EPA/540/G-91/004
                           OSWER Directive: 9360.7-03
                                  October 1990
Continuous Release—Emergency
  Response Notification System
                 and
    Priority Assessment Model
       Model Documentation
      Office of Emergency and Remedial Response (OS-210)
          U.S. Environmental Protection Agency
             Washington, DC 20460
                           U/S Printed on Recycled Paper

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The policies and procedures set forth here are intended as guidance to Agency and
other government employees. They do not constitute rulemaking by the Agency, and
may not be relied on to create a substantive or procedural right enforceable by any
other person.  The Government may take action that is at variance with the policies
and procedures in this manual.

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                                TABLE OF CONTENTS
1.     INTRODUCTION	   1
      1.1    Background	   1
      1.2    Purpose of Documentation	   2

2.     FATE AND TRANSPORT MODELS	.	..   3
      2.1    Atmospheric Dispersion Model	..-	   4
      2.2    Surface Water Model		   8
      2.3    Ground-water Model	:  10

3.     AUXILIARY DATA BASES  ..	,	  13
      3.1    SOILDATA ...	.	  13
      3.2    STARDATA 		  20
      3.3    CHEMTOX ....	  22

4.     EVALUATION OF MODELING RESULTS	  25
      4.1    Calculation of Air and Surface Water Intakes	  25
             4.1.1  Chemical Intakes via Inhalation	  26
             4.1.2  Chemical Intakes via Ingestion of Drinking Water	  26
             4.1.3  Radionuclide Intakes via Inhalation	  27
             4.1.4  Radionuclide Intakes via Ingestion of Drinking Water	  27
      4.2    Evaluation of Human Health and Ecological Effects	  27
             4.2.1  Calculation of Cancer Risk	  27
             4.2.2  Calculation of Noncancer Hazard Quotient	  28
             4.2.3  Evaluation of Radionuclide Effects	  28
             4.2.4  Evaluation of Ecological Effects  	  29
      4.3    Aggregation of Evaluation Results  	  29
             4.3.1  Cancer Risks	  30
             4.3.2  Noncarcinogenic Effects	  30
             4.3.4  Ecological Effects	  30
      4.4    Assignment of Evaluation Flags to PAM Results	  31

5.     UNDERSTANDING PAM OUTPUTS	  33
      5.1    Summary Facility Evaluation Report	  33
      5.2    Model Input Parameter Report  	  36
      5.3    Detailed Evaluation Report  	  44

Appendix A:  Radionuclide Fate and Transport Equations 	  55

Appendix B:  PAM Reports	  59
                                          111

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1.
INTRODUCTION
1.1    Background

       The Continuous Release Emergency Response Notification System/Priority Assessment
Model (CR-ERNS/PAM) is an integrated data base management system and screening level risk
assessment model developed by the U.S. Environmental Protection Agency (EPA) Emergency
Response Division. CR-ERNS/PAM will assist in implementing the continuous release reporting
regulations issued under section 103(f)(2) of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980, as amended (CERCLA). CR-ERNS and PAM are
installed in each EPA Region, typically on the Regional WASTELAN networks which currently
house the existing ERNS software.

       Under the continuous release reporting regulation, facilities may qualify for reduced
reporting for releases of hazardous substances that are equal to or greater than a reportable
quantity (RQ), if those releases are "continuous" and "stable in quantity and rate."  The reduced
reporting requirements for continuous releases consist of the following notifications:

       •      initial telephone notification;
       •      initial written notification;
       •      one-time written follow-up notification;
       •      immediate notification of a statistically significant increase in a release; and
       •      written notification of any other changes in a release.

All of the information in these notifications  is  collected and  tracked using CR-ERNS.

       PAM was developed to assist EPA Regional Superfund On-Scene Coordinators (OSCs) in
determining whether a continuous release poses a threat to human health or the environment.
PAM simulates releases of CERCLA hazardous substances (including the 757 specifically listed
radionuclides) to air, surface water, and soil/ground  water from a variety of sources:

       •      vents, valves, tanks, and other ground releases to air;
       •      volatile and particulate releases from waste piles to air;
       •      leakage from land-based units and tanks to ground water;
       •      stack releases to  air; and
       •      point source discharges to surface water.

PAM utilizes standard Superfund exposure and risk assessment protocols to estimate annual
average ambient contaminant concentrations in air and surface water  and their corresponding
cancer  risks and other chronic effects on human health, and  to estimate contaminant movement in
ground water. Based on these exposure and risk estimates, OSCs may quickly evaluate the effects
from continuous releases of hazardous substances and determine the need for a Federal response
action.

       PAM evaluates only the chronic (i.e., long-term) effects of releases of hazardous
substances; acute (i.e., short-term) effects of these releases are not evaluated.  If the reported
release consists of a few large releases per year rather than a series of more regular releases (i.e.,
daily or weekly), it  may be appropriate to consider the potential acute effects from these releases
in addition to the chronic or carcinogenic effects evaluated by PAM.

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1.2    Purpose of Documentation

       The purpose of this model documentation is to provide a detailed description of the
modeling and risk analysis procedures used in CR-ERNS/PAM to assist OSCs and other
Superfund decision-makers in interpreting the system results. PAM is a screening-level model; to
properly interpret PAM's outputs, the user must understand the limitations and uncertainties in
the equations and data used to generate these results.  Chapter 2 presents the system's fate and
transport models and describes the assumptions associated with these equations. Chapter 3
describes PAM's auxiliary data bases and provides the source(s) of each parameter and the
methods by which values were selected.  Chapter 4 explains the methods and exposure
assumptions used to estimate exposures to hazardous substances and to evaluate the risks and
hazards associated with,these exposures. Chapter 5 presents examples of reports generated by
PAM and explains  the meaning of the "flags" assigned to hazardous substances, media,  and
facilities.  Appendix A contains versions of the fate and transport equations used for
radionuclides.  Appendix B contains copies of PAM's reports.

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2.    FATE AND TRANSPORT MODELS

      This chapter documents the fate and transport models incorporated in PAM to assist users
in understanding the model results.  PAM uses information reported by facilities in Initial Written
and Follow-up Notifications to perform fate and transport analyses for the following
environmental media:

      •     air;
      •     surface water; and
      •     soil/ground water.

      In evaluating environmental threats from continuous releases, the user must remember that
PAM has been designed to be a screening-level model.   Because of limitations in data that will
be provided by facilities in their notifications, the fate and transport models are relatively simple
and rely on non-site-specific data for important hydrogeologic and climatic parameters. The
model results provide rough estimates of the magnitude of threats posed by continuous releases.

      The models  selected for inclusion in PAM were evaluated against the following criteria:

      (1)   Acceptance within the scientific community. EPA evaluated modeling approaches
            developed for or by the Agency, or modeling approaches that it has evaluated and
            accepted.  All of the models incorporated into PAM are referenced in EPA's
            Superfund Exposure Assessment Manual (SEAM).1

      (2)   Ability to run on limited site-specific data.  The models are all capable of evaluating
            risks based on readily available data on a regional level. The models do not require
            extensive site-specific data.

      (3)   Ability to run on limited Regional computer space.  Limitations in EPA Regional
            computer space eliminated the option of using complex numerical fate and transport
            programs that require considerable random access memory (RAM) and disk storage
            space.

      (4)   Accuracy appropriate for screening-level risk evaluations. The models provide
            reasonable, conservative estimates of human health and environmental threats
            sufficient to assist decision-makers in determining the need for response.

      PAM was developed to evaluate threats posed by continuous releases, not episodic releases
such as hazardous substance spills. The models incorporated into PAM provide estimates of
chronic (long-term) effects of continuous releases on human health and aquatic life.  The PAM
evaluation does not generate short-term concentrations of hazardous substances or evaluate the
acute (short-term)  effects of the releases on human health or aquatic life.  PAM, therefore, will
not typically provide concentration estimates consistent with actual sampling data taken from
    1 USEPA, Superfund Exposure Assessment Manual. Office of Emergency and Remedial
Response, April 1988. EPA/540/1-88/001.

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facilities, which generally reflect shorter-term measurements.  The system estimates only long-term
average hazardous substance concentrations.

      The sections below describe the methods chosen for each fate and transport model and the
assumptions of those methods, present the equations used, and briefly describe the sources of the
data required to support each model.

2.1   Atmospheric Dispersion Model

      The air transport component of PAM estimates exposure concentrations of hazardous
substances for two major types of release sources:  (1) stack sources and (2) area sources (e.g.,
waste piles, surface impoundments, and ground-level vents and releases). The primary criteria for
selecting an atmospheric fate and transport model were the following:  (1) the ability to evaluate
release and transport of volatile (vapor phase) hazardous substances, particulates, and
radionuclides; (2) the ability to simulate releases from both area and point sources; and (3) the
ability to predict contaminant concentrations at specific points of exposure.  Because of
differences in the mathematical solutions pertaining to these two kinds of sources, PAM
incorporates two distinct algorithms for estimating exposure concentrations from stack and area
sources.  Both algorithms use a Gaussian dispersion model to represent transport and dispersion
of hazardous substances.

      The atmospheric dispersion model selected for the area source component of PAM was
taken from MMSOILS, a multimedia fate and transport model developed by EPA's Office of
Research and Development (ORD) for use at Superfund sites.2 The model selected for
simulating releases from stacks was adapted from a component of the SCREEN model, developed
by EPA's Office of Air Quality Planning and Standards.   These models share the following
underlying basic assumptions:

      (1)   Emission rate  is uniform and continuous over the source.  This assumption means
            the model cannot evaluate short-term or periodic release events, but must treat all
            releases as steady state.  With this assumption, PAM will underestimate short-term
            exposure concentrations, but will provide reasonable estimates of long-term average
            exposure concentrations  as appropriate for the evaluation of chronic effects.

      (2)   Meteorological conditions remain constant between the source and receptor
            locations. The  assumption of steady-state meteorological conditions  may or may not
            be conservative, depending on the nature of the changes in meteorological conditions
            between the release source and receptor. Constant meteorological conditions must
            be assumed for any but the most complex atmospheric dispersion models.
   2 USEPA, Methodology for Estimating Multimedia Exposures to Soil Contamination, Office
of Health and Environmental Assessment, July 1989.

   3 USEPA, Screening Procedures for Estimating the Air Quality Impact of Stationary Sources.
Office of Air Quality Planning  and Standards, August 1988.

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      (3)   No aerodynamic downwash of the plume by nearby buildings occurs.  The model
            does not consider the tendency of building to draw the contaminant plume towards
            the ground.  This assumption will underestimate exposure concentrations at exposure
            points between the buildings and the source and overestimate exposure
            concentrations at exposure points beyond the buildings. This assumption is necessary
            due to the lack of site-specific information concerning building locations that will be
            available from continuous release notification reports.

      (4)   Plume does not impact on elevated terrain. The model assumes that receptors are
            located at the same elevation as the release source. Like the previous  assumption,
            this assumption means that PAM may either underestimate or overestimate exposure
            concentration, depending on the relative locations of the receptors and the elevated
            terrain.  Again, this assumption is necessary because site-specific topographic
            information will not be available for PAM evaluations.

The equations used for nonradioactive hazardous substances in these models are described below.
The equations for radionuclides differ only in units because concentrations of radionuclides are
expressed in units of activity rather than mass.  The corresponding equations for radionuclides  are
provided in Appendix A.

      Stack Sources

      The equation used to estimate  atmospheric concentrations at exposure points due to
releases from stack sources is as follows:4
                                Qs
                                   ^ exp
Parameters

      Ca(x,y,z)
concentration at receptor point (x,y,z) in the downwind direction (gm/m3
for particulates or vapors);

annual average mass flux of contaminant into atmosphere (gm/s for
particulates or vapors);

3.14159 (unitless);

mean wind velocity (m/s);

standard deviation of Gaussian plume in y and z directions (m);
   4 R.J. Bibbero and I.G. Young, Systems Approach to Air Pollution Control. John Wiley &
Sons, Inc., p. 317.

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            z     =     height of receptor (m); and

            h     =     effective height of plume (i.e., stack height H- buoyancy rise of plume,
                        m).

      If deposition of emitted particles is considered, z' is used in place of z.
where ve = deposition velocity (m/s).
       &
      The value for the emission rate (Qs) is derived from the release information provided by
the facility in the initial written report:  the annual average daily emission rate is calculated as  the
product of the upper bound of the normal range of the release (over a 24-hour period) and the
number of release periods per year divided by 365 days per year.  The emission rate is then
converted to grams per second by dividing the daily emission rate by 86,400 seconds per day.
Although this will not represent the actual emission rate at most facilities, it allows the model to
calculate an annual average air concentration at exposure points and the corresponding chronic
risks. As discussed previously, all of the effects evaluated for the air pathway are chronic effects,
and their evaluation involves the use of long-term average exposures.

      The value for effective height of plume (h) is derived from the stack height and exit
velocity information provided in the continuous release written notifications.  If the facility does
not provide an exit velocity, PAM uses a conservative default value of 2 meters per second. The
stack source model incorporates a default receptor height (z) of 2 meters (the average height of
an  adult presented in one significant figure) and calculates exposure concentrations at several
distances from the source (100, 500, 1500, 3000, and 5000 meters).  These five model-defined
distances may be modified by the CR-ERNS Coordinator in an EPA Region to reflect site-
specific or Region-specific characteristics or concerns.  The model also calculates the distance
from the source at which the maximum hazardous substance concentration at the receptor height
occurs. This distance, which represents the exposure point where risks from the release are
greatest, is provided in the PAM output in addition to the concentrations at four of the five
model-defined distances.

      Values  for the meteorological parameters v, oy,  and oz are derived from information
contained in PAM's STARDATA climatic data base. This data base contains information from
weather stations around the U.S.; PAM automatically selects the weather station located nearest
to the facility using the latitude and longitude of the facility supplied in the  written notifications
(see Chapter 3 for a detailed description of climatic data).

      Area Sources

      Transport and dispersion of hazardous "substances in the atmosphere from area sources is
modeled using a sector-averaged Gaussian dispersion model similar to the one used to simulate
point sources. Because the standard mathematical solution to the Gaussian dispersion equation is

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limited to the simulation of point source emissions, however, it is necessary to mathematically
simulate an area source as an "equivalent point source" located upwind from the actual site when
modeling releases from area sources.  As illustrated in Exhibit 1, the distance between the
downwind boundary of the actual area source and this equivalent point source is known as the
virtual distance (Xy). By adding the virtual distance to the actual distance between the facility
boundary and the exposure point (x),  PAM can simulate the exposure concentrations resulting
from emissions from an area source.
                                        Exhibit 1
                       Illustration of Virtual Distance
                        Area Source
                                                                      Exposure
                                                                         Point
  x  = Actual Distance to Exposure Point
  xu= Virtual Distance
     The sector averaged form of the Gaussian plume model used to estimate the transport of
area source releases is as follows:5
\(x,z)  = V2.03
                                                  exp
                                                    p

    5 Ibid, Section 3.3.

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Parameters

      Ca(x,z) =   average concentration within a directional sector (22.5 degrees) (g/nr*);
                                                                                 ,3v
             =   annual average mass flux of contaminant into the atmosphere (g/s for
                  particulates or vapors);

             =   source depletion factor (unitless);

             =   mixing coefficient in z direction, standard deviation of Gaussian plume (m);

             =   distance in x coordinate direction (parallel to velocity v) from source to point
                  of interest (m);

             =   virtual distance required for hypothetical point source plume to spread to the
                  edge of the area source (m);

             =   distance in z coordinate direction (perpendicular to velocity v) from source to
                  exposure point (i.e., receptor height) (m);

             =   frequency of the specific stability array parameters for classification i (stability
                  class) (dimensionless); and

             =   average wind speed for classification i (m/s).
      The value for emission rate (Qa) is derived from information provided by the facility in the
continuous release written notifications. The area source model assumes the same receptor
height (2 meters) and distances from the source (100, 500, 1500, 3000, and 5000 meters) as the
stack source model (again, these distances can be set by the Regional CR-ERNS coordinator).
The values for the meteorological parameters oz,  f;, and vwi are derived from information
contained in the STARDATA data base associated with the latitude and longitude of the facility.
A value of 1 is used for the source depletion factor.

2.2   Surface Water Model

      PAM uses a simple surface water dilution model that incorporates first-order decay to
estimate exposure concentrations of hazardous substances in streams and rivers. This model has
been used extensively by EPA's Office of Water Regulations and Standards.  This approach
accounts for the initial dilution of the substance in the river/stream and first-order decay via
hydrolysis. The model does not account for the following transport phenomena:

      (1)   Time-varying flow.  Like most simple surface water models, PAM is a steady-state
            model  that does  not account for fluctuations in river flow rate. Accounting for time-
            varying flow would result in higher hazardous substance concentrations during
            periods of low flow and lower hazardous substance concentrations  during periods  of
            high flow.  A more complex model that would include time-varying flow, however,
                                             8

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            requires site-specific information that is not readily available and thus not required in
            continuous release notifications.

      (2)    Sorption to sediments. The surface water model does not account for sorption of
            hazardous substances to sediments. This is a conservative assumption that results in
            higher water column concentrations of hazardous substances, as it does not simulate
            the settling of sediments out of the water column.  This modeling assumption,
            however, will result in an underestimation of the impacts of the release on benthic
            (i.e.,  bottom-dwelling) organisms.

      (3)    Decay via volatilization, photolysis, or biodegradation.  Omitting the decay
            mechanisms of volatilization, photolysis, and biodegradation is a conservative
            assumption that results in higher estimated water column concentrations of hazardous
            substances.

      The equation used to predict surface water exposure concentrations  of nonradioactive
hazardous substances is presented below:6
                                             Q
                                                exp
                                                     -khX
Parameters

      CSW(X) =

      MSW   =

      Q

      kh     =

      X
concentration in stream/river at point of exposure (mg/L);

mass input of contaminant to stream/river (g/yr);

average flow rate in stream/river (m3/yr);

first-order hydrolysis rate constant (yr"1);

downstream distance from source location to exposure point (m); and

average stream velocity (m/yr).
      The equation used for radionuclides differs only in units because concentrations of
radionuclides are expressed in units of activity rather than mass. The corresponding equation for
radionuclides is presented in Appendix A.  The values for M^, Q, and us are provided by the
facility in the continuous release written notifications.  The annual average mass input of
contaminant to the stream/river (Msw) is calculated as the product of the upper bound of the
    6 USEPA, Water Quality Assessment:  A Screening Procedure for Toxic and Conventional
Pollution in Surface and Ground Water. Office of Water Regulations and Standards, September
1985.

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normal range and the number of release periods per year (i.e., frequency).  PAM evaluates all
surface water releases at the point of release and at 1000 meters downstream from the release
point.  Values for kh have been compiled in PAM's chemical-specific data base, CHEMTOX
(discussed in Chapter 3).

23   Ground-water Model

      The ground-water component of PAM uses equations that predict time of travel (TOT)
through the unsaturated zone and TOT through the saturated zone.  This model component does
not predict ambient ground-water concentrations of hazardous substances. Although estimating
exposure concentrations (as done in the air and surface water models) would provide more
information for decision-makers, the extensive hydrogeologic data and source characterization
information that are needed to perform this type of modeling are not available from the
continuous release information submitted by facilities.  To address the paucity of ground-water
modeling data, PAM relies on two equations to  estimate TOT.  The first equation presented
below provides an estimate of the time required for substances to travel to the  water table, and
the sura of the results of both equations provides an estimate of the time it takes for substances
to travel to the nearest well.  This information will enable the OSC to determine the imminence
of the potential threat of a particular release to  potentially exposed populations.

      Travel Through the Unsaturated Zone

      This unsaturated zone transport analysis evaluates the processes of contaminant advection
due to net annual recharge and incorporates retardation due to contaminant/soil interactions.
The equations used to represent fluid flow and contaminant transport through the unsaturated
zone include the following standard assumptions, commonly incorporated  into screening-level
ground-water fate and transport models:

      (1)    Steady state conditions.  Recharge  is assumed to percolate through the unsaturated
            zone at a constant rate, even though, in reality, recharge occurs intermittently
            following natural storm events. The steady state assumption  represents an averaging
            of the recharge rate,  and generally will be "risk neutral", however, it may
            underestimate the risks in situations where there is a large  storm event in arid
            climates.

      (2)    One-dimensional flow conditions.  The ground-water model ignores.lateral
            movement.  This assumption  is reasonable because recharge percolates mainly in the
            downward direction and the lateral  movement of recharge is generally minimal and
            has little impact on the travel time.

      (3)    Homogeneous, isotropic soil. This assumption may either overestimate or
            underestimate TOT, depending on the geology of the site.  Cracks or piping in the
            unsaturated zone medium will decrease travel time, while the presence of clay lenses
            can increase travel time.  While few actual soil systems can be called homogeneous or
            isotropic, this is an  assumption common to virtually all analytic ground-water
            equations.
                                            10

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      (4)   No degradation of chemicals occurs.  Omitting degradation of chemicals from the
           model will have little effect on the estimated travel time.

 The equation for TOT through the unsaturated zone is presented below:7
      TOTmsac =  (Z) (1/qr) (6.
                                                               (Ra)
Parameters
      TOT,
          unsat

            Z

            q

            ©
            Pb
=     time of travel from ground surface to water table (yr);

=     thickness of unsaturated zone (cm);

=     annual recharge rate (cm/yr);

=     saturated volumetric water content of the specific soil type
      (dimensionless);

=     saturated hydraulic conductivity of the specific soil type (cm/yr);

=     soil-specific exponent parameter representing the moisture retention
      relationship (dimensionless);

=     chemical-specific retardation factor (dimensionless);
                                             /j
=     bulk density of the specific soil type  (g/cm ); and

=     chemical-specific soil-water partition coefficient (mL/g).
      All of the parameters, except Kd, are related to the hydrogeologic setting of the facility.
The values for these parameters are tabulated by U.S. county in PAM's hydrogeologic data base
SOILDATA.  Kjj is a chemical-specific parameter for which values have been compiled in PAM's
CHEMTOX data base. These data bases are discussed fully in Chapter 3 of this document.
    7 USEPA, Methodology for Estimating Multimedia Exposures to Soil Contamination, Office
 of Health and Environmental Assessment, July 1989.

                                             11

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      Travel Through the Saturated Zone

      The equations used to represent fluid flow and contaminant transport through the saturated
zone are based on Darcy's law of fluid flow through porous media.  Like the equation for travel
through the unsaturated zone, this equation incorporates assumptions of steady state flow,
isotropic and homogeneous aquifer medium, no dispersion, and no degradation of chemicals. This
model considers retardation due to contaminant/soil interactions based on the soil-water partition
coefficient.  The equation for TOT through the saturated zone is presented below:^
                                    TOT.
                                                 KJ
Parameters
      TOTsat =
                  time of travel in the saturated zone (yr);                            .  ;

      X     =   distance to exposure point (m);                . .-    .

      E     =   porosity of aquifer medium (dimensionless);
                                                    n
      pb     =   bulk density of aquifer medium (g/cm );

      Kd     =5   soil-water partition coefficient (mL/gm);

      K     =   hydraulic conductivity of the aquifer (m/yr); and

      J      =   regional gradient (m/m).

      The sources of the hydrogeologic parameters and Kd are the same as for the unsaturated
zone TOT component. Values for X, distance to exposure point, are provided by the facility in
the continuous  release written notifications.  In addition, PAM will evaluate TOT to a
hypothetical well located at a distance of 30 meters from the facility as a standard for all facilities,
to allow the OSC to compare the relative threats to ground water posed by releases of hazardous
substances by a number of different facilities.
     Ibid.
                                            12

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3.     AUXILIARY DATA BASES

      PAM uses parameter values from the following data bases to support its fate and transport
modeling and risk assessment components:

      •    SOILDATA - contains hydrogeologic data indexed by U.S. county;

      •    STARDATA - contains regional atmospheric data indexed by latitude/longitude; and

      •    CHEMTOX - contains chemical, physical, and toxicological data indexed by chemical.

The sections below describe the source(s) of data for each of the parameters contained in these
data bases.

3.1   SOILDATA

      Evaluating the potential effects of releases to soil/ground water requires many site-specific
hydrogeologic parameters that may not be readily available to facilities subject to the CERCLA
release reporting requirements and which are, therefore, not part of the continuous release
reporting requirements.  The ground-water screening model must rely on conservative,  non-site-
specific values for these parameters to make a "reasonable worst case"  evaluation of impact.
Rather than selecting these conservative values for parameters at a national level, however, PAM
uses county-level data to the greatest extent possible.

      The SOILDATA data base contains values for ten hydrogeologic parameters indexed by
county.  The information in this data base is derived from a data base providing hydrogeologic
settings for counties in the U.S.  that was created by EPA's Office of Toxic Substances (OTS) for
its Graphical Exposure Modeling Systems (GEMS).9 The GEMS data base incorporates values
for hydrogeologic parameters estimated  using the National Water Well Association's (NWWA)
DRASTIC methodology for evaluating vulnerable hydrogeologies.10 The DRASTIC
hydrogeologic settings incorporate the major hydrogeologic factors that affect and control ground-
water movement:  Depth to ground water, net Recharge, Aquifer media, Soil media, Topography,
Impact of the vadose zone,  and hydraulic Conductivity of the aquifer.  Each of the seven
DRASTIC factors is divided into several categories, representing either a particular soil or aquifer
medium, or a range of values (e.g., net recharge ranges of 0-2, 2-5, 5-8, 8-10 inches per year).
Exhibit 2 presents the DRASTIC ranges and ratings for each of the DRASTIC factors.  Higher
DRASTIC ratings are associated with higher pollution potential.
    9 USEPA, Graphical Exposure Modeling System. Office of Toxic Substances, April 24, 1986.

    10 USEPA, A Standardized System for Evaluating Ground Water Pollution Potential Using
Hydrogeologic Settings. Office of Research and Development, Robert S. Kerr Environmental
Research Laboratory, May 1985.  EPA/600/2-85/018.

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                                                      EXHIBIT 2
                                    DRASTIC PARAMETER RANGES AND RATINGS
Ranges and Ratings for Depth to Water

        Depth to Water (feet)

        Range          Rating
        0-5
        5-10
        18-30
        30-50
        50-75
        75-100
        100+
10
 9
 7
 5
 3
 2
 1
Ranges and Ratings for Net Recharge

        Net Recharge (inches)

        Range          Rating
Ranges and Ratings for Topography

        Topography (percent slope)

        Range          Rating
                        10
                         9
                         5
                         3
                         1
Ranges and Ratings for Hydraulic
	Conductivity	

  Hydraulic Conductivity (GPD/ft2)

        Range          Rating
        1-300
        100-300
        300-700
        700-1,000
        1,000-2,000
        2,000+
1
2
4
6
8
                                                Ranges and Ratings for Aquifer Media
                                                       Aquifer Media
                                        Range
Massive Shale                           1-3
Metamorphic/Igneous                    2-5
Weathered Metamorphic/Igneous          3-5
Thin Bedded Sandstone, Limestone,
  Shale Sequences                       5-9
Massive Sandstone                       4-9
Massive Limestone                       4-9
Sand and Gravel (Till)                   4-9
Basalt                                  2-10
Karst Limestone                        9-10
                                             Ranges and Ratings for Soil Media
          Typical Rating

                2
                3
                4

                5
                5
                5
                8
                9
                10
                                                                                            Soil Media
                                                                Range
                              Thin or Absent                                         10
                              Gravel                                                10
                              Sand                                                   9
                              Peat                                                   8
                              Shrinking and/or Aggregated Clay                          7
                              Sandy Loam                                            5
                              Loam                                                  5
                              Silty Loam                                              4
                              Clay Loam                                     .         3
                              Muck                                                  2
                              Nonshrinking and Nonaggregated Clay                1
                                     Ranges and Ratings for Impact of Vadose Zone Media
                                                                Range
Silt/Clay
Shale
Limestone
Sandstone
Bedded Limestone, Sandstone, Shale
Sand & Gravel with Significant
 Silt and Clay
Metamorphic/Igneous
Sand and Gravel
Basalt
Karst Limestone
1-2
2-5
2-7
4-8
4-8
4-8

2-8
6-9
2-10
8-10
                                                                              Typical Rating

                                                                                     1
                                                                                     3
                                                                                     6
                                                                                     6
                                                                                     6
                                                                                     6
 9
10
                                                         14

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      The GEMS data base provides the percentage of each county that falls within each range
of a DRASTIC factor. Because a conservative value is desirable for a risk-screening model, PAM
incorporates a single value for each parameter for each county that will result in a conservative
estimate of time of travel.  Some parameter values are taken directly from the GEMS data base,
while others are calculated using the DRASTIC values contained in GEMS. For example, soil or
aquifer medium-specific parameters are taken whenever possible from tables of medium-specific
hydrogeologic parameters presented in the Superfund Exposure Assessment Manual (SEAM).

      The value for each DRASTIC factor that was chosen for each county and incorporated into
PAM's SOILDATA data base is an 85th percentile value.  That is, 85 percent of the county has
characteristics that would yield a shorter TOT. For parameters that are directly proportional to
TOT (i.e., smaller values give a shorter TOT), the value incorporated into SOILDATA is less
than or equal to the value applicable to 85 percent of the county.  For parameters that are
inversely proportional to TOT (i.e., larger values give a shorter TOT), the value incorporated into
SOILDATA is greater than or equal to the value applicable to 85 percent of the county.  For
example, a hypothetical county has the following percentages of depth to water: 0-5 ft. ~ 5%; 5-
10 ft. - 8%; 10-15 ft. - 26%; 15-30 ft.  - 40%; 30-50 ft. - 14%; 50-75 ft. -- 7%.  Because a lesser
depth to ground water results in a shorter TOT, the shallower values correspond to  more
conservative estimates. For this hypothetical county, the 85th percentile lies within the range 10
to 15 feet.  The conservative end of this range (i.e., 10 feet) is incorporated into SOILDATA and
used by PAM to calculate TOT for this county.

      The GEMS data base contains DRASTIC data for 17 states in the U.S.  Only two of these
states, however, have been completely  "mapped", or assigned values for the DRASTIC
parameters, at the county level.  The other 15 states have been partially mapped at the county
level; in some of these states only one  county has been mapped. For each of the 15 partially
mapped states and the 33 unmapped states, default values for the DRASTIC parameters were
incorporated  into  the SOILDATA data base.  All unmapped counties within a given state were
assigned the same default data set, based on the following methodology.

      First, the DRASTIC ground-water regions and corresponding subregions  that  occur in each
state were determined. DRASTIC subregions characterize generalized hydrogeologic settings in
the U.S.; ranges of values for the DRASTIC parameters have previously been developed for all
the subregions. Second, those subregions that would be unlikely locations for facilities with the
potential for hazardous substance releases were eliminated from further consideration  (e.g.,
mountain slopes and crests).  Of the remaining subregions characterizing each state, the subregion
with the most vulnerable ground-water setting (i.e., the highest DRASTIC rating) was  selected to
represent all unmapped counties within the state.

            SOILDATA contains county-specific information for the following DRASTIC
parameters:

      •     thickness of the unsaturated zone;
      •     annual recharge rate;
    11 USEPA, Superfund Exposure Assessment Manual. Office of Emergency and Remedial
Response, April 1988.  EPA/540/1-88/001.

                                            15

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            hydraulic conductivity;
            regional gradient;
            soil medium; and
            aquifer medium.
The approach for selecting 85th percentile values (at the county level) for each parameter is
described below.

      Thickness of Unsaturated Zone

      The GEMS  data base tabulates the percentage of each county within the following
DRASTIC ranges  of depth to ground water:

            0 to 5 feet;
            5 to 10 feet;
            10 to  15 feet;
            15 to 30 feet;
            30 to 50 feet;
            50 to 75 feet;
            75 to  100 feet; and
            greater than 100 feet.

Because unsaturated zone TOT increases with increasing depth to water, a conservative value for
depth to ground water will be found at the shallow end of the range.  Therefore, the shallow end
of the range that is less than or equal to 85 percent of the values for the county (i.e., the 15th
percentile value) was selected to provide a conservative county-wide estimate for the depth of the
unsaturated zone.  The values also were converted from feet to meters.

      Annual Recharge Rate

      A primary source of ground water is precipitation that infiltrates through the surface of the
ground and percolates to the water table. Net recharge indicates the amount of water per unit
area of land that penetrates the ground surface and reaches the water table.  The GEMS data
base tabulates the  percentage of each county within the following DRASTIC ranges of annual net
recharge rate:

            0 to 2 inches;
            2 to 4 inches;
            4 to 7 inches;
            7 to 10 inches; and
      ~     10 to 20 inches.

Because TOT decreases as recharge rate increases, a conservative approach for estimating annual
recharge rate would be to assume a larger value for net recharge. Therefore, the upper end of
the range that is greater than or equal to  85 percent of the values for the county (i.e.,  the 85th
percentile value) was selected as  a conservative value representative of that county.  The recharge
rate was converted from inches to centimeters.
                                            16

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      Hydraulic Conductivity

      Hydraulic conductivity refers to the ability of the aquifer materials to transmit water, which
in turn, controls the rate at which ground water will flow under a given hydraulic gradient.
Hydraulic conductivity is controlled by the amount and interconnection of void space within the
aquifer.  The GEMS data base tabulates the percentage of each county within the following
ranges of hydraulic conductivity:

            1-100 gallons per day per square foot (gpd/ft2);
            100-300 gpd/ft2;
            300-700 gpd/ft2;
            700-1000 gpd/ft2;
            1000-2000 gpd/ft2; and
            2000-3000 gpd/ft2.

Because TOT decreases as hydraulic conductivity increases, a conservative approach for estimating
hydraulic conductivity would be to assume a larger value for hydraulic conductivity. Therefore, the
upper end of the range that is greater than or equal to 85 percent of the values for the county
(i.e., the 85th percentile value) was selected as a conservative county-wide estimate.  The values
were converted from gpd/ft2 to m/yr.

      Regional Gradient

      The GEMS data base tabulates the percentage of each county within the following ranges
of land slope:

            0-2%;
            2-6%;
            6-12%;
            12-18%; and
            18%.

A relationship between land slope and hydraulic gradient was developed based on empirical data
from hundreds of site studies.12 This relationship was used to make the following assignments
of regional gradient based on the  GEMS land slope ranges.
                    Land Slope (%)
Regional Hydraulic Gradient (%)
                         0-2
                         2-6
                         6-12
                         12-18
        0.1
        0.5
        1.0
        5.0
        10
    10
      USEPA, Report to Congress on Special Wastes from Mineral Processing Volume II:
Methods and Findings. Office of Solid Waste, July 1990.
                                            17

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Because TOT decreases as regional hydraulic gradient increases, a conservative approach for
estimating regional hydraulic gradient would be to assume a larger value for regional gradient.
Therefore, the value corresponding to the range that is greater than or equal to 85 percent of the
values for the county (i.e., the 85th percentile value) was selected as a conservative estimate for
each county.

      Soil Medium

      The GEMS data base tabulates the percentage of each county exhibiting soils in each of
the following DRASTIC soil media categories:

            thin or absent;
            gravel;
            sand;
            shrinking clay;
            sandy loam;
            loam;
            silty loam;
            clay loam; and
            nonshrinking clay.

      Because soil media are  identified above in the order of decreasing pollution potential (i.e.,
sand has a higher pollution potential than silty loam), the soil medium that is of greater or equal
pollution potential than 85 percent of the soil in each county (i.e.,  the 15th percentile soil
medium) was selected as a conservative representative of the soil medium for each county.

      Several of the parameters for the hydrogeologic models are related to the soil medium at a
facility. Values for saturated volumetric water content ( s), saturated hydraulic conductivity (K,.),
and exponent for moisture retention (b) are provided in SEAM for soil media as  categorized by
the USDA classification system. Because these two systems use different soil  classification
systems, each DRASTIC soil medium category was assigned to the USDA classification that most
closely matched the soil composition in terms of transport properties. This "translation" from
DRASTIC soil type to USDA soil classification allowed the assignment of values  for the
parameters  s, Kg, and b. Values for bulk density of each  soil medium ( b) were  assigned based
on data provided  in Mining Geophysics13 and in the U.S. Department of Energy's Multimedia
Environmental Pollutant Assessment System  (MEPAS).14  The values assigned to each
parameter for each DRASTIC soil medium are' presented  in Exhibit 3.
    13 D.S. Parasnis, Mining Geophysics. Elsevier Publishing Company, New York, NY, 1966.

    14 U.S. Department of Energy, Multimedia Environmental Pollutant Assessment System.
Addendum A: Guidelines for Recording Ranking Unit Data, Office of Environmental Safety and
Health, 1987.

                                            18

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                EXHIBIT 3




SOILDATA PARAMETERS BASED ON SOIL MEDIUM

DRASTIC Soil Type
Gravel
Sand
Shrinking/
Aggregated Clay
Sandy Loam
Loam
Silty Loam
Clay Loam
Nonshrinking/
Nonaggregated Clay
a USEPA, Superfund
blbid. Table 3-8.

USDA
Soil Type
Sand
Sand
Sand
Sandy Loam
Loam
Silty Loam
Clay Loam
Clay
Saturated
Volumetric
Water
Content3
s (unitless)
0.437
0.437
0.437
0.453
0.463
0.501
0.464
0.475

Saturated
Hydraulic
Conductivity13
KS (cm/yr)
1.8 x 105
1.8 x 105
1.8 x 10s
2.3 x 104
1.2 x 104
6.0 x 103
2.0 x 103
5.4 x 102

Exponent
for Moisture
Retention0
b (unitless)
4.05
4:05
4.05
4.90
5.39
5.30
8.52
11.40
Exposure Assessment Manual. Office of Emergency and Remedial Response, April
clbid. Table 3-11.
d D.S. Parasnis, Mining Geophysics. 1966. U.S. Department of
Addendum A: Guidelines for Recording Ranking Unit Data, C
e Value was assigned based on the DRASTIC soil medium clay.
Energy, Multimedia

Bulk
Densityd
b (g/cm )
2.0
1.64
1.39e
1.48
1.42
1.42
1.39
1.39
1988. Table 3-10.
Environmental Pollutant Assessment Svstem.
iffice of Environmental Safety and Health,
1987.

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      Aquifer Medium

      The GEMS data base tabulates the percentage of each county underlain by each of the
following DRASTIC aquifer media:

           massive shale;
           metamorphic/igneous;
           weathered metamorphic/igneous;
           thin bedded sandstone, limestone, shale sequences;
           massive sandstone;
           massive limestone;
           sand and gravel;
           .basalt; and
           karst limestone.

      Because the aquifer media are listed in order of increasing pollution potential (i.e.,
metamorphic/igneous has lower pollution potential than sand and gravel), the aquifer medium that
is of greater or equal pollution potential than 85 percent of the aquifer media in each county (i.e.,
the 85th* percentile aquifer medium) is selected as a conservative representative of aquifer
medium for each county.

      Based on the aquifer medium, values for saturated zone bulk density ( b) and saturated
zone porosity (E) were assigned. The values for porosity were assigned based on data from
several sources.   The values for bulk density of aquifer medium were assigned based on data
in Mining Geophysics16 and MEPAS17 The values assigned to these parameters for each
DRASTIC aquifer medium are presented in Exhibit 4.

3.2   STARDATA

      STARDATA is a  binary data base file especially created for PAM from the GEMS  data
base. STARDATA contains meteorological data for more than 200 metropolitan areas in the
U.S.  The meteorological information obtained from STARDATA and used for air transport
modeling includes the following data for each location:
    15 EG. Driscoll, Groundwater and'Wells. Johnson Division, St. Paul, MN, 1987.  R.A Freeze
 and J.A. Cherry, Groundwater Pollution in the United States. Prentice Hall, Englewood Cliffs,
 NJ, 1979. S.P. Clark, Jr., Handbook of Physical Constants, The Geological Society of America,
 New York, NY,  1966. B.K. Hough, Basic Soils Engineering. The Ronald Press Company, New
 York, NY, 1957.

    16 D.S. Parasnis,  Mining Geophysics. Elsevier Publishing Company, New York, NY, 1966.

    17 U.S. Department of Energy, Multimedia Environmental Pollutant Assessment System.
 Addendum A: Guidelines for Recording Ranking Unit Data, Office of Environmental Safety and
 Health, 1987.

                                            20

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                                     EXHIBIT 4

               SOILDATA PARAMETERS BASED ON AQUIFER MEDIUM
DRASTIC Aquifer Medium
Saturated Zone Porosity3
      E (cm3/cm3)
Saturated Zone
 Bulk Densityb
    /• /   "^\.
  Pb
Massive Shale
Metamorphic/Igneous
Weathered Metamorphic/Igneous
Thin Bedded Sandstone,
Limestone, Shale
Massive Sandstone
Massive Limestone
Sand and Gravel
Basalt
Karst Limestone
.01
.01
.01
.01
.05
.01
.15.
.10
.10
2.40
2.70
2.50
2.55
2.65
2.65
1.82
3.00
2.60
a Values derived from several sources.  See footnote 15.
b D.S. Parasnis, Mining Geophysics, Elsevier Publishing Company, New York, NY, 1966.
                                         21

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            six stability classes;
            frequency of occurrence for each stability class;
            frequency of occurrence for each of the 16 wind directions; and
            average wind speeds for these 16 directions.
      The six stability classes are indicators of atmospheric turbulence.  The stability class at any
given time will depend upon static stability (related to the change in temperature with elevation),
thermal turbulence (caused by heating of air at ground level), and mechanical turbulence (a
function of wind speed and surface roughness).

      To obtain this meteorological information from STARDATA for a specific facility, PAM
identifies the closest weather station to the facility (using the latitudeAongitude information
supplied by the facility in the continuous release written notifications) and uses data from that
weather station to represent the average meteorological conditions for the facility.  Air transport
modeling is performed only for the prevailing wind direction, because it represents a conservative
scenario by which an individual would be exposed to  airborne hazardous substances.
Concentrations of the pollutants at a downwind receptor are estimated for each of the stability
classes using the equations for stack and area sources (see Chapter 2). The concentrations of
hazardous substances are then averaged across all stability classes, based on the corresponding
frequencies of occurrence for each stability class.  This should represent a reasonable estimate of
the long-term concentrations of hazardous substances at receptor locations.

33   CHEMTOX

      CHEMTOX is PAM's chemical-specific data base. CHEMTOX contains two types of
information:  chronic toxicity values for estimating human health and environmental impacts, and
physical/chemical constituent properties  necessary for fate  and transport modeling.  The contents
of this data base and the sources of data are described below.

      Toxicity Values

      CHEMTOX incorporates sk kinds of chronic human health-based toxicity values:

            chronic  oral reference dose (RfD0) in mg/kg-day;
            chronic  inhalation reference dose (RfDj) in mg/kg-day;
            oral slope factor (SF0), in (mg/kg-day) ;
            inhalation slope factor (SFj) in (mg/kg-day)"1;
            oral annual limit of intake (ALI0) in  Ci/yr; and
            inhalation annual limit of intake (ALI;) in  Ci/yr.

      In accordance with guidance provided in Risk Assessment Guidance for Superfund, Volume
1: Human Health Evaluation Manual (Part A), the primary source of these data is EPA's
Integrated Risk Information System (IRIS).  If data were not available in IRIS, values from
Health Effects Assessment Summary Tables (HEAST) were used.18
    18 Values were from IRIS as of 3/90 and HEAST as of 5/89.

                                             22

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      The toxicity benchmarks used for radionuclides in CHEMTOX are annual limits of intake
(ALI), which are radionuclide-specific. An ALI is the quantity of a radionuclide which, if taken
into the body of a reference man by inhalation or by ingestion in one year, would not exceed a 5-
rem committed effective dose to the whole body or a 50-rem committed dose to any organ or
tissue. The ALI values for radionuclides are those developed by the International Commission on
Radiological Protection (ICRP) and published in the Federal Register by the Nuclear Regulatory
Commission (51 FR 1092; January 9, 1986). Although slope factors are the preferred measure for
toxicity of radionuclides, they were not used in the PAM evaluation because slope factors are
currently unavailable for most radionuclides.

      The ecological benchmarks in CHEMTOX are Clean Water Act Ambient Water Quality
Criteria (AWQC) for the protection of aquatic life.19 The value used is the chronic, freshwater
AWQC.  For compounds containing metals or cyanide, mole ratios were used to derive an
"equivalent" AWQC for the metal- or cyanide-containing compound, based on the AWQC for the
metal or cyanide.

      Physical/Chemical Properties

      CHEMTOX incorporates the following physical/chemical properties:

           organic carbon partition coefficient (Koc) in mL/g;
           soil/water partition coefficient (Kd) in mL/g;
           "lumped" first order decay constant (kj) in yr"1; and
           first order hydrolysis rate constant (kh)in yr"1.

      The parameters Koc and Kd provide measures of the extent of chemical partitioning
between organic carbon (for K^,) or soil  (for Kd)  and water. The higher the Koc or Kd the more
likely  a chemical is to bind to soil than to remain in water.  The  primary source for Koc and Kow
is a data base of physical constants developed by EPA's Office of Toxic Substances (OTS).20
The secondary source for Koc and K^ is a chemical data base of physical constants developed for
the U.S. Department of Energy's Multimedia Environmental Pollutant Assessment System
(MEPAS).2r
    19 USEPA, Quality Criteria for Water 1986. Office of Water Regulations and Standards, May
1986. EPA 440/5-86-001.

    20 USEPA, SARA Title in Section 313 Physical Chemical Properties Data Base. Office of
Toxic Substances, March 1990.

    21 U.S. Department of Energy, Chemical Data Bases for the Multimedia Environmental
Pollutant Assessment System (MEPAS): Version 1. Office of Environmental Audit, D.L. Strenge,
S.R. Peterson, September 11,  1989.

                                           23

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      The source for all K^ values for metals is the MEPAS data base.  All Kd values for
radionuclides were taken from a data base of physical and toxicological data for radionuclides
developed by EPA's Office of Solid Waste and Emergency Response (OSWER).22

      The primary source for kh values is a compilation of chemical degradation constants
prepared by OTS.23 The Superfund Chemical Data Matrix, a data base of chemical and
physical properties developed by EPA's Hazardous Site Control Division,24 was  used as a source
of kj values for hazardous substances not included in the OTS compilation of degradation data.
Decay constants for radionuclides were taken from the radionuclide data base developed  by
OSWER.
   22 USEPA, The Radionuclides Database: Version 1.02. Office of Solid Waste and Emergency
Response, Emergency Response Division, December 19, 1988.  '

   23 USEPA, Chemical Fate Rate Constants for SARA Section 313 Chemicals and Superfund
Health Evaluation Manual Chemicals, Office of Toxic Substances, August 1989.

   24 USEPA, Superfund Chemical Data Matrix, Office of Emergency and Remedial Response,
May 1990.

                                           24

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 4.    EVALUATION OF MODELING RESULTS

      After PAM has generated modeling results for each hazardous substance and each medium
 of concern, standard risk assessment methodology is used to evaluate the risk or hazard posed by
 ambient chemical concentrations in air and surface water.  All of the equations and parameters
 used to estimate exposure to nonradioactive hazardous substances and the effects of these
 exposures are taken from Risk Assessment Guidance for Superfund: Volume 1 Human Health
 Evaluation Manual fPart A\lt> The equations and paramptp.rs m^vi tn p«Hmate exposure to
 radionuclides and corresponding cancer risks are the recommendations of the ICRP and were
 published by the Nuclear Regulatory Commission in the January 9, 1986 Notice of Proposed
 Rulemaking (51 FR 1092).  Because model outputs in the ground-water pathway are in terms of
 travel times, the ground-water modeling results are not evaluated using further risk assessment
 procedures, but rather are placed into time frame categories to facilitate prioritization.

      For each type of effect (i.e., carcinogenic effects, noncarcinogenic effects, ecological effects,
 and TOT), a default prioritization scale is used to categorize releases in terms  of severity of
 threats.  This scale uses red, yellow, and green flags to signal releases of high, moderate, and low
 priority.  The default values associated with each flag for each effect are discussed in more detail
 below. The Regional CR-ERNS/PAM system coordinator can change the values associated with
 the flags based on his/her professional judgment regarding the uncertainty in the facility data and
 modeling parameters.

      If  the effects of a release cannot be evaluated because no AWQC is available for a
 substance released to surface water or because neither a reference dose nor a slope factor is
 available for a substance released to  air or surface water, the substances or effects that were not
 evaluated will be indicated in the substance-specific section of the detailed evaluation report (see
 Chapter  5).

      This chapter describes the methods used in the following steps of the evaluation process:

            calculation of air and surface water intakes;
      •     evaluation of human health and ecological effects;
            aggregation of evaluation results; and
      •     assignment of evaluation flags to PAM results.

 4.1    Calculation  of Air and Surface Water Intakes

      Exposure is defined as the contact of an organism with a chemical or physical agent. If
 exposure occurs over time, the total exposure can be divided by a time period of interest to
 obtain an average exposure rate per unit time.  This average exposure rate also can be expressed
 as a function of body weight. Exposure normalized for time and body weight is termed "intake"
 and is expressed in units of mg chemical/kg body weight-day.
      USEPA, Risk Assessment Guidance for Superfund: Volume 1 Human Health Evaluation
Manual TPart A). Office of Emergency and Remedial Response, December 1989.  EPA/540/1-
89/002.

                                            25

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      All of the intake equations presented below use an exposure frequency of 365 days per
year.  Although the release of a hazardous substance may not occur every day, the exposure
concentrations generated by the air and surface water models are annual average concentrations
(see Chapter 2) and, therefore, it is appropriate to assume that the exposure frequency is 365
days per year. In other words, release quantities reported in the continuous release written
notifications have been normalized by PAM to reflect total annual amounts released, assuming
the release is a daily occurrence.

      4.1.1  Chemical Intakes via Inhalation

      The air modeling component of PAM generates exposure concentrations for each
hazardous substance at a number of distances  from the source. Each exposure concentration is
used to estimate a corresponding intake that is used to evaluate the effect of that hazardous
substance on human health. In  addition, an exposure concentration and corresponding intake are
calculated for a receptor 1000 meters downstream from the point of release. The following
equation is used to calculate a chronic daily intake (GDI) of airborne hazardous substances via
inhalation:

      GDI (mg/kg-day) = CAxIRxEFxED
                              BWx AT

where:

      CA =  chemical concentration in air (mg/m3);
      IR = inhalation rate = 30 m3/day (adult, suggested upper bound value);
      EF = exposure frequency = 365 day/yr (daily);
      ED =  exposure duration  = 70 yr (lifetime, by convention);
      BW  = body weight = 70  kg (adult, average); and
      AT =  averaging time = 365 day/yr x 70 yr.

      4.1.2  Chemical Intakes via Ingestion of Drinking Water

      The  surface water modeling component of PAM generates exposure concentrations for
each hazardous substance at the point of release and at 1000 meters downstream from this point.
This maximum concentration is used to calculate a chronic daily intake based on ingestion of
drinking water only. This intake is used  to evaluate the effect of that  hazardous substance on
human  health.  The following equation is used to estimate the GDI of hazardous substances  in
drinking water:

      GDI (mg/kg-day) = CW x IR x EF x ED
                              BWx AT
where:
      CW = chemical concentration in water (mg/L);
      IR = ingestion rate = 2 L/day (adult, 90th percentile);
      EF = exposure frequency = 365 day/yr (daily);
      ED = exposure duration = 70 yr (lifetime, by convention);

                                            26

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       BW = body weight = 70 kg (adult, average); and
       AT = averaging time =  365 day/yr x 70 yr.

       4.1.3  Radionuclide Intakes via Inhalation

       The intakes calculated by PAM for radionuclides are annual intakes (in  Ci/yr), rather than
 the chronic  daily intakes used to evaluate other hazardous substances, and are not normalized
 with respect to body weight. The following equation is used to estimate intake of radionuclides
 via inhalation:

       Intake (  Ci/yr) = CA x IR x EF

 where:

       CA = chemical concentration  in air (  Ci/m3);
       IR =  inhalation rate = 30 nrVday (adult, suggested upper bound value); and
       EF  = exposure frequency = 365 day/yr (daily).

       4.1-4  Radionuclide Intakes via Ingestion of Drinking Water

       The following equation is used to calculate annual intake of radionuclides via ingestion of
 drinking water:

       Intake (  Ci/yr)  = CW x IR x EF

 where:

       CW = chemical concentration  in water (  Ci/L);
       IR = ingestion rate = 2 L/day (adult, 90th percentile value); and
       EF =  exposure frequency = 365 day/yr (daily).

 4.2    Evaluation of Human Health and Ecological Effects

       4.2.1  Calculation of Cancer Risk

       For carcinogenic effects of hazardous substances other than radionuclides, risks are
 estimated as  the incremental probability of an individual'developing cancer over a lifetime as a
 result of exposure to the potential carcinogen (i.e., excess lifetime individual cancer risk).  A
 chemical-specific slope factor (SF) is  a plausible upper-bound estimate of the probability of a
 response per unit intake of a chemical over a lifetime.  The slope factor is used to estimate an
 upper-bound probability of an individual developing cancer as a result of a  lifetime of exposure to
 a particular level of a potential carcinogen. The one-hit equation for high carcinogenic risk  levels
 is used in this model to estimate cancer risks.  This equation is as follows:
      Risk = 1 - exp(- GDI x SF)
where:
                                             27

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      Risk = a unitless probability of an individual developing cancer;
      GDI = chronic daily intake averaged over 70 years (mg/kg-day); and
      SF = slope factor, expressed in (mg/kg-day)"1.                  .

This equation will give results consistent with the more frequently used linear low dose cancer risk
equation (Risk = GDI x SF) at low risk levels (i.e., less than 0.01), but is more appropriate at
higher risk levels.                                               ,

      4.2.2  Calculation of Noncancer Hazard Quotient

      The potential for noncarcinogenic effects is evaluated by comparing an exposure level over
a specified time period (in this case, lifetime) with a reference dose derived for a similar exposure
period. A chronic reference dose (RfD) is a chemical-specific estimate of a daily exposure level
for the human population, including sensitive subpopulations, that is likely to  be without an
appreciable risk of deleterious effects during a lifetime.  The ratio of exposure to toxicity is called
a hazard quotient (HQ) and is calculated as follows:

      Noncancer Hazard Quotient = CDI/RfD

where:

      GDI = chronic daily intake in mg/kg-day; and
      RfD = reference dose in mg/kg-day.

The noncancer hazard quotient assumes that there is a level of exposure (i.e., the RfD) below
which it is unlikely for even sensitive populations to experience adverse health effects. If the
intake exceeds this threshold (i.e., HQ > 1), there may be concern for potential noncancer
effects. As a rule, the greater the value of HQ above 1, the greater the level of concern. The
values for HQ are not, however, statistical probabilities. An HQ of 0.001 does not mean that
there is a one in one thousand chance of the effect occurring. Furthermore, the level of concern
does not increase linearly as the RfD is approached or exceeded because RfDs do not have equal
accuracy or precision and are not based on the same severity of toxic effects.

      4.2.3  Evaluation of Radionuclide Effects

      To evaluate the risk associated with exposure to a radionuclide, the radionuclide-specific
All is used to convert the annual intake in  Ci/year to a dose in rem/yr as follows:

      Dose (rem/yr) = Intake ( Ci/yr) x 5  rem/ALI ( Ci)

This dose in rem/yr can be converted to a lifetime cancer risk by multiplying by factors
representing the risk of fatal cancer per rem and the number  of years assumed in  a lifetime (70
years by convention):

      Lifetime Cancer Risk = Dose (rem/yr) x 5 x 10"4 risk/rem  x 70 yr.
                                             28


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This factor represents a conservative risk coefficient based on results reported by the National
Research Council.26

      4.2.4  Evaluation of Ecological Effects

      Ecological effects are evaluated by comparing the release point exposure concentration with
freshwater, chronic AWQC for the protection of aquatic life.  If the release point exposure
concentration is greater than the AWQC, then the release is potentially harmful to aquatic life.
PAM evaluates ecological effects by calculating the ratio of exposure concentration to the AWQC
for that hazardous substance as follows:

      Ecological Index =  CW/AWQC

      where:

            CW = release point exposure concentration in ug/L; and
            AWQC = freshwater, chronic AWQC in ug/L.

4.3   Aggregation of Evaluation Results

      Aggregation of PAM's evaluation results for a number of releases or sources  at a facility is
useful for two reasons.  First, under section 103 of CERCLA, a release is reportable if, over a 24-
hour period, a facility or vessel releases  an amount equal to or greater  than a reportable quantity
(RQ). A facility can have multiple releases sources (e.g., several smoke stacks).  The amount
released from all sources at a facility of  a single hazardous substance must be aggregated for the
purpose of determining whether an RQ or more is being released. Therefore, it is important to
consider the effect of the release of a hazardous substance across all release sources at a facility.
Second, the release of a number of hazardous substances by a facility may be of greater concern
than the release of any one of the individual hazardous substances.  For this reason, PAM
aggregates the risks and/or hazards across all hazardous substances released from a facility to an
environmental medium.

      PAM aggregates release information at two levels:

      •     aggregation of concentrations of a single hazardous substance released from all
           sources at a facility to a single medium; and

      •    aggregation of carcinogenic, noncarcinogenic, and ecological effects of all hazardous
           substances released to a single medium.

      The first aggregation step results in a total exposure concentration for each hazardous
substance regardless of the number of release sources.  The second aggregation step allows PAM
to evaluate the cumulative  effects of multiple hazardous substances in an exposure medium, in
addition to evaluating the effects for each individual hazardous substance.
    26 National Research Council, Health Effects of Exposures to Low Levels of Ionizing
Radiation. BIER V. Committee on Biological Effects of Ionizing Radiation, 1990.
                                             29

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      4.3.1  Cancer Risks

      The following equation is used to estimate the incremental individual lifetime cancer risk
for simultaneous exposure to multiple carcinogens:

      RiskT = S Riskj

where:

      RiskT = the total cancer risk, expressed as a unitless probability; and
      Risk; = the cancer risk estimate for the ith hazardous substance.

Because of differences in the way that risk estimates for radionuclides and nonradioactive
hazardous substances are calculated, cumulative risks are calculated separately for radionuclides
and nonradioactive hazardous substances. For example, toxicity values for radionuclides are much
more likely to be derived from human epidemiological data than toxicity values for nonradioactive
hazardous substances, and thus are associated with a different level of uncertainty. In addition,
different methods are used to calculate risks and intakes  for these  two types of hazardous
substances.

      4.3.2 Noncarcinogenic Effects

      The method used by the Superfund program to assess the overall potential for
noncarcinogenic effects posed by more than one hazardous substance assumes that simultaneous
exposures to several hazardous substances at levels below their respective RfDs could result in
adverse health effects. The noncancer hazard index for exposure to multiple hazardous
substances is defined as:
       Hazard Index = S (CDIj/RfDj)
 where:
       CDIj = chronic daily intake for the ith toxicant; and
       RfDj = reference dose for the ith toxicant.

       4.3.4  Ecological Effects

       The method used to assess the overall effect of a number of hazardous substances on
 aquatic life parallels the hazard index approach described above. The ecological index for
 exposure to multiple hazardous substances is defined as:
       Ecological Index = 2 (CW/AWQC;)
 where:
       CWj = release point concentration of the ith hazardous substance; and
       AWQCj = freshwater, chronic ambient water quality criterion for the il
                  hazardous substance.
                                              30

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4.4   Assignment of Evaluation Flags to PAM Results

      Exhibit 5 presents the risk and hazard ranges associated with the red, yellow, and green
flags assigned for each effect for each medium. These flags are assigned at three levels:

      (1)   Flag for individual hazardous substance in each exposure medium;

      (2)   Rag for cumulative effects of multiple hazardous substances in a single medium; and

      (3)   Facility-wide flag for all effects from all hazardous substance releases across all
            media.

                                        EXHIBIT 5
         Assignment of Default Flags  for Individual Hazardous Substances by Medium
MEDIUM/EFFECT
Air
Cancer
Noncarcinogenic
Surface Water
Cancer
Noncarcinogenic
Ecological
Soil/Ground Water
TOTd (aquifer)
TOT (well)
RED
Risk > 10-4
HQa > 1
Risk > 10'4
HQ > 1
CWb > AWQC°
TOT < 50 yr.
TOT < 50 yr.
YELLOW
10'6 . 100 yr
TOT > 100 yr
3 HQ = noncancer hazard quotient
b CW = concentration in water in ng/L
c AWQC = freshwater ambient water quality criterion for the protection of aquatic life in ug/L
  TOT = time of travel in years


The same ranges are used for the flags at all three levels.  The use and interpretation of these
flags in PAM's reports is discussed in Chapter 5 of this document.

      The flags assigned to cancer risk are based on the risk range for Superfund sites as
described in the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).27
The red, yellow, and green ranges for noncarcinogenic and ecological effects were developed by
applying a one order-of-magnitude uncertainty factor (to account for the higher uncertainty in the
facility data and modeling parameters relative to Superfund sites) to essentially "red or green"
evaluation criteria. For example, if the  HQ is greater than one, a red flag is generated.
Generally, an HQ of less than one represents a low hazard situation. For purposes of the PAM
   27 National Oil and Hazardous Substances Pollution Contingency Plan; 40 CFR Part 300 (55
FR 8666; March 8, 1990).
                                            31

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reports, however, an HQ between 0.1 and 1 will generate a yellow flag, and an HQ less than or
equal to 0.1 will generate a green flag.  Similarly, a CW above the AWQC is generally considered
to be a hazard and a CW below the AWQC is generally considered to be relatively nonhazardous.
In order to conform with our "three flag approach" as opposed to a "yes/no" approach, and to
ensure that risks and hazards are not underestimated or the wrong signals are generated, a yellow
flag range was created to reflect result where  the HQ or CW/AWQC is between 0.1 and 1.0. The
red, yellow, and green levels for TOT are conservative values based on professional judgment.
The Regional CR-ERNS/PAM Coordinator has the option of using more conservative evaluation
criteria for all effects by applying an additional uncertainty factor.
                                            32

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5.    UNDERSTANDING PAM OUTPUTS

      When PAM is used to evaluate a facility's hazardous substance releases or continuous
releases from a number of facilities, three types of outputs are generated:
       •     summary facility evaluation report;
       •     model input parameter report; and
       •     detailed facility evaluation report.

The summary facility evaluation allows the user to see at a glance which facilities, media, and
hazardous substances are of greatest concern.  The model input parameter report provides a
record of all of the input parameters, both facility-specific and model defaults, used in the PAM
evaluation.  The detailed evaluation report provides complete information concerning the PAM
evaluation, including the modeled exposure concentrations or TOTs for each hazardous substance
in each release medium; the corresponding risk, hazard quotient, or ecological index;  and the
aggregated evaluation results.  Each of these reports is described in detail below.

5.1   Summary Facility Evaluation Report

      Exhibit  6 is an example of PAM's Summary Facility Evaluation Report.  This report
indicates the overall facility status, the priority flag assigned to each medium, the effect of concern
for each medium, and the hazardous substance of greatest concern for each medium.  Each  piece
of information in this report is discussed below.

                                         EXHIBIT 6
                             PAM SUMMARY FACILITY EVALUATION  REPORT
           CR-ERNS Number: 000000000001                           Run Date: 10/19/90

           Facility Name: BLANCO INDUSTRIES                       PAM version: 0.90e

           Facility Status:  Red     Number of Chemicals above "Red" Level:  2

           Number of Media of Concern: 1


           Median                                                          Total
            of   Medium                                       Effect       Medium
           Concern Status  Chemical with Highest Level  of Concern   of Concern     Result
            AIR   Red   ARSENIC
             SW   Green  BENZENE
             GW   Green  ARSENIC
 Cancer Risk    5.E-02
 Cancer Risk    7.E-09
Years to Well   2.E+02
                                             33

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CR-ERNS Number and Facility Name. These fields identify the reporting facility by name
and by the CR-ERNS number that was assigned to the facility by the National Response
Center (NRC) when the facility made its Initial Telephone Notification. The CR-ERNS
number is used to track all notifications by a particular facility.

Run Date.  This field indicates the date on which the PAM evaluation was performed.

Facility Status.  The facility status flag represents  the highest level of concern (i.e., the
"worst" evaluation outcome) of all the transport media evaluated.  The interpretation of
these flags is as follows:

•     If the overall facility flag is green, then all media affected by a continuous release
      received green flags.

•     If the overall facility flag is yellow, then at least one affected medium received a
      yellow flag, but no medium received a red flag.

•     If the overall facility flag is red, then at least one medium affected by a continuous
      release received a red flag.

The status of the example facility is red, which  means that at least one transport medium
received a red flag.

Number of Chemicals above "Red" Level. This number indicates the total number of
hazardous substances (released to all environmental media) that received "red" evaluations.
Exhibit 5 (Section 4.4) provides the red thresholds for the human health and ecological
effects evaluated by PAM.  Two chemicals released from the example facility are above the
red threshold. In this example, one of the chemicals identified in the summary report as
receiving a "red" evaluation is listed in this report (i.e.,  arsenic to air).  The detailed report
should be consulted to identify the other chemical(s) that received red flags.  The listed
chemicals in the summary report are simply the "worst actors". For this evaluation, the
detailed report indicates that cadmium released to air also received a red flag.

Number of Media of Concern.  This number indicates how many transport media received a
"red" evaluation. The paragraph below entitled "Medium Status" outlines the criteria for
assigning flags to transport media.  One transport medium received a red evaluation in the
example report.

Medium of Concern.  This column lists all of the media to which hazardous substances are
released from a facility. The example facility released to all three media:  air, surface water,
and ground water.

Medium Status. Exhibit 5 presents the flag assignments for individual hazardous
substances for each medium and each effect of concern.  The interpretation of these flags
at the transport medium level is as follows:

•     If the transport medium flag is green, then every hazardous substance released to
      that medium received a green flag for every effect, and the cumulative risk and

                                       34

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      hazard across all hazardous substances released to that medium also are below the
      yellow threshold.

      If the transport medium flag is yellow, then at least one hazardous substance received
      a yellow flag for one effect, or the cumulative effects of a number of hazardous
      substances were above the yellow threshold (but still below the red threshold).

      If the transport medium flag is red, then at least one hazardous substance received a
      red flag for one effect, or the  cumulative effects of a number of hazardous substances
      were above the red threshold for that medium.

Note that a medium can receive a yellow or red flag when each chemical in that medium
received a green or yellow flag due to the cumulative effects of multiple hazardous
substances.

      In the example summary report,  the medium flag for air is red, the medium flag for
surface water is green, and the medium flag for ground water is green.  The flag for air is
red because the cumulative medium cancer risk is above the red threshold for cancer risk of
10" .  The  flag for surface water is green because the cumulative medium cancer risk is
below the yellow threshold of 10'6.  The flag for ground water is green because the TOT
for arsenic of 200 years is longer than the yellow threshold of 100 years.

Chemical with  Highest Level of Concern,  Effect of Concern, and Total  Medium Result.
The hazardous  substance and effect of concern for each medium indicates which of the
hazardous substances  released to that medium poses  the greatest risk or hazard and which
effect is of concern.  If the "red" threshold for more than one effect is exceeded for any
medium, the following arbitrary hierarchy is used to report the single effect of concern that
can be listed in the summary report:

1)    carcinogenic effects for radionuclides;
2)    carcinogenic effects for nonradioactive hazardous substances;
2)    noncarcinogenic effects; and
3)    ecological effects.

The hazardous substance of concern  is  the hazardous substance that exceeds the "red"
threshold of the effect of concern by the greatest amount.

In the example report, the hazardous substance and effect of concern for air is cancer risk
due to arsenic.  The hazardous substance and effect of highest concern for surface water is
cancer risk due to due to benzene. For ground water, the hazardous substance with the
shortest TOT is arsenic. The "total medium result" column presents the cumulative value
for the effect of concern across all sources and chemicals.  For example, the "total medium
result" for air of 5 x 10"2 represents the cumulative cancer risk across all chemicals released
to air, including the risks  associated with arsenic (5 x 10'2),  cadmium (1 x 10"3), and
benzene (9 x 10'11).
                                      35

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5.2   Model Input Parameter Report

      PAM's Input Parameter Report includes a listing of all of the parameters used to run
PAM. These inputs include:

      •     information from the facility's continuous release notifications (e.g., release sources,
            identity of hazardous substances, release quantities, stack height, facility location);

      •     information from auxiliary data bases (e.g., hydrogeologic parameters, toxicity values,
      •     evaluation criteria (i.e., threshold values for red and yellow levels for each effect);
            and

      •     program default values (e.g., deposition velocity, stack gas temperature and exit
            velocity, distances to exposure points).

Reviewing these input data allows the user to identify the inputs (e.g., default values or regional
hydrogeologic data) used in generating the results.  This report can be generated along with the
summary evaluation  report.  To use PAM properly, it is important to understand the nature of
the inputs used in generating these screening-level, non-site-specific risk estimates.  In some cases,
the PAM default hydrogeologic, climatic, or source parameters may not accurately reflect the
actual facility conditions.

      The Input Parameter Report is divided into two major sections: facility level data and
chemical-specific data. Exhibits 7, 8, 9, and 10 present sections of the Input Parameter Report
for the example facility. The complete Input Parameter Report is in Appendix B.

      Exhibit 7 contains a portion of Section I of the Input Parameter Report.  The introductory
section provides information that identifies the facility.  Part A includes facility-level data used in
the fate and transport  models such as distances to reference exposure points and hydrogeologic
parameters. The information contained in Exhibit 7 is described in detail below.

Facility Identifiers

      CR-ERNS Case Number. This is the number assigned to the facility by the NRC when the
      facility made its  Initial Telephone Notification and is used by CR-ERNS to track all
      notifications made by a particular facility.

      Name of Facility or Vessel. This information identifies the facility or vessel.  The example
      facility is Blanco Industries in Cleveland, Ohio.  The state and county are used to assign
      county-level hydrogeologic parameters.  (See Section 3.1 for additional information on
      hydrogeologic parameters.)

      Dun and Bradstreet Number for Facility.  This information  is reported by the facility in its
      continuous release notifications and is also used to identify the facility.
                                             36

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                                    EXHIBIT 7
                              PAM INPUT PARAMETERS
                            Report Run Date:10/19/90

I.   FACILITY LEVEL DATA
  CR-ERNS Case Number:  000000000001
  Name of Facility or Vessel:   BLANCO  INDUSTRIES
                               WHITE ROAD
                               CLEVELAND
                      County:   CUYAHOGA

  Dun  and Bradstreet  Number  for Facility:  123123123123123

  Facility/Vessel  Latitude   Deg: 041  Hin: 17  Sec: 00
  Location        Longitude  Deg: 081  Hin: 60  Sec: 00
                                                             OH  44124-
                                                                 100. (m)
                                                                 500. (m)
                                                                1500. (m)
A. Static Facility Data


 1. For Releases to Air

   Downwind distance for air concentration reference point  1:
   Downwind distance for air concentration reference point  2:
   Downwind distance for air concentration reference point  3:   .„„„.  X111/
   Downwind distance for air concentration reference point  4:  3000.  
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      Facility Latitude/Longitude. This information is reported by the facility in its written
      notifications and is used for locating the weather station nearest to the facility to identify
      the most appropriate regional climatic data.

Air Model Parameters

      Downwind distance for air concentration reference points.  The distances in this report
      (100, 500, 1500, 3000, and 5000 meters) are the default distances between the source and
      exposure points that are used by the air model to calculate exposure concentrations.  These
      distances can be changed by the CR-ERNS Coordinator.  (See Section 2.1 for detailed
      information concerning the air models.)

      Receptor Height. This value is a model default and is set at 2 meters (the average height
      of an adult expressed in one significant figure).

      Average Ambient Air Temperature. This number (283 Kelvin = 10 °C = 50 °F) represents
      the air temperature in the vicinity of the release and is a model  default.

Surface Water Model Parameters

      Downstream distance for water concentration reference point.  In addition to estimating
      hazardous substance concentrations at the point of release, the surface water model also
      estimates concentrations at a distance 1000 meters from the point of release.

Ground Water Model Parameters

      All of the following parameters are assigned a conservative county-specific value when data
are available.  When data for a particular county are not available, conservative values are
assigned on a state-specific basis. (See Section 3.1 for detailed information concerning the ground
water model parameters.)

      Depth to Ground Water.  This number represents the depth to ground water in meters.
      Depth to ground water for the example facility is 4.6  meters.

      Ground Water Recharge Rate. Annual recharge indicates the amount of water per unit
      area of land that penetrates the ground surface and reaches the water table. Annual
      recharge rate for the example facility is 25 cm/yr.

      Volumetric Water Content. This dimensionless parameter is assigned based on soil medium
      and represents the volume of water per volume of soil. The volumetric water content for
      the example facility is 0.440.

      Saturated Hydraulic Conductivity. Saturated hydraulic conductivity is assigned based on
      soil medium and refers to the ability of the soil medium to transmit water.  The saturated
      hydraulic conductivity for the example facility is 1.8 x 105 cm/yr.
                                             38

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       Soil Moisture Retention Parameter. This dimensionless parameter relates soil matric
       potential and moisture content and is assigned based on soil medium.  The soil moisture
       retention parameter for the example facility is 4.05.

       Unsaturated Zone Bulk Density.  Unsaturated zone bulk density is assigned based on soil
       medium and refers to  the density (mass per unit volume) of the soil type.  The unsaturated
       zone bulk density for the example facility is 2.00 gm/cm3.

       Saturated Zone Porosity.  Saturated zone porosity is assigned based on aquifer medium and
       refers to the fraction of the pore spaces in the aquifer that contribute  to flow of water.
       The saturated zone porosity for the example facility is 0.100 cm3/cm3.

       Saturated Zone Bulk Density.  Saturated zone bulk density is assigned based on aquifer
       medium and refers to the density (mass per unit volume) of the aquifer medium.  The
       saturated zone bulk density for the example facility is 2.60 gm/cm3.

       Hydraulic Conductivity. Hydraulic conductivity refers to the ability of the aquifer medium
       to transmit water. The hydraulic conductivity for the example facility is 29745 m/yr.

       Regional Gradient. Regional gradient is the change in the elevation of the water table
       over distance.  The regional gradient for the example facility is 1 percent.

       Downgradient distance to nearest well (reference). This value of 30 meters is a default
       distance to a hypothetical well that is  used as a reference for all releases.  A source-specific
       distance to nearest well is reported by the facility in its continuous release notifications.

      Exhibit 8 contains the portion of the Input Parameter Report that describes the evaluation
criteria that are used to assign red, yellow, and green flags to releases, media, and facilities.
These flags are discussed in detail in Section 4.4 of this document.  The values in Exhibit 8 are
default values and can be adjusted by the CR-ERNS Coordinator.  The evaluation criteria are
described briefly below.

      Red Flag Threshold. The red flag thresholds represent the selected levels above which (in
      the cases of carcinogenic risk, hazard quotient, and ecological index) or below which (in the
      case of TOT) a facility  will  receive the PAM evaluation category representing the greatest
      threat.

      Yellow Flag  Threshold.  The yellow flag thresholds represent the selected levels above
      which (in the cases of carcinogenic risk, hazard quotient, and ecological index) or below
      which (in the case of TOT) a facility will receive the PAM evaluation category representing
      a potential threat.

      Cancer Risk. The default yellow and red thresholds for cancer  risk (for both radionuclides
      and nonradioactive hazardous substances) are 1 x 10"6 and 1 x 10"4, respectively.
                                            39

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                                        EXHIBIT 8
           B. Evaluation Criteria
                                Yellow Flag
                                 Threshold
Red Flag
Threshold
            Criteria

            Cancer Risk:

            Hazard Quotient:

            Ecological  Index:
 1.E-04   (dimensionless)

   1.0    (dimensionless)

   1.0    (dimensionless)
            Time of Travel:
              in unsaturated zone:
              total time to well:
      Hazard Quotient.  The default yellow and red thresholds for noncancer hazard quotient are
      0.1 and 1.0, respectively.

      Ecological Index. The default yellow and red thresholds for ecological index are 0.1 and
      1.0, respectively.

      Time of Travel. The default yellow and red thresholds for time of travel (both in the
      unsaturated zone and total time to well) are 100 years and 50 years, respectively.

      Exhibits 9 and 10 are examples of the substance-specific portion of the Input Parameter
Report. This section provides toxicity information (e.g., slope factors and reference doses),
physical/chemical properties (e.g., decay constants), and source descriptions. The information in
Exhibits 9 and 10 is described below.

Substance Parameters

      Substance Name and Substance CAS.  These fields provide the name of the hazardous
      substance and the Chemical Abstracts Service (CAS) Registry Number used to identify that
      substance. Substance 1 in this example is 1,2,4-trichlorobenzene and substance 2 is arsenic.

      Substance Type. This field is used to distinguish nonradioactive hazardous substances from
      radionuclides.  The number 1 in this field in the example report indicates that 1,2,4-
      trichlorobenzene and arsenic are nonradioactive hazardous substances.  Radionuclides are
      indicated with the number 2.
                                              40

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                                       EXHIBIT 9
      II.  SUBSTANCE (CHEMICAL) SPECIFIC DATA


       Substance   1
       Substance Name: 1,2,4-TRICHLOROBENZENE
       Substance CAS:      120821
       Substance Type (particulate,volatile=1,radionuclide=2):  1
       Cancer Slope Factor:
       Reference Dose:
       ALI:
 Oral         Inhalation
O.OE+00         O.OE+00   
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                                    EXHIBIT 10
     Substance  2
     Substance Name: ARSENIC
     Substance CAS:     7440382
     Substance Type (particulate,volatile=1,radionuclide=2): 1
     Cancer Slope Factor:
     Reference Dose:
     ALI:
 Oral         Inhalation
O.OE+00         5.0E+01   (mg/kg/d)-1
1.0E-03         O.OE+00   (mg/kg/d)
O.OE+00         O.OE+00   (uCi/yr)
     Ambient Water Quality Criterion:  O.OOE+00  (ug/l)

     Deposition Velocity:                          O.OE+00  (m/s)
     Surface Water Decay Coefficient:               2.5E-01  (1/yr)
     Ground Water Soil/Water Partition Coefficient:   5.9E+00  (ml/gm)

        Source Data for ARSENIC

        Source   1
        Source Description:           Electroplating sludge drying bed #1
        Mediun Affected:              GROUND WATER
        Downstream distance to nearest well:         12.0   (m)
        Source   2
        Source Description:
        Medium Affected:
        Source Type (stack=1,area=2):
        Average Annual Emission Rate:
        Stack Height:
        Stack Inside Diameter:
        Stack Gas Exit Velocity
        Stack Gas Exit Temperature:
        Air emissions stack #52.
        AIR
        1
               8.1E-03  gm/s/m2
              10.
               3.0
               1.0
             366.
(m)

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      Surface Water Decay Coefficient.  This parameter (kh or kt) is used only in the surface
      water pathway to account for reduction in water column concentration of a hazardous
      substance due to decay via hydrolysis (kh) or via a number of physical and chemical
      processes (kj). (See Section 3.3 for information regarding kh and kt.)   The decay constant
      for 1,2,4-trichlorobenzene is 0.20 yr"1; the decay constant for arsenic is 0.25 yr"1.

      Soil/Water Partition Coefficient.  This parameter (Kd or K^) is used only in the ground
      water pathway and provides  a measure of the extent of chemical partitioning between soil
      and water. The  soil/water partition coefficient for 1,2,4-trichlorobenzene and arsenic are
      1400 mL/g and 5.9 mL/g, respectively.

Source Parameters

      Source Description. This field  provides the source description reported by  the facility in  its
      continuous release written notification. In this example 1,2,4-trichlorobenzene Source 1 is
      NPDES effluent discharge South.  Arsenic Source 1 is electroplating sludge drying bed  #1;
      arsenic Source 2 is air emissions stack #52.

      Medium Affected.  This field indicates which environmental medium (surface water, air, or
      ground water) is the primary medium affected by the source.  1,2,4-trichlorobenzene Source
      1 affects surface water; arsenic Source  1 affects ground water; arsenic Source 2 affects air.

      Annual Average  Emission Rate. Annual average emission rate is  a parameter that is  used
      for the surface water and air models only. (See Sections 2.1 and 2.2 for information
      concerning the calculation of emission rates.) The annual average emission rate for 1,2,4-
      trichlorobenzene Source 1 is 3.3 x 10  g/yr.  The annual average emission rate for  arsenic
      Source 2 is 8.1 x 10'3 g/s-m2.

      Stream/River Name. This field provides the name of the stream or river affected by the
      hazardous substance release. The example facility releases into Big Stream.

      Average Annual  Flow.  This parameter is the annual average volume of water that flows in
      the stream or river affected by the release in cubic feet per second.  Facilities are required
      to provide this information in their continuous release written notifications.  The annual
      average flow rate for the river in the example facility is 3.8 x 104 ft3/s.

      Annual Average  Velocity.  Annual average velocity is the average speed at which water
      flows in the stream or river in feet per second.  CR-ERNS provides a built-in look-up table
      to assist users  in determining an appropriate velocity when one is not reported by the
      facility.  The annual average velocity for the river in the example facility is 1 ft/s.

      Source Type.  This field is used for releases to air only, and indicates whether the release
      source is a stack source (1) or an area source (2). The number 1 in  this field for arsenic
      Source 2 indicates that this source is a stack source.

      Stack Height.  This field is used for stack releases to air only, and indicates the height of
      the stack (from ground level to  top of stack) from which the release  occurs. The height of
      air emission stack #52 is 10 meters.
                                             43

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     Stack Inside Diameter. This number represents the diameter of the stack from which a
     release occurs. Facilities are requested to supply this information in the Written
     Notifications. If this information is not reported, however, a default value of 2 meters is
     used. The stack inside diameter for this source is 3 meters.

     Stack Gas Exit Velocity.  Stack gas exit velocity is  the speed at which gas is discharged
     from a stack. Facilities are requested to supply this information in the Written
     Notifications. If this information is not reported, however, a conservative default value of 2
     m/s is used.  The exit velocity for this stack was reported as  1 m/s.

     Stack Gas Exit Temperature. Stack gas temperature is the temperature at which gas is
     discharged from a stack.  Facilities are requested to supply this information in the Written
     Notifications. If this information is not reported, however, a default value of 383 Kelvin
     (110 °C) is used.  The reported stack gas temperature for the example facility is 366
     Kelvin.

5.3  Detailed Evaluation Report

     PAM's Detailed Evaluation Report provides complete information concerning the PAM
evaluation for each facility and should always be consulted for facilities that received a red or
yellow  flag for one or more media in the Summary Facility Evaluation Report.  A complete
Detailed Evaluation Report  is provided in Appendix B.  Sections of this Detailed Evaluation
Report are used in the exhibits  below to illustrate the types of information found in this  report.
The Detailed Evaluation Report consists of three major  sections:  facility-wide information,
chemical-specific information, and medium-specific information. Each of these sections is
described below.

      Facility-wide Information

      The facility-wide information is  listed in the first section of the Detailed Evaluation Report.
The facility-wide information section is presented in Exhibit 11,. and the data in this report are
described below.

      CR-ERNS Case Number. This field identifies the reporting facility by the CR-ERNS
      number that was assigned to the facility by the NRC when the facility made its Initial
      Telephone Notification.

      Name of Facility or Vessel.  These fields provide  the name and address of the facility.
      The example facility is Blanco Industries, located  on White Road in Cleveland, Ohio.

       Dun and Bradstreet Number for Facility.  This number is reported by the facility in its
       Written Notifications.

       Latitude/Longitude.  These numbers are also reported by the facility in its Written
       Notifications and are used for locating the weather station nearest to the facility to identify
       the most appropriate regional climatic data.
                                             44

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                                     EXHIBIT 11
      PAH  - Detailed Evaluation Report

Run Date: 10/19/90
PAH version: 0.90e
      CR-ERNS Case Number:  000000000001
      Name of Facility or Vessel:  BLANCO INDUSTRIES
                                WHITE ROAD
                                CLEVELAND
                        County:  CUYAHOGA

      Dun and Bradstreet Number for Facility: 123123123123

      Latitude:  Deg:  41.  Min: 17.  Sec:  0.
      Longitude: Deg:  81.  Hin: 60.  Sec:  0.

      Station and Climatic  Data for Nearest Weather Station

      Station Name:      CLEVELAND/HOPKINS OH
      Station ID:          269
      State FIPS Code:      39
      Station Latitude:   41.40 (decimal degrees)
      Station Longitude:  81.85 (decimal degrees)
      Distance from facility:  1.803E+01 (Km)

      Prevailing Wind Direction: S
      Frequency of Wind  in  Prevailing Direction (pet.): 15.64
  OH  44124-
Station Name. This field contains the name of the weather station in the STARDATA
climatic data base that was determined to be nearest to the reporting facility. For the
example facility, the nearest weather station is  Cleveland/Hopkins, Ohio.

Station ID and State FIPS Code.  These numbers are used to identify the weather station.

Station Latitude/Station Longitude. These fields contains the location of the chosen
weather station in decimal degrees. In this example,  the station latitude is 41..40 degrees
and the station longitude is 81.85 degrees.

Distance from Facility. This number represents the distance in kilometers from the chosen
weather station to the facility.  The distance from the Cleveland/Hopkins weather station to
Blanco Industries is 18.03 kilometers.

Prevailing Wind Direction.  This field indicates the prevailing wind direction at the  chosen
weather station. The air transport modeling is  performed for this prevailing wind direction.
The prevailing wind direction at the Cleveland/Hopkins weather station is from the south.
                                         45

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      Frequency of Wind in Prevailing Direction. This number represents the percentage of
      time at which the wind is in the prevailing direction. In this example, the wind is from the
      south 15.64 percent of the time.

      Chemical-specific Information

      Facility release information is reported on a source-specific basis in the continuous release
written notifications (i.e., for each release source, all of the hazardous substances released from
that source and their quantities are reported).  PAM rearranges this information and presents it
in the detailed  report in a chemical-specific fashion (i.e.,  for each hazardous substance  released,
all release sources of that hazardous substance and their  quantities are reported).

      Exhibit 12 is a portion of the detailed report for the example facility.  This page  of the
report provides the PAM evaluation for 1,2,4-trichlorobenzene, which is released to surface water.
Each line of this report is described below.

      Source.  Each release source of a particular hazardous substance is numbered  (1 to n, n =
      number of release sources of that hazardous substance) and the source description from the
      continuous release written notification is included.  For this facility, the only release source
      of 1,2,4-trichlorobenzene is NPDES effluent discharge South.

      Medium Affected. The environmental medium affected by the release of the above source
      is indicated  in capital letters. The affected medium for Source 1 in this example is surface
      water.

      Exposure Distance.  The exposure distances for surface water are set at zero (i.e., point of
      release)  and 1000 meters.

      Exposure Concentration. The model-generated surface water concentrations at the
      exposure distances are given in mg/L.  In this example, the surface water concentration of
       1,2,4-trichlorobenzene at both zero and 1000 meters is 9.7 x 10'5 mg/L. This indicates that
       1,2,4-trichlorobenzene undergoes a negligible degree of hydrolysis in the first 1000 meters.

       Chronic Daily Intake.  The chronic daily intakes (based on drinking water ingestion) are
       calculated based on  the above  exposure concentrations as described in Section 4.1. In this
       example, the chronic daily intake (GDI) is  estimated as 2.8 x 10'6 mg/kg-day.

       Cancer Risk. Cancer risk is calculated based on the above GDI as described in  Section 4.2.
       In this example, cancer risk is reported as zero. This indicates that cancer risk was not
       evaluated because an oral slope factor was not available.

       Radionuclides: Cancer Risk. Cancer risk due  to radionuclides is calculated using the
       methodology outlined in Sections 4.1 and 4.2.  Because 1,2,4-trichlorobenzene is not a
       radionuclide, the radionuclide cancer risk is reported as  zero.
                                              46

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                                       EXHIBIT 12
      Chemical  1  1,2,4-TRICHLOROBENZENE
        Source  1   NDPES South.

        Medium affected is SURFACE WATER
        Exposure Distance (m):
        Exposure Concentration  (mg/L):
        Chronic Daily Intake (mg/kg day):
        Cancer Risk:
        Radionuclides: Cancer Risk:
        Hazard Quotient:
        EcologicaU Index
    .0
9.7E-05
2.8E-06
 O.E+00
 O.E+00
 1.E-04
 2.E-03
 1000.0
 9.7E-05
 2.8E-06
  O.E+00
  O.E+00
  1.E-04
  2.E-03
      Totals Over All Sources: Chemical
                                          1  1,2,4-TRICHLOROBENZENE
        Exposure Medium = AIR
          Exposure Distance (m)
          Cancer Risk
          Radionuclides:  Cancer Risk
          Hazard Quotient
        Exposure Medium = SURFACE WATER
         Exposure Distance (m)
         Cancer Risk
         Radionuclides: Cancer Risk
         Hazard Quotient
         Ecological  Index
       Exposure Medium = GROUNDWATER
         Exposure Distance (m)
         Time of Travel (yrs)
           Unsaturated Zone
           Total Time to Well
    N/A
    N/A
    N/A
    N/A
      0.
  O.E+00
  O.E+00
  1.E-04
  2.E-03
    N/A

    N/A
    N/A
 1000.
O.E+00
O.E+00
1.E-04
2.E-03
Hazard Quotient  The noncancer hazard quotient is calculated based on the above GDI as
described in Section 4.2. In this example, the hazard quotient associated with 1,2,4-
trichlorobenzene at exposure points of zero and 1000 meters is 1 x W4 which receives a
green flag.  A hazardous substance with a hazard quotient greater than 0.1 would receive a
yellow flag, and a hazardous substance with a hazard quotient greater than 1.0 would
receive a red flag.
                                          47

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      Ecological Index. The ecological index is calculated based on the model-generated
      exposure concentrations as described in Section 4.2. The ecological index associated with
      1,2,4-trichlorobenzene in this example is 2 x 10'3.  Because the yellow threshold for the
      ecological index is 0.1, 1,2,4-trichlorobenzene receives a green flag for effects on aquatic
      life.

The information below the "Totals Over All Sources" divider provides the total risks and hazards
for each medium across all sources of a single hazardous substance. Note that these totals are
given for each medium, not summed across all media.

      Exposure Medium = AIR. Because no release source of 1,2,4-trichlorobenzene affects air,
      N/A (not applicable) is displayed for all of the effects associated with air.

      Exposure Medium = SURFACE WATER.  Because there is only one release source of
      1,2,4-trichlorobenzene to water, the hazard quotient and ecological index are simply those
      calculated for source 1 (NPDES effluent discharge South).  If more than one release
      source affected surface water, the total hazard index and ecological index would be
      calculated as the summation of the individual release source hazard quotients or ecological
      indices.  (See Section 4.3 for further detail on how these would be calculated.)

      Exposure Medium = GROUND WATER.  Because no release source of 1,2,4-
      trichlorobenzene affects ground water, N/A (not applicable) is displayed for all  of the
      effects associated with ground water.

      Exhibit 13 is a portion of the detailed report for the example facility. This page of the
 report provides the PAM evaluation for arsenic, which is released to ground water and air.  The
 detailed report for arsenic is described below.

       Source 1.  Release Source 1 for arsenic in the example report is electroplating  sludge
       drying bed #1.

       Medium Affected.  The environmental medium affected by source 1 is ground water.

       Exposure Distance.  The first exposure distance listed on the report (12 meters in this
       example) is the distance to the nearest well as reported by the facility.  The second
       exposure distance (30 meters) is the standard distance used to evaluate all continuous
       releases.

       Time of Travel -- Unsaturated Zone. This value is the model-generated time of travel
       (TOT) through the unsaturated zone (described in Section 2.3). This number  represents
       the time for the hazardous substance to reach the water table and is independent of the
       position of the well. TOT to the water table is the primary effect that is evaluated for
       releases to soil/ground water.  TOT through the unsaturated zone for arsenic is 200 years.
       Arsenic would receive a green flag for ground water because the  TOT is greater than the
       yellow threshold of 100 years.
                                              48

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                                   EXHIBIT 13
Chemical  2  ARSENIC
  Source  1  Electroplating sludge drying bed #1
  Medium affected is GROUND WATER
  Exposure Distance (m)
  Time of Travel (yrs)
    Unsaturated Zone
    Total Time to Well
  12.0

2.E+02
2.E+02
     30.0

   2.E+02
   2.E+02
  Source  2  Air emissions stack #52.

  Medium affected is AIR
  Exposure Distance (m)               219.    500.       1500.    3000.
  Exposure Concentration (mg/m3)   2.5E-03   1.4E-03   6.9E-04  5.8E-04
  Chronic Daily Intake (mg/kg day)  1.1E-03   6.0E-04   3.0E-04  2.5E-04
  Cancer Risk                       5.E-02    3.E-02    1.E-02   1.E-02
  Radionuclides: Cancer Risk        O.E+00    O.E+00    O.E+00   O.E+00
  Hazard Quotient                   O.E+00    O.E+00    O.E+00   O.E+00
                             5000.
                          3.9E-04
                          1.7E-04
                           8.E-03
                           O.E+00
                           O.E+00
Totals Over All  Sources:  Chemical
                                     2  ARSENIC
  Exposure Medium = AIR
    Exposure Distance 
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Time of Travel -- Total Time to Well. This value represent the sum of the model-
generated TOT through the unsaturated zone and TOT through the saturated zone
(described in Section 2.3).  These numbers represent the time for the hazardous substance
to reach the nearest well reported by the facility and the reference well at 30 meters.  In
this example, TOT to the nearest well for arsenic is 200 years.  Again, arsenic would receive
a green flag for ground water because the TOT is greater than the yellow threshold of 100
years.

Source 2. Release source 2 for arsenic in the example report is air emissions stack #52.

Medium Affected. The medium affected by source 2 is air.

Exposure Distance.  The four defined exposure distances for the air model are 500, 1500,
3000, and 5000 meters. The first exposure distance (219 meters for this source) is the
distance at which the maximum arsenic concentration at receptor height occurs. This
number will vary according to the characteristics of the source and the release.

Exposure Concentration. The model-generated exposure concentrations at each of the
exposure distances are listed directly below the distances. In this example, the  maximum
exposure concentration of arsenic (2.5 x 10"3 mg/m3) occurs at a distance of 219 meters
from the source.

Chronic Daily. Intake. The chronic daily intakes for each exposure distance (based on
inhalation) are calculated based on the above exposure concentrations as described in
Section 4.1.  In this  example, the maximum chronic daily intake (GDI) is estimated as 1.1 x
 10"3 mg/kg-day.

 Cancer Risk. The cancer risks associated with the GDI at each exposure distance are
 calculated as described in Section 4.2.  The maximum cancer risk associated with arsenic in
 this example is 5 x 10"2.  Because this is above the red threshold of  10"4,  arsenic would
 receive a red flag for cancer risk.

 Radionuclides: Cancer Risk.  Because arsenic is not a radionuclide, zero is displayed for all
 exposure distances.

 Hazard Quotient  The hazard quotients are calculated for each exposure distance based on
 the respective GDIs. In this example, the hazard quotient of zero indicates that
 noncarcinogenic effects were not evaluated because an inhalation reference dose was not
 available for arsenic.

 Totals Over All Sources. Again, the numbers in this section  represent the total risks and
 hazards combined across all sources of a hazardous substance that affect the same medium.
 The methods used to estimate total risks, hazards, and TOTs  are described in Section 4.3.
                                        50

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                                          EXHIBIT 14
            FACILITY EFFECT TOTALS OVER ALL CHEMICALS AND SOURCES
              Route of Exposure = AIR
                Exposure Distance (m)         219.
                Cancer Risk                 5.E-OH
                Radionuclides: Cancer Risk   O.E+00
                Hazard Index                O.E+00
              Route of Exposure = SURFACE WATER
                Exposure Distance (m)
                Cancer Risk
                Radionuclides: Cancer Risk
                Hazard Index
                Ecological Index
              Route of Exposure = GROUNDWATER
                Exposure Distance (m)
                Time of Travel (yrs)
                  Unsaturated Zone
                  Total Time to Well
 500.    1500.    3000.    5000.
3.E-02   2.E-02   1.E-02   9.E-03
O.E+00   O.E+00   O.E+00   O.E+00
O.E+00   O.E+00   O.E+00   O.E+00
        0.
    7.E-09
    O.E+00
    1.E-04
    2.E-03
      12.0
 1000.
7.E-09
O.E+00
1.E-04
2.E-03
              30.0
    2.E+02   2.E+02
    2.E+02   2.E+02
      Medium-specific Information

      The report section titled "Facility Effect Totals Over All Chemicals and Sources" presents
the cumulative risks and hazards from all hazardous substances released to each environmental
medium (Exhibit 14).  The methods discussed in Section 4.3 are used to sum the cancer risks,
noncancer hazard quotients, and ecological indices for all hazardous substances released to a
medium.  For ground water, the shortest TOT for any hazardous substance is reported as the
ground-water "total".

      Route of Exposure = AIR.  This section provides the cumulative risks and hazards for all
      substances released to air.

      Exposure Distance.  The distances reported here are the four defined distances and the
      distance at which the maximum effect associated with a release from any stack occurs.
      Because the releases from this facility involve only one stack, the maximum exposure
      distance is 219 meters.

      Cancer Risk. These numbers represent the cumulative risks due to all nonradioactive
      hazardous substances released to air at each of the exposure distances. In the example
      report, the total cancer risk for exposure via air of 5 x 10~2 is the sum of the risks
                                              51

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associated with arsenic (5 x 10"2), cadmium (1 x 10'3), and benzene (9 x 10"11). This effect
receives a red flag.

Radionuclides: Cancer Risk.  These numbers represent the cumulative risks associated
with all radionuclides released to air at each of the exposure distances.  Because none of
the hazardous substances released by the example facility are radionuclides, the total here is
zero.

Hazard Index. These numbers represent the total noncancer hazards associated with all
nonradioactive hazardous substances released to air at each of the exposure distances. The
noncancer hazard index for air in this example is zero because the hazardous substances
released to air were not evaluated for noncarcinogenic effects  (due to lack of inhalation
Route of Exposure = SURFACE WATER. This section provides the cumulative risks,
hazards, and ecological effects for all substances released to surface water.

Exposure Distance. These are the same exposure distances (zero and 1000 meters) used to
evaluate the individual releases.

Cancer Risk. These numbers represent the cumulative risks associated with all
nonradioactive hazardous substances released to surface water at each of the exposure
distances.  The cumulative cancer risk in this example is equal to the cancer risk for
benzene (7 x 10"9) because the other substance released to surface water was not evaluated
for cancer risk.  This effect receives  a green flag.

Radionuclides:  Cancer Risk.  These numbers represent the cumulative risks due to all
radionuclides released to surface water at each of the exposure distances.  Because none of
the hazardous substances released by the example facility are radionuclides, the total here is
zero.

Hazard Index. These numbers represent the total noncancer hazards associated with all
nonradioactive hazardous substances released to surface water at each of the exposure
 distances.  The hazard index in this example  is equal to the hazard quotient for 1,2,4-
 trichlorobenzene because the other substance released to surface water was not evaluated
 for noncancer effects. This effect receives a green flag.

 Ecological Index.  These numbers represent  the total ecological index over all hazardous
 substances released to surface water. The ambient water quality quotient for this example
 is 2 x 10"3 and receives a green flag.

 Route of Exposure = GROUND WATER. This section provides overall information on all
 substances released to ground water.

 Exposure Distance. These are the same exposure distances used to evaluate each release
 (i.e., distance to nearest well reported by the facility and at the standard distance of 30
 meters). For the example facility the nearest well is located at a distance of 12 meters.
                                        52

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Time of Transport. The "total" effects for both time of travel through the unsaturated
zone and total time to the well represent the shortest TOT for any chemical evaluated.
The "total" values for TOT (200 years to the unsaturated zone and to the nearest well) are
the TOTs for arsenic, the hazardous substance that moves most quickly.
                                     53

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                                      APPENDIX A
                  RADIONUCLIDE FATE AND TRANSPORT EQUATIONS

Atmospheric Dispersion Model

      Stack Sources

      The equation used to estimate atmospheric concentrations of radionuclides at exposure
points due to releases from stack sources is as follows:28
               Ca(x,y, z) =
                       2-Ji0yozv
                             — exp
-y2
202
                                                                    20*
Parameters
Ca(x,y,z)    =    concentration at receptor point (x,y,z) in the downwind direction
                 (microcuries/m3);

      Qs   =    annual average mass flux of contaminant into atmosphere
                 (microcuries/s);

      it.    =    3.14159 (unitless);

      v     =    mean wind velocity (m/s);

           = .    standard deviation of Gaussian plume in y and z directions (m);

           =    height of receptor (m); and
      °y °z
           h    =    effective height of plume (i.e., stack height + buoyancy rise of plume,
                       m).

      If deposition of emitted particles is considered, z' is used in place of z.
                                      z> = z -
                                                V
where v  = deposition velocity (m/s).
   28 R.J. Bibbero and LG. Young, Systems Approach to Air Pollution Control. John Wiley &
Sons, Inc., p. 317.
                                           55

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      Area Sources

The equation used to estimate atmospheric concentrations of radionuclides at exposure points due
to releases from area sources is as follows:29
                                      2.03
Parameters

      Ca(x,z)
        Wl
    average concentration within a directional sector (22.5 degrees)
    (microcuries/m3);

=   annual average mass flux of radionuclide into the atmosphere (microcuries/s);

=   source depletion factor (unitless);

=   mixing coefficient in z direction, standard deviation of Gaussian plume (m);

=   distance in x coordinate direction (parallel to velocity v) from source to point
    of interest (m);

=   virtual distance required for hypothetical point source plume to spread to the
    edge of the area source (m);

=   distance in z coordinate direction (perpendicular to velocity v) from source to
    exposure point (i.e.,  receptor height) (m);

=   frequency of the specific stability array parameters for classification i (stability
    class) (dimensionless); and

=   average wind speed for classification i (m/s).
     29 Ibid, Section 3.3.
                                              56

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Surface Water Model

      The equation used to predict surface water exposure concentrations of radionuclides is as
follows:30
                                        Msw] I  1
                                        Q ) I IOC
                                   exp
Parameters

      CSW(X)

      Msw

      1/1000

      Q

      kd

      X

      uc
concentration in stream/river at point of exposure (microcuries/L);

mass input of radionuclide to stream/river (microcuries/yr);

=    conversion factor from m3 to L (m3/L);

average flow rate in stream/river (m3/yr);

first-order degradation constant (yr"1);

downstream distance from source location to exposure point (m); and

average stream velocity (m/yr).
    *2n
    M USEPA, Water Quality Assessment: A Screening Procedure for Toxic and Conventional
Pollution in Surface and Ground Water, Office of Water Regulations and Standards, September
1985.

                                            57

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                                 APPENDIX B
                                PAM REPORTS
                     PAM SUMMARY FACILITY EVALUATION REPORT
CR-ERNS Number: 000000000001                             Run Date: 10/19/90

Facility Name: BLANCO INDUSTRIES                         PAM version: 0.90e

Facility Status:  Red       Number of Chemicals  above  "Red" Level:  2

Number of Media of Concern:  1
Medium                                                                 Total
  of    Medium  .                                          Effect       Medium
Concern Status  Chemical with Highest Level  of  Concern   of Concern     Result
  AIR    Red    ARSENIC
   SW    Green  BENZENE
   GW    Green  ARSENIC
 Cancer Risk    5.E-02
 Cancer Risk    7.E-09
Years to Well   2.E+02
                                    59

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                              PAM INPUT PARAMETERS
                            Report Run Date:10/19/90
I,  FACILITY LEVEL DATA
  CR-ERNS Case Number: 000000000001
  Name of Facility or Vessel:  BLANCO INDUSTRIES
                               WHITE ROAD
                               CLEVELAND                       OH  44124-
                      County;  CUYAHOGA

  Dun and Bradstreet Number for Facility:  123123123123123

  Facility/Vessel Latitude   Deg; 041  Min: 17  Sec: 00
  Location        Longitude  Deg: 081  Min: 60  Sec: 00
  A. Static Facility Data


   1. For Releases to Air

     Downwind distance for air concentration reference point 1:   100, (m)
     Downwind distance for air concentration reference point 2:   500. (m)
     Downwind distance for air concentration reference point 3:  1500. (m)
     Downwind distance for air concentration reference point 4:  3000. (m)
     Downwind distance for air concentration reference point 5:  5000. (m)

     Receptor Height:                    2. (m)
     Average Ambient Air Temperature:  283. (K)


   2. For Releases to Surface Water

     Downstream distance for water concentration reference point:  1000.  (m)


  , 3, For Releases to Ground Water


     a, Unsaturated Zone Transport

        Depth to Ground Water:                    4.. 6   (m)
        Ground Water Recharge Rate:             25,    (cm/yr)
                                      61

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       Volumetric Water Content:
       Saturated Hydraulic Conductivity:
       Soil Moisture Retention Parameter:
       Unsaturated Zone Bulk Density:

    b. Saturated Zone Transport
                     0.440 (dimensionless)
                 180000.    (cm/yr)
                      4.05  (dimensionless)
                      2.00  (gm/cm3)
       Saturated Zone  Porosity:                             0.100  (cm3/cm3)
       Saturated Zone  Bulk Density:                         2.60   (gm/cm3)
       Hydraulic Conductivity:                           29745.     (m/yr)
       Regional  Gradient:                     .              1-0    (m/m)
       Downstream distance to nearest well  (reference):     30.     (m)
  B.  Evaluation Criteria
Criteria
Cancer Risk:
Hazard Quotient:
Ecological Index:
Time of Travel:
in unsaturated zone:
total time to well:
Yellow Flag
Threshold
l.E-06
0.1
0.1
100.
100.
Red Flag
Threshold
l.E-04
1.0
1.0
50.
50.

( dimens ionle s s )
(dimensionless)
(dimensionless)
(yrs)
(yrs)
II.  SUBSTANCE (CHEMICAL) SPECIFIC DATA
  Substance
  Substance Name: 1,2,4-TRICHLOROBENZENE
  Substance CAS:      120821
  Substance Type (particulate,volatile=l,radionuclide=2):  1
  Cancer Slope Factor:
  Reference Dose:
  ALI:
 Oral         Inhalation
0.OE+00         0.OE+00   (mg/kg/d)-1
2.0E-02         3.0E-03   (mg/kg/d)
0.OE+00         0.OE+00   (uCi/yr)
  Ambient Water Quality Criterion:  5.00E+01  (ug/1)

  Deposition Velocity:                            0.OE+00  (m/s)
  Surface Water Decay Coefficient:   ,             2.0E-01  (1/yr)
  Ground Water Soil/Water Partition Coefficient:  1.4E+03  (ml/gm)
                                      62

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  Source Data for 1,2,4-TRICHLOROBENZENE

  Source   1
  Source Description:            NDPES South.
  Medium Affected:               SURFACE WATER
  Annual Average Emission Rate:  3.3E+06   (gm/yr)

  Stream/River Data:
  Stream/River Name:  New Stream
  Average Annual Flow:      3.8E+04  (ft3/s)
  Average Annual Velocity:  l.OE+00  (ft/s)

End of Source(s) for Substance: 1,2,4-TRICHLOROBENZENE
Substance
Substance Name: ARSENIC
Substance CAS:     7440382
Substance Type (particulate,volatile=l,radionuclide=2): 1
Cancer Slope Factor:
Reference Dose:
ALI:
 Oral
0.OE+00
l.OE-03
0.OE+00
Inhalation
  5.OE+01
  0.OE+00
  0.OE+00
(mg/kg/d)-l
(mg/kg/d)
(uCi/yr)
Ambient Water Quality Criterion:  O.OOE+00  (ug/1)
Deposition Velocity:
Surface Water Decay Coefficient:
Ground Water Soil/Water Partition Coefficient:

  Source Data for ARSENIC
                        0.OE+00  (m/s)
                        2.5E-01  (1/yr)
                        5.9E+00  (ml/gm)
  Source   1
  Source Description:            Electroplating sludge drying bed #1
  Medium Affected:               GROUND WATER
  Downstream distance to nearest well:          12.0   (m)
  Source   2
  Source Description:
  Medium Affected:
  Source Type (stack=l,area=2):
  Average Annual Emission Rate:
  Stack Height:
  Stack Inside Diameter:
  Stack Gas Exit Velocity
  Stack Gas Exit Temperature:
         Air emissions stack #52.
         AIR
         1
                8.IE-03  gm/s/m2
                         (m)
 10,
  3,
  1.
366.
                         (m)
                         (m/s)
                         (K)
                                    63

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End of Source(s) for Substance: ARSENIC
Substance
Substance Name: BENZENE
Substance CAS:       71432
Substance Type (particulate,volatile=l,radionuclide=2): 1
Cancer Slope Factor:
Reference Dose:
ALT:
         Oral         Inhalation
        2.9E-02         2.9E-02    (mg/kg/d)-l
        0.OE+00         0.OE+00    (mg/kg/d)
        O.OE+00         0.OE+00    (uCi/yr)
Ambient Wa_er Quality Criterion:  O.OOE+00  (ug/1)

Deposition Velocity:                            O.OE+00
Surface Water Decay Coefficient:                1.9E+02
Ground Water Soil/Water Partition Coefficient:  3.1E+01

  Source Data for BENZENE
                                         (m/s)
                                         d/yr)
                                         (ml/gin)
  Source   1
  Source Description:
  Medium Affected:
  Annual Average Emission Rate:
                 NDPES  South.
                 SURFACE WATER
                 3.0E+05  (gm/yr)
  Stream/River Data:
  Stream/River Name:  New Stream
  Average Annual Flow:      3.8E+04  (ft3/s)
  Average Annual Velocity:  1.OE+00  (ft/s)
  Source   2
  Source Description:
  Medium Affected:
  Source Type  (stack=l,area=-2) :
  Average Annual Emission Rate:
  Height of Release:
  Surface Area of Release:
                 Washwater holding pond #3a.
                 AIR
                 2
                        1.2E-07   gm/s/m2
                        3.5E+01   (m)
                        4.0E+03   (m2)
End of Source(s) for Substance: BENZENE
Substance
Substance Name:
Substance CAS:
CADMIUM
   7440439
                                    64

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 Substance Type (particulate,volatile=l,radionuclide=2):  1
 Cancer Slope Factor:
 Reference  Dose:
 ALI:
                        Oral
                       O.OE+00
                       5.0E-04
                       O.OE+00
 Inhalation
   6.1E+00    (mg/kg/d)-l
   O.OE+00    (mg/kg/d)
   O.OE+00    (uCi/yr)
Ambient Water  Quality Criterion:   1.10E+00   (ug/1)
Deposition Velocity:
Surface Water  Decay Coefficient:
Ground Water Soil/Water Partition Coefficient:

  Source Data  for CADMIUM
                                               O.OE+00  (m/s)
                                               2.5E-01  (1/yr)
                                               1.5E+01  (ml/gm)
   Source    1
   Source Description:
   Medium Affected:
   Source Type  (stack=l,area=2):
   Average Annual Emission Rate:
   Stack Height:
   Stack Inside Diameter:
   Stack Gas Exit Velocity
   Stack Gas Exit Temperature:
                               Air emissions  stack #52.
                               AIR
                               1
                                       1.3E-03   gm/s/m2
                                     10.        (m)
                                       3.0       (m)
                                       1.0       (m/s)
                                    366.        (K)
End of Source(s) for Substance: CADMIUM
Substance  . 5
Substance Name: TETRACHLOROETHYLENE
Substance CAS:      127184
Substance Type (particulate,volatile=l,radionuclide=2):  1
Cancer Slope Factor:
Reference Dose:
ALI:
                       Oral
                      0.OE+00
                      l.OE-02
                      O.OE+00
Inhalation
  O.OE+00   (mg/kg/d)-1
  0.OE+00   (mg/kg/d)
  O.OE+00   (uCi/yr)
Ambient Water Quality Criterion:  8.40E+02  (ug/1)

Deposition Velocity:                            O.OE+00  (m/s)
Surface Water Decay Coefficient:                1.8E+02  (1/yr)
Ground Water Soil/Water Partition Coefficient:   2.4E+02  (ml/gm)
  Source Data'for TETRACHLOROETHYLENE


                                 Pipe discharge to pit,  Building 5
Source   1
Source Description:
                                    65

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    Medium Affected:               GROUND  WATER
    Downstream distance to nearest well:           1.0   (m)

  End of Source(s) for Substance: TETRACHLOROETHYLENE
  „_...•,•«•.. — — — — •••• — — — — — — — — - — — — — — — — - — — -- — — •- — — ---- — — — ••-•••--



End of Substance(s) for CR-ERNS  Case  Number:  000000000001
                                       66

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PAM - Detailed Evaluation Report
                                       Run Date:  10/19/90
                                       PAM version:  0.90e
CR-ERNS Case Number: 000000000001
Name of Facility or Vessel:  "BLANCO INDUSTRIES
                             WHITE ROAD
                             CLEVELAND
                    County:  CUYAHOGA

Dun and Bradstreet Number for Facility:  123123123123

Latitude:  Deg:  41.  Min: 17.  Sec:  0.
Longitude: Deg:  81.  Min: 60.  Sec:  0.

Station and Climatic Data for Nearest Weather Station
                                         OH  44124-
Station Name:
Station ID:
State FIPS Code:
Station Latitude:
Station Longitude:
CLEVELAND/HOPKINS OH
   269
    39
 41.40 (decimal degrees)
 81.85 (decimal degrees)
Distance from facility:  .1.803E+01 (Km)

Prevailing Wind Direction: S
Frequency of Wind in Prevailing Direction (pet.): 15.64
                                     67

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Chemical  1  1,2,4-TRICHLOROBENZENE
  Source  1  NDPES South.

  Medium affected is SURFACE WATER
  Exposure Distance (m):
  Exposure Concentration (mg/L):
  Chronic Daily Intake (mg/kg day):
  Cancer Risk:
  Radionuclides:  Cancer Risk:,
  Hazard Quotient:
  Ecological Index
            .0
        9.7E-05
        2.8E-06
         0.E+00
         0.E+00
         l.E-04
         2.E-03
1000.0
9.7E-05
2.8E-06
 0.E+00
 0.E+00
 l.E-04
 2.E-03
Totals Over All Sources:  Chemical
1  1,2,4-TRICHLOROBENZENE
  Exposure Medium — AIR
    Exposure Distance (m)
    Cancer Risk
    Radionuclides:  Cancer Risk
    Hazard Quotient
             N/A
             N/A
             N/A
             N/A
  Exposure Medium = SURFACE WATER
    Exposure Distance (m)
    Cancer Risk
    Radionuclides: Cancer Risk
    Hazard Quotient
    Ecological Index
               0.
           0.E+00
           0.E+00
           l.E-04
           2.E-03
 1000.
0.E+00
0.E+00
l.E-04
2.E-03
  Exposure Medium - GROUNDWATER
    Exposure Distance (m)
    Time of Travel (yrs)
      Unsaturated Zone
      Total Time to Well
             N/A

             N/A
             N/A
                                     68

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Chemical  2  ARSENIC
  Source  1  Electroplating sludge drying bed #1
  Medium affected is GROUND WATER
  Exposure Distance (m)
  Time of Travel (yrs)
12.0
     30.0
Unsaturated Zone
Total Time to Well
Source 2 Air emissions stack #52
Medium affected is AIR
Exposure Distance (m)
Exposure Concentration (mg/m3) 2
Chronic Daily Intake (mg/kg day) 1
Cancer Risk
Radionuclides : Cancer Risk
Hazard Quotient
Totals Over All Sources : Chemical
Exposure Medium = AIR
Exposure Distance (m)
Cancer Risk 5
Radionuclides : Cancer Risk 0
Hazard Quotient 0


.

219.
.5E-03
.1E-03
5.E-02
0 . E+00
0 . E+00
2.E+02
2 . E+02


500.
1.4E-03
6.0E-04
3. E-02
0 . E+00
0 . E+00
2
2


1500.
6.9E-04
3.0E-04
l.E-02
0 . E+00
0 . E+00
.E+02
.E+02


3000.
5.8E-04
2.5E-04
l.E-02
0 . E+00
0 . E+00




5000.
3.9E-04
1.7E-04
8.E-03
0 . E+00
0 . E+00
2 ARSENIC

219.
.E-02
.E+00
.E+00

500.
3. E-02
0 . E+00
O.E+00

1500.
l.E-02
O.E+00
0 . E+00

3000.
l.E-02
0 . E+00
0 . E+00

5000.
8.E-03
0 . E+00
0 . E+00
  Exposure Medium = SURFACE WATER
    Exposure Distance (m)
    Cancer Risk
    Radionuclides:  Cancer  Risk
    Hazard Quotient
    Ecological Index
    N/A
    N/A
    N/A
    N/A
    N/A
 .Exposure Medium = GROUNDWATER
    Exposure  Distance  (m)
    Time  of Travel (yrs)
     Unsaturated Zone
     Total Time  to Well
    12.0

  2.E+02
  2.E+02
  30.0

2.E+02
2.E+02
                                    69

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Chemical  3  BENZENE
  Source  1  NDPES South.

  Medium affected is SURFACE WATER
  Exposure Distance (m):
  Exposure Concentration (mg/L):
  Chronic Daily Intake (mg/kg day):
  Cancer Risk:
  Radionuclides: Cancer Risk:
  Hazard Quotient:
  Ecological Index
               .0
           8.8E-06
           2.5E-07
            7.E-09
            0.E+00
            0.E+00
            0.E+00
              1000.0
              8.7E-06
              2.5E-07
               7.E-09
               0.E+00
               0.E+00
               0.E+00
  Source  2  Washwater holding pond #3a.

  Medium affected is AIR
  Exposure Distance (m)               100.
  Exposure Concentration (mg/m3)   7.6E-09
  Chronic Daily Intake (mg/kg day) 3.3E-09
  Cancer Risk                       9.E-11
  Radionuclides: Cancer Risk        O.E+00
  Hazard Quotient                   O.E+00
          500.
         3.0E-07
         1.3E-07
          4.E-09
          0.E+00
          0.E+00
           1500.
         2.5E-07
         1.1E-07
          3.E-09
          0.E+00
          0.E+00
           3000.
         1.4E-07
         5.8E-08
          2.E-09
          0.E+00
          0.E+00
           5000.
         7.5E-08
         3.2E-08
          9.E-10
          0.E+00
          0.E+00
Totals Over All Sources:  Chemical
   3  BENZENE
  Exposure Medium — AIR
    Exposure Distance (m)
    Cancer Risk
    Radionuclides: Cancer Risk
    Hazard Quotient

  Exposure Medium - SURFACE WATER
    Exposure Distance (m)
    Cancer Risk
    Radionuclides: Cancer Risk
    Hazard Quotient
    Ecological Index

  Exposure Medium = GROUNDWATER
    Exposure Distance (m)
    Time of Travel (yrs)
      Unsaturated Zone
      Total Time to Well
  100.
9.E-11
0.E+00
0.E+00
  500.
4.E-09
0.E+00
0.E+00
1500.
3.E-09
O.E+00
O.E+00
 3000.
2.E-09
0.E+00
0.E+00
 5000.
9.E-10
0.E+00
0.E+00
                  0.
              7.E-09
              0.E+00
              0.E+00
              0.E+00
                N/A

                N/A
                N/A
               1000.
              7.E-09
              0.E+00
              0.E+00
              0.E+00
                                     70

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Chemical  4  CADMIUM
  Source  1  Air emissions stack #52.

  Medium affected is AIR
  Exposure Distance (m)               219.
  Exposure Concentration (mg/m3)   4.0E-04
  Chronic Daily Intake (mg/kg day) 1.7E-04
  Cancer Risk                       l.E-03
  Radionuclides:  Cancer Risk        O.E+00
  Hazard Quotient                   O.E+00
       500.
      2.3E-04
      9.7E-05
       6.E-04
       0.E+00
       0.E+00
   1500.
 1.1E-04
 4.8E-05
 3.E-04
 0.E+00
 O.E+00
   3000.
 9.3E-05
 4.0E-05
 2.E-04
 0.E+00
 0.E+00
   5000.
 6.3E-05
 2.7E-05
 2.E-04
 0.E+00
 0.E+00
Totals Over All Sources: Chemical
4  CADMIUM
  Exposure Medium = AIR
    Exposure Distance (m)            219 .
    Cancer Risk                    l.E-03
    Radionuclides:  Cancer Risk     0.E+00
    Hazard Quotient                O.E+00
        500.
      6.E-04
      0.E+00
      0.E+00
1500.
3.E-04
0.E+00
O.E+00
 3000.
2.E-04
0.E+00
0.E+00
 5000.
2.E-04
0.E+00
0.E+00
  Exposure Medium = SURFACE WATER
    Exposure Distance (m)
    Cancer Risk
    Radionuclides:  Cancer  Risk
    Hazard Quotient
    Ecological Index
             N/A
             N/A
             N/A
             N/A
             N/A
  Exposure Medium =  GROUNDWATER
    Exposure  Distance  (m)
    Time  of Travel (yrs)
     Unsaturated Zone
     Total Time  to  Well
            N/A

            N/A
            N/A
                                    71

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Chemical  5  TETRACHLOROETHYLENE
  Source  1  Pipe discharge to pit, Building 5.
  Medium affected is GROUND WATER
  Exposure Distance (m)
  Time of Travel (yrs)
    Unsaturated Zone
    Total Time to Well
        12.0

      8.E+03
      8.E+03
    30.0

  8.E+03
  8.E+03
Totals Over All Sources: Chemical
5  TETRACHLOROETHYLENE
  Exposure Medium = AIR
    Exposure Distance  (m)
    Cancer Risk
    Radionuclides: Cancer Risk
    Hazard Quotient
             N/A
             N/A
             N/A
             N/A
   Exposure Medium -  SURFACE WATER
     Exposure  Distance  (m)
     Cancer Risk
     Radionuclides: Cancer  Risk
     Hazard Quotient
     Ecological Index
             N/A
             N/A
             N/A
             N/A
             N/A
   Exposure Medium - GROUNDWATER
     Exposure Distance (m)
     Time of Travel (yrs)
       Unsaturated Zone
       Total Time to Well
             12.0

            .E+03
            .E+03
  30.0

8.E+03
8.E+03
                                      72

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 FACILITY EFFECT TOTALS OVER ALL CHEMICALS AND SOURCES
    Route of Exposure = AIR
      Exposure Distance (m)
      Cancer Risk
      Radionuclides:  Cancer Risk
      Hazard Index
219.
5.E-02
0 . E+00
0 . E+00
500.
3.E-02
O.E+00
O.E+00
1500.
2.E-02
0 . E+00
O.E+00
3000.
l.E-02
O.E+00
0 . E+00
5000.
9.E-03
0 . E+00
0 . E+00
   Route  of Exposure = SURFACE WATER
      Exposure Distance (m)
      Cancer Risk
      Radionuclides:  Cancer  Risk
      Hazard Index
      Ecological  Index
    0.
7.E-09
0.E+00
l.E-04
2.E-03
 1000.
7.E-09
0.E+00
l.E-04
2.E-03
   Route of Exposure = GROUNDWATER
     Exposure Distance (m)
     Time of Travel (yrs)
        Unsaturated Zone
        Total Time to  Well
  12.0

2.E+02
2.E+02
  30.0

2.E+02
2.E+02
FACILITY EVALUATION

Facility Status:  Red

Number of Chemicals above "Red" Level:

Number of Pathways of Concern: 1
Medium
  of    Medium                                              Effect
Concern Status  Chemical with Highest Level of Concern   of Concern
                       Total
                       Medium
                       Result
  AIR    Red    ARSENIC
   SW    Green  BENZENE
   GW    Green • ARSENIC
        Cancer Risk    5.E-02
        Cancer Risk    7.E-09
       Years  to Well   2.E+02
                                     73
                                                 GOVERNMENT PRINTING OFFICE: 1991 - $48-187/205*1

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