluation Manual - Interim Final. EPA/540/1-89/001.
March 1989.
102. Oak Ridge National Laboratory. Environmental Sciences Division User's
Manual For Ecological Risk Assessment, L.W. Barnthouse and G.W. Suter
II - Editors. U.S. EPA, Office of Research and Development. ORNL-
6251, DE86 010063. March 1986.
7-9
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APPENDIX A
USEFUL CONTACTS AND TELEPHONE NUMBERS
-------
APPENDIX A
USEFUL CONTACTS AND TELEPHONE NUMBERS
1. EPA Regional Offices
Each EPA regional office has the following staff positions:
• Air/Superfund Coordinator;
• ARARs Coordinator; and
• Air Toxics Coordinator.
The Air/Superfund coordinator is the best single point of contact for air issues
related to Superfund Sites. The individuals in the staff positions listed above can be
reached through the office switchboards at the following numbers:
Region
I
II
ni
IV
V
VI
VII
VIII
IX
X
Location
Boston
New York
Philadelphia
Atlanta
Chicago
Dallas
Kansas City
Denver
San Francisco
Seattle
Telephone Number
(617) 565-3420
(212) 264-2657*
(215) 597-9800
(404) 347-3004
(312) 353-2000
(214) 655-6444
(913) 551-7000
(303) 293-1603
(415) 744-1305
(206) 442-1200
*Air Programs Branch x-2517
2. Air/Superfund Program Contact
The primary contact for the Air/Superfund program is Mr. Joseph Padgett of
EPA's Office of Air Quality Planning and Standards at (919) 541-5589.
3. Document Ordering Information
Documents can be obtained through the National Technical Information Service
(NTIS) at (703) 487-4650. Information of Air/Superfund reports that are not yet in the
NTIS system can be obtained from Environmental Quality Management at (919) 489-
5299.
-------
4.
Other sources of documents include:
EPA's Control Technology Center (CTC) at (919) 541-0800;
• EPA's Center for Environmental Research Information (CERI) at (513)
569-7562; and
U.S. Government Printing Office (USGPO) at (202) 783-3238.
Other Useful Contacts
Air and Waste Management Associates (412) 232-3444.
5. Hotlines
(See Appendix B for descriptions)
OAQPS TTN Modem #
The OAQPS TTN consists of the following:
AIRS Database
BLIS Database
(RACT/BACT/LAER)
NATICH Database
TOXNET
IRIS
Andrea Kelsey
Joe Steigerwald
Vasu Kilaru
Information
User Support
(919) 541-5742
Bulletin Board
AMTIC
APTI
CHIEF
CTC
EMTIC
OAQPS
SCRAM
Contact
Joe Elkins
Betty Abramson
Michael Hamlin
Joe Steigerwald
Dan Bivins
Herschel Rorex
Russ Lee
Phone Number
(919) 541-5653
(919) 541-2371
(919) 541-5232
(919) 541-2736
(919) 541-5244
(919) 541-5637
(919) 541-5638
(919) 541-5549
(919) 541-2736
(919) 541-0850
(301) 496-6531
(513) 569-7254
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APPENDIX B
DESCRIPTION OF COMPUTER BULLETIN BOARDS
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APPENDIX B
DESCRIPTION OF COMPUTER BULLETIN BOARDS
1.
Office of Air Quality Planning and Standards (OAQPS) Technology
Transfer Network (TTN)
Modem #
919/541-5742 (2400/1200 baud)
919/541-1447 (9600 baud)
Assistance # 919/541-5384
The OAQPS Technology Transfer Network consists of a number of
individual bulletin boards:
AMTIC Ambient Monitoring Technology Information Center.
AMTIC provides information on ambient air monitoring
methods. Monitoring methods (e.g., Toxic Organic or TO
methods) can be downloaded. Updates and corrections to
current standard monitoring methods are also provided.
APTI Air Pollution Training Institute. The APTT bulletin board
posts course summaries, schedule changes, fees, and
registration information for courses offered by the APTI.
CAAA Clean Air Act Amendments. This bulletin board provides
summaries and the full text for each title of the 1990 CAAA.
CHEIF ClearingHouse for Inventories and Emission Factors. CHIEF
provides information on air emission inventories, emission
factors, inventory guidance, and agency announcements.
CTC Control Technology Center. This bulletin board provides
information on projects supported by the CTC related to
control technologies. A summary of CTC documents is
available, as are several emission models (e.g., SIMS).
EMTIC Emission Measurement Technology Information Center.
EMTIC provides technical information and guidance related
to source testing methods.
SCRAM Support Center for Regulatory Air Models. SCRAM is a
source of regulatory air dispersion models (e.g., ISC2).
SCRAM also provides updates and corrections to current
regulatory models, as well as surface meteorolgoical data and
mixing height data for many areas.
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2. OSVVER Electronic Bulletin Board
Modem # 202/589-8366 or 301/589-8366
The OSWER bulletin board is designed to facilitate communication and
the dissemination of information among EPA staff. The major features include
information bulletins, message exchange, file exchange, technical publication ordering,
and on-line databases and directories.
3. RODS Database
Registration # 202/252-0056
RODS contains Superfund Records of Decision (ROD) that describe the
planned course of action to clean up a site.
4. Alternative Treatment Technology Information Center (ATTIC)
Modem # 301/670-3808 (2400/1200 baud)
301/670-3813 (9600 baud)
Assistance # 301/670-6294
ATTIC provides access to four on-line databases: 1) treatment
bibliography, 2) water treatability database, 3) technical assistance directory, and 4)
calendar of events.
5. Center for Exposure Assessment Modeling (CEAM)
Modem # 706/546-3402 (9600/2400/1200 baud)
Assistance # 706/546-3549
CEAM provides exposure assessment software programs and databases.
6. Cleanup Information (CLU-IN)
Modem # 301/589-8366 (2400/1200 baud)
Assistance # 301/589-8368
CLU-IN provides information bulletins, databases, and a bibliography for
corrective action technology.
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APPENDIX C
BIBLIOGRAPHY OF NTGS DOCUMENTS
-------
APPENDIX C
BIBLIOGRAPHY OF NTGS DOCUMENTS
ASF-1 Stoner, R., et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 1 - Application of
Air Pathway Analyses for Superfund Activities. EPA-450/1-89-001 (NTIS
PB90-113374/AS). July 1989.
ASF-2 Schmidt, C., et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 2 - Estimation of
Baseline Air Emissions at Superfund Sites (Revised). EPA-450/l-89-002a
(NTIS PB90-270588). August 1990.
ASF-3 Eklund, B., et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 3 - Estimation of
Air Emissions From Clean-up Activities at Superfund Sites. EPA-450/1-
89-003 (NTIS PB89-180061/AS). January 1989.
ASF-4 Stoner, R., et al. Procedures for Conducting Air Pathway Analyses for
Superfund Activities, Interim Final Document: Volume 4 - Procedures for
Dispersion Modeling and Air Monitoring for Superfund Air Pathway
Analyses. EPA-450/1-89-004 (NTIS PB90-113382/AS). July 1989.
ASF-5 U.S. EPA, Procedures for Conducting Air Pathway Assessments for
Superfund Sites, Interim Final Document: Volume 5 - Dispersion
Modeling. [Proposed document].
ASF-6 TRC Environmental Consultants. A Workbook of Screening Techniques
For Assessing Impacts of Toxic Air Pollutants. EPA-450/4-88-009 (NTIS
PB89-134340). September 1988.
ASF-7 Salmons, C., F. Smith, and M. Messner. Guidance on Applying the Data
Quality Objectives For Ambient Air Monitoring Around Superfund Sites
(Stages I & II). EPA-450/4-89-015 (NTIS PB90-204603/AS). August 1989.
ASF-8 Pacific Environmental Services. Soil Vapor Extraction VOC Control
Technology Assessment. EPA-450/4-89-017 (NTIS PB90-216995).
September 1989.
ASF-9 TRC Environmental Consultants. Review and Evaluation of Area Source
Dispersion Algorithms for Emission Sources at Superfund Sites. EPA-
450/4-89-020 (NTIS PB90-142753). November 1989.
ASF-10 Letkeman, J. Superfund Air Pathway Analysis Review Criteria Checklists.
EPA-450/1-90-001 (NTIS PB90-182544/AS). January 1990.
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ASF-11 Smith, R, C. Salmons, M. Messner, and R. Shores. Guidance on Applying
the Data Quality Objectives For Ambient Air Monitoring Around
Superfund Sites (Stage III). EPA-450/4-90-005 (NTIS PB90-204611/AS).
March 1990.
ASF-12 Saunders, G. Comparisons of Air Stripper Simulations and Field
Performance Data. EPA-450/1-90-002 (NHS PB90-207317). March 1990.
ASF-13 Damle, A.S., and T.N. Rogers. Air/Superfund National Technical
Guidance Study Series: Air Stripper Design Manual. EPA-450/1-90-003
(NTIS PB9M25997). May 1990.
ASF-14 Saunders, G. Development of Example Procedures for Evaluating the Air
Impacts of Soil Excavation Associated with Superfund Remedial Actions.
EPA-450/4-90-014 (NTIS PB90-255662/AS). July 1990.
ASF-15 Paul, R. Contingency Plans at Superfund Sites Using Air Monitoring.
EPA-450/1-90-005 (NTIS PB91-102129). September 1990.
ASF-16 Stroupe, K., S. Boone, and C. Thames. User's Guide to TSCREEN - A
Model For Screening Toxic Air Pollutant Concentrations. EPA-450/4-90-
013 (NTIS PB91-141820). December 1990.
ASF-17 Winges, KD.. User's Guide for the Fugitive Dust Model (FDM)(Revised),
User's Instructions. EPA-910/9-88-202R (NTIS PB90-215203, PB90-
502410). January 1991.
ASF-18 Thompson, P., A. Ingles, and B. Eklund. Emission Factors For Superfund
Remediation Technologies. EPA-450/1-91-001 (NTIS PB91-190-975),
March 1991.
ASF-19 Eklund, B., C. Petrinec, D. Ranum, and L. Hewlett. Database of Emission
Rate Measurement Projects -Draft Technical Note. EPA-450/1-91-003
(NTIS PB91-222059). June 1991.
ASF-20 Eklund, B., S. Smith, and M. Hunt. Estimation of Air Impacts For Air
Stripping of Contaminated Water. EPA-450/1-91-002 (NTIS PB91-
211888), May 1991 (Revised August 1991).
ASF-21 Mann, C. and J. Carroll. Guideline For Predictive Baseline Emissions
Estimation Procedures For Superfund Sites. EPA-450/1-92-002 (NTIS
PB92-171909). January 1992.
ASF-22 Eklund, B., S. Smith, P. Thompson, and A. Malik. Estimation of Air
Impacts For Soil Vapor Extraction (SVE) Systems. EPA-450/1-92-001
(NTIS PB92-143676/AS), January 1992.
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ASF-23 Carroll, J. Screening Procedures For Estimating the Air Impacts of
Incineration at Superfund Sites. EPA-450/1-92-003 (NTIS PB92-171917).
February 1992.
ASF-24 Eklund, B., S. Smith, and A. Hendler. Estimation of Air Impacts For the
Excavation of Contaminated Soil. EPA-450/1-92-004 (NTIS PB92-171925),
March 1992.
ASF-25 Draves, J. and B. Eklund. Applicability of Open Path Monitors for
Superfund Site Cleanup. EPA-451/R-92-001. May 1992.
Reports Hearing Completion
Eklund, B. and C. Albert. Models For Estimating Air Emission Rates
From Superfund Remedial Actions. EPA Contract No. 68-DO-0125, WA75.
Report to James Durham, U.S. EPA, RTF, NC. July 31, 1992.
U.S. EPA. Contingency Response Modeling Guidance. In press.
Affiliated Reports Nearing Completion
Eklund, B., et al. Control of Air Emissions From Superfund Sites. Final
Revised Report (in press). U.S. EPA, Center for Environmental Research
Information, August 31, 1992.
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APPENDIX D
INDEX TO VOLUMES II, III, AND IV
of the
National Technical Guidance Studies Series
-------
Index to NTGS Volumes II, III, and IV
Acid gas emissions from incinerator
Acronyms/abbreviation
Air emissions from hazardous waste sites
average from various sources
receptor
estimation using flux measurements
magnitude
NPL sites
parameters affecting estimates of
routes of exposure
Air monitoring plan
source data
receptor data
environmental characteristics
monitoring network
Air pathways analysis
flowchart, for remediation
example guide
Air stripping
applicable control technologies
emissions estimation
emission sources
key parameters
illustration
Analysis
of modeling results
of monitoring results
Tech. Asist. Doc. for VOCs
Atmospheric dispersion modeling
environmental characteristics
receptor data
source data
Background concentrations to dispersion model
Bibliography
air monitoring methods
baseline emission estimates
emissions during remediation
Boundary layer emission monitoring
Case Studies
Bruin Lagoon
dispersion study 1
Lowry Landfill
Vol. II
85
xi
9
22
23
C-2
21
21,24
20
16
34
A-l
104
192
203
Vol. Ill
xii
70
38
88
34
36
15
2-1
2-58
A-l
Vol. IV
iv
3-1
3-8
3-11
3-12
3-41
C-2
2-67
3-98
B-2
2-21
2-19
2-17
A-2
4-4
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Index to NTGS Volumes II, III, and IV
monitoring study 1
monitoring study 2
monitoring study 3
monitoring study 4
Outboard Marine Corp. Lagoon/Landfill
Western Processing Landfill
Chemical properties
affecting emission estimates
Concentration profile screening technique
Controls
air stripping
efficiencies
emission parameters for
for each remedial option
in-situ venting
soils handling
thermal destruction
Dioxins, furans, PCDD, PCDF
emissions from incinerator
Dispersion modeling plan
background calculations
data quality objectives
emission inventory
modeling constituents
met. database
receptor grid
Dispersion estimation procedures
Dumping(see soil handling)
Emission factors
baseline VOCs for hazardous wastes
conversion to per unit time
excavation and grading
incineration
soils handling
Emission inventory for dispersion modeling
plan
Emission values, by source
Environmental characteristics
for dispersion modeling
for air monitoring
Estimation procedures
dispersion
Vol. II
219
212
B-l
96
D-l
74
Vol. Ill
38
58
67
72
49
56,68
27
77
2-37
104
120
100
79
97
2-46
Vol. IV
4-12
4-16
4-20
4-24
2-58
2-40
2-46
2-40
2-49
2-53
2-21
3-12
D-l
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Index to NTGS Volumes II, III, and IV
dumping emissions
excavation emissions
incinerator emissions
soils handling emissions
storage emissions
transport emissions
VOC emissions
Excavation (see also soil handling)
emissions estimation flowchart
Flux chamber
Fugitive emissions
hazardous waste sites model
from incinerator
Grading (see also soil handling)
emissions estimation flowchart
Headspace
samplers
analysis of bottled samples
Incineration (see thermal destruction)
factors to consider in selecting
In-situ soil venting
air-flow patterns in
applicable control technologies
emissions estimation
emission sources
illustrations
key parameters
Lagoons
aerated
general description
non-aerated
parameters affecting emissions
screening technologies
Landfills
closed landfills with internal gas generation
closed landfills with no internal gas
generation
general description
open landfills
parameters affecting emission
screening technologies
Landtreatment
Vol. II
69
155
64
66
40
40
121,124
11,14,18
120,124,171
19
43
116,137
115,126
10,12,17
117,144
19
43
Vol. Ill
Vol. IV
109
107
78
94
110
108
103
107
87
111
43
49
89
40
41-45
46
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Index to NTGS Volumes II, III, and IV
emission model
Leaks
emission model
Mast sample (see concentration-profile)
Measurement techniques
comparison of screening
concentration profile
flux chamber
Real-time instrument
relative ranking of screening
soil vapor probes
soil vapor
undisturbed waste, screening
upwind/downwind
vent samplers
wind tunnel
Metals
emissions from incinerator
enrichment on fugitive dust
vapor pressure
Meteorological data for dispersion model
Model constituents for dispersion modeling
Models:
aerated lagoons
closed landfills with no internal gas
generation
closed landfills with internal gas generation
dispersion see dispersion models
fugitive dust
landtreatment
leaks and spills on soil
non-aerated lagoons
open landfills
overall source, using flux measurements
National Priority List (Superfund)
emissions
most frequently reported emissions
abbreviations/acronyms
glossary
NOx
emissions from incinerator
Particle size
Vol. II
151
154
54
96
69,86
94
55
78
82
180
91
88
73
167
126
137
155
151
154
161
144
C-l
21
24
Vol. Ill
Vol. IV
83
112
84
2-49
2-40
xn
B-l
87
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Index to NTGS Volumes II, III, and IV
applicable control technologies
emissions estimation
Soil vapor extraction (see in-situ soil venting)
Source data
for dispersion modeling
for air monitoring
Spills
Stabilization/solidification
applicable control technologies
emissions estimation
emission sources
key parameters
Staff qualifications
dispersion modeling
air monitoring
Storage (see soil handling)
Thermal destruction
applicable control technologies
comparison of different technologies
emissions estimation
emission sources
key parameters
Process flow diagram
emission model
Transect screening technique
Upwind/downwind screening technique
Vent samplers
VOCs
conditions causing emissions of
flowchart for estimating emissions of
Tech. Assist. Doc. for sampling and analysis
Wind tunnel measurement technique
Vol. II
9
154
99
91
88
35
73
Vol. Ill
56
93
65
123
63
63
27
C-l
76
10
18
15
103
Vol. IV
2-17
3-8
2-60
3-91
B-2
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Index to NTGS Volumes II, III, and IV
distribution in emissions
multipliers
Paniculate emissions
baseline
conditions causing
from incinerator
from soil handling
monitoring techniques
Precipitation
no. of days with > 0.254 cm, by area
Physical properties (see chemical properties)
Pollutants
commonly addressed by state, local agencies
examples of broad-band, class, and indicator
potential, by type
sampling techniques
QA/QC
air monitoring plan
data quality objectives: dispersion modeling
plan
data quality objectives: emissions estimation
screening study
worst-case conditions for measurement
Real-time instrument screening technique
Receptor grid for dispersion model
Receptor data
for dispersion modeling
for air monitoring
References
References - baseline emission estimates
Solid Waste Landfill Survey
Sampling
Tech. Asist. Doc. for VOCs
Screening techniques (see measurement
techniques)
Soil boring
Soil Transport (see soil handling)
Soil vapor monitoring wells
Soil vapor probes
Soils handling
emission sources
key parameters
Vol. II
155
35
25
42
33
45
61
94
225
D-2
82
78
50
Vol. Ill
101
99
82
100
116
159
2-53
5-1
50
52
Vol. IV
3-24,3-64
3-60,3-62
3-94
2-40
2-19
3-11
B-2
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO. 2.
EPA-450/1/89-OOla
4. TITLE AND SUBTITLE
Air/Superfund National Technical Guidance Study Series
Volume I - Overview of Air Pathway Assessments for
Superfund Sites (Revised)
7. AUTHOR(S)
Bart EkTund .
9. PERFORMING ORGANIZATION NAME ANO ADDRESS
Radian Corporation
8501 Mb-Pac Boulevard
Austin, Texas 78759
12. SPONSORING AGENCY NAME ANO ADDRESS
U S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
November 1992
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
13. TYPE OF REPORT ANO PERIOD COVERED
Interim Final
14. SPONSORING AGENCY CODE
18. SUPPLEMENTARY NOTES
16. ABSTRACT
This document introduces and provides an overview of air pathway assessments
for Superfund sites. The specific objectives of this document are to 1) introduce the
basic elements of air pathway assessments (APA) for Superfund sites; 2) identify and
discuss the key issues related to APA work; and 3) identify the best sources of
published information and guidance for each typical component of APA work.
An APA is a systematic evaluation of the potential or actual effects on air
quality of an emission so.urce such as a Superfund site. The APA may involve modeling
or monitoring to estimate these effects. The primary components of an APA are:
characterization of air emission sources; determination of the effects of atmospheric
processes such as transport and dilution; and evaluation of the exposure potential
at receptors of interest.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Air Pollution
Superfund
Air Pathway Analysis
8. DISTRIBUTION STATEMENT
19. SECURITY CLASS (ThisReport)
21. NO. OF PAGES
20. SECURITY CLASS (This page)
22. PRICE
EPA Form 2220-1 (R«v. 4-77) PRCVIOU* COITION is OBSOLETE
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APPENDIX E
ANNUAL UPDATES
(annual updates will be added to this document in coming years that
identify any new sources of information or guidance)
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