Industrial Waste
Management
-------
This Guide provides state-of-the-art tools and
practices to enable you to tailor hands-on
solutions to the industrial waste management
challenges you face.
WHAT'S AVAILABLE
Quick reference to multimedia methods for handling and disposing of wastes
from all types of industries
Answers to your technical questions about siting, design, monitoring, operation.
and closure of waste facilities
Interactive, educational tools, including air and ground water risk assessment
models, fact sheets, and a facility siting tool.
Best management practices, from risk assessment and public participation to
waste reduction, pollution prevention, and recycling
-------
;NOWLEDGEMENTS
The rdowing members of the Industrial Waste Focus Group and the Industrial Waste Steering Commiw are grateUy
acknowledged far al of their time and assistance in the development of this guidance document
Current Industrial Waste Focus
Group Members
Paul Bar*, The Dow Chemical
Company
Walter Carey. Nestle USA Inc and
New Miltord Farms
Rama Chaturvedi Bethlehem Steel
Corporation
H.C. Clark. Rice University
Barbara Dodds, League of Women
voters
Chuck Feerick. Exxon Mobil
Corporation
Stacey Ford. Exxon Mobil
Corporation
Robert Giraud OuPont Company
John Harney Citizens Round
Tabte/PURE
Kyle Isakower. American Petroleum
Institute
Richard Jarman, National Food
Processors Association
James Meiers, Cinergy Power
Generation Services
Scott Murto. General Motors and
American Foundry Society
James Roewer, Edison Electric
Institute
Edward Repa. Environmental
Industry Association
Tim Savior, International Paper
Amy Schaffer. Weyerhaeuser
Ed Skemofc, WMX Technologies. Inc
Michael Wach Western
Environmental Law Center
David Wens, University of South
Wabnms Medical Center
Pat Gwn Cherokee Nation of
Oklahoma
Past industrial Waste Focus
Group Members
Dora Cetofius. Sierra Club
Brian Forrestal. Laidlaw Waste
Systems
Jonathan Greenberg. Browning-
Ferris Industries
Michael Gregory, Arizona Toxics
Information and Sierra Club
Andrew Mites The Dexter
Corporation
Gary Robbins, Exxon Company
Kevin Sail. National Paint & Coatings
Association
Bruce SteJne. American Iron & Steel
Lisa Williams, Aluminum Association
Cuircnt Industrial Waste Steering
Committee Members
Keiiy Catalan Aaaocauon oi Slate
and Territorial Solid Waste
Management Officials
Marc Crooks, Washington State
Department ot Ecology
Cyndi Darling. Maine Department of
Environmental Protection
Jon DilDard Montana Department of
Environmental Qualty
Anne Dobbs. Texas Natural
Resources Conservation
Commission
Richard Hammond New York State
Department of Environmental
Conservation
Elizabeth Haven California State
Waste Resources Control Board
Jim Hul Missouri Department of
Natural Resources
Jim Knudson, Washington State
Department of Ecology
Chris McGuire, Florida Department
of Environmental Protection
Gene Mitchell Wisconsin
Department of Natural Resources
William Pounds, Pennsylvania
Department of Environmental
Protection
Bijan Sharafkhani Louisiana
Department of Environmental
Qualty
James Warner, Minnesota Pollution
Control Agency
ittustrial Waste Steering
Pamela um*. nianie
Environmental Protection
NormGumenik Arizona Department
of Environmental Qualty
Steve Jenkins, Alabama Department
of Environmental Management
Jim North Arizona Department of
Environmental Quality
-------
Industrial waste is generated by the production
of commercial goods, products, or services.
Examples include wastes from the production
of chemicals, iron and steel, and food goods.
-------
ADDENDUM
USER'S GUIDE FOR THE
INDUSTRIAL SOURCE COMPLEX (ISC3) DISPERSION MODELS
VOLUME I - USER INSTRUCTIONS
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Emissions, Monitoring, and Analysis Division
Research Triangle Park, North Carolina 27711
April 2000
-------
ACKNOWLEDGMENTS
The Addendum to the User's Guide for the ISC3 Models has been prepared by Roger W.
Erode of Pacific Environmental Services, Inc., Research Triangle Park, North Carolina, under
subcontract to EC/R, Inc., Chapel Hill, North Carolina. This effort has been funded by the
Environmental Protection Agency under Contract No. 68D98006, with Dennis G. Atkinson as
Work Assignment Manager.
INDEX-xiii
-------
USER INSTRUCTIONS FOR THE
REVISED ISCST3 MODEL (DATED 00101)
This document provides user instructions for recent enhancements of the ISCST3 model,
including the most recent version dated 00101 (April 10, 2000). The enhancements described in
this Addendum include changes to the processing of multi-year averages for post-1997 PM10
NAAQS analyses, enhancements to the model which were formerly available in draft form as
ISCST390 (dated 97365), enhancements to the model for air toxics applications, and an option
to specify variable emission rate factors that vary by season, hour-of-day, and day-of-week. The
enhancements from the draft ISCST390 model include a conversion to Fortran 90 in order to
make use of allocatable arrays for data storage, incorporation of the EVENT processing from
the ISCEV3 model, an INCLUDED keyword option for the source, receptor and event
pathways, and two new options for specifying area sources. The use of allocatable arrays
provides much more flexibility for the end user of the ISCST3 model. The enhancements for air
toxics applications include the Sampled Chronological Input Model (SCEVI) option,
optimizations for the area source and dry depletion algorithms, inclusion of the gas dry
deposition algorithms based on the draft GDISCDFT model (dated 96248), and the option to
output results by season and hour-of-day (SEASONHR). User instructions for these
enhancements are provided below.
ENHANCEMENTS INTRODUCED WITH ISCST3 (DATED 98348)
Post-1997 PMin Processing
A new NAAQS for modeling PM10 was promulgated in July 1997. This guidance
utilizes the expected second high value of the 24-hour NAAQS replaced by a 3-year average of
the 99th percentile value of the frequency distribution and a 3-year average of the annual mean.
Since the Guideline on Air Quality Modeling precludes the use of a 3-year data set, a policy was
established that uses unbiased estimates of the 3-year averages, utilizing all meteorological data
(both single and multiple years of data) available. An unbiased estimate of the 99th percentile is
the fourth highest concentration, if one year of meteorological data are input to the model, or the
multi-year average of the fourth highest concentrations, if more than one year of meteorological
data are input to the model. Similarly, an unbiased estimate of the 3-year average annual mean
is simply the annual mean, if only one year of meteorological data are input to the model, or the
multi-year average annual mean if multiple years of meteorological data are used. Analogously
to the original NAAQS situation, the entire area is in compliance when the highest fourth high
(or highest average fourth high) and the highest annual mean (or the highest average annual
mean) are less than or equal to the NAAQS.
The revised ISCST3 model will process the 24-hour and annual averages for PM10
according to the new NAAQS if the pollutant ID specified on the CO POLLUTE) card is PM10
or PM-10, and the CO MULTYEAR card is not present. In this case, the model will compute
an average of the fourth highest concentrations at each receptor across the number of years of
INDEX-1
-------
meteorological data being processed. For a single year of data, the model will report the fourth
highest concentration at each receptor. For a five year period of data, the model will report the
average of the five fourth-highest values at each receptor. Also, for multiple year data files, the
annual average will first be calculated for each individual year of data, and the average of these
across the number of years will be calculated. This processing of the annual average across
multiple years may give slightly different results than the PERIOD average across the same time
period, due to differences in the number of calms from year to year. In order to accommodate
this difference, the new PM10 NAAQS makes use of the ANNUAL average keyword for
specifying the long-term average.
Users should be aware of the following restrictions which are applied to the new PM10
NAAQS processing.
1. The averaging periods are limited to the 24-hour and ANNUAL averages. Use of the
PERIOD average or a short-term average other than 24-hour will result in a fatal error
message being generated.
2. Only the FOURTH (or 4TH) highest value may be requested on the RECTABLE card
for 24-hour averages. Specifying another high value on the RECTABLE card will result
in a fatal error message being generated.
3. The model will only process complete years of meteorological data, although there is no
restriction on the start date for the data. If less than one complete year of data is
processed, a fatal error message will be generated. If additional meteorological data
remains after the end of the last complete year of data, the remaining data will be
ignored, and a non-fatal warning message will be generated specifying the number of
hours ignored.
4. The MULTYEAR card cannot be used with the new PM10 NAAQS. Multiple year
analyses should be accomplished by including the multiple years of meteorology in a
single data file.
5. Since the 24-hour average design values for post-1997 PM10 analyses may consist of
averages over a multi-year period, they are incompatible with the EVENT processor. If
the MAXIFILE option is used to output 24-hour average threshold violations, these may
be used with the EVENT processor. Therefore, if the EVENTFIL option is used without
the MAXIFILE option for post-1997 PM10 analyses, a non-fatal warning message will be
generated, and the EVENTFIL option will be ignored.
The revised ISCST3 model may still be used to perform PM10 analyses according to the
pre-1997 NAAQS. This may be accomplished as before by use of the MULTYEAR card on the
CO pathway, except that the syntax for this keyword has been changed slightly. The syntax and
type are now as follows:
INDEX-2
-------
Syntax:
CO MULTYEAR H6H Savfil (Inifil)
Type: Optional, Non-repeatable
where H6H is a new secondary keyword that identifies this as a pre-1997 analysis, the Savfil
parameter specifies the filename for saving the results arrays at the end of each year of
processing, and the Inifil parameter specifies the filename to use for initializing the results
arrays at the beginning of the current year. The Inifil parameter is optional, and should be left
blank for the first year in the multi-year series of runs. Other than the additional secondary
keyword of H6H, the MULTYEAR card works the same as in previous versions of ISCST3. A
non-fatal warning message will be generated if the MULTYEAR card is used for pre-1997
NAAQS analyses.
Memory Allocation
The revised ISCST3 model will allocate data storage as needed based on the number of
sources, receptors, source groups, and other input requirements, up to the maximum amount of
memory available on the computer being used. The minimum system requirements for this
version of the model are a 386 or higher processor with a math coprocessor and at least 2 MB of
extended memory.
The revised ISCST3 model uses allocatable arrays to allocate data storage at model
runtime rather than at compile time, as done by the previous version of ISCST3. The ISCST3
model preprocesses the model runstream input file to determine the data storage requirements
for a particular model run, and then allocates the input data arrays before processing the setup
data. Once the setup processing is completed, the model allocates storage for the result arrays.
When allocating data storage, the ISCST3 model traps for errors, e.g., not enough memory
available to allocate. If the allocation is unsuccessful, then an error message is generated by the
model and further processing is prevented. If the CO RUNORNOT NOT option is selected, the
model will still go through all array allocations so that the user can determine if sufficient
memory is available to complete the run. Also, an estimate of the total amount of memory
needed for a particular run is printed out as part of the first page of printed output.
The parameters that are established at model runtime are as follows:
NSRC = Number of Sources
NREC = Number of Receptors
NGRP = Number of Source Groups
NAVE = Number of Short Term Averaging Periods
NVAL = Number of High Values by Receptor (RECTABLE Keyword)
NTYP = Number of Output Types (CONC, DEPOS, DDEP and WDEP)
NMAX = Number of Overall Maximum Values (MAXTABLE Keyword)
NQF = Number of Variable Emission Rate Factors Per Source
NPDMAX = Number of Particle Diameter Categories Per Source
IXM = Number of X-coord (Distance) Values Per Receptor Network
INDEX-3
-------
IYM = Number of Y-coord (Direction) Values Per Receptor Network
NNET = Number of Cartesian and/or Polar Receptor Networks
NEVE = Number of Events for EVENT processing
In the case of NPDMAX, if no particle information is present in the input runstream, then
NPDMAX is set to 1, otherwise it is set to 20. Other parameters are set to the actual numbers
required for a particular model run.
A change has also been made that affects the length of filenames that may be specified
in the ISCST3 model input file. A new PARAMETER called ILEN_FLD has been added to
MODULE MAIN1 in MODULES.FOR, which is initially assigned a value of 80. This
PARAMETER is now used to specify the maximum length of individual fields on the input
runstream image, and also to declare the length of all filename and format variables. This
includes the input and output filenames specified on the command line.
EVENT Processing
The revised ISCST3 model incorporates the EVENT processing from the ISCEV3
model. Currently, ISCST3 can be run in either the original ISCST3 mode or in the ISCEV3
mode for a particular model run. The input requirements of each mode are the same as for the
original ISCST3 and ISCEV3 models, respectively. In other words, ISCST3 will accept input
files that have been setup for either ISCST3 or ISCEV3.
INCLUDED Option
The INCLUDED keyword option allows for the user to incorporate source, receptor,
and/or event data from a separate file into an ISCST3 model runstream file. Multiple
INCLUDED cards may be placed anywhere within the source, receptor and/or event pathway,
after the STARTING card and before the FINISHED card (i.e., the STARTING and FINISHED
cards cannot be included in the external file). The data in the included file will be processed as
though it were part of the runstream file. The syntax and type of the INCLUDED keyword are
summarized below:
Syntax- so INCLUDED incfil
J ' RE INCLUDED Incfil
EV INCLUDED Incfil
Type: Optional, Repeatable
where the Incfil parameter is a character field of up to 80 characters (controlled by the
ILEN_FLD PARAMETER in MAIN1) that identifies the filename for the included file. The
contents of the included file must be valid runstream images for the applicable pathway. If an
error is generated during processing of the included file, the error message will report the line
number of the included file. If more than one INCLUDED file is specified for a particular
pathway, the user will first need to determine which file the error occurred in.
INDEX-4
-------
AREAPOLY and AREACIRC Source Type Options
The ISCST3 model includes two new options for specifying area sources. These are
identified by the AREAPOLY and AREACIRC source types on the SO LOCATION keyword.
The syntax, type and order of the LOCATION keyword are summarized below:
Syntax: so LOCATION Srcid Srctyp Xs Ys (Zs)
Type: Mandatory, Repeatable
Order* Must be first card for each source input
where the Srcid parameter is the alphanumeric source ID defined by the user (up to eight
characters), Srctyp is the source type, which is identified by one of the secondary keywords -
POINT. VOLUME. AREA. AREAPOLY. or AREACIRC - and Xs, Ys, and Zs are the x, y, and
z coordinates of the source location in meters. All three of the area source types use the same
numerical integration algorithm for estimating impacts from area sources, and are merely
different options for specifying the shape of the area source. The AREA source keyword may
be used to specify a rectangular-shaped area source with arbitrary orientation; the AREAPOLY
source keyword may be used to specify an area source as an irregularly-shaped polygon of up to
20 sides; and the AREACIRC source keyword may be used to specify a circular-shaped area
source (modeled as an equal-area polygon of up to 20 sides). Note that the source elevation, Zs,
is an optional parameter. The x (east-west) and y (north-south) coordinates are for the center of
the source for POINT. VOLUME, and AREACIRC sources, and are for one of the vertices of
the source for AREA and AREAPOLY sources. The source coordinates may be input as
Universal Transverse Mercator (UTM) coordinates, or may be referenced to a user-defined
origin.
The main source parameters for the AREAPOLY and AREACIRC source types are
input on the SRCPARAM card, which is a mandatory keyword for each source being modeled.
These inputs are described below
AREAPOLY Source Type
The AREAPOLY source type may be used to specify an area source as an arbitrarily-
shaped polygon of between 3 and 20 sides (the number of sides allowed may be increased by
modifying the NVMAX and NVMAX2 parameters in MODULES.FOR). This source type
option provides the user with considerable flexibility for specifying the shape of an area source.
The syntax, type and order for the SRCPARAM card for AREAPOLY sources are summarized
below:
Syntax: so SRCPARAM Srcid Aremis Relhgt Nverts (Szinit)
Type* Mandatory, Repeatable
Order: Must follow the LOCATION card for each source input
INDEX-5
-------
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source, and the other parameters are as follows:
Aremis - area emission rate in g/(s-m2),
Relhgt - release height above ground in meters,
Nverts - number of vertices (or sides) of the area source polygon,
Szinit - initial vertical dimension of the area source plume in meters (optional).
As with AREA sources, the emission rate for the source is an emission rate per unit area, which
is different from the point and volume source emission rates, which are total emission rates (g/s)
for the source. The number of vertices (or sides) used to define the area source polygon may
vary between 3 and 20. The locations of the vertices are specified by use of the AREA VERT
keyword, which applies only to ARE APPLY sources. The syntax, type and order for the
AREA VERT keyword used for ARE APPLY sources are summarized below:
Syntax:
SO AREAVERT Srcid Xv(l) Yv(l) Xv(2) Yv(2)
Yv(I)
Xv(I)
Type:
Mandatory for AREAPOLY sources, Repeatable
Order: Must f°ll°w the LOCATION and SRCPARAM card for each source
input
where the Xv(I) and Yv(I) are the x-coordinate and y-coordinate values of the vertices of the
area source polygon. There must by Nverts pairs of coordinates for the area source, where
Nverts is the number of vertices specified for that source on the SRCPARAM card. The first
vertex, Xv(l) and Yv(l), must also match the coordinates given for the source location on the
LPCATIPN card, Xs and Ys. The remaining vertices may be defined in either a clockwise or
counter-clockwise order from the point used for defining the source location.
AREACIRC Source Type
The AREACIRC source type may be used to specify an area source as a circular shape.
The model will automatically generate a regular polygon of up to 20 sides to approximate the
circular area source. The polygon will have the same area as that specified for the circle. The
syntax, type and order for the SRCPARAM card for AREACIRC sources are summarized
below:
Syntax:
SO SRCPARAM Srcid Aremis Relhgt Radius (Nverts) (Szinit)
Type:
Mandatory, Repeatable
Order:
Must follow the LOCATION card for each source input
INDEX-6
-------
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source, and the other parameters are as follows:
Aremis - area emission rate in g/(s-m2),
Relhgt - release height above ground in meters,
Radius - radius of the circular area in meters,
Nverts - number of vertices (or sides) of the area source polygon (optional, 20 sides
will be used if omitted),
Szinit - initial vertical dimension of the area source plume in meters (optional).
As with AREA sources, the emission rate for the source is an emission rate per unit area, which
is different from the point and volume source emission rates, which are total emission rates (g/s)
for the source.
ENHANCEMENTS INTRODUCED WITH ISCST3 (DATED 99155)
TOXICS Option
The revised ISCST3 model includes enhancements for air toxics applications. These
enhancements include the Sampled Chronological Input Model (SCEVI) option, optimizations
for the area source and dry depletion algorithms, inclusion of the gas dry deposition algorithms
based on the draft GDISCDFT model (dated 96248), and the option to output results by season
and hour-of-day (SEASONHR). In order to utilize these enhancements, the user must include
the TOXICS keyword on the CO MODELOPT card. Since the TOXICS option is a non-
regulatory default option, the DFAULT keyword should not be included on the MODELOPT
card. If the DFAULT keyword is present on the MODELOPT card, the DFAULT option will
override the TOXICS option if it is present, and any other enhancements dependent on the
TOXICS option. The enhancements associated with the TOXICS option are described below.
Sampled Chronological Input Model (SCEVI) Option
If the non-default TOXICS option is specified, the user may also use the SCEVI option to
reduce model runtime. The SCEVI option can only be used with the ANNUAL average option,
and is primarily applicable to multi-year model simulations. The approach used by the SCEVI
option is to sample the meteorological data at a user-specified regular interval to approximate
the long-term (i.e., ANNUAL) average impacts. Since wet deposition does not occur at regular
intervals, the user can also specify a separate wet sampling interval to reduce the uncertainty
introduced by sampling for wet deposition. The DEPOS option is ignored when SCEVI is
selected because, depending upon whether or not the user selected the separate wet hour
sampling, the dry deposition and wet deposition rates can be based on different sets of sampled
ENDEX-7
-------
hours. Therefore, the annualized deposition rates for the two types of deposition are calculated
separately. For this reason, the user is advised to calculate dry and wet deposition rates
separately (using DDEP and WDEP, respectively) and add the two to obtain the total deposition
rate when the SCEVI option is used. Studies have shown that the uncertainty in modeled results
introduced by use of the SCEVI option is generally lower for area sources than for point sources.
When only the regular sampling is selected, all hourly impacts (concentration, dry
deposition flux and the wet deposition flux) are calculated in the normal fashion for each
sampled hour. The annual average concentration is then simply calculated by dividing the
cumulative concentration for the sampled hours by the number of hours sampled (arithmetic
average), and the annual dry and the wet deposition fluxes are calculated by scaling the
respective cumulative fluxes for the sampled hours by the ratio of the total hours to the sampled
hours. The following illustrates the calculation of the ANNUAL impacts when only the regular
sampling is selected:
c CS/NS
D Ds (Nt/Ns)
W Ws (Nt /Ns)
where:
C, D, W Calculated cone, dry flux and wet flux, respectively
Cs, E>s, Ws 'Cumulative impacts for the sampled hours
Ns 'Number of sampled hours
Nt 'Total number of hours in the data period
When the wet hour sampling is also selected along with regular sampling, the impacts
are calculated slightly differently. The concentrations and the dry deposition fluxes are based on
the weighted contributions from the regular samples, modeled as dry hours, and the wet hour
samples. The regular samples consist of all the hours based on regular sampling interval, but
the effects of precipitation are ignored so that their contribution represents only dry conditions,
while the contribution from the wet hour samples represents only wet conditions. The wet
deposition fluxes are only based on the wet hour samples. The following illustrates the
calculation of the ANNUAL impacts when both the regular sampling as well as the wet hour
sampling are selected:
INDEX-8
-------
c ..*ed(Ntd/Nsd) '"Cw(Ntw/Nsw)
Nt
D Dd(Ntd/Nsd) Dw(Ntw/Nsw)
W Ww(Ntw/Nsw)
where:
C,D,W Calculated cone, dry flux and wet flux, respectively
Cd, E>d Cumulative impacts for regular (dry) sampled hours
Cw, E>w, Ww 'Cumulative impacts for sampled wet hours
Nsd 'Number of regular sampled hours, modeled as dry
Nsw 'Number of sampled wet hours
Ntd 'Total number of dry hours in the data period
Ntw 'Total number of wet hours in the data period
Nt 'Total number of hours in the data period (Ntd *'Ntw)
To use the SCIM option, the user must include the SCIM and TOXICS keywords on the
CO MODELOPT card, and also specify the SCIM sampling parameters on the ME SCIMBYHR
card. The SCIM parameters on the SCIMBYHR card specify the starting hour and sampling
interval for the regular or dry sample, and also for the wet sample if used. The syntax and type
of the SCIMBYHR keyword are summarized below:
Syntax- ME SCIMBYHR NRegStart NReglnt NWetStart NWetlnt
J ' (Filnam)
Type' Optional, Non-repeatable
where the NRegStart and NReglnt parameters specify the first hour to be sampled and the
sampling interval when performing the regular sampling, respectively, and NWetStart and
NWetlnt parameters specify the first wet hour to sample and the wet hour sampling interval,
respectively. Optionally, the user can create an output file by specifying the Filnam parameter
containing the meteorological data for the sampled hours (in the same format used in the
summary of the first 24 hours of data included in the main output file).
Although the ME SCIMBYHR is an optional card, it is required when using the SCIM
option. NRegStart is required to have a value from 1 through 24, i.e., the first sampled hour
must be on the first day in the meteorological data file. There are no restrictions for NReglnt;
however, NReglnt would generally be greater than 1. For example, NReglnt could be based on
the formula (24n+l), where "n" is the number of days to skip between samples, in order to
ensure a regular diurnal cycle to the sampled hours (e.g., 25 or 49). NWetStart must be no
INDEX-9
-------
greater than NWetlnt. An input of 0 (zero) for NWetlnt indicates that the user has not selected
the wet hour sampling.
Optimized Area Source and Dry Depletion Algorithms
When the TOXICS option is specified, the area source and dry depletion integration
routines are optimized to reduce model runtime. This is accomplished by incorporation of a 2-
point Gaussian Quadrature routine for numerical integration for some situations instead of the
Romberg numerical integration utilized in the regulatory default mode. In addition, for area
sources with dry depletion, another optimization option is available to reduce model runtime by
specifying the AREADPLT keyword on the CO MODELOPT card. When the AREADPLT
option is specified the model will apply a single "effective" depletion factor to the undepleted
area source integral, rather than applying the numerical integration for depletion within the area
source integral. If AREADPLT is selected, the DRYDPLT option for non-area sources is
automatically selected.
Gas Dry Deposition Algorithm
The revised ISCST3 model has the option to model the effects of dry deposition for
gaseous pollutants. In order to utilize this algorithm, the non-default TOXICS option must be
specified on the CO MODELOPT card. There are three new keywords on the CO pathway and
one new keyword on the SO pathway that are used for specifying inputs for the gas dry
deposition algorithm. The user has the option of specifying the deposition velocity to be used
with the CO GASDEPVD card, or allowing the model to calculate the deposition velocities. If
the user does not specify the deposition velocity with the GASDEPVD keyword, then the state
of vegetation must be specified with the CO VEGSTATE card, and the source parameters for
gas deposition must be specified with the SO GASDEPOS card. The user also has the option to
override certain default reference parameters through use of the CO GASDEPRF card. The
inputs for these keywords are described below. The use of the gas dry deposition algorithm in
ISCST3 also requires additional meteorological parameters, which can be provided by the
MPRM meteorological preprocessor. The formats for the meteorological data input file for gas
dry deposition applications is also described below.
Specifying the State of Vegetation
An optional keyword is available on the Control pathway to allow the user to specify the
state of vegetation for use with the gaseous dry deposition algorithm of the ISCST3 model.
Three options are available on this keyword, one for active and unstressed vegetation, one for
active and stressed vegetation, and another for inactive vegetation.
The syntax and type of the VEGSTATE keyword are summarized below:
Syntax:
CO VEGSTATE UNSTRESSED or STRESSED or INACTIVE
Type: Optional, Non-repeatable
INDEX-10
-------
where the secondary keyword options describe the three options for the state of vegetation. The
state of vegetation is used in the model, along with ambient temperature and incoming short-
wave radiation, to determine the resistance to transport through the stomatal pores. For
unirrigated vegetation, the user should select the appropriate option for vegetation state based on
existing soil moisture conditions. For irrigated vegetation, the user should assume that the
vegetation is active and unstressed.
Option for Overriding Default Reference Parameters for Gas Dry Deposition
An optional keyword is available on the Control pathway to allow the user to override
the default reference parameters of cuticle resistance, ground resistance, and pollutant reactivity
for use with the gas dry deposition algorithm.
The syntax and type of the GASDEPRF keyword are summarized below:
Syntax: co GASDEPRF Rcutr Rgr Reactr (Refpoll)
Type: Optional, Non-repeatable
where the parameter Rcutr is the reference value for cuticle resistance, Rgr is the reference value
for ground resistance, Reactr is the reference value for pollutant reactivity, and Refpoll is the
optional name of the reference pollutant. If the GASDEPRF keyword is omitted, then the
following default reference values for SO2 are used by the model: Rcutr = 30 s/cm; Rgr =10
s/cm; and Reactr = 8.
Option for Specifying the Deposition Velocity for Gas Dry Deposition
An optional keyword is available on the Control pathway to allow the user to specify the
deposition velocity for use with the gaseous dry deposition algorithm of the ISCST3 model. A
single deposition velocity can be input for a given model run, and is used for all sources of
gaseous pollutants. Selection of this option will by-pass the algorithm for computing deposition
velocities for gaseous pollutants, and should only be used when sufficient data to run the
algorithm are not available. Results of the ISCST3 model based on a user-specified deposition
velocity should be used with extra caution.
The syntax and type of the GASDEPVD keyword are summarized below:
Syntax:
CO GASDEPVD Uservd
Type* Optional, Non-repeatable
where the parameter Uservd is the gaseous dry deposition velocity (m/s). A non-fatal warning
message is generated by the model if a value of Uservd greater than 0.05 m/s (5 cm/s) is input
by the user. When the GASDEPVD keyword is used, the VEGSTATE and GASDEPRF
INDEX-11
-------
keywords for the CO pathway, and the GASDEPOS keyword for the SO pathway, are no longer
applicable and cannot be used in the same model run.
Specifying Source Parameters for Gas Dry Deposition
The input of source parameters for gas dry deposition is controlled by the GASDEPOS
keyword on the SO pathway. The gas dry deposition variables may be input for a single source,
or may be applied to a range of sources.
The syntax, type, and order for the GASDEPOS keyword are summarized below:
Syntax: so GASDEPOS Srcid (or Srcrng) Diff Alphas Reac Rsubm
Henry
Type* Optional, Repeatable
Order: Must follow the LOCATION card for each source input
where the Srcid or Srcrng identify the source or sources for which the inputs apply, the
parameter Diff is the molecular diffusivity for the pollutant being modeled (cm2/s), Alphas is the
solubility enhancement factor (a*) for the pollutant, Reac is the pollutant reactivity parameter,
Rsubm is the mesophyll resistance term (rm) for the pollutant (s/cm), and Henry is the Henry's
Law coefficient for the parameter. Values of these physical parameters for several common
pollutants may be found in chemical engineering handbooks and various publications, such as
the Air/Superfund National Technical Guidance Study Series (EPA, 1993). The Alphas and
Henry parameters are only used when applying the algorithm over a water surface. If no water
surfaces are present in a particular application, then dummy (non-zero) values may be input for
Alphas and Henry. The model converts the input units for Diff to m2/s and Rsubm to s/m before
being used in the computations.
Meteorological Formats for Gas Dry Deposition
Since the deposition algorithms require additional meteorological variables, the exact
format of ASCII meteorological data will depend on whether the dry and/or wet deposition
algorithms are being used. If the deposition algorithms are being used, then the unformatted
data file cannot be used. The order of the meteorological variables for the formatted ASCII files
and the default ASCII format are as follows when the CARD option is used:
INDEX-12
-------
ASCII Meteorological Formats With the CARD Option
Variable
Year (last 2 digits)
Month
Day
Hour
Flow Vector (deg.)
Wind Speed (m/s)
Ambient Temperature (K)
Stability Class
(A=1,B=2, ...F=6)
Rural Mixing Height (m)
Urban Mixing Height (m)
Wind Profile Exponent
(CARD only)
Vertical Potential
Temperature Gradient (K/m)
(CARD only)
Friction Velocity (m/s)
(Dry or Wet Deposition Only)
Monin-Obukhov Length (m)
(Dry or Wet Deposition Only)
Surface Roughness Length (m)
(Dry or Wet Deposition Only)
Incoming Short-wave Radiation (W/m2)
(Gas Dry Deposition Only)
Leaf Area Index
(Gas Dry Deposition Only)
Precipitation Code (00-45)
(Wet Deposition Only)
Precipitation Rate (mm/hr)
(Wet Deposition Only)
Fortran
Format
12
12
12
12
F9.4
F9.4
F6.1
12
F7.1
F7.1
F8.4
F8.4
F9.4
F10.1
F8.4
F8.1
F8.3
14
F7.2
Columns
1-2
3-4
5-6
7-8
9-17
18-26
27-32
33-34
35-41
42-48
49-56
57-65
66-74
75-84
85-92
93-100
101-108
109-112
(93-96
without Gas
Dry Deposition)
113-119
(97-103
without Gas
Dry Deposition)
INDEX-13
-------
The order and default format of the meteorological variables for the formatted ASCII files
without the CARD option are as follows:
ASCII Meteorological Formats Without the CARD Option
Variable
Year (last 2 digits)
Month
Day
Hour
Flow Vector (deg.)
Wind Speed (m/s)
Ambient Temperature (K)
Stability Class
(A=1,B=2, ...F=6)
Rural Mixing Height (m)
Urban Mixing Height (m)
Friction Velocity (m/s)
(Dry or Wet Deposition Only)
Monin-Obukhov Length (m)
(Dry or Wet Deposition Only)
Surface Roughness Length (m)
(Dry or Wet Deposition Only)
Incoming Short-wave Radiation (W/m2)
(Gas Dry Deposition Only)
Leaf Area Index
(Gas Dry Deposition Only)
Precipitation Code (00-45)
(Wet Deposition Only)
Precipitation Rate (mm/hr)
(Wet Deposition Only)
Fortran
Format
12
12
12
12
F9.4
F9.4
F6.1
12
F7.1
F7.1
F9.4
F10.1
F8.4
F8.1
F8.3
14
F7.2
Columns
1-2
3-4
5-6
7-8
9-17
18-26
27-32
33-34
35-41
42-48
49-57
58-67
68-75
76-83
84-91
92-95
(76-79
without Gas
Dry Deposition)
96-102
(80-86
without Gas
Dry Deposition)
INDEX-14
-------
Season by Hour-of-Dav Output Option (SEASONFOO
When the non-default TOXICS option is specified, the user may request an output file
containing the average results (CONC, DEPOS, DDEP and/or WDEP) by season and hour-of-
day. To select this option, the user must include the SEASONHR keyword on the OU pathway.
The syntax, type, and order for the SEASONHR keyword are summarized below:
Syntax: ou SEASONHR GroupID FileName (FileUnit)
Type* Optional, Repeatable
where the GroupID parameter specifies the source group to be output, FileName specifies the
name of the output file, and the optional FileUnit parameter specifies an optional file unit and
must be greater than 20. If FileUnit is left blank, then the model will dynamically assign a file
unit based on the formula 302+IGRP*10, where IGRP is the group index number. A sample
from a SEASONHR output file is shown below:
INDEX-15
-------
* ISCST3 (99155): Example of SEASONHR Output File Option
* MODELING OPTIONS USED:
* CONC WDEP RURAL FLAT TOXICS
WETDPL
* FILE OF SEASON/HOUR VALUES FOR SOURCE GROUP: ALL
* FOR A TOTAL OF 216 RECEPTORS.
* FORMAT: (4( IX . F13 . 5) . IX . F8. 2 . 2X . A8. 2X . 14 . 2X . 14 . 2X . 14
* X
HOUR NET ID
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
8
POL1
17
POL1
86
POL1
173
POL1
868
POL1
1736
POL1
17
POL1
34
POL1
171
POL1
342
POL1
1710
POL1
3420
POL1
25
POL1
50
POL1
250
POL1
500
POL1
2500
POL1
5000
POL1
68241
36482
82409
64818
24091
48181
10101
20201
01007
02014
10071
20142
00000
00000
00000
00000
00000
00000
49
98
492
984
4924
9848
46
93
469
939
4698
9396
43
86
433
866
4330
8660
Y AVERAGE CONC
24039
48077
40387
80774
03857
07715
98463
96926
84631
69263
46289
92578
30127
60254
01270
02539
12695
25391
0
0
0
2
2
0
0
0
0
2
6
4
0
0
0
2
2
1
00000
00000
18098
52520
07470
93252
00000
00000
15772
48554
09119
49830
00000
00000
10114
12970
79993
97200
WET DEPO
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00603
00177
00008
00001
00000
00000
00002
00000
00000
00000
00000
00000
00017
00001
00000
00000
00000
00000
?x
ZELEV
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
A8)
GRP
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
ALL
NHRS SEAS
87
87
87
87
87
87
87
87
87
87
87
87
87
87
87
87
87
87
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
The NHRS column in the output file contains the number of non-calm and non-missing hours
used to calculate the season-by-hour-of-day averages. The SEAS column is the season index,
and is 1 for winter, 2 for spring, 3 for summer and 4 for fall. The records loop through hour-of-
day first, and then through the seasons.
INDEX-16
-------
ENHANCEMENTS INTRODUCED WITH ISCST3 (DATED 00101)
Removal of UNIFORM Option for Meteorological Data
The unformatted (binary) meteorological data option (ME INPUTFIL UNFORM) is no
longer supported by the ISCST3 model. Unnecessary code has been removed, and proper error
handling has been implemented. Users with unformatted meteorological data should first
convert the data to an ASCII format using the BINTOASC utility program available on the
SCRAM website. The unformatted data file option has been removed due to unformatted files
are not portable across different computer systems and compilers, and unformatted files cannot
be used with the deposition algorithms in ISCST3.
Season by Hour-of-Day and Day-of-Week Emission Factors
The variable emission rate factor option controlled by the EMISFACT keyword on the
SO pathway has been modified to include an option to specify variable emission rate factors that
vary by season, hour-of-day, and day-of-week. The day-of-week variability allows for different
emission factors to be specified for Weekdays (Monday-Friday), Saturdays, and Sundays.
The syntax, type and order of the EMISFACT keyword are summarized below:
Syntax: so EMISFACT Srcid (or Srcrng) Qflag Qfact(i),i=l,n
Type: Optional, Repeatable
Order* Must follow the LOCATION card for each source input
where the Srcid parameter is the same source ID that was entered on the LOCATION card for a
particular source. The user also has the option of using the Srcrng parameter for specifying a
range of sources for which the emission rate factors apply, instead of identifying a single source.
This is accomplished by two source ID character strings separated by a dash, e.g.,
STACK1-STACK10.
The parameter Qflag is the variable emission rate flag, and is one of the following
secondary keywords:
SEASON emission rates vary seasonally (n=4),
MONTH emission rates vary monthly (n=12),
HROFDY emission rates vary by hour-of-day (n=24),
STAR emission rates vary by speed and stability category (n=36),
SEASHR emission rates vary by season and hour-of-day (n=96), and
INDEX-17
-------
SHRDOW emission rates vary by season, hour-of-day, and day-of-week [M-F,
Sat., Sun.] (n=288)
The Qfact array is the array of factors, where the number of factors is shown above for each
Qflag option. The EMISFACT card may be repeated as many times as necessary to input all of
the factors, and repeat values may be used for the numerical inputs. An example of each of
these options is presented below, with column headers to indicate the order in which values are
to be input.
** WINTER SPRING SUMMER FALL
SO EMISFACT STACK1 SEASON 0.50 0.50 1.00 0.75
** JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
SO EMISFACT STACK1 MONTH 0.1 0.2 0.3 0.4 0.5 0.5 0.5 0.6 0.7 1.0 1.0 1.0
** 1 2 3 4 5 6 7 8 9 10 11 12
SO EMISFACT STACK1 HROFDY 0.0 0.0 0.0 0.0 0.0 0.5 1.0 1.0 1.0 1.0 1.0 l.C
** 13 14 15 16 17 18 19 20 21 22 23 24
SO EMISFACT STACK1 HROFDY 1.0 1.0 1.0 1.0 1.0 0.5 0.0 0.0 0.0 0.0 0.0 O.C
** or, equivalently:
SO EMISFACT STACK1 HROFDY
1-5 6 7-17 18 19-24
5*0.0 0.5 11*1.0 0.5 6*0.0
** Stab. Cat.:
Cat.)
SO EMISFACT STACK1 STAR
A B C D E F (6 WS
6*0.5 6*0.6 6*0.7 6*0.8 6*0.9 6*1.0
SO EMISFACT STACK1 SEASHR
SO EMISFACT STACK1 SEASHR
enter 24 hourly scalars for each of the four
seasons (winter, spring, summer, fall), e.g.,
Winter Spring Summer Fall
24*0.50 24*0.50 24*1.00 24*0.75
SO EMISFACT STACK1 SHRDOW
Saturdays ,
** Weekdays:
SO EMISFACT STACK1 SHRDOW
** Saturdays:
SO EMISFACT STACK1 SHRDOW
** Sundays:
SO EMISFACT STACK1 SHRDOW
enter 24 hourly scalars for each of the four
seasons (winter, spring, summer, fall), first
for Weekdays (Monday-Friday) , then for
and finally for Sundays, e.g.
Winter
24.1.0
Spri ng
24*0.8
Summer
24*0.6
Fall
24*0.i
24*0.5 24*0.4 24*0.3 24*0.4
24*0.25 24*0.2 24*0.15 24*0.2
References
Environmental Protection Agency, 1993: Air/Superfund National Technical Guidance Study
Series, Models for Estimating Air Emission Rates from Superfund Remedial Actions.
EPA-451/R-93-001, U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina 27711.
INDEX-18
-------
INDEX-19
-------
& EPA
United States
Environmental Protection
Agency
Office Of Air Quality
Planning And Standards
Research Triangle Park, NC 27711
EPA-453/R-99-001
March 1999
Air
RESIDUAL RISK
Report to Congress
-------
EPA-453/R-99-001
RESIDUAL RISK
REPORT TO CONGRESS
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
March 1999
-------
Acknowledgements
This report was prepared by the U.S. Environmental Protection Agency's Office of Air Quality
Planning and Standards (OAQPS) with substantial input and review by other EPA Offices and
other federal agencies. Certain individuals and offices are specifically recognized below. Review
was also provided by staff from the Office of the Surgeon General and the Department of Health
and Human Services as part of EPA's consultation with those agencies. Valuable comments
which contributed to the final report were received on the public comment draft from EPA's
Science Advisory Board review and from State agencies, State organizations, and various
industry groups. Additionally, valuable technical support for report development was provided
by ICF Incorporated.
OAQPS staff who have contributed to the development of this document include:
Mr. Michael Dusetzina Ms. JoAnn Rice
Mr. James Hemby *Ms. Kelly Rimer
Mr. Robert Hetes Ms. Vicki Sandiford
Ms. Kathy Kaufman Mr. Mark Schmidt
Mr. Vasu Kilaru Dr. Roy Smith
Mr. William Maxwell Mr. Jim Szykman
Ms. Laura McKelvey Mr. Jawad Touma
*Dr. Deirdre Murphy Ms. Amy Vasu
*Mr. Dennis Pagano Mr. Tom Walton
Mr. Ted Palma Mr. Al Wehe
Ms. Anne Pope Mr. James White
* Primary project leads
Staff from outside OAQPS who contributed to the development of the document include:
Dr. Robert Fegley, Dr. Dan Guth, Dr. Eric Hyatt, Dr. Anne Sergeant, and others, Office of
Research and Development
Mr. Mark Kataoka and Ms. Patricia Embry, Office of General Counsel
Ms. Joanne Held, New Jersey Department of Health
In addition, substantial review of the document also was provided by the following other EPA
offices:
EPA, Office of Policy Analysis and Review EPA, Office of Water
EPA, Office of Solid Waste and Emergency EPA, Region 4
Response EPA, Region 9
-------
Residual Risk Report to Congress
Contents
Page
LIST OF EXHIBITS v
ACRONYM LIST vi
ABBREVIATED GLOSSARY OF TECHNICAL TERMS ix
EXECUTIVE SUMMARY ES-1
1. INTRODUCTION 1
1.1 Scope of Report 2
Section 112(f)(l)(B) 3
Section 112(f)(l)(C) 4
Section 112(f)(l)(D) 4
1.2 Peer Review 5
2. BACKGROUND: AIR Toxics PROGRAM 7
2.1 History of the Air Toxics Program: 1970-1990 7
2.2 Strategy For Air Toxics: Post-1990 9
Emissions Control Under MACT - CAA Section 112(d) 10
Special Areas of Evaluation 11
Urban Air Toxics Strategy 12
Residual Risk 13
2.3 State and Local Air Toxics Programs 13
3. SECTION 112 (f)(l)(A): METHODS FOR ASSESSING RISKS EPA's GENERAL RISK
ASSESSMENT APPROACH FOR AIR Toxics 15
3.1 Background Development of Human Health and Ecological Risk
Assessment Methods 15
3.1.1 National Academy of Sciences Reports of 1983 and 1994 15
3.1.2 CRARM 18
The Commission's Mandate 19
The Commission's Report 20
Residual Risk Recommendations of the Commission 22
3.1.3 Development of Human Health Risk Assessment at EPA 22
3.1.4 Development of Ecological Risk Assessment at EPA 25
* * * March 1999 Page i * * *
-------
Residual Risk Report to Congress
3.2 Framework for Risk Assessment 31
3.3 Exposure Assessment 32
3.3.1 Emissions (Source) Characterization 34
Data and Tool Availability, Limitations, and Closing Gaps 35
3.3.2 Environmental Fate and Transport Characterization 35
Data and Tool Availability, Limitations, and Closing Gaps 37
3.3.3 Characterization of the Study Population 41
Data and Tool Availability, Limitations, and Closing Gaps 42
3.3.4 Exposure Characterization 44
3.4 Effects Assessment 46
3.4.1 Human Health Effects 46
Hazard Identification 46
Dose-response Assessment 49
Data Availability, Limitations, and Closing Data Gaps 56
3.4.2 Ecological Effects 61
Data Availability, Limitations, and Closing Data Gaps 64
3.5 Risk Characterization 65
3.5.1 Human Health Effects 66
Integration of Exposure and Effects Analyses 66
Interpretation and Presentation of Risks 70
Data Availability, Limitations, and Closing Data Gaps 71
3.5.2 Ecological Effects 73
Integration of Exposure and Effects Analyses 73
Interpretation and Presentation of Risks 75
Data Availability, Limitations, and Closing Data Gaps 76
4. OTHER STATUTORY REPORT REQUIREMENTS OF SECTION 112(f)(l) 77
4.1 Section 112(f)(l)(B) 77
4.1.1 Public Health Significance 77
4.1.2 Available Methods and Costs of Reducing Residual Risks 78
MACT Emission Standards 79
Available Control Strategies 80
Control Strategy Cost 83
4.2 Section 112(f)(l)(C) 84
4.2.1 Epidemiological and Other Health Studies 84
Current State of Knowledge 84
Strategy for Considering Epidemiology/Other
Health Information in Residual Risk Analyses 89
4.2.2 Risks Posed by Background Concentrations 90
EPA Programs and Rules that Consider Background
Concentrations and Risks 91
Difficulties in Addressing Background Risk 92
* * * March 1999 Page ii * * *
-------
Residual Risk Report to Congress
Defining Background for Residual Risk Analyses 93
Strategy for Considering Background in Residual Risk Analyses 93
4.2.3 Uncertainties in Risk Assessment Methods 94
Approaches to Addressing Uncertainty and
Variability in the Estimation of Residual Risks 97
Uncertainty and the Management of Residual Risks 100
4.2.4 Negative Health or Environmental Consequences 101
4.3 Section 112(f)(l)(D): Legislative Recommendations 102
5. THE RESIDUAL RISK ANALYSIS FRAMEWORK 105
5.1 Legislative Context 105
5.1.1 The Context for the Analyses 105
5.1.2 Compliance Schedule and Effective Date 106
5.1.3 Area Sources (CAA Section 112(f)(5)) 106
5.1.4 Unique Chemical Substances (CAA Section 112(f)(6)) 107
5.2 Objectives 107
5.3 Residual Risk Assessment Strategy Design 109
5.3.1 Stakeholder Involvement Ill
5.3.2 Priority Setting 113
5.3.3 Problem Formulation and Data Collection 113
Developing the Conceptual Model 116
5.3.4 Screening Analyses 116
Human Health 117
Ecological 118
5.3.5 Refined Analyses 122
Human Health 123
Ecological 125
5.3.6 Risk Management/Risk Reduction Decisions 126
5.3.7 Comparison to CRARM Recommendations 128
5.4 Summary 130
REFERENCES 133
APPENDIX A: FULL TEXT OF CLEAN AIR ACT SECTION 112(f) A-l
APPENDIX B: PREAMBLE EXCERPTS FROM 1989 BENZENE NESHAP B-l
APPENDIX C: SCHEDULE FOR SOURCE CATEGORY MACT STANDARDS C-l
* * * March 1999 Page iii
* * *
-------
Residual Risk Report to Congress
APPENDIX D: SUMMARY OF RESPONSE TO SCIENCE ADVISORY BOARD'S (SAB)
REVIEW OF EPA's APRIL 14,1998 DRAFT RESIDUAL RISK REPORT TO
CONGRESS D-l
APPENDIX E: SUMMARY OF MACT STANDARDS AND CONTROL
TECHNOLOGIES E-l
March 1999 Page iv * * *
-------
Residual Risk Report to Congress
List of Exhibits
Page
Exhibit 1: Projected Annual Cumulative HAP Emission Reductions 11
Exhibit 2: NRC Risk Assessment/Risk Management Paradigm 17
Exhibit 3: CRARM's Framework for Risk Management 20
Exhibit 4: CRARM's Residual Risk Recommendations for Air Toxics 23
Exhibit 5: Ecological Risk Assessment Framework 28
Exhibit 6: Conceptual Model Diagram for Exposure of Piscivorous Birds to HAPs 31
Exhibit 7: Conceptual Model Diagram for Multipathway Exposure to Air Toxics 37
Exhibit 8: Urban Air Toxics Monitoring Program Sites (1997) and Ozone
Nonattainment Areas (1998) 40
Exhibit 9: Sources of Information for Hazard Identification 47
Exhibit 10: Summary of Major Differences in the Hazard Identification Step
Between EPA's 1986 Guidelines (EPA 1986b) and 1996 Proposed
Guidelines for Carcinogen Risk Assessment (EPA 1996b) 50
Exhibit 11: Summary of Major Differences Related to Dose-response Assessment
Between EPA's 1986 Guidelines (EPA 1986b) and 1996 Proposed
Guidelines for Carcinogen Risk Assessment (EPA 1996b) 55
Exhibit 12: Cancer Dose-response Curve 57
Exhibit 13: Examples of Chronic Toxicity Criteria 59
Exhibit 14: Examples of Acute Toxicity Criteria 60
Exhibit 15: Sources of Information for Ecological Effects 62
Exhibit 16: Guiding Principles with Respect to Risk Descriptors 66
Exhibit 17: Conditions for an Acceptable Risk Assessment that Uses
Probabilistic Analysis Techniques 72
Exhibit 18: An Ecological Risk Assessment Case Study: Ozone Risk to
Agroecosystems 74
Exhibit 19: 17 HAP Classes Listed Under CAA Section 112(b) 108
Exhibit 20: Overview of Residual Risk Framework Iterative Approach 110
Exhibit 21: Summary of Assumptions and Criteria for Evaluating Public
Health Risks 119
Exhibit 22: Summary of Assumptions and Criteria for Evaluating
Environmental Risks 121
* * * March 1999 Page v *
* *
-------
Residual Risk Report to Congress
Acronym List
ADI Acceptable daily intake
AEGL Acute exposure guidance level
AEL Adverse effects level
AIHA American Industrial Hygiene Association
AIRS Aerometric Information Retrieval System
ARE Acute reference exposure
ATSDR Agency for Toxic Substances and Disease Registry
AWQC Ambient Water Quality Criteria
BAF Bioaccumulation factor
BCF Bioconcentration factor
BMC Benchmark concentration
BMD Benchmark dose
CAA Clean Air Act
CAS Chemical Abstracts Service
CRARM Commission on Risk Assessment and Risk Management
CWA Clean Water Act of 1972
DDT Di chl orodiphenyltri chl oroethane
DNA Deoxyribonucleic acid
DOE Department of Energy
DWEL Drinking water equivalent level
ED10 Effective dose at 10 percent response
EFH Exposure Factors Handbook
EHS Extremely hazardous substance
EMAP Environmental Monitoring and Assessment Program
EOM Extractable organic matter
EPA Environmental Protection Agency
ERPG Emergency Response Planning Guidelines
FACA Federal Advisory Committee Act
FEL Frank effects level
FIFRA Federal Insecticide, Fungicide, and Rodenticide Act
FQPA Food Quality Protection Act
GACT Generally Available Control Technology
GIS Geographic information system
GLWQI Great Lakes Water Quality Initiative
HAP Hazardous air pollutant
HEM Human Exposure Model
HEAST Health Effects Assessment Summary Tables
HEC Human Equivalent Concentration
HI Hazard index
HQ Hazard quotient
IDLH Immediately dangerous to life and health
March 1999 Page vi
* * *
-------
Residual Risk Report to Congress
IBM Indirect Exposure Model
IRIS Integrated Risk Information System
ISCST3 Industrial Source Complex Short-Term 3
Koc Organic carbon-water partition coefficient
Kow Octanol-water partition coefficient
LEC10 Lower 95% confidence limit on effective concentration at 10% response
LED10 Lower 95% confidence limit on effective dose at 10% response
LOAEL Lowest-observed-adverse-effect level
LOG Level of concern
LOEL Lowest-observed-effect level
MACT Maximum achievable control technology
MCLG Maximum contaminant level goal
MEI Maximum exposed individual
MIR Maximum individual risk
MOE Margin of exposure
MRL Minimum risk level
NAAQS National Ambient Air Quality Standard
NAS National Academy of Sciences
NCLAN National Crop Loss Assessment Network
NESHAP National Emission Standard for Hazardous Air Pollutants
NOAEL No-observed-adverse-effect level
NOEL No-observed-effect level
NRC National Research Council
NRDC Natural Resources Defense Council
NTI National Toxics Inventory
OAQPS EPA Office of Air Quality Planning and Standards
OERR EPA Office of Emergency and Remedial Response
ORD EPA Office of Research and Development
ORNL Oak Ridge National Laboratories
OSW EPA Office of Solid Waste
PAH Polycyclic aromatic hydrocarbon
PAMS Photochemical Assessment Monitoring Station
PCB Polychlorinated biphenyl
PIC Product of incomplete combustion
POM Polycyclic organic matter
P2 Pollution prevention
QSAR Quantitative SAR
RAC Risk Assessment Council
RfC Reference concentration
RfD Reference dose
RSC Relative source contribution
SAB Science Advisory Board
SAR Structure-activity relationship
* * *
March 1999 Page vii * *
-------
Residual Risk Report to Congress
SPEGL Short-term public emergency guidance level
TCDD 2,3,7,8-tetrachlorodibenzo-p-dioxin
TEF Toxic equivalency factor
TEQ Toxicity equivalent
TRI Toxics Release Inventory
TRIM Total Risk Integrated Methodology
TRV Toxicity reference value
TSCA Toxic Substances Control Act
UATMP Urban Air Toxics Monitoring Program
UF Uncertainty factor
URE Unit risk estimate
VOC Volatile organic compound
* * *
March 1999 Page viii * *
-------
Residual Risk Report to Congress
Abbreviated Glossary of Technical Terms
acceptable daily intake (ADI): An estimate of the daily exposure that is likely to be without
deleterious effect even if continued exposure occurs over a lifetime.
acute exposure: One dose (or exposure) or multiple doses (or exposures) occurring within a
short time relative to the life of a person or other organism (e.g., approximately 24 hours or less
for humans).
adverse environmental effect: Defined in CAA section 112(a)(7) as "any significant and
widespread adverse effect, which may reasonably be anticipated, to wildlife, aquatic life, or other
natural resources, including adverse impacts on populations of endangered or threatened species
or significant degradation of environmental quality over broad areas."
assessment endpoint: An explicit expression of the actual environmental value that is to be
protected, operationally defined by an ecological entity and its attributes. For example, salmon
are valued ecological entities; reproduction and age class structure are some of their important
attributes. Together "salmon reproduction and age class structure" form an assessment endpoint.
benchmark dose (BMD), benchmark concentration (BMC): An exposure level that
corresponds to a predetermined level of response, such as 10 percent of test animals affected.
bioaccumulation: The net accumulation of a substance by an organism as a result of uptake
from all routes of exposure (e.g., ingestion of food, intake of drinking water, direct contact, or
inhalation).
bioaccumulation factor (BAF): The concentration of a substance in tissue of an organism
divided by its concentration in an environmental medium in situations where the organism and its
food are exposed (i.e., accounting for food chain exposure as well as direct chemical uptake).
bioconcentration: The net accumulation of a substance by an organism as a result of uptake
directly from an environmental medium (e.g., net accumulation by an aquatic organism as a
result of uptake directly from ambient water, through gill membranes or other external body
surfaces).
bioconcentration factor (BCF): The concentration of a substance in tissue of an organism
divided by the concentration in an environmental medium, typically in situations where exposure
is by contact or uptake directly from that medium (e.g., the concentration of a substance in an
aquatic organism divided by the concentration in the ambient water, in situations where the
organism is exposed through the water only).
March 1999 Page ix * *
-------
Residual Risk Report to Congress
bootstrap analysis: A method of statistical analysis in which the user empirically constructs
sampling distributions when data are limited.
chronic exposure: Multiple exposures occurring over an extended period of time or a
significant fraction of the animal's or the individual's lifetime.
confounder: A condition or variable that may be a factor in producing the same response as the
agent under study. The effects of such factors may be discerned through careful design and
analysis.
default assumption: Defined by the National Research Council as "essentially policy judgments
of how to accommodate uncertainties. They include various assumptions that are needed for
assessing exposure and risk, such as scaling factors to be used for converting test responses in
rodents to estimated responses in humans."
dose-response assessment: The quantitative characterization of the relationship between the
amount of an agent (either administered, absorbed, or believed to be effective) and changes in
certain aspects of the biological system (e.g., critical adverse effects) apparently in response to
that agent.
drinking water equivalent level (DWEL): A lifetime exposure concentration protective of
adverse, non-cancer health effects that assumes all of the exposure to a contaminant is from a
drinking water source.
ecological receptor: A general term that may refer to a species, a group of species, an ecosystem
function or characteristic, or a specific habitat. An ecological entity is one component of an
assessment endpoint.
ED10 or EC10: Dose or concentration associated with a 10 percent level of response.
extrapolation: An estimation of a numerical value of an empirical (measured) function at a
point outside the range of data that were used to calibrate the function. The quantitative risk
estimates for carcinogens are generally low dose extrapolations based on observations made at
higher doses.
hazard index (HI): The sum of more than one hazard quotient for multiple substances and/or
multiple exposure pathways.
hazard quotient (HQ): The ratio of a level of exposure for a single substance over a specified
time period to a reference level (e.g., RfC) for that substance derived from a similar exposure
period.
* * * March 1999 Page x
* * *
-------
Residual Risk Report to Congress
hazardous air pollutant (HAP): Defined by the CAA as any air pollutant listed under CAA
section 112(b) (in this document, synonymous with air toxics).
human equivalent concentration (HEC): Exposure concentration for humans that has been
adjusted for dosimetric differences between experimental animal species and humans to be
equivalent to the exposure concentration associated with observed effects in the experimental
animal species. If occupational human exposures are used for extrapolation, then human
equivalent concentration represents the equivalent human exposure concentration adjusted to a
continuous basis.
LED10, LEC10: The 95 percent lower confidence limit on the ED10 or EC10 (dose or
concentration associated with a 10 percent level of response).
lowest-observed-adverse-effect level (LOAEL): The lowest exposure level at which there are
statistically or biologically significant increases in frequency or severity of adverse effects
between the exposed population and its appropriate control group.
margin of exposure (MOE): The ratio of the level or dose derived from a toxicity or
epidemiologic study (e.g., the NOAEL, the dose associated with a 10 percent response rate, etc.)
to the estimated exposure level or dose.
Monte Carlo method: A repeated random sampling from the distribution of values for each of
the parameters in a generic equation to derive an estimate of the distribution of outputs of the
equation.
no-observed-adverse-effect level (NOAEL): An exposure level at which there are no
statistically or biologically significant increases in the frequency or severity of adverse effects
between the exposed population and its appropriate control. In an experiment with several
NOAELs, the regulatory focus is primarily on the highest one, leading to the common usage of
the term NOAEL as the highest exposure without adverse effect.
octanol-water partition coefficient (K,,w): The ratio of a chemical's solubility in n-octanol to
its solubility in water at equilibrium. The logarithm of this value is often used as an indication of
a chemical's ability to bioconcentrate in organisms.
pharmacokinetics: The study of the absorption, distribution, metabolism, and excretion of
chemicals in living organisms and the genetic, nutritional, behavioral, and environmental factors
that modify these parameters.
primary effect: An effect where the stressor (e.g., chemical) acts on the ecological component
of interest itself, not through effects on other components of the ecosystem (synonymous with
direct effect).
March 1999 Page xi * *
-------
Residual Risk Report to Congress
reference concentration (RfC) or reference dose (RfD): An estimate (with uncertainty
spanning perhaps an order of magnitude) of a continuous inhalation exposure or a daily exposure
to the human population (including sensitive subgroups) that is likely to be without an
appreciable risk of deleterious non-cancer effects during a lifetime.
relative risk: The ratio of incidence or risk among exposed individuals to incidence or risk
among non-exposed individuals.
safety factor: see uncertainty factor.
secondary effect: An effect where the stressor acts on supporting components of the ecosystem,
which in turn have an effect on the ecological component of interest (synonymous with indirect
effects).
stressor: Any physical, chemical, or biological entity that can induce an adverse response
(synonymous with agent).
uncertainty factor (UF): One of several, generally 10-fold factors, used in operationally
deriving the RfD or RfC from experimental data. UFs are intended to account for: (1) the
variation in sensitivity among the members of the human population; (2) the uncertainty in
extrapolating animal data to the case of humans; (3) the uncertainty in extrapolating from data
obtained in a study that is of less-than-lifetime exposure; and (4) the uncertainty in using LOAEL
data rather than NOAEL data.
unit risk estimate (URE): The upper-bound excess lifetime cancer risk estimated to result from
continuous exposure to an agent (e.g., chemical) at a concentration of 1 microgram per cubic
meter in air or 1 microgram per liter in water.
* * * March 1999 Page xii * * *
-------
Residual Risk Report to Congress
Executive Summary
Purpose of Report
Section 112(f) of the Clean Air Act (CAA), as amended, directs EPA to prepare the
Residual Risk Report to Congress on the methods to be used to assess the risk remaining (i.e., the
residual risk) after control technology standards applicable to emission sources of hazardous air
pollutants (HAPs)1 have been promulgated and applied. CAA section 112(f)(l) contains several
specific requirements for the Report, which are summarized in Exhibit ES-1 along with a
reference to where each is addressed in the Report. Though not specifically required to be
included in the Report to Congress, EPA also presents a discussion of its residual risk assessment
framework for addressing the requirements under section 112(f)(2) to promulgate standards, if
required, to "provide an ample margin of safety to protect public health" or to set more stringent
standards, if necessary, "to prevent, taking into consideration costs, energy, safety, and other
relevant factors, an adverse environmental effect." EPA ecological risk assessment methods are
also described in the Report.
EXHIBIT ES-1
CROSSWALK BETWEEN SECTION 112(f)(l) REQUIREMENTS AND REPORT
Section 112(f)(l) Provision
112(f)(l)(A) - Methods of calculating the risk to public health remaining, or likely to remain,
from sources subject to regulation under section 112 after application of standards
112(f)(l)(B) - The public health significance of such estimated remaining risk
112(f)(l)(B) - The technologically and commercially available methods and costs of reducing
such risks
112(f)(l)(C) - The actual health effects with respect to persons living in the vicinity of sources
112(f)(l)(C) - Any available epidemiological or other health studies
112(f)(l)(C) - Risks presented by background concentrations of HAPs
112(f)(l)(C) - Uncertainties in risk assessment methodology or other health assessment
technique
112(f)(l)(C) - Any negative health or environmental consequences to the community of efforts
to reduce such risks
112(f)(l)(D) - Recommendations as to legislation regarding such remaining risk
Discussed in
Report
Chapters 3 and 5
Section 4. 1.1
Section 4. 1.2
Section 4. 2.1
Section 4.2.1
Section 4.2.2
Section 4. 2. 3
Section 4.2.4
Section 4. 3
1 The CAA defines HAP as any air pollutant listed under section 112(b), and provides procedures for
adding and deleting pollutants from the list. The terms "hazardous air pollutants," "HAPs," and "air toxics" are
used throughout this Report synonymously to refer to the pollutants listed under section 112(b).
* * * March 1999 Page ES-1 * * *
-------
Residual Risk Report to Congress
Background
The 1970 CAA mandated a health-based program that required EPA to identify and list
HAPs based on human health criteria. EPA was to then promulgate standards (national emission
standards for hazardous air pollutants, or NESHAPs) for each pollutant at a level that would
ensure the protection of public health with "an ample margin of safety." In the 20 years
following enactment of the 1970 legislation, EPA identified eight pollutants as HAPs and
regulated sources of seven of them.
In the 1990 CAA Amendments, Congress shifted the focus from individual pollutants to
industrial and commercial source categories, and a phased approach to controlling air toxics
emissions was developed. In the first regulatory phase, EPA must promulgate national,
technology-based emission standards for source categories emitting any of the 188 currently
listed HAPs in amounts exceeding specific emission thresholds. The fundamental approach is
the use of available control technologies or work practice changes to achieve emission reductions
in a timely manner for as many of the listed HAPs as possible, without explicit consideration of a
HAP's inherent toxicity and potential risk. This technology-based standards program is
commonly referred to as the maximum achievable control technology (MACT) program.
Regulation of air toxics emissions through the MACT program is expected to achieve significant
reductions in emissions of HAPs. As of October 1998, 53 source categories have been subjected
to MACT standards, resulting in estimated emission reductions of more than one million tons of
HAPs per year as well as significant reductions in emissions of criteria pollutants through co-
control.
In the second regulatory phase, the 1990 Amendments provide for a human health risk-
and adverse environmental effects-based "needs test." In this phase, referred to as residual risk
standard setting, EPA will consider the need for additional standards following regulation under
section 112(d) to protect public health and the environment. Section 112(f) of the CAA specifies
that such residual risk standards "provide an ample margin of safety to protect public health."
Section 112(f) also requires EPA to determine whether residual risk standards are necessary to
prevent "an adverse environmental effect," taking into consideration "costs, energy, safety, and
other relevant factors" in deciding what level is protective.
Also included in the 1990 CAA Amendments are provisions that EPA study several
specific topics. In accordance with this mandate, EPA has published a number of reports to
Congress, including the Mercury, Great Waters, and Utilities Reports to Congress, and continues
to study these and other special topics. Additionally, EPA currently is refining its strategy for
reducing risks in urban areas resulting from the emission of HAPs. The draft Urban Air Toxics
Strategy released in August 1998 proposes to address the problems of cumulative exposures to
air toxics in urban areas through an integrated approach that considers stationary and mobile
sources of urban air toxics. These programs, in combination with the residual risk program, will
provide a coordinated federal approach to address air toxics.
* * * March 1999 Page ES-2 * * *
-------
Residual Risk Report to Congress
In the absence of a strong federal air toxics program prior to passage of the CAA
Amendments of 1990, many State and some local agencies began to respond to the air toxics
problem by developing their own programs. Many States in the country currently have an air
toxics control program in place addressing, at a minimum, new sources of toxic air pollutants.
Some have their own regulations that allow them to actively control air toxics emissions to a
level protective of human health; others rely on comprehensive policies or authority provided to
implement the federal program. Some State and local programs are risk-based, while others are
technol ogy-b ased.
The State and local programs have made progress in protecting the health of their people
and their environment from exposure to air toxics. A successful comprehensive air toxics
program will be one that integrates the residual risk and other federal programs with State and
local programs and strengthens those existing programs. Program integration will involve
interactive sharing of expertise, data, analyses, and methodologies. Additionally, State and local
authorities may complement the federal program by addressing local risk issues that may not be
effectively addressed nationally.
EPA is fully committed to environmental protection that is founded on sound and
credible science. Objective, independent peer review of the scientific and technical bases of the
Agency's actions is critical to accomplishing the Agency's mission. Although most of the major
references that form the foundation of this Report have undergone (or are currently undergoing)
external peer review, EPA requested and obtained from its Science Advisory Board an
independent evaluation of the presentation of risk assessment methods and supporting data. This
final Report was developed in consideration of both the SAB review comments and the
comments received during the public comment period.
Risk Assessment Methods and Their Development
Three external reports have greatly influenced the development of human health risk
assessment methods for air toxics at EPA: (1) the National Research Council's (NRC) 1983
report on risk assessment; (2) the NRC's 1994 risk assessment report; and (3) the
Presidential/Congressional Commission on Risk Assessment and Risk Management's (CRARM)
1997 report. The 1983 NRC report, entitled Risk Assessment in the Federal Government:
Managing the Process, describes the four-step paradigm for risk assessment that continues to
serve as EPA's model for human health risk assessments. In a follow-up report entitled Science
and Judgment in Risk Assessment mandated by the 1990 CAA Amendments, the NRC observed
that several themes were common to all elements of the risk assessment process and noted that
these themes were usually the focal points for criticisms of specific risk assessments. The NRC's
discussion of these points and their recommendations in the different areas were viewed as a way
to increase the effectiveness and accuracy of the risk assessment process. This Report describes
EPA methods and strategies, which have incorporated many of their suggestions. The third
document, the 1997 CRARM report, builds on the methods presented in these NRC reports.
Section 303 of the CAA Amendments of 1990 mandated formation of the CRARM in response
* * * March 1999 Page ES-3 * * *
-------
Residual Risk Report to Congress
to unresolved questions about the approach EPA should take in determining whether significant
risks to human health remain after the implementation of technology-based HAP emission
controls under CAA section 112. The CRARM's framework fosters an integrated approach to
addressing complex, real-world issues that affect more than one environmental medium and
involve exposures to mixtures of chemicals.
Ecological risk assessment at EPA began in the 1970s primarily in two program areas,
water quality and pesticide registration. In 1986, the Agency published standardized guidelines
for deriving water quality criteria and separate standard evaluation procedures for estimating
pesticides' effects. By the late 1980s, EPA recognized a need for consistency in evaluating
ecological risks across program offices and a need to make its ecological research efforts more
responsive to its risk assessment needs Agency-wide. In 1992, the Agency's Risk Assessment
Forum published the Framework for Ecological Risk Assessment, which could accommodate all
the diverse kinds of ecological risk assessments. Various Agency-wide efforts to improve
ecological risk assessment have followed. In 1998, EPA issued Guidelines for Ecological Risk
Assessment, which are the basis of the residual risk approach to ecological risk assessment.
The following text box summarizes the components of EPA's current risk assessment
methodology. The 1998 ecological risk assessment guidelines present a general three-phase
framework (problem formulation, analysis, and risk characterization) that is consistent with and
also appropriate for human health risk assessment. The traditional human health risk assessment
paradigm (described by NR.C in 1983) includes components of the analysis and characterization
phases of risk assessment. Because the problem formulation phase is appropriate for both
ecological and human health risk assessment, the Agency will use the three-phase framework
(inclusive of the NRC paradigm components) in both human health and ecological risk
assessments performed for residual risk analysis of air toxics. Consistent with the CRARM and
NRC reports and with risk assessment practices throughout the Agency, the risk assessment
process for residual risk analyses includes the use of screening-level analyses, as appropriate, and
additional analysis, when warranted, using more refined data and/or tools.
In addition to the improvements and refinements in risk assessment methods and
guidance since the 1983 NRC report, there have been significant enhancements in the available
data and tools for conducting risk assessments on air toxics. As knowledge has improved
regarding the toxicology of environmental pollutants, EPA has responded by modifying
assessment methods (e.g., the proposed revisions to EPA's carcinogen risk assessment
guidelines). The development and revision of EPA human health risk assessment guidelines are
shown in the text box below.
The number of hazardous air pollutants for which EPA has developed quantitative dose-
response assessments for use in risk assessment has also substantially increased. However, as
EPA's coverage does not yet include all 188 HAPs, residual risk assessment activities will
* * * March 1999 Page ES-4 * * *
-------
Residual Risk Report to Congress
FRAMEWORKS FOR RISK ASSESSMENT
The NRC risk assessment paradigm, first described in 1983, consists of four steps.
> Hazard Identification. The first step in a risk assessment is to determine whether the pollutants of concern can be
causally linked to the health effects in question (cancer and/or non-cancer). Factors such as the route of exposure, the
type and quality of the effects, the biological plausibility of findings, the consistency of findings across studies, and the
potential for bioaccumulation all contribute to the strength of the hazard identification statement.
> Dose-response Assessment. This step is the quantitative characterization of the relationship between the
concentration, exposure, or dose of a pollutant and the resultant health effects. When adequate data exist, the typical
end product of the dose-response assessment for non-cancer effects is the identification of a sub-threshold dose or
exposure level that humans could experience daily for a lifetime without appreciable probability of ill effect. Sub-
threshold short-term exposure levels are also under development. For cancer, the typical goal of this step is estimation
of a full dose-response curve for low exposures.
> Exposure Assessment. EPA's current Guidelines for Exposure Assessment, published in 1992, provide the framework
for this step. An exposure assessment for air toxics has four major components: (1) emissions characterization; (2)
environmental fate and transport analysis; (3) characterization of the study population; and (4) exposure
characterization for both inhalation and non-inhalation pathways.
> Risk Characterization. This step is where all the information from the previous steps is integrated to describe the
outcome of the analysis, and where the uncertainty and variability in the results are described. EPA's 1995 Guidance
for Risk Characterization is the foundation for this step of the process.
EPA's Ecological Risk Assessment Framework, presented in the 1998 Guidelines, describes three phases.
> Problem Formulation. In this phase, the problem is defined, the purpose of the risk assessment is articulated, and a
plan for characterizing the risks is developed. Important steps include identifying assessment endpoints, developing
the conceptual model, and preparing an analysis plan.
> Analysis. This phase involves evaluating how exposure to stressors might occur (characterization of exposure) and the
relationship between stressor levels and ecological effects (characterization of effects).
> Risk Characterization. In this phase, the risk is estimated and described through integration of the exposure and
ecological effects profiles generated in the analysis phase.
consider other sources of such information. Regardless of the endpoint of interest (acute or
chronic non- cancer, cancer, or ecological effects), consensus toxicity values are preferred for
conducting risk assessments. Regardless of the endpoint of interest (acute or chronic non-cancer,
cancer, or ecological effects), consensus toxicity values are preferred for conducting risk
assessments. For human health risk assessments, the preferred source of such information is the
Agency's Integrated Risk Information System. Other Agency and outside sources will be
consulted as needed. As assessments for some HAPs may be less current than others, the
Agency will evaluate the appropriateness of these assessments in light of more recent credible
and relevant information. For ecological risk assessments, a hierarchy of preferred data sources
is more difficult to identify and may depend on the type of assessment (e.g., screening versus
refined assessment, type of ecosystem at risk). EPA plans to establish data source hierarchies for
each type of toxicity information to be used in residual risk assessments, and to continue to
improve our ability to assess risks posed by all 188 HAPs.
* * * March 1999 Page ES-5 * * *
-------
Residual Risk Report to Congress
EPA HUMAN HEALTH RISK ASSESSMENT
GUIDELINES
EPA has published final risk assessment guidelines
that address the following areas:
Mutagenicity(1986)
Carcinogenicity (1986)
Chemical mixtures (1986)
Developmental toxicity (1991)
Exposure assessment (1992)
Risk characterization (1995)
Reproductive toxicity (1996)
Probabilistic analysis (1997)
Neurotoxicity (1998)
Draft revisions have been issued for carcinogenicity
(1996) and are under development for mixtures.
The Agency's risk assessment tools (e.g.,
tools for dispersion modeling, exposure
modeling, and uncertainty analyses) have also
improved. The tools currently available have
varying input data requirements and applications.
In residual risk assessments, EPA will target the
use of these tools such that resources are used
most effectively and appropriately. Screening-
level analyses will use simpler, less resource
intensive tools, enabling the Agency to target use
of more refined tools with greater resource needs
where most appropriate. As the Agency gains
experience and knowledge in air toxics risk
assessment, it continues to improve and develop
the tools for this area.
Other Items in CAA Section 112(f)(1)
Section 112(f)(l), parts (B) through (D), of the CAA lists several other items that this
Report should contain in addition to a description of the residual risk assessment methods. These
specific items, and EPA's approach to reporting on them, include the following.
Public health significance of risks remaining after application of a MACT standard
(section 112(f)(l)(B)): Given the CAA schedule for MACT promulgation and for residual risk
determinations, residual risk assessments for source categories have not yet been completed as of
the date of this Report, and EPA is not able to report on the actual public health significance of
any residual risks at this time. As the Agency completes residual risk assessments for individual
source categories, public health significance will be evaluated, and public health information, as
available, will be presented. The Agency considers the ample margin of safety concept as
introduced in the 1970 CAA Amendments and as applied in the 1989 benzene NESHAP a
reasonable approach to evaluate public health significance and to manage residual risks under
CAA section 112.
The available methods for and costs of reducing residual risks (section 112(f)(l)(B)):
Current controls on major sources, which include State actions and federal requirements in
addition to requiring MACT on major sources, do not necessarily guarantee that HAP emissions
will be reduced sufficiently to protect public health. EPA believes that methods to reduce
emissions beyond MACT exist. However, it is not possible to determine specific methods or to
estimate the costs to reduce residual risks because of the timing of this Report in relation to
MACT standard implementation and residual risk analyses. The discussion provided in the
Report focuses on several key factors that will influence available methods for and costs of
reducing residual risk.
* * * March 1999 Page ES-6 * * *
-------
Residual Risk Report to Congress
The current state of knowledge regarding actual health effects of HAPs on humans
(section 112(f)(l)(C)): Very few well-conducted health effects studies have focused on air toxics
exposures to populations near sources of HAPs, largely because of methodological and statistical
limitations to such studies. For this reason, information on health effects of air toxics is
primarily based on laboratory animal and occupational studies. Animal studies are available for
many HAPs and provide information on the potential for adverse human effects, but usually
evaluate chemicals at higher exposures than normally expected for human populations. In
addition, physiology and metabolic pathways that affect responses may differ between animals
and humans. Occupational human data provide evidence of human effects, but are often limited
by a lack of clarity about actual exposure conditions and the fact that occupational exposures are
typically higher than those resulting from the ambient air. Therefore, extrapolation from higher
doses to lower environmental concentrations creates uncertainty. This Report presents a
summary discussion of epidemiological data, laboratory data, and other study data. It also briefly
describes how EPA intends to use these data and any actual source category-specific health
effects data that may become available when residual risk assessments are conducted.
EPA's strategy for collecting and assessing epidemiological and actual health effects
data (section 112(f)(l)(C)): EPA recognizes the difficulties that exist in obtaining actual health
effects data and conducting valid epidemiological studies involving populations near HAP
sources. However, EPA believes that it is useful to incorporate any available health
effects/epidemiology data in the residual risk assessments and intends to use such data wherever
possible in decision-making. In the data gathering stage, EPA will search the scientific literature
for published epidemiological studies related to the specific source categories, HAPs, and/or
locations studied. Where published epidemiological studies are unavailable, EPA will consider
examining other human health data for evaluation of correlations between exposure and adverse
human health effects. However, EPA expects that such data will rarely be available.
Assessing risks of background concentrations (section 112(f)(l)(C)): Background
concentrations are defined generally as the levels of contaminants that would be present in the
absence of source-related contaminant releases. Background concentrations come from either
contaminants that may occur naturally in the environment or contaminants that are emitted by
other (i.e., not the sources being assessed) anthropogenic sources. Narrowly defined for HAPs
and the residual risk program, background concentrations are the levels of HAPs in
environmental media that are attributable to natural and anthropogenic sources other than the
source(s) under evaluation. At this date, EPA does not have comprehensive Agency-wide
guidance or policies on incorporating background concentrations into risk assessments and risk
management decisions. Furthermore, analyses of background concentrations and risks can be
extremely data- and resource-intensive. EPA's general approach in previous risk assessments
and risk management decisions has been to assess the incremental risk of a particular source or
activity and compare that risk to an acceptable risk criterion. The residual risk program will
continue to use this approach, although background concentrations may be considered in the
more refined analyses for some source categories.
* * * March 1999 Page ES-7 * * *
-------
Residual Risk Report to Congress
Uncertainty and variability in the estimation of residual risks (section 112(f)(l)(C)):
The Agency recognizes and supports recommendations of NRC regarding evaluation of
uncertainty and variability in risk assessment. As feasible and appropriate, EPA will follow these
recommendations. The Agency has published several guidance documents addressing this issue,
which will be used to guide our analysis. While the exact approach to be taken has not been
finalized and may differ from source category to source category, a number of general
approaches will be considered for addressing uncertainly and variability in residual risk
assessments, including: (1) qualitative assessment; (2) multi-scenario approaches and limited
sensitivity analysis; (3) systematic sensitivity analysis; and (4) Monte Carlo simulation and
related probabilistic methods.
Negative health or environmental consequences to the community of efforts to
reduce residual risks (section 112(f)(l)(C)): EPA recognizes the possibility of creating or
transferring risks as an unintended by-product of actions that may be taken to reduce residual
risks of HAPs. EPA intends, as part of the section 112(f) standard-setting process, to the extent
feasible, to identify potential negative health and environmental consequences and consider the
risk-risk tradeoffs associated with any standards established under the residual risk program.
Where deemed necessary, EPA will conduct analyses of these tradeoffs at an appropriate level of
detail.
Recommendations to Congress for legislative changes (section 112(f)(l)(D)): At this
time, EPA believes that the legislative strategy embodied in the 1990 CAA Amendments
provides EPA with adequate authority to address residual risks to public health and the
environment and provides a comprehensive and flexible strategy for addressing a variety of air
toxics risk concerns. Therefore, the Agency is not recommending any legislative changes.
Framework for Risk Assessment Under the Residual Risk Program
EPA has developed a residual risk assessment framework to implement the requirements
of CAA sections 112(f)(2) through (6). Those sections require EPA to promulgate standards
beyond MACT when necessary to provide "an ample margin of safety to protect public health"
and to "prevent, considering costs, energy, safety, and other relevant factors, an adverse
environmental effect." The objectives for residual risk activities under section 112(f)(2) are two-
fold:
(1) Assess any risks remaining after MACT standard compliance; and
(2) Set standards for the identified source categories, if additional HAP emission reductions
are necessary to provide an ample margin of safety to protect public health or, taking into
account cost, energy, safety, and other relevant factors, to prevent an adverse
environmental effect.
* * * March 1999 Page ES-8 * * *
-------
Residual Risk Report to Congress
EPA's intent is to implement a residual risk assessment framework that will allow the Agency to
be flexible in its decisions while ensuring that public health and the environment are protected.
EPA's objectives also include integration of all portions of the federal air toxics program,
continuing the partnership with State/local programs in the sharing of data and expertise, and
including groups who may be affected by residual risk decisions (e.g., industry, public interest
groups) as part of the process.
Using knowledge gained from past risk assessments, information from other regulatory
agencies, and guidance from Reports such as the NRC and CRARM reports, the Agency has
developed a general framework for assessing residual risks. Exhibit ES-2 is a flowchart
representation of the general residual risk strategy. This strategy calls for an iterative, tiered
assessment of the risks to humans and ecological receptors through inhalation and, where
appropriate, non-inhalation exposures to HAPs. The first component of the residual risk strategy
is a statement of management goals. Those management goals help direct the problem
formulation phase of both the human health and ecological risk assessments.
As shown in Exhibit ES-2, each human health and ecological risk assessment is
organized into three phases: (1) the problem formulation phase, in which the context and scope
of the assessments are specified; (2) the analysis phase, in which the HAPs' toxicity and
exposure to humans or ecological receptors are evaluated; and (3) the risk characterization phase,
in which the toxicity and exposure analyses are integrated to determine the level of risk that may
exist. As illustrated in Exhibit ES-2, the problem formulation and analysis phases of the human
health and ecological risk assessments will partially "overlap" in that some pathways of concern
for humans (e.g., consumption of contaminated fish) may also be pathways of concern for
ecological receptors (e.g., fish-eating wildlife). Consequently, exposure analyses for some HAPs
may be designed to provide exposure assessments for both ecological and human health
assessments.
In both human health and ecological risk assessments, there is essentially a continuum of
possible levels of analysis from the most basic screening approach to the most refined, detailed
assessment. The screening level or tier of analysis is designed, through the use of conservative
inputs, to identify for no further action or analysis, situations or HAPs for which risks are
unlikely to be of concern. Screening tier analyses are designed to be relatively simple,
inexpensive, and quick, using existing data, defined decision criteria, and models with
simplifying conservative assumptions as inputs. More refined levels of analysis include the
refinement of aspects of the analysis that are thought to influence risk most or may contain the
greatest uncertainty. At the refined tier, each analysis requires more effort, but produces results
that are less uncertain and less conservative (i.e., less likely to overestimate risk). Under residual
risk, an assessment will start at the level considered most appropriate upon examination of the
available information during the scoping or problem formulation phase; iterations of the
assessment, with refinements, will occur when warranted.
* * * March 1999 Page ES-9 * * *
-------
Residual Risk Report to Congress
EXHIBIT ES-2
OVERVIEW OF RESIDUAL RISK FRAMEWORK
ITERATIVE APPROACH
i
Management Goals
\
r
f
Human Health Risk Assessment Ecological Risk Assessment
Problem Formulation
Is human
health risk
acceptable?
Are information
and analysis sufficient
to evaluate
management
options?
Exposure
Analysis
Ecological
Effects
Analysis
^^^^^^^^^^^m ^^^^^^^m
Risk Characterization
Yes
^
1 '
No further action
under Residual Risk
Strategy
"^
1
W
Evaluation of
Risk Management Options
Yes
I
* * * March 1999 Page ES-10 * * *
-------
Residual Risk Report to Congress
Risk Management Decision Points
There will be many opportunities throughout the residual risk process for risk managers
to make decisions that will determine the direction and scope of these assessments. Initially,
EPA plans to set priorities for analyzing the more than 170 source categories based on a number
of considerations, including the MACT promulgation dates for source categories (from which the
statutory time period for residual risk determinations is measured) and any available information
bearing on the relative level of residual risks attributable to various source categories. Following
this, the problem formulation phase will determine how each risk assessment will be framed. For
example, decisions regarding which HAPs, what exposure pathways, and what level of analysis
(early screen or more refined) will be made. Much of the data that will feed these decisions will
come from existing data that are easily accessible and determined to be adequate for this step.
The purpose of a screening analysis is to identify those situations or HAPS for which no
further action is needed and those for which further analysis is needed. When a subsequent
analysis is performed, those aspects of the analysis that are thought to influence risk most or
contain the greatest uncertainty are refined. Although the screening analysis can serve as a basis
for a decision to eliminate low-risk source categories from further consideration under section
112(f), it is not adequate to serve as a basis for establishing additional emission reduction
requirements. The results of a more refined assessment can support either a conclusion of "no
further action" or "additional emissions reductions may be needed," and will be used by EPA to
make decisions on whether additional emission reductions are needed for individual source
categories.
For public health risk management decision-making in the residual risk program, EPA
considers the two-step process culminating with an "ample margin of safety" determination, as
established in the 1989 benzene NESHAP and endorsed by Congress in the 1990 CAA
Amendments as a reasonable approach. In the first step, a "safe" or "acceptable risk" level is
established considering all health information including risk estimation uncertainty. As stated in
the preamble to the rule for benzene, which is a linear carcinogen (i.e., a carcinogen for which
cancer risk is believed or assumed to vary linearly with exposure), "an MIR (maximum
individual risk) of approximately 1 in 10 thousand should ordinarily be the upper-end of the
range of acceptability." In the second step, an emission standard is set that provides an "ample
margin of safety" to protect public health, considering all health information including the
number of persons at risk levels higher than approximately 1 in 1 million, as well as other
relevant factors including costs, economic impacts, technological feasibility, and any other
relevant factors. In notifying the public of the 1989 benzene NESHAP, the Agency stated that it
"strives to provide maximum feasible protection against risks to health from hazardous air
pollutants by (1) protecting the greatest number of persons possible to an individual lifetime risk
level no higher than approximately 1 in 1 million and (2) limiting to no higher than
approximately 1 in 10 thousand the estimated risk that a person living near a plant would have."
* * * March 1999 Page ES-11 * * *
-------
Residual Risk Report to Congress
Thus, the benzene NESHAP established specific risk management policy for the
protection of public health with an "ample margin of safety," and provided a specific application
for public health risks posed by a linear carcinogen, including some numerical criteria, that will
be used in addressing residual risks. Under this risk management policy, EPA is developing risk
management framework applications to specifically address non-cancer public health risks and
public health risks posed by carcinogens with non-linear risk assumptions. Further, the Agency
is also developing a risk management framework to address adverse environmental effects in the
residual risk program. None of these framework applications are presented in this Report.
Summary
This Report responds to section 112(f)(l) of the Clean Air Act and contains EPA's
general framework for assessing risks to public health or the environment remaining after
implementation of emissions standards under 112(d). EPA's risk assessment methods and the
corresponding data and tools have developed substantially since the adoption of the 1990
Amendments containing this section. The Agency will apply these improved assessment
methods, data, and tools, augmented as appropriate with current information or findings, in
assessing the need for standards under section 112(f)(2). The residual risk assessment
framework is intended to provide EPA with appropriate flexibility in its analyses and decisions
while ensuring that public health and the environment are protected from air toxics as envisioned
by Congress in the CAA.
* * * March 1999 Page ES-12 * * *
-------
Residual Risk Report to Congress
1. Introduction
In 1990, Congress amended
section 112 of the Clean Air Act (CAA)
and mandated a new approach to the
regulation of hazardous air pollutants
(HAPs).1 Under the original CAA (1970),
air toxics were addressed through a risk-
based program, and emission standards
were set for individual pollutants. The
new approach first requires the
development of technology-based
emission standards under section 112(d)
for major and, in some cases, area sources
of the currently listed 188 HAPs. The
statute directs that these standards are to
be developed over a 10-year time frame
and based on the maximum achievable
control technology (MACT). The
Environmental Protection Agency (EPA)
is currently in the process of developing
MACT standards for more than 170
categories of HAP sources. As of October
1998, MACT standards had been
promulgated for 53 source categories. When fully implemented, these standards are expected to
result in estimated HAP reductions of approximately a million tons per year, plus more than two
million tons per year of particulate matter and precursors to ground level ozone.
Section 112(f) of the CAA, in addition to requiring this Report to Congress (Report),
calls for an evaluation of the health and environmental risks remaining after technology-based
standards have been promulgated (i.e., the residual risks) and requires more stringent regulation
if certain criteria are not met. Specifically, its focus is to achieve a level of protection that
protects the public health with an "ample margin of safety" (see Section 2.1 for a discussion of
this term) while also ensuring that "taking into consideration costs, energy, safety, and other
SECTION 112(f)(l) REPORT REQUIREMENTS
". . . the Administrator shall investigate and report, after
consultation with the Surgeon General and after opportunity for
public comment, to Congress on:
> Methods of calculating the risk to public health remaining,
or likely to remain, from sources subject to regulation
under this section after the application of standards under
subsection (d) of this section;
> The public health significance of such estimated remaining
risk and the technologically and commercially available
methods and costs of reducing such risks;
> The actual health effects with respect to persons living in
the vicinity of sources, any available epidemiological or
other health studies, risks presented by background
concentrations of hazardous air pollutants, any
uncertainties in risk assessment methodology or other
health assessment technique, and any negative health or
environmental consequences to the community of efforts to
reduce such risks; and
> Recommendations as to legislation regarding such
remaining risk."
1 The Clean Air Act defines hazardous air pollutant as any air pollutant listed under section 112(b), and
also provides procedures for adding and deleting pollutants from the list. The terms "hazardous air pollutants,"
"HAPs," and "air toxics" are used throughout this Report synonymously to refer to the pollutants listed in the CAA
under section 112(b).
* * *
March 1999 Page 1
* * *
-------
Residual Risk Report to Congress
relevant factors," residual emissions do not result in "an adverse environmental effect."2 The
accompanying text box outlines the requirements in section 112(f)(l) that this Report addresses.
1.1 Scope of Report
This Report responds to the statutory directives in section 112(f) of the CAA and also
provides the general framework of EPA's strategy for assessing residual risk remaining from the
HAPs being emitted from source categories subject to MACT standards. This chapter provides a
brief introduction and describes the scope and organization of the Report. It presents the specific
requirements for the Report listed in CAA section 112(f)(l) and briefly discusses each. Chapter
1 concludes with a discussion of peer review in the context of this Report. Chapter 2 provides a
brief legislative and regulatory background on the CAA air toxics program in order to provide
context for what follows. The Report then addresses, in Chapters 3 and 4, the required statutory
elements of the Report, as shown in the text box on page 1. Chapter 3 provides information on
the methods for conducting human and ecological risk assessments for emissions of air toxics,
describes the data required, and discusses limitations in the available methods and data. As
discussed in Section 3.1, the development of the Agency's risk-based program for air toxics has
incorporated input from the National Research Council (NRC), the Commission on Risk
Assessment and Risk Management (CRARM), State and local air toxics programs, and a variety
of risk assessment policies and guidelines developed (and in some cases under development) by
the Agency. Chapter 4 addresses the remaining statutory elements listed in CAA sections
112(f)(l)(B), (C), and (D) in the order listed in the CAA. In Chapter 5, the Report describes the
Agency's strategy to conduct residual risk analyses as well as discusses other provisions in
sections 112(f)(2) through (6) of the CAA. Appendix A provides the full text of CAA section
112(f), Appendix B provides relevant text from the preamble to the 1989 national emission
standard for benzene, Appendix C presents the schedule for promulgation of MACT standards
for industry source categories, and Appendix D provides a summary of EPA's responses to the
major review comments of its Science Advisory Board (SAB).
The intent of this Report is to address the legislative requirements of section 112(f)(l)
and to provide the reader with a basic understanding of the methods and process the Agency
plans to follow in conducting risk analyses for air toxics. In response to section 112(f)(l)(A), the
Report describes methods for human health and ecological risk assessment of air toxics. For
these methods, the current availability and completeness of data or methodology are described
along with how analyses will progress given the existing limitations (e.g., assessments will
necessarily be limited to those HAPs for which toxicity information is adequate) and data and
tool development activities. Methodology is presented in a descriptive manner rather than in
2 The Clean Air Act at section 112(a)(7) defines adverse environmental effect as any significant and
widespread adverse effect, which may reasonably be anticipated, to wildlife, aquatic life, or other natural resources,
including adverse impacts on populations of endangered or threatened species or significant degradation of
environmental quality over broad areas.
* * * March 1999 Page 2 * * *
-------
Residual Risk Report to Congress
guidance form, with sufficient detail to inform the reader of the Agency's intentions and
directions in performing "residual risk" and other air toxics analyses. Indicative of the Agency's
desire to conduct analyses consistent with current, scientifically appropriate data and
methodology, flexibility and the ability to incorporate changes in methodology and new data are
essential to the process.
It is important to note that this Report does not contain the results of any residual risk
analyses or a description of potential EPA actions after conducting such analyses (e.g., additional
emission reductions for a given source category). The Agency is collecting existing data on
source categories for which MACT standards have been promulgated and is beginning to analyze
these data consistent with the framework described here.
In addition to risk assessment methods for residual risk, section 112(f)(l) specifies that
EPA report on elements related to estimates of residual risk. The following section outlines the
presentation of these additional elements within this Report.
Section 112(f)(l)(B)
Public Health Significance. Without having any actual residual risk analyses completed
at this time, the Agency cannot draw conclusions about the public health significance of residual
risks. However, the Agency considers the "ample margin of safety" concept, discussed in
Section 2.1 of this Report, an appropriate basis for determining the significance of and for
managing any residual risks for individual source categories. As residual risk assessments are
completed for individual source categories, public health information, as available, will be
identified along with risk estimates and attendant uncertainties and limitations as part of the risk
characterization and decision-making process.
In making regulatory decisions for air toxics thus far, EPA has emphasized consideration
of cancer risk to humans. However, air toxics can cause health effects other than cancer. EPA
plans to consider non-cancer effects under the residual risk program. Although not available for
discussion in this Report, the Agency currently is developing a policy framework for this
management issue.
Technologically and Commercially Available Methods and Costs. This Report
describes a range of control options for consideration if it is determined that additional control is
needed. The Report provides an overview of these options, with an emphasis on pollution
prevention (P2) approaches.
* * * March 1999 Page 3 * * *
-------
Residual Risk Report to Congress
Section 112(f)(l)(C)
Acute Health Effects/Epidemiological and Other Health Information. The
information available on actual health effects resulting from exposure to air toxics is limited.
This Report presents a summary discussion of epidemiological data, laboratory data, and other
exposure study data. It also briefly describes how the Agency intends to use these data and any
actual source category-specific health effects data that may become available when residual risk
assessments are conducted.
Risks Presented by Background Concentrations. This Report discusses general
information on assessing risks posed by background levels of HAPs and presents a definition of
background concentrations for air toxics and residual risk purposes. It describes approaches used
by several EPA programs and includes examples of rules and guidance that consider the issue of
background concentrations. It also presents a discussion of the difficulties in addressing
background concentrations in residual risk analyses and identifies data needs to assess
background. The discussion concludes by describing the Agency's options to analyze and
consider background concentrations in residual risk analyses.
Uncertainties. This Report provides a general description of uncertainty in residual risk
assessments and how uncertainty affects the level of confidence that can be placed in the
estimates of risk. It also briefly presents approaches to addressing uncertainty and variability in
the estimation of residual risks.
Negative Health or Environmental Consequences to Communities. In specifying that
EPA report on negative health or environmental consequences to communities from efforts to
reduce residual risks, section 112(f) indicates the importance of considering such potential
consequences of risk management or risk reduction options. Pollution control technologies
targeted at a single pollutant (e.g., a specific HAP) and single medium (e.g., air), especially
conventional end-of-the-pipe treatment technologies, can inadvertently transfer pollutants and
risks to different media, different locations, and different receptors, and can unintentionally
create new and different risks in the process of controlling the targeted risk. Thus, as the Agency
conducts residual risk analyses and before it takes subsequent standard-setting actions, efforts
will be made, as feasible, to identify potential negative health and environmental consequences
and to consider the risk-risk tradeoffs associated with any standards established under the
residual risk program.
Section 112(f)(l)(D)
Legislative Recommendations. Section 112(f)(l)(D) requires EPA to investigate and
report to Congress on "recommendations as to legislation regarding such remaining risk." Thus,
if an unacceptable residual risk were identified, and no current authority within the CAA were
determined to be adequate to reduce that risk, then the EPA would recommend an approach that
* * * March 1999 Page 4 * * *
-------
Residual Risk Report to Congress
would assure that risk reductions would occur. However, the Agency believes that the regulatory
approach embodied in the CAA is adequate for maintaining the goal of protecting the public
health and environment, and, therefore, is not recommending any legislative changes.
1.2 Peer Review
The Agency is fully committed to environmental protection that is founded on sound and
credible science. Objective, independent peer review of the scientific and technical bases of the
Agency's actions is critical to accomplishing the Agency's mission. The Agency's commitment
to credible, effective peer review is stated in its Peer Review Policy of June 7, 1994. Full
implementation of this policy remains an Agency priority.
Although most of the major references that form the foundation of this Report have
undergone (or are currently undergoing) external peer review, EPA requested that the SAB
provide an independent evaluation of questions such as whether the Report identified the most
relevant and useful methods of assessing risks from stationary sources and whether it properly
characterized the types of data on which these methods rely. The Residual Risk Subcommittee of
the SAB convened its review panel on August 3, 1998 to review the draft Report. Appendix D
includes a summary of the Agency's responses to SAB's major comments. This final Report was
developed in consideration of both the SAB review comments and the comments received during
the public comment period.
* * * March 1999 Page 5 * * *
-------
Residual Risk Report to Congress
This page left intentionally blank
* * * March 1999 Page 6 * * *
-------
Residual Risk Report to Congress
2. Background: Air Toxics Program
In order to understand the mandate of CAA section 112(f) and the purpose behind its
charge to EPA, it is helpful to understand the legislative approach used to regulate HAPs in the
1970 CAA Amendments, the subsequent regulatory history in the 1970s and 1980s, and the
legislative strategy behind the approach taken by the 1990 CAA Amendments. It is also useful as
background to consider State and local air toxics programs and their role in EPA's air toxics
program.
2.1 History of the Air Toxics Program: 1970-1990
Congress first required regulations limiting emissions of HAPs in 1970 by including an
air toxics provision in the 1970 CAA Amendments. This provision described a health-based
program that required EPA to identify and list HAPs based on human health criteria described in
the Amendments. The EPA was to then promulgate standards for each pollutant, on a source
category-by-source category basis, at a level that would ensure the protection of public health
with "an ample margin of safety." After EPA listed a pollutant, regulation was required within a
short time.
The EPA produced few air toxics regulations under the program established by the 1970
CAA Amendments. In the 20 years following the enactment of this legislation, EPA identified
eight pollutants as HAPs and regulated seven of these. Impediments to regulation included the
amount and type of data needed to establish a chemical as a HAP, emissions standards based on
what the Agency interpreted to be solely human health effects considerations, extremely short
statutory deadlines, and disagreements over how health effects should be assessed. A common
theme running through many of these impediments to regulatory action was the lack of a
consistent risk management framework with which to make regulatory decisions.
The most significant example of EPA's attempts to regulate HAPs under the 1970 CAA
Amendments resulted in a DC Circuit Court decision that would guide the development of
EPA's risk management approach for air toxics (Natural Resources Defense Council v. EPA
1987). Natural Resources Defense Council (NRDC) sued EPA on the Agency's attempt to
establish a national emission standard for hazardous air pollutants (NESHAP) for vinyl chloride,
stating that the Agency improperly used cost in regulating this HAP. The U.S. Court of Appeals
for the DC Circuit Court agreed with NRDC, and in its decision presented a two-step framework
by which to apply the "ample margin of safety" language: (1) first determine a "safe" or
"acceptable risk" level, considering only public health factors, and (2) then set an emission
standard that provides an "ample margin of safety" to protect the public health, considering
relevant factors in addition to health, such as costs, economic impacts, technical feasibility,
uncertainties, and other factors.
* * *
March 1999 Page 7 * * *
-------
Residual Risk Report to Congress
The 1989 NESHAP for benzene (EPA 1989a) presented the following risk management
framework for cancer risk, which reflects the two-step approach suggested by the court. The
benzene rule preamble states that in determining acceptable risk:
The Administrator believes that an MIR [maximum individual risk] of approximately 1 in
10 thousand should ordinarily be the upper-end of the range of acceptability. As risks
increase above this benchmark, they become presumptively less acceptable under section
112, and would be weighed with the other health risk measures and information in
making an overall judgment on acceptability. Or, the Agency may find, in a particular
case, that a risk that includes MIR less than the presumptively acceptable level is
unacceptable in light of the other health risk factors (EPA 1989a).
The EPA believes that the level of the MIR, the distribution of risks in the exposed
population, incidence, the science policy assumptions and uncertainties associated with
risk measures, and the weight of evidence that a pollutant is harmful to health are all
important factors to be considered in the acceptability judgment (EPA 1989a).
The preamble also states that in the second step, where the standard is set with an ample margin
of safety:
EPA strives to provide protection to the greatest number of persons possible to an
individual lifetime risk level no higher than approximately 1 in 1 million. In the ample
margin decision, the Agency again considers all of the health risk and other health
information considered in the first step. Beyond that information, additional factors
relating to the appropriate level of control will also be considered, including costs and
economic impacts of controls, technological feasibility, uncertainties, and any other
relevant factors (EPA 1989a).
In the benzene NESHAP, EPA established risk management policy for the protection of public
health with an ample margin of safety and provided a specific application for cancer risks such as
those posed by benzene. Appendix B provides excerpts of the preamble text from the 1989
benzene NESHAP.
The HAP provisions of the 1970 CAA Amendments were written specifically in terms of
public health effects, with no mention of ecological or environmental effects anywhere in section
112. In its original form, CAA section 112(b) directed that NESHAPs be set to provide ". . . an
ample margin of safety to protect the public health . . ." In fact, HAPs were defined specifically
in terms of human health; section 112(a) of the 1970 CAA defined a HAP as an air pollutant that
"... may reasonably be anticipated to result in an increase in mortality or an increase in serious
irreversible, or incapacitating reversible, illness." Thus, there was no legislative directive to
consider environmental effects in regulating HAPs in the pre-1990 air toxics program.
* * *
March 1999 Page 8 * * *
-------
Residual Risk Report to Congress
2.2 Strategy For Air Toxics: Post-1990
Recognizing that the "health test" (i.e., the requirement for the protection of public health
with an "ample margin of safety") was the most contentious part of section 112 under the 1970
CAA Amendments, Congress shifted the focus from individual pollutants to industrial source
categories and developed a phased approach to controlling air toxics emissions in the 1990 CAA
Amendments. Congress initially listed 189 HAPs in section 112(b), one of which has since been
delisted by EPA (EPA 1996a). As part of the first phase of the new air toxics program, EPA
must promulgate national, technology-based emission standards for sources in 174 source
categories emitting any of the 188 listed HAPs above specific emission thresholds. The overall
approach is to use available control technologies or work practice changes to get emission
reductions in a timely manner for as many of the listed HAPs as possible, regardless of a HAP's
inherent toxicity and potential risk. This technology-based standards program is commonly
referred to as the MACT program.3 Although there is no health test in this phase, it is intended
that effective MACT standards will reduce a majority of the HAP emissions and much of the
significant risk. It is expected that this program will reduce adverse environmental effects as
well.
The revised air toxics legislative strategy embodied in the 1990 CAA Amendments
maintains the goal of protecting the public health and preventing an adverse environmental effect
and provides a more complete approach for dealing with a variety of adverse effects. The
strategy recognizes that not all problems are national in scope or have a single solution. National
emission standards must be promulgated to decrease the emissions of as many HAPs as possible
from stationary major sources4'5 and some area sources,6 but authority is also provided to look at
multiple source exposures in the urban environment and the deposition of HAPs to certain water
bodies in order to address those specific concerns. In addition, there are mechanisms for
increasing partnerships among EPA, States, and local programs in order to address problems
specific to these regional and local environments.
3 MACT is defined as the emission standard specified in CAA section 112(d) as requiring the "maximum
degree of reduction in emissions of the hazardous air pollutants subject to this section . . . that the Administrator,
taking into consideration the cost of achieving such emission reduction,. . . determines is achievable." The MACT
for existing sources in a category or subcategory (with at least 30 sources) must not be less than the average
emission level achieved by the best performing 12 percent of existing sources.
4 A stationary source is defined in CAA section 112(a)(3) as any building, structure, facility, or installation
that emits or may emit any air pollutant.
5 A major source is defined in CAA section 112(a)(l) as a stationary source (or group of stationary sources
located within a contiguous area and under common control) that emits, or has the potential to emit, greater than 10
tons per year of any single HAP or 25 tons per year of any combination of HAPs (see footnote 4).
6 An area source is defined in CAA section 112(a)(2) as any stationary source of HAPs that is not a major
source (see footnote 5). In the context of CAA sections other than 112, this definition may differ.
* * *
March 1999 Page 9 * * *
-------
Residual Risk Report to Congress
The air toxics program developed by the Agency in response to this strategy is multi-
faceted. In addition to the implementation of technology-based national emission standards on
stationary sources of HAPs (see next section), the program contains several risk-based
components. The component that is the subject of this Report (and outlined in a subsection
below) involves the assessment of post-MACT residual risks under section 112(f) and the
promulgation of emission standards, if necessary "to protect public health, ... or to prevent,
taking into consideration costs, energy, safety, and other relevant factors, an adverse
environmental effect." Another component that emphasizes reduction of air toxics associated
public health risks is the integrated Urban Air Toxics Strategy. This strategy, currently in draft
form (EPA 1998a), emphasizes the need to address risks from the cumulative emissions of HAPs
from multiple sources and source types, particularly area and mobile sources. The urban strategy
seeks to combine the complementary authorities of sections 112(k) and 202(1), and other CAA
authorities including 112(f), with State and local authorities to provide a sound basis for the
protection of public health from risks posed by area, major, or mobile sources in individual urban
areas.
In summary, the 1990 CAA Amendments developed a comprehensive strategy that, when
taken as a whole, provides EPA with the flexibility to address a wide range of air toxics
problems. The provisions of this strategy describe the approaches for identifying the nature and
scope of the problem and provide a diversity of authorities for protecting public health and the
environment while managing the identified risk in a cost-effective way.
Emissions Control Under MACT - CAA Section 112(d)
The 1990 CAA Amendments greatly expanded the number of industries that will be
affected by national air toxics emission controls; the emission reductions from these controls are
just beginning to be realized. Major sources of HAPs, which include large industrial complexes
such as chemical plants, oil refineries, marine tank vessel loading operations, aerospace
manufacturers, steel mills, and a number of surface coating operations, are some of the sources
being controlled for toxic air pollution. Where warranted, smaller sources (area sources) of air
toxics such as dry cleaning operations, solvent cleaning activities, commercial sterilizers,
secondary lead smelters, and chromium electroplating facilities are also controlled. Within the
next six years, EPA estimates that emission standards set under section 112(d) will reduce
emissions of toxic air pollutants by well over 1.5 million tons per year.
Regulation of air toxics emissions through the section 112(d) process is beginning to
achieve substantial emission reductions of HAPs. The MACT regulations are also resulting in
substantial co-control of criteria air pollutants.7 Appendix C shows a complete list of the section
112 source categories, along with the status of the MACT standard and compliance dates. As of
October 1998, 53 source categories have been subjected to standards under section 112. With
7 Criteria air pollutants are defined as air pollutants for which national ambient air quality standards
(NAAQS) have been established under the CAA; at present, the six criteria air pollutants are paniculate matter,
ozone, carbon monoxide, nitrogen oxides (NO,,), sulfur dioxide, and lead.
* * *
March 1999 Page 10 * * *
-------
Residual Risk Report to Congress
some exceptions, sources must comply with the MACT regulations within three years of the
effective date of the regulation. Exhibit 1 shows that the estimate of cumulative reductions
expected to be achieved by 2002 with the standards for these 53 source categories is
approximately 1,100,000 tons of HAPs per year.8 Additionally, these regulations will result in
estimated emission reductions of approximately 2,500,000 tons per year of particulate matter (a
criteria pollutant) and volatile organic compounds (VOCs), a class of ozone precursor.
EXHIBIT 1
PROJECTED ANNUAL CUMULATIVE HAP EMISSION REDUCTIONS
^ ^ 1200000 -
K 1, 1000000 n
1 1 800000 -
'i J 600000 -
W 12
j> ^ 400000 -
"I 1 200000 -
o w 0 J
1 1
1 1
1 1
1994 1995 1996 1997 1998 1999 2000 2001 2002
Year
Special Areas of Evaluation
As part of the second phase of the program outlined in the 1990 CAA Amendments, EPA
is to conduct specific studies to assess the potential for adverse effects and, if necessary, take
action to reduce the potential for these effects. These studies include (but are not limited to) the
Mercury Study Report to Congress (EPA 1997a), the Great Waters Studies (EPA 1994a, EPA
1997b), and the Utilities Study (EPA 1998b).
In response to CAA section 112(n)(l)(B), the Mercury Study provides an assessment of
the magnitude of U.S. mercury emissions by source, the health and environmental implications of
these emissions, and the availability and cost of control technologies. Given the continuously
and rapidly evolving state-of-the-science for mercury, this Study is considered a "snapshot" of
EPA's understanding at the time and identifies research needed to reduce the scientific
uncertainty in a number of important areas.
In the Great Waters component of the air toxics program (CAA section 112(m)), the
Agency provides Reports to Congress, at biennial intervals, on the atmospheric deposition of
8 Based on emission reductions as reported in promulgated NESHAPs; see Appendix C: Schedule for
Source Category MACT Standards for Federal Register citations.
* * *
March 1999 Page 11 * * *
-------
Residual Risk Report to Congress
pollutants to the Great Lakes, Chesapeake Bay, Lake Champlain, and certain coastal waters (the
"Great Waters"). In cooperation with the National Oceanic and Atmospheric Administration,
EPA conducts a program to evaluate the extent of atmospheric deposition of HAPs (and a few
other air pollutants) to these waters, investigate sources and deposition rates, and evaluate any
adverse effects to public health or the environment caused by such deposition. Research and
monitoring are a large part of this program, and the results are summarized in the biennial
Reports. In addition, the Reports describe any changes to federal law that have been identified as
necessary to protect human health and the environment.
In CAA section 112(n)(l)(A), the Agency was directed to perform a study of "hazards to
public health reasonably anticipated to occur as a result of emissions by electric utility steam
generating units" of HAPs after imposition of CAA-required controls. In the Utilities Study,
HAP emissions test data from a range of utility units (i.e., boilers) along with facility-specific
information was used to estimate HAP emissions for all 684 utility plants in the U.S. The risks
of priority HAPs and potential control strategies were analyzed and reported. On the basis of this
Study and other information, EPA will determine the need to regulate HAP emissions from the
electric utility industry under section 112.
Urban Air Toxics Strategy
In recognition that emissions of HAPs from area sources (sources emitting lesser amounts
of HAPs than major sources) may "individually, or in the aggregate, present significant risks to
public health in urban areas," section 112(k) directs EPA to develop a strategy aimed at reducing
such emissions and associated public health risks. The strategy, published in draft form in
September 1998 (EPA 1998a), will build on the substantial emission reductions EPA, State, and
local governments have already achieved. EPA's MACT-required emission reductions are
described in a previous subsection. The Agency also has substantially reduced air toxics
emissions through mandated controls on municipal waste combustors, as well as fuel and
emission standards for cars and trucks.
The CAA, under section 112(k), requires EPA to develop a strategy for reducing urban air
toxics with a focus on stationary sources, including a specific emphasis on area sources.
Additionally, under CAA section 202(1), EPA is directed to study the need for and feasibility of
controlling emissions of toxics from motor vehicles, focusing on emissions that pose the greatest
risk to human health, and, based on this study, to promulgate fuel or vehicle standards.
Recognizing the overlapping problems these programs are intended to address, the Agency is
evaluting an integrated approach.
Consistent with the requirements of section 112(k), the final strategy will identify a list of
at least 30 HAPs that EPA believes pose the greatest threat to public health in urban areas. It will
also identify area source categories that are or will be listed under section 112(c) and potentially
subject to regulation under section 112(d). Additionally, the strategy will contain a schedule of
specific actions to reduce public health risks posed by hazardous air pollutants. These activities
will rely on the appropriate regulatory tools implemented by EPA under the CAA or other
* * *
March 1999 Page 12 * * *
-------
Residual Risk Report to Congress
federal environmental statutes or by the States. Following consideration of public comment on
the draft, the final Urban Air Toxics Strategy is scheduled to be published in June 1999.
Residual Risk
To ensure protection of public health and the environment, the 1990 CAA Amendments
include section 112(f), which requires a human health risk- and adverse environmental effects-
based "needs test" in the second regulatory phase of the air toxics program (see Appendix A for
full text of section 112(f)). In this phase, referred to as residual risk standard setting, EPA will
consider the need for additional national standards on stationary emission sources following
regulation under section 112(d) to protect public health and the environment. Congress directed
that such residual risk standards should "provide an ample margin of safety to protect public
health."
Section 112(f) also requires EPA to determine whether residual risk standards are
necessary to prevent adverse environmental effects, taking into consideration "costs, energy,
safety, and other relevant factors" in deciding what level is protective. Adverse environmental
effect is defined in section 112(a)(7) as "any significant and widespread adverse effect, which
may reasonably be anticipated, to wildlife, aquatic life, or other natural resources, including
adverse impacts on populations of endangered or threatened species or significant degradation of
environmental quality over broad areas."
In summary, Congress developed a comprehensive strategy that, when taken as a whole,
provides EPA with the flexibility to address a wide range of air toxics problems. The provisions
of this strategy describe the approaches for identifying the nature and scope of the problem and
the mechanisms for involving all concerned parties in discussions. Congress' strategy provides a
diversity of authorities for managing the identified risk in a cost-effective way while protecting
human and environmental health in the process.
2.3 State and L ocal Air Toxics Programs
An additional component of risk assessment development has been the emergence of
State and local air toxics programs and the interactions that EPA has had with these programs.
Prior to passage of the 1990 CAA Amendments, the federal air toxics program progressed
slowly. In the absence of a strong federal program, many State and some local agencies began to
respond to the air toxics problem by developing their own programs. As a result, many States in
the country currently have air toxics control programs in place addressing, at a minimum, new
sources of toxic pollutants. Some have their own regulations that allow them to actively control
air toxic emissions to a level protective of human health; others rely on comprehensive policies
or authority provided to implement the federal program. Some programs are risk-based, while
others are technology-based (STAPPA/ALAPCO 1989). State programs may also achieve HAP
reductions through regulations developed under CAA section 110 or part D of Title I that control
emissions of air pollutants to meet national ambient air quality standards (NAAQS). Various
State and local government programs have now been in place for many years and, for some of
* * *
March 1999 Page 13 * * *
-------
Residual Risk Report to Congress
the source categories regulated by federal emissions standards under section 112 of the Act, the
State or local government programs have likely reduced air toxics emissions and may have
succeeded in reducing such emissions to levels at or below those required by the federal MACT
standards promulgated under section 112(d).
The State and local programs have focused on three methods for addressing air toxic
emissions: (1) ambient air levels; (2) control technology standards; and (3) risk assessment.
Over time, many have begun to use combination approaches, such as residual risk assessment,
which combines control technology and risk assessment. The main difference between the
State/local residual risk assessment approach and the strategy set forth in sections 112(d) and
112(f) of the CAA is one of timing. While the CAA envisions control of HAPs from major
sources as a two-step process (MACT followed by residual risk), with the two steps separated in
time by as much as nine years, many State and local agencies consider these simultaneously.
Both steps are generally completed within the context of a single permit application.
The State and local air toxics programs were invaluable prior to the CAA, and they
remain invaluable. The EPA has drawn upon the expertise and experience of State and local
agencies to assist in the development of the federal risk program for HAPs. Over the years, more
and more State and local air toxics programs have begun to use risk assessment, especially
residual risk assessment. In a survey of State and local agencies, conducted in August of 1995,
60 percent of the respondents indicated that their air toxics program was risk-based, and 50
percent of those had residual risk programs addressing both new and existing sources.
Most State and local agencies that are currently using residual risk assessments plan to
continue to use them for permitting purposes, so these may be available to EPA as residual risk
assessments are prepared on a national basis. The EPA will identify the programs that are
currently producing residual risk assessments, the situations in which they are produced, and the
type of information contained in the permit applications or accompanying documents in order to
add this information to the national residual risk assessment program.
The State and local programs have made progress in addressing the air toxics problem
and protecting the health of their people and their environment. A successful residual risk
program will be one that integrates the federal program with the State and local programs and
strengthens or complements those existing programs. The federal program will need to integrate
these existing programs through the interactive sharing of expertise, data, analyses, and
methodologies in order to ensure that human health and the environment are protected.
Additionally, the State and local authorities may complement the federal program by addressing
local risk issues that may not be effectively addressed nationally.
* * *
March 1999 Page 14 * * *
-------
Residual Risk Report to Congress
3. Section 112 (f)(1 )(A): Methods for Assessing Risks EPA's
General Risk Assessment Approach for Air Toxics
The information presented thus far provides a summary of the legislative and
programmatic basis for EPA's air toxics risk assessment process as it exists today. The EPA has
refined the process over time using guidance from the reports discussed in Section 3.1,
information from and discussions with State, local, and regional air toxics risk assessors, and
information and experience gathered from the practical application of risk assessments
throughout the Agency. In this chapter, we describe the risk assessment process for air toxics
that has developed at EPA. EPA's air toxics program, including residual risk, necessarily will be
based on these risk assessment methods, and others that will be developed. The application of
these methods to the residual risk assessment process is discussed in Chapter 5. Section 3.1
summarizes the development of human health and ecological risk assessment methods in the
federal government and at EPA, Section 3.2 discusses the basic frameworks for risk assessment,
Section 3.3 describes how we estimate and characterize exposure, Section 3.4 describes the
assessment of human health and environmental effects, and Section 3.5 describes risk
characterization.
3.1 Background Development of Human Health and Ecological Risk
Assessment Methods
This section describes some of the history and key events in the development of EPA's
air toxics risk assessment methodology, and the general residual risk assessment framework
described in this Report. Identifying the nature and scope of the various air toxics problems
through data collection, analysis, and mandated studies is an essential step in implementing the
post-1990 air toxics strategy. Risk assessment is the primary method to be used in determining
the magnitude of potential impacts resulting from continued HAP exposures. In the CAA,
Congress included mechanisms that would assist in the development of the residual risk
assessment process, including the reports discussed in the next two sections. In developing the
air toxics risk assessment methodology, EPA has built on its existing (and continuously
evolving) risk assessment policies and guidance, and also has taken into account State and local
air toxics risk programs.
3.1.1 National Academy of Sciences Reports of 1983 and 1994
The National Academy of Sciences (NAS) has on several occasions been requested by
Congress to evaluate and discuss the processes of risk assessment and risk management. Two of
their studies, published in 1983 and 1994, are especially relevant as a foundation for this Report.
The emerging practice of risk assessment at EPA and other federal agencies spurred Congress to
commission a report from the National Research Council (NRC) of the NAS in the early 1980s.
The result was the landmark 1983 study entitled Risk Assessment in the Federal Government:
Managing the Process (NRC 1983). This report was written at a time when there was an
* * * March 1999 Page 15 * * *
-------
Residual Risk Report to Congress
increasing concern about the risk of cancer
resulting from exposure to chemicals in the
environment - the fear was that policy might
not keep up with the state-of-the-science, which
was changing very rapidly in this area.
PURPOSE OF THE 1983 NRC REPORT
The 1983 NRC report was intended to:
+ "Explore the intricate relations between
science and policy" in the field of risk
assessment; and
"Search for the institutional mechanism that
best fosters a constructive partnership
between science and government."
The 1983 NRC report recognized the
importance of the relationships that exist
between science and risk assessment, and
between risk assessment and risk management,
and undertook the task of clearly defining these
relationships. The NRC acknowledged that
risk assessment must take full advantage of the available science while maintaining the need to
accommodate the various regulatory requirements, and that risk assessment was only one
component of the risk management decision process. To define this more clearly, the NRC made
a series of recommendations. In general, the NRC recommended the development of specific
guidelines for performing risk assessments (at that time, cancer was the main endpoint of
concern), that risk assessments developed using the guidelines be reviewed and distributed to the
public, and that these risk assessments clearly distinguish the science and policy components
from the political, economic, and technical considerations that influence the risk management
decisions. This report also provided a
description of the health risk assessment
paradigm that continues to serve as EPA's
model. Partly in response to this report, EPA
began a process that continues today of
publishing Agency-wide guidelines
addressing important areas of risk assessment
(see Sections 3.1.3 and 3.1.4).
STEPS INTEGRAL TO RISK ASSESSMENT
The NRC risk assessment paradigm includes four steps that
are integral to any risk assessment (NRC 1983, NRC 1994):
> Hazard identification
> Dose-response assessment
> Exposure assessment
> Risk characterization
The NRC's follow-up report, Science
and Judgment in Risk Assessment (NRC
1994), mandated by Congress under section 112(o) of the CAA, took a closer look at current risk
assessment methods, with a statutorily directed focus on carcinogenic risk. The intent (and
mandate) of the report was not to look at EPA's regulatory decisions but the methods used to
support those decisions. The NRC committee observed that several themes were common to all
elements of the risk assessment process and noted that these themes were usually the focal points
for criticisms of specific risk assessments. The themes discussed included the use of default
assumptions; the available data; uncertainty and variability; assessment of multiple chemical
exposures, multiple routes of exposure, and the potential for multiple adverse effects; and steps
taken to validate the methodologies used throughout the risk assessment process. NRC's
concerns, discussions, and recommendations were viewed as a way to increase the effectiveness
and accuracy of the risk process defined in their 1983 report.
* * *
March 1999 Page 16
* * *
-------
Residual Risk Report to Congress
Exhibit 2 shows the risk assessment/risk management paradigm as presented in the 1994 NRC
report.
EXHIBIT 2
NRC RISK ASSESSMENT/RISK MANAGEMENT PARADIGM
RESEARCH
Laboratory and field
observations
Information on
extrapolation methods
RISK ASSESSMENT
Toxicity assessment:
hazard identification
and dose-response
assessment
Research needs identified
from risk assessment process
Field measurements,
characterization of
populations
Exposure assessment
Emissions
characterization
RISK MANAGEMENT
Development of
regulatory options
Evaluation of public
health, economic,
social, political
consequences of
regulatory options
Agency decisions
and actions
Source: NRC 1994
The NRC discussed the use of default options in risk assessment, which it defines to be
"essentially policy judgments of how to accommodate uncertainties. They include various
assumptions that are needed for assessing exposure and risk, such as scaling factors to be used
for converting test responses in rodents to estimated responses in humans." Another example of
a default option in EPA's cancer risk assessment guidelines is the assumption that cancer risk
declines linearly with exposure below the range for which data are available, such that any level
of exposure poses some risk. Under current and proposed revisions to these guidelines this
assumption is recommended when data are unavailable to support an alternate theory. The NRC
concluded that "because of limitations on time, resources, scientific knowledge, and available
data, EPA should generally retain its conservative, default-based approach to risk assessment for
screening analysis in standard-setting; however, several corrective actions are needed to make the
approach more effective." The NRC went on to say:
* * *
March 1999 Page 17
* * *
-------
Residual Risk Report to Congress
EPA should continue to regard the use of default options as a reasonable way to deal with
uncertainty about underlying mechanisms in selecting methods and models for use in risk
assessment;
EPA should explicitly identify each use of a default option in risk assessment;
EPA should clearly state the scientific and policy basis for each default option; and
The Agency should attempt to give greater formality to its criteria for a departure from
default options, in order to give greater guidance to the public and to lessen the possibility
of ad hoc, undocumented departures from default options that would undercut the
scientific credibility of the Agency's risk assessment process. At the same time, the
Agency should be aware of the undesirability of having its guidelines evolve into
inflexible rules.
The committee recommended that EPA develop and use an iterative approach to health risk
assessments to delist source categories and eliminate residual risk. The NRC also proposed a
possible iterative approach that will allow for improvements in the default-based approach by
improving both models and the data used in each successive iteration of analysis. Furthermore,
the committee suggested that EPA present not only point estimates of risk, but also the sources
and magnitudes of uncertainty associated with these estimates.
The NRC also discussed how the risk assessment recommendations in its report could be
implemented in the context of section 112. Section 112 calls for EPA to regulate HAPs in two
stages. In the first, sources would be required to do what is feasible to reduce emissions based on
currently available technology. In the second, EPA would set residual risk standards to protect
public health with an ample margin of safety if the Agency concluded that implementation of the
first stage of standards did not provide such a margin of safety.
The committee indicated that neither the resources nor the scientific data exist to perform
a full-scale risk assessment on all the chemicals listed as HAPs and their sources. Therefore, the
committee supported an iterative approach to risk assessment of HAPs. This approach would
start with relatively inexpensive screening techniques and move to a more resource-intensive
level of data-gathering, model construction, and model application as the particular situation
warranted. The result would be a process that supports the risk management decisions required
by the CAA and that provides incentives for further research, without the need for costly case-by-
case evaluations of individual chemicals at every facility in every source category. It also
recommended a priority-setting scheme based on initial assessments of each chemical's possible
impact on human health and welfare. EPA has been moving, and continues to move, in the
directions recommended by this report as it transitions into the risk-based phase of the CAA
legislative strategy for HAPs.
3.1.2 CRARM
Section 303 of the 1990 CAA Amendments mandated formation of the CRARM in
response to unresolved questions about the approach EPA should take to assessing risks to public
* * * March 1999 Page 18 * * *
-------
Residual Risk Report to Congress
health remaining after implementation of the CAA Amendments' technology-based emission
controls. On June 13, 1996, the CRARM released a draft of its report, Risk Assessment and Risk
Management in Regulatory Decision-Making (CRARM 1996). At the completion of the public
comment period, the CRARM announced that it planned to release its final report in two parts.
Volume I, released in January 1997, focuses on the framework for environmental health risk
management (CRARM 1997a). Volume JJ, released in March 1997, addresses a variety of
technical issues related to risk assessment and risk management, including margin of exposure
(MOE), management of residual risks from air toxics, comparative risk, decision criteria,
uncertainty analysis, and recommendations to specific agencies (CRARM 1997b).
The CRARM's framework fosters an integrated approach to addressing complex, real-
world issues that affect more than one environmental medium and involve exposures to mixtures
of chemicals. The CRARM anticipates that its framework will assist Congressional committees
and subcommittees, and government agencies (e.g., EPA, DOE), in developing integrated
approaches to environmental risk management.
The Commission's Mandate
The Commission's mandate was to investigate "the policy implications and appropriate
uses of risk assessment and risk management in regulatory programs under various federal laws
to prevent cancer and other chronic health effects which may result from exposure to hazardous
substances" (CRARM 1996, 1997a, and 1997b). The CRARM's final report indicated that the
Commission's mandate included:
Assessing uses and limitations of risk assessment and economic analysis in regulatory
decision-making (e.g., setting emission, ambient, and exposure standards for hazardous
substances);
Considering the most appropriate methods for measuring and describing cancer risks and
non-cancer chronic health risks from exposures to hazardous substances;
Evaluating exposure scenarios for risk characterization (e.g., use of site-specific exposure
data in setting emissions standards);
Determining how to describe and explain uncertainties (e.g., associated with
measurement, extrapolation from animal data to humans);
Discussing approaches to determining the existence of synergistic or antagonistic effects
of hazardous substances;
Enhancing strategies for risk-based management decisions;
Considering the desirability of developing a consistent standard of acceptable risk across
various federal programs;
Suggesting ways to improve risk management and risk communication;
Commenting on the conclusions in the NRC report Science and Judgment in Risk
Assessment; and
Making recommendations about peer review.
* * * March 1999 Page 19 * * *
-------
Residual Risk Report to Congress
Although the Commission's mandate was limited to "cancer and other chronic human health
effects," the group did discuss ecological risk assessment for the following reasons:
Human health is related to the health of the environment;
Principles of health risk assessment are relevant to ecological risk assessment; and
Economic analyses should not be limited to human health benefits.
The Commission's Report
The final report of the Commission addresses a number of topics, several of which are
highlighted below to provide additional context for the residual risk information in this report.
EXHIBIT 3
CRARM'S FRAMEWORK FOR
RISK MANAGEMENT
Risk Management Framework. The
Commission's framework for environmental
health risk management is presented
graphically in Exhibit 3. The emphasis on
stakeholders in this framework is consistent
with risk assessment paradigms presented in
other recent studies (e.g., NRC 1996). The
framework calls for some level of stakeholder
involvement during each of the six stages of
risk management. In fact, stakeholder
collaboration is the central element in the
framework. In addition, the framework is
designed to be iterative. If appropriate, the
risk problem can be redefined and reassessed
as new data and new views are found.
Another key principle of the
framework is that risk management should
explicitly consider the comprehensive real-
world context of a risk problem, rather than
limit the problem's context to one that
considers only one type of risk associated with
a single chemical in a single environmental
medium. The Commission identified several risk management contexts:
Multisource context (e.g., the population may be exposed to the same pollutant from
sources other than the one in question);
Multimedia context (e.g., exposure to the pollutant may be occurring from other
environmental media);
Multichemical context (e.g., other pollutants from the same source may pose additional
risks); and
Evaluation xi^^Mx Risks
Engage\
Stakehold
Source: CRARM1997a
* * *
March 1999 Page 20
* * *
-------
Residual Risk Report to Congress
Multirisk context (e.g., the magnitude of risk from one problem may be insignificant
compared to similar risks that a population faces from other stressors).
According to the Commission's framework, the relevant contexts for a risk problem are
first identified and characterized in the problem/context phase of risk management. These risk
contexts are then refined in the risk analysis phase and are addressed in all of the remaining
phases of the risk management process.
Comparative Risk Assessment. The CRARM report recommends that federal agencies
try a comparative risk analysis approach on an experimental or demonstration basis to seek
consensus on priorities for managing environmental risks. The results of such efforts should
influence agency resource allocation. The Commission noted that there is wide disagreement on
the efficacy of this approach for setting priorities, and that experience shows there is no
guarantee that this process will result in consensus among stakeholders, agencies, and funding
authorities. However, the Commission also noted that experience shows that the process itself
can help to build coalitions that favor priority shifting and shifting resources to identified
priorities.
Harmonization of Cancer and Non-cancer Methodologies. The Commission
recommended that the assessment techniques for carcinogens and non-carcinogens be
harmonized, and discussed the margin-of-exposure and margin-of-protection approaches as ways
to do this that would aid in risk communication, risk management decisions and comparative risk
assessment. The margin-of-exposure approach for expressing risks for carcinogens was
recommended as a method which may be more useful for risk managers and stakeholders than
the expression of cancer risk in terms of predicted incidence or numbers of deaths per unit
population, which can imply an "unwarranted" degree of precision. In EPA's 1996 proposed
revisions to the cancer risk assessment guidelines (EPA 1996b), the MOE is defined as the ratio
of a specified dose derived from a tumor bioassay, epidemiologic study, or biologic marker
study, such as the dose associated with a 10 percent response rate, to an actual or projected
human exposure. Lower margins of exposure indicate greater concern. This approach is
comparable to the margin-of-protection methodology that EPA has used in its "hazard quotient"
(HQ) approach for non-cancer risk assessment, which compares an estimated exposure to the
estimated acceptable daily intake (ADI), reference dose (RfD), or reference concentration (RfC)
value.
Realistic Exposure Scenarios. The report states that risk management decisions should
be based on realistic exposure scenarios, rather than on the hypothetical maximum exposed
individual (MEI), and supports agencies' recent progress toward this end. It recommends that
distributions of population's varied exposures be evaluated with explicit attention to segments of
the population with unusually high exposures. The Commission believes that, where possible,
exposure assessments should include information about specific groups: infants, children,
pregnant women, low-income groups, and minority group communities with exposures
influenced by social or cultural practices.
* * * March 1999 Page 21 * * *
-------
Residual Risk Report to Congress
Cost-benefit Analysis. The Commission supports the use of economic analysis as a
consideration in risk management decisions, but not as the overriding factor in a decision. The
report calls for explicit descriptions of assumptions, data sources, sources of uncertainty, and
costs across society to be presented in parallel with descriptions associated with risk assessments.
Interagency Consistency. In conducting risk assessments, agencies should coordinate
their risk assessment methods and assumptions unless there is a specific statutory requirement for
different choices. Scientific disagreements should be explained.
Residual Risk Recommendations of the Commission
The Commission recommended a tiered approach, which is summarized in Exhibit 4, to
manage residual risks of section 112 CAA HAPs after implementation of the CAA's technology-
based (MACT) standards. Specifically, CRARM proposed that EPA develop their approach in
accordance with the five recommendations:
(1) Characterize and articulate the scope of the national, regional, and local air toxics
problems and their public health and environmental contexts;
(2) Use available data and default assumptions to perform screening-level risk assessments to
identify sources with the highest apparent risks;
(3) Conduct more detailed assessments of sources and facilities with the highest risks,
providing guidance and incentives to regulated parties to either conduct these risk
assessments or reduce emissions to below screening thresholds;
(4) At facilities that have incremental lifetime upper-bound cancer risks greater than one in
100,000 persons exposed or that have exposure concentrations greater than reference
standards, examine and choose risk reduction options in light of total facility risks and
public health context; and
(5) Consider reduction of residual risks from source categories of lesser priority.
A specific comparison of EPA's residual risk framework with the Commission's
recommendations is presented in Section 5.3.7.
3.1.3 Development of Human Health Risk Assessment at EPA
While the first NRC document on risk assessment in the federal government was
published in 1983, EPA has used risk assessment techniques since its inception in 1970. Some
quantitative analysis of cancer and other risk was performed prior to 1970 by the Food and Drug
Administration and the Federal Radiation Council. The EPA built on this knowledge soon after
its inception by confronting potential hazards associated with pesticide use. After considering
available human and non-human toxicity data, EPA restricted domestic use of DDT and other
pesticides, in part due to their cancer risks. It was acknowledged by EPA that regulations such as
these needed appropriate scientific basis, and thus information on the cancer risks associated with
these pesticides was collected through administrative hearings and testimony. Summary
* * * March 1999 Page 22 * * *
-------
Residual Risk Report to Congress
EXHIBIT 4
CRARM's RESIDUAL RISK RECOMMENDATIONS FOR AIR TOXICS
\Articulate Air Toxics Problem in Context:
Identify Source Categories Likely to Pose
Highest Risks
c
I
Screening Risk
Assessment
Cancer Risk < 10"6and
Hazard Index < 1
= Low Priority
Cancer Risk
Hazard Index 1 to 10
= Medium Priority
J
Cancer Risk >
Hazard Index > 10
= High Priority
No Further Action
Distribute Screening
Assessment Results
Voluntarily Reduce Emissions to
Achieve Lower Risk Category
r
Voluntarily Reduce
Emissions to Achieve
Lower Risk Category
Detailed Risk Assessment
I Within Source Category
Facilities With Cancer Risk < 1(T5
and Hazard Index < 1
Facilities With Cancer Risk > 10'5
or Hazard Index > 1
Distribute Risk
Assessment Results
CLxamine Options/Choose
Actions to Reduce Risk
Source: CRARM1997b
documents from these hearings were collectively referred to as the "Cancer Principles."
Criticisms of these documents, which were inadvertently perceived as a formal Agency cancer
risk assessment policy, led to the development of interim guidelines published by EPA in 1976.
Three years later, the Interagency Regulatory Liaison Group (a conglomeration of several federal
agencies, including EPA) published additional cancer risk assessment guidelines. At about the
same time, cancer risk assessment techniques were used by EPA in the regulation of toxic
chemicals under the 1976 Toxic Substances Control Act, and by the end of EPA's first decade,
* * *
March 1999 Page 23
* * *
-------
Residual Risk Report to Congress
risk assessment techniques were being used to develop water quality criteria for protection of
human health. Throughout the 1980s, the use of risk assessment in EPA grew significantly and
increasingly covered non-cancer risks in addition to cancer risks. During the 1980s, cancer risk
assessment techniques were used in the development of national emission standards for air toxics
such as vinyl chloride and benzene.
EPA HUMAN HEALTH RISK ASSESSMENT
GUIDELINES
EPA has published final risk assessment guidelines
that address the following areas:
Mutagenicity (EPA 1986a)
Carcinogenicity (EPA 1986b)
Chemical mixtures (EPA 1986c)
Developmental toxicity (EPA 1991)
Exposure assessment (EPA 1992a)
Risk characterization (EPA 1995a)
Reproductive toxicity (EPA 1996c)
Probabilistic analysis (EPA 1997c)
Neurotoxicity (EPA 1998c)
Draft revisions have been issued for carcinogenicity
(EPA 1996b) and are under development for mixtures
(EPA 1997d).
As the use of risk assessment increased
in the 1980s, there was a growing awareness of
both the lack of standard guidance for and the
inconsistencies in the use of risk assessment at
EPA. To address this need, the Agency
undertook some administrative reforms and
published several key guidelines and other policy
documents, particularly during the second half of
the decade. In response to the 1983 NRC report
discussed in Section 3.1.1, the Agency published
Risk Assessment and Management: Framework
for Decision Making (EP A 1984), designed to
address NRC recommendations and help EPA
make better and more rapid decisions about
environmental toxic chemical problems.
Beginning in 1986, EPA has published an
influential series of Agency-wide guidelines in
the Federal Register identifying the recommended methods for assessing human health risks
from environmental pollution. These guidelines (see text box), which cover both cancer and
non-cancer risks, are not meant to be static but may be revised as new information and methods
become available. EPA's use and development of human health risk assessment has continued to
grow through the 1980s and 1990s with establishment of the Integrated Risk Information System
(IRIS) toxicity data base, the repository of Agency consensus non-cancer RfDs and RfCs and
cancer assessments.
Since 1996, EPA has published draft revisions to its carcinogenicity guidelines (EPA
1996b) and is developing revisions to its mixtures guidelines (EPA 1997d). Revisions made to
these guidance documents as a result of increased knowledge are designed to accommodate and
reflect recent changes in the state-of-the-science for risk assessment. Some revised guidelines
explicitly accommodate the replacement of default assumptions when supported by scientifically
sound information (e.g., the 1996 proposed revisions to the cancer risk assessment guidelines).
Human health risk assessment techniques embodied in these Agency-wide guidance documents
are the foundation of the estimation of residual risks from air toxics under the CAA.
* * *
March 1999 Page 24
* * *
-------
Residual Risk Report to Congress
3.1.4 Development of Ecological Risk Assessment at EPA
The development of ecological risk assessment at EPA began in the 1970s primarily in
two program areas, water quality and pesticide registration. The 1972 Clean Water Act (CWA)
set objectives for eliminating surface water pollution based on receiving water uses of "fishable,
swimmable waters." The 1972 amendments to the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA) required that pesticides be evaluated for "any unreasonable adverse
effects on the environment." Subsequent legislation for environmental protection resulted in the
development of other lines of ecological assessment practices in the late 1970s and in the 1980s,
each tailored to the mandates of particular statutes (e.g., the Toxic Substances Control Act).
To meet its statutory mandates and promote consistency among assessments within
program areas, EPA began developing program-specific guidelines for ecological assessments in
the 1980s. Some of EPA's earliest ecological risk assessments were performed to meet the
Agency's CWA mandate. NAS initiated the effort by publishing Water Quality Criteria 1972
(the "Blue Book") (NAS 1973). In 1976, EPA published Quality Criteria for Water (the "Red
Book") (EPA 1976). Then, in 1980, EPA published 64 individual ambient water quality criteria
(AWQC) documents for pollutants listed as toxic in CWA section 307(a)(l) (EPA 1980). The
process for deriving AWQC was formalized in 1986 when EPA published standardized
guidelines on this subject (EPA 1986d). The guidelines specified that the criteria provide a
"reasonable amount of protection of most species in an balanced healthy aquatic community"
(EPA 1986d). For pesticide registration evaluations, EPA developed a framework for evaluating
the effects of pesticides on nontarget organisms such as wildlife or aquatic communities and
published these standard evaluation procedures in 1986 (EPA 1986e). Efforts to develop and
document ecological assessment practices in other EPA program offices followed in the late
1980s (e.g., the Risk Assessment Guidance for Superfund, Volume II: Environmental Evaluation
Mara/a/(EPA 1989b)).
By the mid and late 1980s, EPA recognized a need for consistency in evaluating
ecological risks across program offices and a need to make its ecological research efforts more
responsive to ecological risk assessment needs Agency-wide. In response, the Office of Research
and Development (ORD) began an evaluation of program-specific ecological risk assessment
practices and initiated development of guidelines to establish a consistent and scientific basis for
assessing ecological risks associated with toxic substances, for use Agency-wide. EPA's Risk
Assessment Forum assumed responsibility for the Guidelines in 1990 and initiated three
ecological risk guidance projects: (1) a "framework" to describe the basic principles for
ecological risk assessment; (2) a set of case studies to illustrate the "state-of-the-practice" in
ecological assessments; and (3) a long-range plan for developing specific ecological risk
guidelines.
To accommodate the diverse kinds of ecological risk assessments conducted across
program offices at EPA, the Agency found it necessary to modify the 1983 NRC paradigm for
risk assessment. Most notably, EPA added a problem formulation phase to the beginning of the
* * * March 1999 Page 25 * * *
-------
Residual Risk Report to Congress
ecological risk assessment process. In problem formulation, the scope, context, and ecological
values of concern are identified. In 1992, EPA published its Framework for Ecological Risk
Assessment (EPA 1992b). As the foreword of that document states, "use of the framework ... is
not a requirement within EPA, nor is it a regulation of any kind. Rather, it is an interim product
that is expected to evolve with use and discussion." As an interim method of providing more
detailed guidance for its different program offices, EPA published two volumes of A Review of
Ecological Assessment Case Studies from a Risk Assessment Perspective (EPA 1993 a; EPA
1994b). The case studies are wide-ranging in scope, representing a variety of ecosystems,
ecological endpoints, chemical and non-chemical stressors, and programmatic requirements
within EPA, and illustrate how the Framework could be applied in each case.
As mentioned in Section 3.1.2, the CRARM discussed ecological risk assessment issues
specific to air toxics risks and considered EPA's 1990 Framework document in their 1997 report
(CRARM 1997a,b). CRARM recommended that EPA guidance include explicit involvement of
stakeholders, particularly in the problem formulation stage, as well as a description of how
ecological risk assessment measures and models should be selected.
In April 1998, EPA published its Guidelines for Ecological Risk Assessment (EPA
1998d), as a counterpart to the existing EPA health risk guidelines. The Guidelines, which
expand upon and replace the widely used Framework for Ecological Risk Assessment (EPA
1992b), were developed to improve the quality of and consistency among EPA's ecological risk
assessments. The guidelines are intentionally broad in scope in order to cover the full range of
ecological risk assessment problems and do not provide detailed guidance. In the future, EPA
plans to prepare more detailed guidance on specific areas of ecological risk assessment. The
content and focus of the guidelines include the following.
Ecological risk assessment is defined as a process for organizing and analyzing data,
information, assumptions, and uncertainties to evaluate the likelihood of adverse
ecological effects.
Ecological risk assessments consist of three primary phases.
Problem formulation includes identifying goals and assessment endpoints,
preparing a conceptual model, and developing an analysis plan. It is a formal
process for generating and evaluating preliminary hypotheses about why
ecological effects have occurred, or may occur, from human activities (EPA
1998d). It provides a foundation upon which the entire ecological risk assessment
depends. However, because problem formulation is inherently interactive and
iterative, rather than linear, substantial re-evaluation is expected to occur within
and among all products of problem formulation.
Analysis is the technical stage in which exposure and effects are characterized.
Analysis of exposure includes the collection of data on source emissions and their
* * * March 1999 Page 26***
-------
Residual Risk Report to Congress
fate and transport that results in exposure to human or environmental receptors.
Effects characterization includes the evaluation of toxicity of these emissions and
takes into account any criteria that have been established for these substances.
Risk characterization is the phase in which risks are estimated by integrating the
estimates of exposure and effects developed in the analysis phase (e.g., stressor-
response profiles) and, of equal importance, are presented in the manner most
informative to risk managers. This includes a discussion of the assessment's
strengths, limitations, assumptions, and major uncertainties.
The interaction between risk assessors
and risk managers is highlighted. The
guidelines emphasize the
complementary roles of assessors and
managers in determining the scope and
boundaries of the assessment and
selecting endpoints that will be the
focus of the assessment. When the risk
characterization is complete, the risk
assessor must communicate the risks
"in a manner that is clear, transparent,
reasonable, and consistent" with
Agency risk characterizations of similar
scope. The interaction between risk
assessors and risk managers is critical
to ensure that the results of the assessment
EPA ECOLOGICAL RISK ASSESSMENT
GUIDANCE DOCUMENTS
Since 1990, EPA has published several documents (listed
below) intended to improve the quality and consistency of
Agency ecological risk assessments.
> Frame-work for Ecological Risk Assessment (EPA
1992b)
> A Review of Ecological Assessment Case Studies
from a Risk Assessment Perspective (EPA 1993a;
EPA 1994b)
> Guidelines for Ecological Risk Assessment (EPA
1998d)
can be used to support a management decision.
The ecological risk assessment
framework presented in the Guidelines is
shown in Exhibit 5 and explained in more
detail in later sections. In refining
environmental risk assessment methods for the
air toxics program in general, and residual risk
analyses specifically, we will be referring to
the framework and general approaches
contained in the Guidelines, the companion
case study document, and future supplements.
The framework for ecological risk
assessment is conceptually similar to the
approach used for human health but is distinctive in its emphasis in three areas. First, ecological
risk assessment should consider effects beyond those on individuals of a single species,
examining effects at a population, community, or ecosystem level. Second, no single set of
EXAMPLES OF ASSESSMENT ENDPOINTS
Sustained aquatic community structure, including
species composition and relative abundance and
trophic structure.
Sufficient rates of survival, growth, and reproduction
to sustain populations of carnivores typical for the
+ Sustained fishery diversity and abundance.
Source: EPA 1997e
* * *
March 1999 Page 27
* * *
-------
Residual Risk Report to Congress
EXHIBITS
ECOLOGICAL RISK ASSESSMENT FRAMEWORK
3 Integrate Available Information
jrce and Ecosystem Ecological
tposure Potentially at Effects
acteristics Risk
PROBLEM
FORMULATION
Characterization of Exposure
Characterization of Ecological Effects
Measures of
Exposure
1
^ ^
i
\
Measures of
Ecosystem and
Receptor
Characteristics
^ ^
!
!
Measures of
Effect
k
r
Ecological Response
Analysis
Stressor-
Response
Profile
RISK
CHARACTERIZATION
Source: EPA 1998d
Communicating Results to
the Risk Manager
A
1
k
r
Risk Management
* * *
March 1999 Page 28
* * *
-------
Residual Risk Report to Congress
ecological values to be protected can generally be applied. Rather, these values are selected from
a number of possibilities based on both scientific and policy considerations. Given these
complexities in the ecological risk assessment process, and its more recent history in EPA
guidance, the reader is provided here with a description of some of the unique aspects of the
problem formulation stage. The problem formulation stage of ecological risk assessment
includes the determination of assessment endpoints, a conceptual model, and an analysis plan.
An assessment endpoint is an explicit expression of the "actual environmental value that
is to be protected" or is of concern (EPA 1992b), and includes the identification of the ecological
entity for the analysis (e.g., a species, ecological resource, habitat type, or community) and the
attribute of that entity that is important to protect and that is potentially at risk (e.g., reproductive
success, production per unit area, surface area coverage, or biodiversity) (EPA 1998d). A
manageable subset of the most important assessment endpoints is selected for the risk
assessment, and the measures by which these endpoints will be assessed are also identified.
Additional issues important to the identification of assessment endpoints, which will be
considered in ecological risk assessments for air toxics, are provided in the Guidelines for
Ecological Risk Assessment (EPA 1998d).
Appropriate selection of relevant assessment endpoints is critical in order that the risk
assessment provide valuable input to the associated risk management decisions. Assessment
endpoints that can be measured directly are most effective, although assessment endpoints that
cannot be measured directly, but can be represented by measures that are easily monitored or
modeled may also be used. Additional uncertainty is introduced depending on the relationship
between the measure and the assessment endpoint. Examples of assessment endpoints, measures
of effect, and other elements of the problem formulation phase are presented in the text box for
EPA's water quality criteria derivation process.
A second component of the problem formulation phase for ecological risk assessment is
the development of a conceptual model to describe potential interactions between pollutant
emission and the assessment endpoints. The model includes both the relevant risk hypotheses
and a diagram which links pollutant emissions, exposure pathways, ecological receptors, and
ecological effects. Risk hypotheses are statements that describe possible relationships between
emissions of a pollutant, exposure, and assessment endpoint response. They include the
information that sets the problem in perspective as well as an identification of the proposed
relationships that need evaluation (EPA 1998d). Consequently, conceptual models developed
early in the process are intended to be broad in scope and identify as many potential relationships
as possible. As more information is incorporated, we assess the plausibility of specific
hypotheses and identify the most appropriate risk hypotheses for subsequent evaluation in the
analysis phase of the risk assessment. The following examples, one specific and one generic,
illustrate risk hypotheses involving the contribution of air pollutants to aquatic ecosystem risks
(EPA 1998d).
* * * March 1999 Page 29 * * *
-------
Residual Risk Report to Congress
Nutrient loadings from septic systems,
air pollution, and lawn fertilizers
cause eelgrass loss in Waquoit Bay by
shading due to algal growth and direct
toxicity from nitrogen.
When a specific chemical (e.g., a
HAP) is released to the environment
at a specific rate, based on the
chemical's Kow, its mode of action,
and the food web of the target
ecosystem, it will bioaccumulate
sufficiently in "X" years to cause
developmental problems in receptors
of concern (e.g., fish).
Conceptual model diagrams are used,
along with the risk hypotheses, to select the
pathways to be evaluated in the analysis
phase of the ecological risk assessment, as
well as to assist in communication with risk
managers. There is no set configuration for
conceptual model diagrams. Exhibit 6 is a
conceptual model diagram for exposure of
piscivorous birds to HAPs.
In preparation for the analysis step,
the data and measures to be used in
evaluating the risk hypotheses are identified
in an analysis plan (EPA 1996d). That is, we
identify the ways we will quantify HAP
exposure (e.g., incorporating information
such as emission rates, dispersion, persistence
and partitioning properties) and effects (e.g.,
survival, growth, reproduction, and
community structure). In the analysis plan we
also specify how risks will be characterized.
AN EXAMPLE OF ECOLOGICAL RISK
ASSESSMENT PROBLEM FORMULATION:
EPA'S WATER QUALITY CRITERIA
A specific example of elements of the problem
formulation phase in a national-level ecological risk
assessment, as provided in EPA's Guidelines for
Ecological Risk Assessment (EPA 1998d) can be found in
the development of AWQC by EPA's Office of Water
under the CWA. Water quality criteria have been
developed for the protection of aquatic life from chemical
stressors (EPA 1986d). This text box shows how the
elements of a water quality criterion correspond to
elements of problem formulation, which include
management goals, management decisions, assessment
endpoints, and measures. These elements of problem
formulation support subsequent analyses in the risk
assessment.
Regulatory Goal
> CWA, section 101: Protect the chemical, physical,
and biological integrity of the Nation's water
Program Management Decisions
> Protect 99% of individuals in 95% of the species in
aquatic communities from acute and chronic effects
resulting from exposure to a chemical stressor
Assessment Endpoints
> Survival of fish, aquatic invertebrate, and algal
species under acute exposure
> Survival, growth, and reproduction of fish, aquatic
invertebrate, and algal species under chronic
exposure
Measures of Effect
> Laboratory LC50s for at least eight species meeting
certain requirements
> Chronic no-observed-adverse-effect levels
(NOAELs) for at least three species meeting certain
requirements
Measures of Ecosystem and Receptor Characteristics
> Water hardness (for some metals)
<- pH
The water quality criterion is a benchmark level derived
from a distributional analysis of single-species toxicity
data. It is assumed that the species tested adequately
represent the composition and sensitivities of species in a
natural community (EPA 1986d).
* * *
March 1999 Page 30
* * *
-------
Residual Risk Report to Congress
EXHIBIT 6
CONCEPTUAL MODEL DIAGRAM FOR EXPOSURE OF PISCIVOROUS BIRDS TO HAPs
!
Primary Secondary Primary Secondarv
Source Source Receptor !>«,h,7
(Stack ^ (Surface ~ (Aquatic ~ ._. '
Emissions) Water) Invertebrate) u"'*n'
<
Tertiary
Receptor
^ (Piscivorous
Bird)
I
!
(Assessment N.
Endpoint \
(Reproductive /
Success) /
3.2 Framework for Risk Assessment
Using knowledge gained from past risk assessments, information from other regulatory
agencies, and guidance from Reports such as the NRC and CRARM reports, the Agency has
developed a general framework for assessing residual risks. Consistent with the recently
published Guidelines for Ecological Risk Assessment (EPA 1998d), and noted in Section 3.1.4,
each human health and ecological risk assessment is organized into three phases.
In the problem formulation phase, the content and scope of the assessments are
specified. This phase includes identifying goals and assessment endpoints, preparing a
conceptual model, and developing an analysis plan.
The analysis phase involves evaluating exposure and effects and the relationship between
them.
Risk characterization requires estimating and interpreting risk through integration of the
exposure and effects analyses. The risk results are presented in context with the
uncertainties and limitations of the analysis and other relevant information.
* * *
March 1999 Page 31
* * *
-------
Residual Risk Report to Congress
Current thinking regarding both human health and ecological risk assessments
recommends reliance on a tiered or iterative approach, beginning with a simple screening
analysis and moving as warranted to a more detailed and resource intensive analyses (NRC 1994;
CRARM 1997a,b; EPA 1998d). When the available information precludes the need for
screening analysis, it may be omitted. Each assessment includes the three phases.
Three of the four components of the risk assessment paradigm introduced by NAS (as
described in Section 3.1.1) - exposure assessment, hazard identification, and dose-response
assessment - fall within the analysis phase of risk assessment. The fourth component of the
NAS paradigm is the risk characterization. In the NAS paradigm, information from the three
types of analysis is combined to yield a characterization of risk.
The level of exposure being received by people from the pollutant source is estimated in
the exposure assessment.
The type and severity of adverse effects that can be caused by the pollutant are assessed in
the hazard identification step of the effects assessment.
The adverse effects of a pollutant observed at different levels of exposure and the
relationship between exposure and effects are considered in the dose-response assessment
step of the effects assessment.
The presentation in this chapter of both human health and ecological risk assessment
methods is organized into three sections, which parallel the three components of the analysis
phase: Exposure Assessment in Section 3.3, Effects Assessment (includes both hazard
identification and dose-response assessment) in Section 3.4, and Risk Characterization in Section
3.5.
3.3 Exposure Assessment
The nature and complexity of the exposure assessment is often a function of the particular
risk management question (or other purpose) to be addressed. Simple screening analyses, using
conservative default assumptions, are appropriate to rule out the need for further analyses or
action. On the other hand, a detailed exposure analysis may be needed to determine the necessity
for or type of emission controls, particularly when those controls are associated with large
economic consequences. In some cases, the critical policy question may be to estimate the risks
to a small subset of the population at high exposure levels, whereas in another, the overall risks
across the entire nation may be the driving policy question. Either human health or ecological
risks may be the main focus of a given exposure assessment. Thus, there is no single "right" way
to conduct an exposure assessment.
The initial EPA Guidelines for Exposure Assessment were issued on September 24, 1986
(EPA 1986f) and the Proposed Guidelines for Exposure-related Measurements on December 2,
* * * March 1999 Page 32 * * *
-------
Residual Risk Report to Congress
1988 (EPA 1988a). In response to recommendations from the EPA Science Advisory Board and
the public, the 1986 Guidelines were updated and combined with the 1988 Proposed Guidelines
and reissued as the 1992 Guidelines for Exposure Assessment., which were published in final
form on May 29, 1992 (EPA 1992a). Publication of the 1992 Guidelines made information on
the principles, concepts, and methods used by the Agency available to all interested members of
the public. The Guidelines establish a broad framework for Agency exposure assessments by
describing the general concepts of exposure assessment, including definitions and associated
measurement units, and by providing broad guidance on the planning and conduct of an exposure
assessment. The Guidelines also provide information on presenting the results of the exposure
assessment and characterizing uncertainty. Although the Guidelines focus on exposure of
humans to chemical substances, much of the guidance also pertains to assessing ecological
exposure to chemicals, or to human exposures to biological, radiological, or other agents.
In the Guidelines, EPA established a specific definition of exposure to minimize
ambiguity in the use of terms and units for quantifying exposure (EPA 1992a). Human exposure
is defined as contact with a chemical or agent at the visible external boundary of a person,
including skin and openings into the body such as mouth and nostrils (but not necessarily contact
with exchange boundaries where absorption may take place, such as skin, lung, and
gastrointestinal tract). Therefore, an exposure assessment is the quantitative or qualitative
evaluation of contact, and includes such characteristics as intensity, frequency, and duration of
contact. Often, an assessment also will evaluate the rate and route at which a chemical crosses
the external boundary (dose) and the amount absorbed (internal dose). The numerical output of
an exposure assessment may be either exposure or dose, depending on the purpose of the
evaluation.
Exposure characterization for ecological risk assessment describes potential or actual
contact or co-occurrence of air toxics concentrations with ecological receptors. It is based on
measures of exposure and ecosystem and receptor characteristics that are used to analyze HAP
sources, their distribution in the environment, and the extent and pattern of contact or co-
occurrence. The objective is to produce a summary exposure profile that identifies the exposed
ecological entity, describes the course a stressor takes from the source to that entity (i.e., the
exposure pathway), and describes the intensity and spatial and temporal extent of co-occurrence
or contact. The profile also describes the impact of variability and uncertainty on exposure
estimates and reaches a conclusion about the likelihood that exposure will occur (EPA 1998d).
An exposure assessment has four major components: emissions characterization,
environmental fate and transport characterization, characterization of the study population, and
exposure characterization. These components are discussed individually in this section.
* * * March 1999 Page 33 * * *
-------
Residual Risk Report to Congress
3.3.1 Emissions (Source) Characterization
In the first step of exposure assessment for air toxics, the specific HAPs emitted and the
sources of their airborne emissions are determined. Data are collected on the emission rates of
the pollutants and parameters of the source. Knowledge of the emission rate and release
characteristics enables the pollutant fate and transport to be estimated.
HAPs THAT ARE GROUPS OF CHEMICALS
As described later in Exhibit 19, there are 17 HAPs that
represent groups of chemicals rather than individual
compounds, substantially complicating the exposure
assessment process. In the case of the 12 elements listed
(e.g., mercury compounds), obtaining emissions
information may be complicated by speciation of the
element as well as its combination with other chemicals.
As another example, the HAP polycyclic organic matter
(POM) is a complex mixture of thousands of polycyclic
aromatic compounds. In order to obtain consistent
emission estimates for such a complex chemical group, the
Agency has identified three representative subgroups for
which emissions inventories are usually compiled: (1)7-
PAH includes the seven polynuclear aromatic hydrocarbons
that we have identified as probable human carcinogens; (2)
16-PAH includes the 7-PAH group plus nine other
commonly measured PAHs; and (3) EOM (extractable
organic matter) is the extractable subfraction of particulate
matter that some research indicates may provide a better
estimate of POM cancer risk than any of the individual
PAHs or PAH subgroups.
Ideally, the emission estimates are
from direct measurements of source
emissions. Although direct measurement is
likely to provide the most accurate data for an
emission source, these data are typically not
available, as such sampling is often time- and
resource-intensive. When specific emission
measurements are not feasible or available,
other emission estimation methods, including
material balances and emission factors, are
sometimes used as an alternate method.
Emission factors indicate the quantity of a
pollutant typically released to the atmosphere
for a particular source operation, and are
usually considered to be representative of an
industry or emission type as a whole. Actual
emissions from a specific source may be
higher or lower or may be comprised of a
different set of individual HAPs than the
emission factors indicate because of site-
specific process design, control equipment, operation and maintenance practices, or other factors.
Before using an emission factor, available documentation on how the emission factor was
derived should be studied to determine whether it is appropriate for the source under
consideration. Each approach to estimating emissions, including use of direct measurement data,
has an inherent level of uncertainty, which adds to the overall uncertainty of a risk analysis.
Source parameters define how the pollutant is released to the environment, and they affect
the initial dispersion of the pollutant in the atmosphere. For point sources of air toxics, source
parameters can include the volume flow rate or exit velocity of the stack gas, stack gas exit
temperature, stack height, inner stack diameter, knowledge of the proximity of structures to the
release point, and other characteristics. For small sources within a larger facility (e.g., emissions
from storage piles or ponds), the dimensions of the small source should be identified. While
point source emission rates are expressed in terms of mass per unit time, non-point source
emission rates are more typically modeled in terms of mass per unit time per unit area. Another
important consideration in specifying the source emission rates is whether the rates should reflect
short-term or annual operating conditions. Ideally, it is better to have hourly or daily emission
* * *
March 1999 Page 34
* * *
-------
Residual Risk Report to Congress
rates; however, these data are not typically available. Short-term emission rates provide the
flexibility to model emissions over a range of release times, to assess risk over shorter intervals
than annual, and to permit more accurate assessments through the incorporation of
microenvironment and population activity pattern analyses.
Depending on the analysis, source and emissions data can be derived from broad-scale
emission inventories, specific data collection efforts with particular industries, or information
from regional, State, or local air toxics agencies. Other information, such as the geographic
location of release points, the temporal pattern of emissions (e.g., periodic "puffs" vs. constant
emission rates), and the release height may be necessary depending on the level of detail needed
or types of exposure examined in the assessment.
Data and Tool Availability, Limitations, and Closing Gaps
In the analyses to be performed under the residual risk program, it is important that the
data, regardless of the form in which they are obtained, represent post-MACT emissions (i.e.,
estimated or measured HAP emissions for a source that has already implemented MACT
standards). In collecting the variety of information for each source category (e.g., emissions,
source characteristics), there are several data sources we will be consulting:
EPA's National Toxics Inventory (NTI) (see text box below);
State or local air toxics agencies;
Industry;
EPA's Aerometric Information Retrieval System (AIRS);
EPA's Toxic Release Inventory (TRI); and
MACT development data.
While the 1996 and future generations of the NTI are intended to contain facility-specific data
and to support site-specific modeling applications, the timing for completion of the 1996 version
precludes its use for the initial residual risk analyses. For these analyses, data will be obtained
from the same sources (see preceding list) that are being consulted in development of the 1996
NTI. The hierarchy of preference for source data for assessments will be consistent with that
established to ensure the rigor of the NTI. For source categories for which the MACT
compliance date has not yet occurred, however, a screening risk assessment may be performed
based on information compiled by EPA during the MACT rule development process for that
source category. Refined analyses will typically rely on the availability of post-MACT emissions
data.
3.3.2 Environmental Fate and Transport Characterization
After the pollutants of interest and their sources and emission rates are defined, the
exposure assessment process continues with estimation of pollutant fate and transport. This step
describes how the pollutant is transported, dispersed, and transformed over the area of interest.
* * * March 1999 Page 35 * * *
-------
Residual Risk Report to Congress
THE NATIONAL TOXICS INVENTORY
In 1995, EPA initiated development of the National Toxics Inventory (NTI), a central repository of air toxics emissions and
inventory data for HAPs. Although its development was not explicitly required by the CAA, the NTI is useful in assisting
stakeholders in conducting the analyses required by the Act. The NTI is updated every three years, on the same schedule as
the criteria air pollutant inventories.
The goal of the NTI is to compile the best available emissions information about the 188 HAPs for many of approximately
960 source categories. The data are from multiple data sources, which we have prioritized to provide the most complete,
consistent data repository. The hierarchy of data sources is: (1) data developed by State and local air agencies; (2) data we
collected and developed as part of the MACT development process; (3) data from inventories developed to support
requirements of section 112(c)(6) and 112(k); (4) emissions reported in the TRI; and (5) emissions generated by the Agency
using widely recognized emission factors and activity factors. We have recently compiled the NTI for 1993 and are
currently compiling the 1996 inventory, which following review by States is scheduled for completion in October 1999.
(For more information on the NTI, see EPA's 1997 Trends Report (EPA 1999).)
Initially, the fate of the emitted pollutants is largely determined by the source release
characteristics. After pollutants are released to the atmosphere, their transport, dispersion, and
transformation are governed by meteorological principles, terrain characteristics, wet and dry
deposition rates, and certain chemical properties of the HAP (such as aqueous solubility, vapor
pressure, air-water partition coefficient (i.e., Henry's Law constant), molecular diffusivity, phase
partition coefficient, melting point, and adsorptivity). For a limited subset of HAPs, it is
important to consider deposition from air to soil, vegetation, or waterbodies. For others, such
deposition is not important.
A variety of mathematical models, each with specific data needs, has been developed or is
under development to describe the transport and fate of pollutants released to the atmosphere.
The model chosen must be appropriate for the intended application, which may vary among
estimates of short-term peak concentrations immediately adjacent to a facility, long-term
concentrations over a city-wide area, or deposition over hundreds or even thousands of miles.
The HAP's reactivity and persistence will influence its fate as well and can be important factors
in estimating exposure for certain pollutants. Additionally, secondary transformation products of
some HAPs may need to be identified for consideration in risk assessment. High quality,
representative meteorological information is crucial to a valid exposure assessment for air toxics,
as well as information on local topography. Any available HAP monitoring data can be used
either to check the validity of modeled concentration estimates or as a primary or supplemental
source of information for the exposure assessment itself.
Many studies indicate that a limited number of pollutants emitted into the atmosphere
(e.g., mercury) are passed to humans or wildlife through non-inhalation pathways (EPA 1990).
An example would be a HAP depositing from the air onto the soil, followed by ingestion of the
soil by a child or by biota in an ecosystem. Exhibit 7 is an example of the conceptual model
diagram for an ecological risk scenario involving multipathway exposure to HAPs. For a limited
subset of HAPs, greater human and ecological exposures to the HAP occur through non-
* * * March 1999 Page 36 * * *
-------
Residual Risk Report to Congress
EXHIBIT 7
CONCEPTUAL MODEL DIAGRAM FOR MULTIPATHWAY EXPOSURE TO AIR TOXICS
Ingestion of Contaminated
Plants and Soil
Uptake by A
Benthfc Organisms Aquatic Plants
inhalation exposures than through inhalation exposures. These HAPs typically are persistent in
the environment, have a strong tendency to bioaccumulate, and exhibit moderate to high toxicity.
Data and Tool Availability, Limitations, and Closing Gaps
Modeling. The Agency relies on a variety of models for air dispersion modeling. Tier 1
from A Tiered Modeling Approach for Assessing the Risks Due to Sources of Hazardous Air
Pollutants (EPA 1992c), SCREENS (EPA 1995b), and others (NRC 1994) are available for
simpler types of applications and needs. As the applications and needs become more complex,
the Industrial Source Complex Short-Term 3 model (ISCST3), a Gaussian plume model, can be
used to estimate both short-term peak and long-term average air concentrations and deposition
rates (EPA 1995c). In addition, the Agency is working with the scientific community to develop
improved dispersion models such as AERMOD (EPA 1998e).
* * *
March 1999 Page 37
* * *
-------
Residual Risk Report to Congress
Regardless of the model used in the exposure assessment, it is important to ensure that
the averaging time of exposure estimates derived from a modeling exercise are appropriate for
the time frame of interest (e.g., short-term acute exposure or long-term chronic exposure).
Dispersion models such as ISCST3 are designed to estimate ambient pollutant concentrations on
the order of an hour or to run multiple hourly iterations to calculate longer-term averages such as
seasonal or annual average concentrations. It should be noted, however, that ISCST3 is designed
to calculate ambient pollutant concentrations resulting from an emission source that has an
essentially constant release rate over an extended period of time (e.g., over a month or year).
Therefore, ambient concentrations that result from intermittent emissions (such as those resulting
from an industrial batch process) may not be predicted accurately by this model. Other EPA
models can predict short-term concentrations from pulse or intermittent releases. It is also
important to note that the type and quality of input data available to the model can affect the
accuracy and usefulness of the modeling results (e.g., whether available meteorological data are
representative of site conditions, whether emissions estimates are available on an annual or
monthly basis, whether the site is in simple or complex terrain).
Various equations and scenarios are available for modeling exposures that occur through
routes other than inhalation, and each equation requires the appropriate input data. The simplest
multipathway exposure assessments require chemical-specific data (e.g., octanol-water partition
coefficient (Kow)) to model the partitioning of the chemical in the environment and uptake rates
(e.g., 3 liters water/day) to predict intakes. Combining this information yields general
predictions of non-inhalation exposure.
The EPA's initial detailed guidance on multipathway exposure assessment methods was
issued by ORD in 1990 (EPA 1990), updated a few years later (EPA 1993b), and recently
consolidated and updated again (EPA 1997f). These documents present the Indirect Exposure
Model (IEM), which consists of equations and default input values to be used in calculating
exposure levels for a set of multimedia, multipathway exposures. The associated equations for
such an analysis typically start with atmospheric deposition rates and require additional chemical
data and many other input parameters related to the environmental setting and population. For
example, modeling pollutant fate and transport through a waterbody requires information such as
waterbody location, size, and drainage area for each waterbody being evaluated. As another
example, modeling exposure via vegetable consumption involves parameters such as soil type,
soil depth, annual rainfall, and vegetable type (e.g., root, leafy). A critical input to these
calculations for the location(s) being assessed is the HAP deposition rate (i.e., amount per unit
time being deposited from the air to land and/or surface water), which can be estimated using air
models such as EPA's ISCST3. The Total Risk Integrated Methodology (TRIM) model, a new
multimedia, multipathway exposure model under development by EPA is discussed in a later
section.
Monitoring Data. With the exception of monitoring for a limited number of volatile
organic HAPs, there is no national ambient air quality monitoring network making routine
measurements of air toxics levels. Therefore, ambient data for individual HAPs are limited (both
* * * March 1999 Page 38 * * *
-------
Residual Risk Report to Congress
spatially and temporally) in comparison to the data available from the long-term, nationwide
monitoring for the six criteria air pollutants. However, several State and local agencies operate
independent toxics monitoring programs. For example, the California Air Resources Board has
administered a 30-site Toxics Data Network since 1985, and the Texas Natural Resources
Conservation Commission initiated a 22-site Community Air Toxics Monitoring Network in
1992. In addition, EPA sponsors the Urban Air Toxics Monitoring Program (UATMP), a
"participatory" or voluntary program through which State and local agencies can take part in air
toxics monitoring. The UATMP involves measurements of 38 volatile organic compounds and
16 carbonyl compounds; in 1997, the UATMP was comprised of 12 monitoring stations in five
States (see Exhibit 8).
Although designed primarily as an effort to monitor and characterize ozone precursors,
the Photochemical Assessment Monitoring Stations (PAMS) program also includes measurement
of several HAPs: acetaldehyde, benzene, ethyl benzene, formaldehyde, hexane, styrene, toluene,
2,2,4-trimethylpentane, and xylenes (m,p,o-xylene). Initiated in February 1993, the PAMS
program requires establishment of an enhanced monitoring network in all ozone nonattainment
areas classified as serious, severe, or extreme. The 24 affected areas, shown in Exhibit 8, cover
approximately 120 thousand square miles and have a total population of 84 million people
(approximately 30 percent of the U.S. population). The PAMS program may play a significant
role as a foundation for future ambient monitoring for air toxics. Additionally, ambient air
quality data for some HAP constituents of particulate matter (e.g., some elements and semi-
volatile organic compounds) may be obtained under the current plans for the national PM2 5 (fine
particulate matter) speciation network.
Without a national mandate for ambient monitoring for air toxics, there is also little
incentive for the data from these various programs to be centrally archived. The Agency is
attempting to remedy this problem through an ongoing effort to identify all sources of ambient air
quality data for toxics. The newly identified data are being compiled into a data base, which is
updated on a quarterly basis. Recognizing competing resource needs, EPA is encouraging State
and local agencies to tailor their monitoring programs to address their most pressing air toxics
issues and local needs. EPA is also requesting that the State and local agencies work with EPA
to develop a monitoring network distribution that capitalizes on existing efforts and capabilities.
EPA expects to add 17 new monitoring sites to this network in 1999. This will include one new
site in the major metropolitan areas of each of the 10 EPA Regions and an additional site in each
of the seven areas with existing PAMS networks. EPA expects to increase that number by up to
40 additional sites in 2000.
It should be noted, however, that for the purposes of risk assessments, specifically
residual risk assessments, even comprehensive and high quality monitoring data would not be
adequate and would need to be supplemented with modeling data. For example, the
contributions of individual sources and source categories often cannot be determined based on
monitoring data alone.
* * * March 1999 Page 39 * * *
-------
Residual Risk Report to Congress
EXHIBIT 8
URBAN AIR TOXICS MONITORING PROGRAM SITES (1997)
AND PHOTOCHEMICAL ASSESSMENT MONITORING STATIONS OR PAMS (1998)
Burlington, VT
Winooski, VT
Rutland, VT
Underbill, VT
Camden, NJ
LEGEND:
Areas subject to photochemical
assessment monitoring station (PAMS)
ozone and ozone precursor monitoring
Locations of Urban Air Toxics
Monitoring Program Sites
While not collected specifically for air toxics assessment purposes, monitoring data for
non-air media (e.g., soil, sediments, surface water, biota) are collected under programs sponsored
by EPA and other federal agencies and by the States. A number of these programs collect data
on sets of pollutants that overlap with the 188 HAPs. For example, the Agency's Environmental
Monitoring and Assessment Program (EMAP) monitors polycyclic aromatic hydrocarbon (PAH),
polychlorinated biphenyl (PCB), DDT, other pesticide, and butyltin levels in sediments in three
large estuarine areas (Mid-Atlantic, Gulf of Mexico, and Louisiana). Under the National Status
and Trends programs implemented by the National Oceanic and Atmospheric Administration,
chemical contaminant levels are monitored in fish and surficial sediments from 170 coastal and
estuarine sites, and chemical contaminant trends in mollusks are tracked at 287 coastal and
estuarine sites. Fish, shellfish, and sediment monitoring is also conducted by many States. In
addition, air deposition of a small subset of HAPs is measured in selected regions of the country
under the CAA Great Waters program. Any of these data sources may be consulted as
appropriate for verification of multimedia modeling output or identification of background
contaminant levels.
* * *
March 1999 Page 40
* * *
-------
Residual Risk Report to Congress
3.3.3 Characterization of the Study Population
After ambient concentrations have been derived, human and/or ecological exposures to
these concentrations are determined. In this component, the study population is defined in terms
of geographic distribution and other characteristics relevant to the exposure pathways of concern.
For the more frequently performed human inhalation exposure analyses, the locations of
resources, homes, workplaces, schools, and other receptor points will partially determine the
extent of actual exposure. Factors such as age, sex, and activity patterns affect the amount of
pollutant actually inhaled by an individual, while mobility of the subject affects the concentration
levels to which an individual is exposed over time. In screening analyses, potential exposure
may be estimated using the maximum off-site concentration, which may be more easily
calculated than an exposure estimate linked to population location and behavior. In a refined
assessment, we will incorporate more specific information about actual receptor points and the
population's movement throughout the area, including, if appropriate, the amount of time spent
in specific microenvironments (e.g., indoors at home, outdoors, in motor vehicles). Depending
on the focus of the analysis, output of the exposure assessment may vary. In some cases the most
highly exposed 5 to 10 percent of the population may need to be well-characterized, while for
others, the distribution of exposures across a wider area is needed. Information on specific
sensitive populations, such as children or the elderly, is another layer of detail that may often be
needed in refined analyses.
As with inhalation, assessing non-inhalation exposure to human populations involves
combining pollutant concentration information with relevant information concerning the study
population. The kinds of information needed depend on the relevant exposure pathways. EPA's
Office of Solid Waste and Emergency Response has considered multipathway exposures in
various risk assessment activities, including the assessment of hazardous waste combustion (EPA
1994c; EPA 1998f). Examples of recommended pathways include:
Air deposition > §oil motion > Human
Air deposition + uptake of vapor phase > AboVC-grOUnd Vegetable "^eStl°n > Human
Air fseeabove)> Soil + Above-ground Vegetable in^estlon > Beef m^estlon > Human
Air fseeabove)> Soil + Above-ground Vegetable in^estlon > Milk ^estlon > Human
Air deposition + runoff + erosion > WaterbOdy blOaCCUmulatlOn > Fish ln^StlOn > Human
Air deP°sltlon > Surface Water m^estlon > Human
Air deposition > §oil overland flow > Surface Water motion > Human
After identification of the relevant exposure pathways, information such as soil, drinking
water, and food ingestion rates (often including specific foods, such as fish, beef, pork, eggs, root
vegetables, grains, fruit), generally for both adults and children, as well as contact frequencies
with soil and surface water, may be needed. Some activities of particular interest for non-
inhalation modeling are subsistence farming and subsistence fishing because of the unique
dietary habits of these two groups (i.e., eating much more garden vegetables and fish,
* * * March 1999 Page 41 * * *
-------
Residual Risk Report to Congress
respectively). Also, as with inhalation exposure, the extent to which these factors are included in
the risk assessment depends on the purpose of the assessment, available resources, uncertainties
in the assessment, and data quality and quantity. Not only are the data requirements often
extensive, particularly when many different pathways are being assessed, but the computational
demands also can be quite large in a multimedia, multipathway assessment.
To relate estimated ambient concentrations to exposures in ecological assessments,
characteristics of the ecosystem and ecological population are identified. These include
behavior, location, and important life history characteristics that may affect the exposure or
response of assessment endpoints to the HAPs. Examples include the timing of the study
population's reproductive cycles or migration patterns in relation to ambient concentrations, as
well as features of ecosystem habitats which may affect exposures. A screening-level
multipathway assessment may be used to identify potentially significant exposure pathways and
to develop an exposure profile for ecological receptors of concern.
Data and Tool Availability, Limitations, and Closing Gaps
Human Population Assessment. Exposure and risk to human populations via the
inhalation route involves combining pollutant concentration information with information on the
geographical distribution of people in the study area, including consideration of data on the
activities and characteristics of the exposed population. Human exposure and susceptibility and
sensitivity to pollutant effects may vary with factors such as age, gender, intensity and amount of
activity, time spent in microenvironments, diet, overall health, lifestyle, genetic factors, and the
concentration of pollutant. The extent to which these factors are included in the risk assessment
depends on the purpose of the assessment as defined in the problem formulation step, available
resources, uncertainties in the assessment, and data quality and quantity.
In characterizing the exposed population, the U.S. Bureau of Census is a major source of
population information (i.e., the 1990 Census). In air toxics exposure assessment, the Agency
typically uses population and demographic data that are based on the census block level. There
are approximately 6.9 million census blocks in the U.S. The number of people residing in each
census block and the geographical center of each are specifically used in the assessments. The
population included within a census block is highly variable (from less than 10 to a few
thousand), but, on average, about 30 to 40 people reside in each block. These data provide a
good estimate of how people are geographically distributed near emitting sources, and are also
useful for defining the population cohorts for analysis. Cohorts may be defined on the basis of
age, gender, race, income levels, length of time in primary residence, or other characteristics.
Data on population characteristics relevant to exposure potential are obtained from documents
and studies such as EPA's Exposure Factors Handbook (EFH) (EPA 1997g) and national
population surveys of people's activity patterns, including where they spend each hour of a day
(microenvironment) and each hour's activity level (EPA 1994d).
In estimating inhalation exposure from stationary sources of HAPs for residual risk
analyses, we currently use modeling techniques such as the Human Exposure Model (HEM)
* * * March 1999 Page 42** *
-------
Residual Risk Report to Congress
(EPA 1986g). In residual risk analyses, we will be relying on an approach that incorporates more
sophisticated techniques using detailed and site-specific information when warranted. Some of
these techniques are currently being developed by EPA, e.g., TRIM (described below). In the
interim, HEM, which contains meteorological data, census data, an EPA air dispersion model,
and to address population activities and the variability associated with exposure assessment, an
add-on Monte Carlo simulation routine, will continue to be used in air toxics risk assessments.
Predictions of ambient concentrations and atmospheric deposition derived from
atmospheric dispersion models have rarely been validated. Model validation is a difficult,
resource intensive process that relies heavily on monitoring data, and often, models predict
concentrations that are below the levels that can be detected using current analytic methods.
Nevertheless, we continue to seek to improve our modeling techniques by enhancing their
capacity to incorporate exposure assessment tools and exposure data bases. For example, over
the past decade the Agency has significantly expanded available data bases on human activity
patterns (e.g., recent development of the Combined Human Activity Database (CHAD)),
breathing rates, residential occupancy periods, and microenvironmental exposures. The outputs
of these improvements along with improvements in dispersion models can be used as inputs to
HEM, along with more detailed and realistic exposure profiles, to generate better estimates of
individual and population risk.
As discussed in Section 3.3.2, the primary tool currently used by the Agency for
multipathway exposure modeling of the subset of HAPs for which this is appropriate is the IEM.
This model includes a fate and transport component that estimates multimedia concentrations
and a component that estimates multipathway exposures. The recently released draft guidance
document on hazardous waste combustion risk assessment for human health risks (EPA 1998f)
includes a full discussion of multimedia exposures and assessment of the resulting risks. This
document will be considered in refining our human multipathway exposure assessment
methodology.
Additionally, the Agency is currently developing the TRIM, which is a multimedia,
multipathway modeling system being designed to address all quantitative dimensions of a
complete residual risk evaluation, including the exposure assessment. The TRIM will provide a
framework for assessing human health and ecological risks from exposure to hazardous and
criteria air pollutants. It will allow for the evaluation of multipathway exposure to air pollutants,
using a dynamic mass-balance approach to estimate the exposure and dose profiles received by
selected receptors. Both uncertainty and variability will be explicitly treated within the model
framework. The TRIM will consist of four modules: (1) the Environmental Fate, Transport, and
Exposure module (TRTM.FaTE), (2) the TRIM exposure event module (TRTM.Expo), which will
track population cohorts through time and space, (3) a dosimetry module to account for pollutant
uptake, biokinetics, and dose-response in humans, and (4) a risk characterization module. The
first module was reviewed initially by EPA's SAB in May 1998, and comments received are
* * * March 1999 Page 43 * * *
-------
Residual Risk Report to Congress
being addressed through further development and testing efforts. The first, second, and fourth
modules are scheduled to be reviewed by the SAB in 1999. These three modules should be
available for EPA use in the year 2000.
Ecological Exposure Assessment. Emission sources, HAP distribution in the
environment, and contact with ecological receptors are described in the ecological exposure
characterization. Much of the information used in this characterization is similar to that used for
the human exposure assessment. For example, monitoring data and emissions and multipathway
modeling are major sources of information. As with human exposure assessment, non-inhalation
pathways may be important for a limited subset of HAPs that are persistent and/or have the
potential for bioconcentration and biomagnification in aquatic and terrestrial food webs. This
potential is evaluated based on fate and transport data specific to the pollutant of concern, such as
the Kow, organic carbon-water partition coefficient (Koc), and bioconcentration factor (BCF) or
bioaccumulation factor (BAF) values.
Some of the information needed to characterize the contact of a pollutant such as a HAP
with potential receptors, however, is specific to the ecological risk assessment methodology. For
example, an understanding of the site characteristics, including such factors as site topography,
soil and water types, and habitat types, is important. Furthermore, the "significance" of potential
ecological effects depends on other site-related factors, including the type and significance of the
ecological receptors affected and the areal extent of exposures at concentrations sufficient to
cause adverse effects. Tools risk assessors can use to determine the locations and types of
ecological receptors in areas surrounding the sources include information gathered using maps
(e.g., U.S. Geological Survey, National Wetlands Inventory, and EPA's ESTAT Geographical
Information System), aerial photographs, communication with scientists knowledgeable about
the area (e.g., State agencies, U.S. Fish and Wildlife Service, National Oceanic and Atmospheric
Administration), and site surveys.
In the absence of readily available site-specific information and prior to the
recommendation of a site-specific ecological risk assessment, it may be appropriate to use
approximate source location information to infer the existence of adjacent aquatic and terrestrial
ecosystems, and a set of assessment endpoints can be selected that represent the most appropriate
sensitive elements of those ecosystems for the contaminants in question. The Agency is
considering these issues in developing an approach for use in residual risk ecological exposure
assessment activities.
3.3.4 Exposure Characterization
In the exposure characterization component, the pollutant concentration and study
population are spatially integrated to characterize exposure (EPA 1993c). For a human health
inhalation risk assessment, predicted ambient air concentrations for a certain location - for
example, the location of the individual most exposed (see text box) - are compared to the
population at that point, taking into account factors that can affect the population's exposure as
* * * March 1999 Page 44 * * *
-------
Residual Risk Report to Congress
MIR, MEI, AND INDIVIDUAL MOST EXPOSED
Maximum individual risk (MIR) is a concept included in the benzene NESHAP and is similar but not identical to the
concept of maximum exposed individual (MEI) risk. An MIR represents the highest estimated risk to an exposed individual
in areas that people are believed to occupy. The MEI risk represents the highest estimated risk to a hypothetical exposed
individual, regardless of whether people are expected to occupy that area. Thus, MEI risk is greater than or equal to MIR.
Depending on the expected magnitude of risk and ready availability of appropriate data, we may use the maximum modeled
off-site concentration in screening-level risk assessments. Where risks are expected to be elevated, in order to conserve
resources, we may pass over this conservative assumption step and incorporate population data to derive the MIR for areas
that people are believed to occupy.
We are proposing that the "individual most exposed," a phrase used in CAA section 112(f)(2), be considered equivalent to
the MIR for areas that people are believed to occupy for the purposes of regulation under the residual risk program.
described above. If non-inhalation (multimedia) exposures are of concern, these pathways and
the potentially affected populations are considered as well.
The exposure characterization of an ecological risk assessment describes the sources of
HAPs, the distribution of HAPs in the environment, and the contact of HAPs with ecological
receptors. The characterization is based on measures of exposure and of ecosystem and receptor
characteristics developed initially in the problem formulation phase. Many aspects of the
exposure characterization process, especially analyzing the sources and distribution of HAPs in
the environment, are similar for the ecological and the human health exposure assessment. The
primary difference is that the exposure points for ecological receptors can differ from those for
humans. Moreover, for ecosystems, exposure "areas" may be more meaningful than exposure
"points."
In recent years, there has been increasing interest in explicitly characterizing the extent of
uncertainty and variability in risk assessment, and especially in the exposure assessment step. To
do this, we may use various approaches, including a technique known as Monte Carlo simulation
analysis. Using this technique, important variables in the exposure assessment (as well as in the
other parts of the risk assessment) are specified as distributions (rather than as single values)
according to what can be expressed about their underlying variability and/or uncertainty.
Variables are sampled repeatedly from these distributions and combined in the analysis to
provide a range of outcomes. While this technique can offer a useful summary of complex
information, it must be noted that the analysis is only as good as the underlying data. It is
important that the individual modeled variables are expressed in a way consistent with the best
information available, or the results of the Monte Carlo analysis can do more to confuse than
enlighten.
* * * March 1999 Page 45 * * *
-------
Residual Risk Report to Congress
3.4 Effects Assessment
3.4.1 Human Health Effects
Hazard Identification
An initial step in the effects
assessment is to determine whether the
pollutants of concern are causally linked to
adverse health effects. This is the hazard
identification. Factors such as the route of
exposure, the type and quality of the effects,
the biological plausibility of findings, the
consistency of findings across studies, and the
potential for bioaccumulation all contribute to
the strength of the hazard identification
statement. There are many sources of
information that can be brought to bear in the
hazard identification. Exhibit 9 summarizes
important sources of information for hazard
identification.
The types of effects that are relevant
to a particular chemical (e.g., cancer, non-
cancer) are determined as part of the hazard
identification. The current approaches for
dose-response assessment and risk
characterization can differ for various types of effect.
Non-cancer Effects - Chronic and Acute. In large part due to the wide variety of
endpoints, hazard identification procedures for non-cancer effects are less formally described in
EPA guidance than procedures for the identification of carcinogens. The EPA has published
guidelines for assessing several specific types of non-cancer effects, including mutagenicity
assessment (EPA 1986a), developmental toxicity assessment (EPA 1991), neurotoxicity
assessment (EPA 1998c), and reproductive toxicity assessment (EPA 1996c). Rather than
specifying risk assessment methodology, these non-cancer guidelines tend to focus on the proper
conduct of testing and the appropriate toxicological interpretation of results of the commonly
performed assays. The guidance for hazard identification decisions is fairly general.
For assessment of chronic toxic effects other than cancer, EPA's general approach to
hazard identification is to review the health effects literature and characterize its strengths and
weaknesses, using primarily a narrative approach rather than a formal classification scheme.
Available data on different endpoints are arrayed and discussed, and the effects (and their
HAZARD IDENTIFICATION FOR MIXTURES
While some groups of pollutants, when part of a multiple
chemical exposure, act independently in causing health
effects, others may interact and elicit an effect that may be
different or may occur at a different exposure level than
would be expected if exposure were to the chemicals
individually. Even when individual pollutant levels are so
low that exposure to them one at a time would not be
expected to pose harm, some mixtures of pollutants may
work together such that their potential for harm adds up
and exposure to the mixture poses risk. For some groups of
pollutants that can interact chemically, the total risk they
pose as a group is greater than what would be expected
from adding up the individual risk posed by each. This is
known as a synergistic relationship. Antagonistic
relationships between chemicals are also possible. In this
case, the pollutants interfere with one another and the
potential for harm is lessened. This is a significant
simplification, but the important point to note is that
depending on the mixture of pollutants, the total effect may
be different than what would be expected from separate
exposures to the individual pollutants because of the
potential for additive, synergistic, or antagonistic
relationships among some chemicals.
* * *
March 1999 Page 46
* * *
-------
Residual Risk Report to Congress
EXHIBIT 9
SOURCES OF INFORMATION FOR HAZARD IDENTIFICATION
Epidemiologic Data. Epidemiologic studies of human populations exposed to HAPs in occupational settings
or in the general environment can provide valuable information on the effects of HAPs. These studies have
advantages over other sources of information in that they directly assess the effects of exposure to humans and,
in the case of studies of the general population, address exposures that actually occur in the environment. In
addition, recent work with biomarkers (chemicals in the body which allow for better quantification of exposure)
promises to boost the utility of epidemiology in the future. Shortcomings include concerns about the relevance
of high exposure levels often seen in occupational studies to environmental concentrations, concerns over the
control of confounding variables (such as tobacco use) that may obscure true causal relationships (or imply
false ones), difficulties in adequately characterizing exposure, and the difficulty most epidemiologic studies
have in discerning subtle effects (see Section 4.2.1 for a more complete discussion of epidemiologic data in the
context of section 112(f)).
Human Data from Case Reports or Controlled Exposure Studies. Where available, human health effects
data from case reports or controlled exposure studies can be extremely valuable, although such data generally
have shortcomings. Case reports often involve one or a small number of people, limiting the ability to
generalize from them, and they may involve exposures very different than typical environmental exposures. For
most HAPs and effect types of interest, controlled human exposure studies are unlikely to be available.
Animal Toxicology Data. High quality studies of human populations exposed to HAPs are rare, due to both
expense and the inherent limitations of epidemiology. As a result, EPA and others commonly rely on animal
studies to infer potential risk to humans. Animal toxicologic data are typically much easier to obtain than good
epidemiologic data, and effects can be explicitly linked with exposure to the HAP(s) being tested with little fear
of confounding. However, issues of high-to-low dose relevance are compounded by the need to extrapolate the
effects seen in animals to those anticipated in humans. Although there have been considerable advances in
understanding the relevance of specific results in animal studies to human biology, such extrapolations remain a
considerable source of uncertainty. The EPA has operated under the conservative public health policy that
assumes that adverse effects seen in animal studies indicate potential effects in humans.
Short-term in Vitro Assays. In vitro tests can be carried out quickly and at relatively low cost, and they can
provide valuable information on specific aspects of a pollutant's toxicity, such as a particular mechanism of
mutagenicity that may be an initiating event for cancer. However, such tests typically provide only supporting
information about a pollutant's effects, as few tests have been developed that are specific to a particular effect
or disease.
Structure-activity Relationships (SARs). By comparing the molecular structure of a pollutant with that of
others of known toxicity, toxic effects can sometimes be inferred, particularly if there is knowledge about the
mechanism of action. This approach is often useful when examining the hazards associated with individual
compounds within a class of related compounds (e.g., dioxins) or when identifying compounds for future study.
Although structure-activity analyses are rarely a substitute for existing experimental or epidemiologic data, and
represent a relatively uncertain basis for hazard identification, they are useful when experimental data are
absent.
attendant dose/exposure levels) are described. While there may be no formal hierarchy,
particular attention is given to effects that occur at relatively low doses or that may have
particular relevance to human populations. The narrative description of the data base discusses
factors such as the methodological strengths and weaknesses of individual studies (as well as the
overall data base), the time period over which the studies were conducted (e.g., chronic vs.
subchronic), routes of exposure, and possible biological mechanisms. In the course of this
narrative, there is discussion of effects, which may range from severe frank effects that can cause
* * * March 1999 Page 47 * * *
-------
Residual Risk Report to Congress
incapacitation or death to subtle effects that may occur at the cellular level but are early
indicators of toxic effects. Not all effects observed in laboratory studies are subsequently judged
to be adverse effects. The distinction between adverse and non-adverse effects is not always
clear-cut, and considerable professional judgment is required in applying criteria to identify
adverse effects. All of these observations are integrated into a presentation that gives a concise
profile of the toxicological properties of the pollutant.
In addition to toxicity related to long-term exposures, many HAPs also can cause toxic
effects after short-term exposures lasting from minutes to several hours. Indeed, for some
pollutants acute exposures are of greater concern than chronic exposures. The hazard
identification step for acute effects is comparable to that for chronic effects, with the primary
difference being the duration of exposure. As with chronic exposures, the severity of effects
from acute exposures may vary widely. The selection of a severity level for acute effects
assessment may vary with the purpose of the assessment. While various EPA offices have
addressed acute exposures across a variety of regulatory programs, Agency-wide guidance on
how to assess toxic effects from short-term exposures is only recently being developed. This
guidance for acute reference exposure (ARE) levels is intended to assist Agency acute risk
assessment activities (EPA 1998g). Additionally, a discretionary federal advisory committee
supported by EPA currently is assessing hazard and developing quantitative values (referred to as
acute exposure guidance levels (AEGLs) for acute toxicity of specific chemicals (EPA 1997h),
following guidance published by NRC (NRC 1993).
Cancer. The EPA's 1986 Guidelines for Carcinogen Risk Assessment (EPA 1986b)
provide guidance on hazard identification for carcinogens. The approach recognizes three broad
categories of data: (1) human data (primarily epidemiological); (2) results of long-term
experimental animal bioassays; and (3) a variety of data on short-term tests for genotoxicity and
other relevant properties, pharmacokinetic and metabolic studies, physio-chemical properties,
and structure-activity relationships (S AR). In hazard identification of carcinogens under the
1986 guidelines, the human data, animal data, and "other" evidence are combined to characterize
the weight of evidence regarding the agent's potential as a human carcinogen into one of several
hierarchic categories.
Group A - Carcinogenic to Humans: Applies when there are adequate human data to
demonstrate the causal association of the agent with human cancer (typically
epidemiologic data).
Group B - Probably Carcinogenic to Humans: Agents with sufficient evidence (i.e.,
indicative of a causal relationship) from animal bioassay data, but either limited (i.e.,
indicative of a possible causal relationship, but not exclusive of alternative explanations)
human evidence (Group Bl), or with little or no human data (Group B2).
Group C - Possibly Carcinogenic to Humans: Agents with limited animal evidence
and little or no human data.
* * * March 1999 Page 48 * * *
-------
Residual Risk Report to Congress
Group D - Not Classifiable as to Human Carcinogenicity: Agents without adequate
data either to suggest or refute the suggestion of the human carcinogenicity.
Group E - Evidence of Noncarcinogenicity for Humans: Agents that show no
evidence for carcinogenicity in at least two adequate animal tests in different species or in
both adequate epidemiologic and animal studies (EPA 1986b).
In 1996, EPA proposed major revisions of the carcinogen hazard identification scheme.
The proposed revision to the cancer risk assessment guidelines (EPA 1996b), which is expected
to be finalized in 1999, focuses on narrative statements describing the main lines of evidence and
their interpretation, in place of the current pre-defined hierarchical categories with alphabetic
designations. Rather than the three-step process used under the 1986 guidelines of separately
evaluating human evidence, evaluating animal evidence, and combining these judgments into an
overall weight of evidence (while considering the short-term test data), the proposed guidelines
suggest a single comprehensive evaluation process. This process stresses the explicit
consideration of coherence of the various data elements into one scientific interpretation that
evaluates, to the extent possible, how well the commonality of mode of carcinogenic action
between human beings and the various test systems has been established. Emphasis is also
placed on defining the qualitative conditions under which carcinogenic hazards might be
expected. If warranted, limitations to the finding of carcinogenic hazard can be drawn based on
route of exposure, necessity of some other factors for which tumorigenesis is necessary, and
doses below which elevation of cancer risk is not expected. Key differences in the hazard
identification step between the 1996 proposed revised cancer guidelines and the original 1986
guidelines are highlighted in Exhibit 10.
Dose-response Assessment
Dose-response assessment is the
characterization of the relationship between
the concentration, exposure, or dose of a
pollutant and the resultant health or
environmental effects. The nature of
quantitative dose-response assessment varies
among pollutants. Sufficient data often exist
for criteria air pollutants, such as ozone or
carbon monoxide, so that relatively complete
dose-response relationships can be
characterized. In such cases, there is no need
for extrapolation to lower doses because
adequate health effects data are available,
often in humans, at environmental levels.
Such is not the case for most air toxics. Most
DOSE-RESPONSE ASSESSMENT FOR MIXTURES
The EPA mixtures guidelines (EPA 1986c), which are
currently in the process of being updated (EPA 1997d),
indicate the following hierarchy for evaluating mixtures:
+ Use toxicity data on the specific mixture of concern;
+ If such data are not available, use toxicity information
on a similar mixture; and
+ If such data are not available, use toxicity information
on the components of the mixture.
It is unlikely that mixtures of HAPs from sources under
review for residual risk will have been studied as
independent entities because of their variability. Thus, the
default has been and will continue to be to evaluate data on
the individual mixture components, in accordance with
EPA's guidelines.
* * *
March 1999 Page 49
* * *
-------
Residual Risk Report to Congress
EXHIBIT 10
SUMMARY OF MAJOR DIFFERENCES IN THE HAZARD IDENTIFICATION STEP BETWEEN
EPA'S 1986 GUIDELINES (EPA 1986b) AND 1996 PROPOSED GUIDELINES
FOR CARCINOGEN RISK ASSESSMENT (EPA 1996b)
1986 Guidelines 1996 Proposed Guidelines
Weighing Evidence of Hazard
Decisions are based almost exclusively on tumor > Decisions take into account all available evidence (e.g..
findings in animals and/or humans. structure-activity relationships, mode of action).
Human and animal evidence are evaluated > All data are evaluated in a single comprehensive
separately and combined into the overall weight of evaluation process.
evidence.
Classification Descriptors
Substance is assigned a weight of evidence > A narrative statement with descriptors (e.g.,
classification (A through E) regarding its potential "known/likely" to be carcinogenic) is developed for a
to cause cancer in humans. substance, and includes information on the lines of
evidence, exposure pathways, conclusions, and
limitations.
epidemiologic and toxicologic data on HAPs typically result from exposure levels that are high
relative to environmental levels.
In summary, dose-response assessment methods for HAPs generally consist of two parts.
First is the evaluation of data in the observable range, and second is the extrapolation from the
observable range to low doses/risks. Recent terminology refers to the result of analysis in the
observable range as the "point of departure," from which extrapolation begins. The approaches
used for evaluation in the observable range are similar for all types of effects, while the Agency's
current extrapolation methods differ considerably for cancer and non-cancer effects.
Non-cancer Effects - Chronic. The inhalation RfC and oral RfD are the primary
Agency consensus quantitative toxicity values for use in non-cancer risk assessment. The RfC or
RfD is defined as an estimate, with uncertainty spanning perhaps an order of magnitude, of an
inhalation exposure/oral dose to the human population (including sensitive subgroups) that is
likely to be without appreciable risks of deleterious effects during a lifetime. The RfC or RfD is
derived after a thorough review of the health effects data base for an individual chemical and
identification of the most sensitive and relevant endpoint and the principal study(ies)
demonstrating that endpoint. As discussed above under hazard identification, not all effects that
can be observed in studies are determined to be adverse effects; a non-adverse effect would not
be selected as the critical effect on which to base an RfC or RfD. Inhalation RfCs are derived
according to the Agency's Methods for Derivation of Inhalation Reference Concentrations and
Application of Inhalation Dosimetry (EPA 1994e). The RfC or RfD should represent a synthesis
* * * March 1999 Page 50 * * *
-------
Residual Risk Report to Congress
of the entire data array. The evaluation of and choice of data on which to base the RfC or RfD
derivation are critical aspects of the assessment and require scientific judgment.
Derivation of the RfC or RfD begins with identification of the critical adverse effect from
the available valid human and animal study data, followed by identification of a lowest-observed-
adverse-effect level (LOAEL) or, preferably, a no-observed-adverse-effect level (NOAEL). The
LOAELs or NOAELs from animal studies are converted to human equivalent concentrations
(HECs) using dosimetric methods (described in EPA 1994e). The NOAEL[HEC] or
LOAEL[HEC] from one or a few studies that is representative of the threshold region of
observable effects is the key value gleaned from evaluation of the dose-response data. Recently,
the benchmark dose (BMD) or benchmark concentration (BMC) approach (described below) has
sometimes been used to effectively derive the LOAEL or NOAEL used as the "departure point"
for extrapolation to the human exposure of interest. The RfC or RfD is then derived by
consistent application of uncertainty factors (UFs) to account for recognized uncertainties in the
extrapolation from the experimental data and exposure conditions to an estimate (the RfC or
RfD) appropriate to the assumed human lifetime exposure scenario (EPA 1994e).
The standard UFs are applied as appropriate for the following extrapolations or areas of
uncertainty:
Laboratory animal data to humans;
Average healthy humans to sensitive humans;
Subchronic to chronic exposure duration;
LOAEL to NOAEL; and
Incomplete data base.
Other chemical-specific uncertainty factors (sometimes called modifying factors) may
also be applied for individual HAPs depending on the existing health effects data set. The UFs
that are generally applied range from a factor of three to an order of magnitude. The composite
UF will depend on the number of extrapolations required. RfCs have been derived using
composite UFs that range from 10 to 3,000, with most RfCs using factors of 100 to 1,000. The
UF for animal to human extrapolation in RfC development often is less than an order of
magnitude due to the dosimetric adjustments employed. It is also common that chemical-specific
information is used to reduce the UF in other extrapolations. For example, the subchronic to
chronic UF for acrylic acid was reduced because a comparison of two-week and 90-day studies
showed minimal difference in the incidence or severity of effect, suggesting that there was little
difference at various exposure durations. Likewise, the LOAEL to NOAEL extrapolation UF has
been reduced for several RfC derivations because the effect at the LOAEL was very mild. In
general, studies (e.g., Baird et al. 1996) have shown that the default UF of 10 may be
conservative in many cases, and the UF is therefore a key parameter for examination in
uncertainty analyses. When reductions in the UF are used, a factor of three is used as a
convention because it is a half-order of magnitude on a logarithmic scale (i.e., 10 1/2), rounded to
one significant figure. It is also common to reduce the composite UF when four areas of
* * * March 1999 Page 51 * * *
-------
Residual Risk Report to Congress
uncertainty are present, in recognition of the lack of independence of these areas. The result of
this procedure, subject to peer review, is an RfD for oral (ingestion) exposure to an agent or an
RfC for inhalation exposure. In addition to a numeric RfD or RfC, EPA also develops a degree
of confidence statement (of either high, medium, or low).
The use of order-of-magnitude uncertainty factors for RfCs and RfDs and the definition
of the RfC or RfD as having "uncertainty, spanning perhaps an order of magnitude" are
indications of the general lack of precision in the estimates. The uncertainty resulting from any
single area of extrapolation is not well understood or precisely defined. Current efforts to
develop more rigorous statistical descriptions of the uncertainty in extrapolating from, for
example, animals to humans or subchronic to chronic exposures may lead to a probabilistic
method for assigning UFs. The current state-of-the-art, however, relies on point estimates of
uncertainty and therefore results in point estimates of the RfC or RfD. The individual UFs are
generally considered to be somewhat conservative, when they have not been reduced in
conjunction with the availability of data relevant to the various extrapolations. It follows that the
greater the overall magnitude of the UF (i.e., the more individual UFs that were combined to get
the total UF), the more conservatism is included. The precision of "an order of magnitude"
should be considered to apply on the average. Less precision would be implied in the case of an
RfC with a greater UF (e.g., >1,000), and more precision would be suggested for RfCs with
lower overall UFs (e.g., <100). The relative precision and the magnitude of the composite UFs
will be important considerations in decisions involving comparisons of HQ for different
chemicals and in assessing the hazard index (HI) for a mixture of chemicals.
Recently, the BMC/BMD approach has been used to supplement the approaches based on
LOAELs and NOAELs. The BMD approach is an alternative to the NOAEL approach as a way
to identify a dose associated with a given level of response, or a dose without appreciable effect
based on experimental data. The BMD approach fits a dose-response curve to the data in the
observed experimental range. A lower bound on the dose causing some specified level of risk
above background (e.g., 10 percent) is calculated, and this dose value is used as a point of
departure for the application of UFs in place of the experimental NOAEL or LOAEL. That is, it
is taken as a standardized measure of a dose level near that at which an experimental response
would no longer be expected to be evident using standard study designs. The BMD considers the
entire data set, including the steepness of the dose-response relationship, accounts for the sample
size, and does not depend on a single data point as does the NOAEL. A primary problem with a
NOAEL is the wide range of risk that may be present at the NOAEL, depending on experimental
design; the benchmark approach minimizes this problem. The benchmark approach has been
used by EPA in several recent RfC and RfD assessments.
It should be noted that exposures above an RfD or RfC do not necessarily imply
unacceptable risk or that adverse health effects are expected. Because of the inherent
conservatism of the RfC/RfD methodology, the significance of exceedances must be evaluated
on a case-by-case basis, considering such factors as the confidence level of the assessment, the
* * * March 1999 Page 52 * * *
-------
Residual Risk Report to Congress
size of UFs used, the slope of the dose-response curve, the magnitude of the exceedance, and the
number or types of people exposed at various levels above the RfD or RfC.
Non-cancer Effects - Acute. Methods for dose-response assessment of acute exposures
are substantially similar to the approach for chronic exposure. Risk assessment for acute
inhalation exposure is complicated by the steep concentration-response curves that are often
observed, and because small differences in exposure duration (in some cases, a few minutes)
need to be taken into account. Because increased exposure duration increases the incidence and
severity of response, acute toxicity criteria or exposure guideline values are developed for a
specified duration (e.g., one hour). An acute toxicity study providing well-characterized
exposure and effects data for the exposure route of interest is used as the basis. Many acute
toxicity studies only report on the incidence of death. It is preferred, however, to base the
development of acute toxicity criteria on studies that evaluate additional endpoints, including
clinical signs, clinical chemistry, and histopathology. For an inhalation criterion, the exposure
duration of the study should ideally be the same as the one of interest (e.g., one hour). If
significant interpolation across exposure durations is required, multiple studies are preferred to
improve the quality of the interpolation. Such approaches based on applying uncertainty factors
to acute toxicity data points (e.g., LOAEL, lower 95 percent confidence limit on effective
concentration at 10 percent response (LEC10), NOAEL) have been developed and used by various
groups (see further discussion under following section, "Data Availability, Limitations, and
Closing Data Gaps"). We are currently developing a new Agency method for acute dose-
response assessment, the resultant value of which is termed an acute reference exposure (ARE)
(EPA 1998g).
In developing the new Agency method, in addition to the use of either a LOAEL or
NOAEL, or a BMC/BMD, an approach referred to as categorical regression is being evaluated.
This approach allows the combination of data from different studies in order to evaluate the role
of both exposure concentration and duration in producing the effect (EPA 1998g). Data are
combined by expressing various effects on a common scale of severity and performing a
regression analysis of severity versus concentration and duration. The results of a categorical
regression analysis are used in the same way as a BMC/BMD or a NOAEL, i.e., as the departure
point for extrapolation to the human exposure of interest. In the case of the NOAEL or the
BMC/BMD, the departure point is a point estimate. In categorical regression, the departure point
can be a line on a concentration versus time plot, with the result that any duration of acute
exposure can be interpolated along that line. The line is actually a composite of likelihood
estimates calculated from the regression results. For example, a concentration-time line
indicating the 10 percent likelihood of observing a specific category of effect, termed an ECT10
line, could be generated that is analogous to a BMD10 or BMC10 as a point of departure. The
appropriate approach for dose-response analysis will depend on the amount and quality of the
available data. In general, the NOAEL, BMC/BMD, and categorical regression techniques have
increasing data requirements, so the most appropriate approach will be dictated by the available
data with the expectation that use of the data intensive categorical regression method may be
* * * March 1999 Page 53 * * *
-------
Residual Risk Report to Congress
somewhat limited. After the best estimate of a point of departure is determined, the derivation of
the ARE proceeds with the consistent application of UFs.
Cancer. The EPA's cancer risk assessment guidelines of 1986 adopted a default
assumption that chemical carcinogens would exhibit risks at low doses (EPA 1986b).
Extrapolation of cancer risk using the linearized multistage model, which results in a linear
extrapolation of risk in the low dose region, was proposed as a reasonable upper-bound on risk,
and this approach has been used for most chemicals with adequate data since then. However, as
stressed in the Proposed Guidelines for Carcinogen Risk Assessment (EPA 1996b), when there
are adequate mechanistic data to suggest that other models would be more appropriate to
estimate low exposure risk, they may be used on a case-by-case basis. In the absence of such
data, the assumption of response linearity is maintained although the modeling scheme has been
simplified.
In cancer dose-response assessments relying on oral animal studies for which chemical-
specific data are not available to guide the scaling of results to human equivalents, a default
scaling factor based on the body mass raised to the 3/4 power of the test animals relative to
humans is generally used to calculate a human equivalent dose.9 For inhalation exposure studies,
dosimetric methods such as those used in developing RfCs are generally used to calculate a HEC
from animal data. Dose-response models such as the multistage model have historically been
used to calculate upper-bound unit risk estimates (UREs). Typically, EPA has relied on the URE
as a quantitative measure of potential cancer hazard. A URE represents an estimate of the
increased cancer risk from a lifetime (assumed 70-year) exposure to a concentration of one unit
of exposure. The URE for inhalation exposures is typically expressed as risk per //g/m3 for air
contaminants. The URE is a plausible upper-bound estimate of the risk (i.e., the risk is not likely
to be higher but may be lower and may be zero).
Since the publication of the EPA's original cancer guidelines (EPA 1986b), considerable
new knowledge has been developed regarding the processes of chemical carcinogenesis and the
evaluation of human cancer risk. Currently, a revision of the cancer guidelines is in process
(EPA 1996b) that represents a considerable departure from the original guidelines (see Exhibit
11 for key differences in the dose-response assessment step between the two sets of guidelines).
As mentioned above, a fundamental and important advance in the proposed revision is the
distinction between linear and nonlinear modes of action. The cancer data in the observable
range are analyzed using a dose-response model similar to the models used in the BMC approach
for non-cancer effects. The LED10 (the 95 percent lower confidence limit on dose associated
with the estimated 10 percent increase in tumor or tumor-related response) is proposed as a
9 As specified in the July 5, 1992, Federal Register (EPA 1992d), "in the absence of adequate information
on pharmacokinetic and sensitivity differences among species, doses of carcinogens should be expressed in terms of
daily amount administered per unit of body mass raised to the 3/4 power. Equal doses in these units (i.e., in
mg/kg3/4/day), when experienced daily for a full lifetime, are presumed to produce equal lifetime cancer risks across
mammalian species." This scaling method is assumed to be intermediate between scaling by body mass and scaling
by body surface area.
* * * March 1999 Page 54 * * *
-------
Residual Risk Report to Congress
EXHIBIT 11
SUMMARY OF MAJOR DIFFERENCES RELATED TO DOSE-RESPONSE ASSESSMENT BETWEEN
EPA'S 1986 GUIDELINES (EPA 1986b) AND 1996 PROPOSED GUIDELINES
FOR CARCINOGEN RISK ASSESSMENT (EPA 1996b)
1986 Guidelines
Default model used for linear dose-response
relationships is the "linearized multistage"
procedure.
Dose-response evaluation is limited to
carcinogenicity data.
1996 Proposed Guidelines
Biologically based dose-response models are used
whenever data are sufficient. Recommended default
approaches include the margin of exposure approach
and linear extrapolation to zero dose, zero response.
If appropriate, data on noncarcinogenic effects may be
used to help characterize the carcinogenicity dose-
response relationship.
possible point of departure for extrapolation, although other options are being considered. The
method of extrapolation to lower doses from the point of departure differs depending on whether
the assessment of the available data on the mode of action of the chemical indicates a linear or
nonlinear mode of action. A linear extrapolation is generally appropriate when the evidence
supports a mode of action of gene mutation due to direct DNA reactivity or another mode of
action that is thought to be linear in the low dose region. For linear extrapolation, a straight line
is drawn from the point of departure to the origin, and the risk at any concentration is determined
by interpolation along that line. A linear mode of action also will serve as a default when
available evidence is not sufficient to support a nonlinear extrapolation procedure, even if there
is no evidence for DNA reactivity.
An assumption of nonlinearity is used when there is sufficient evidence to support a
nonlinear mode of action. A nonlinear mode of action could involve a dose-response pattern in
which the response falls much more quickly than linearly with dose, but still indicating risk at
low doses. Alternatively, the mode of action may theoretically have a threshold if, for example,
the cancer response is a secondary effect of toxicity or an induced physiological change which is
a threshold phenomenon. In most cases, EPA will not try to distinguish between modes of action
with a "true threshold" and those that are nonlinear through the origin, because data are rarely
sufficient to make this determination. As a default science policy, nonlinear extrapolation to low
doses will not be performed because there is no current basis to choose a model or determine the
shape of the dose-response function. However, as more specific information on a HAP's
mechanism of action becomes available and where the data are sufficient to support the use of
alternative models, EPA will use them.
For carcinogens with nonlinear modes of action, the Agency has proposed a "margin-of-
exposure" (MOE) approach to cancer risk assessment (EPA 1996b). The MOE approach has also
be advocated as a method to harmonize cancer and non-cancer non-response assessment
methodology (Proposed Guidelines for Carcinogen Risk Assessment., EPA 1996b; CRARM
* * *
March 1999 Page 55
* * *
-------
Residual Risk Report to Congress
report, CRARM 1997b). In the proposed MOE approach, the point of departure as described
above is compared directly with the estimated exposure level (rather than having uncertainty
factors applied), and the current understanding of the phenomena that may be occurring as
exposure decreases below the observed data is considered. It is possible that the point of
departure will be based on effects other than tumor data if, for example, the cancer response is
determined to be secondary to a non-cancer effect.
In the proposal for this approach, the Agency recommends that additional dose-response
information also be supplied to the risk manager. The information should include points such as
the slope of the dose-response curve, the nature of the response, the human variability in
sensitivity, persistence of the agent in the body, and relative sensitivity of humans and animals.
The point of providing related information is to allow the risk manager to consider all aspects of
the data to inform the decision about the appropriate MOE and the amount of reduction in risk
associated with reduction in exposure below the point of departure. The endpoints relevant to the
cancer assessment are determined based on a review of all relevant data.
Linear Extrapolation. The dose-response approach for cancer-causing agents for which
there is evidence of direct-acting genotoxicity is to model the data in the observable range to
determine the point of departure (e.g., LEC10). The only difference between the LEC10 approach
and the BMC approach for non-cancer effects is that the cancer modeling may be done using a
single default approach, rather than the evaluation of several models and statistical comparisons
to determine the best-fitting model as currently proposed for non-cancer endpoints. Using the
LEC10 as the point of departure, the low-concentration extrapolation is done by extending a
straight line from the LEC10 to zero dose and zero risk (the origin). The risk at any exposure
concentration is then determined using that line. Exhibit 12 depicts the linear cancer dose-
response curve being discussed. The linearity assumption implies, among other things, that some
risk exists at low doses.
Nonlinear Extrapolation. The dose-response approach for nonlinear carcinogens is to
model the data in the observable range in the same way as for linear carcinogens. Extrapolation
from the point of departure (e.g., LEC10) would involve an MOE analysis in which various other
types of data would be considered to determine whether there is an adequate margin between the
estimated exposures and the point of departure. This approach is qualitatively different than the
linear extrapolation described above because the explicit consideration of exposure estimates
moves it into the realm of risk characterization. Exhibit 12 also depicts the MOE approach being
discussed.
Data Availability, Limitations, and Closing Data Gaps
Regardless of the endpoint of interest (acute, chronic non-cancer, or cancer effects),
consensus toxicity criteria are preferred for conducting risk assessments. For chronic non-cancer
and cancer criteria, the preferred source of data is EPA's IRIS. This data base provides toxicity
criteria that have undergone internal peer review, and, for recent assessments, external peer
* * * March 1999 Page 56 * * *
-------
Residual Risk Report to Congress
EXHIBIT 12
CANCER DOSE-RESPONSE CURVE
0)
(0
O
Q.
(0
0)
10%
0%
Extrapolation Range
Observed Range
Human
Exposure
of Interest
5r
-MOE-
LEC
-H-
10
EC
10
Concentration
Source: Adapted from EPA 1996b
review, and have been approved Agency-wide. The toxicological basis for the criterion is
provided, as well as other supporting data and information regarding the uncertainty in the
assessment. Other chronic toxicity criteria that have undergone less rigorous internal Agency
review are available in the Health Effects Assessment Summary Tables (HEAST), which may be
consulted for residual risk assessments when data are unavailable in IRIS. For HAPs not having
adequate toxicity information in IRIS, EPA will develop and follow a hierarchy of data sources,
including various kinds of Agency health effects assessment documents, ATSDR toxicological
profiles, and other sources. Consensus toxicity values for effects of acute exposures have been
developed by several different organizations, and EPA is beginning to develop such values. The
EPA also intends to develop and use a data source hierarchy for acute toxicity information.
Consequently, we will not be relying exclusively on IRIS values, but will be considering all
credible and readily available assessments. In more refined assessments, which may become the
basis for a risk management regulatory decision, we will consider all credible and relevant
toxicity information.
* * *
March 1999 Page 57
* * *
-------
Residual Risk Report to Congress
Significant progress is needed to improve the Agency's ability to comprehensively assess
risks of the 188 HAPs. Assessments are currently available in IRIS for approximately two-thirds
of the 188 HAPs, although these assessments may be incomplete. Inhalation assessment values
(either cancer or non-cancer) are available for slightly less than half. Reliance on assessments
from outside EPA, at least in initial screening-level assessments, provides inhalation assessment
values (either cancer or non-cancer) for approximately 80 percent. The need to update
assessments with newly available data as well as the need to round out the availability of
assessments for all HAPs increases the importance of Agency activities to update IRIS (EPA
1998h). The Agency is in the final stages of a pilot program of improvements to IRIS, and is
transit!oning to full implementation of the improved system. Among the improvements, EPA
has standardized the method for solicitation of scientific information from the public via a
Federal Register notice and the use of rigorous external peer review procedures for both IRIS
summaries and the new Toxicological Review documents. During fiscal year 1998, the Agency
was able to update IRIS files for 10 substances and may increase that number during fiscal year
1999 and future years.
Chronic Non-cancer Effects Assessment. For chronic non-cancer risk assessment, the
inhalation RfC and oral RfD are the primary quantitative consensus values used by EPA, the
primary source for which is EPA's IRIS. The derivation of these values was discussed in detail in
the dose-response section above. The RfC and RfD values in IRIS have undergone internal peer
review, and, for recent assessments, external peer review, and have been approved Agency-wide.
The toxicological basis for the values is provided, as well as other supporting data and
information regarding the uncertainty in the assessment. As the IRIS assessments for some
HAPs are less current than others, the Agency will evaluate the appropriateness of some
assessments in light of more recent credible and relevant information.
To begin closing the gaps in human health effects toxicity data for HAPs, especially in
IRIS, EPA has proposed a test rule for HAPs under section 4(a) of the Toxic Substances Control
Act (TSCA) (EPA 19971). Under the toxicity test rule, the Agency will require manufacturers
and processors of certain HAPs to test these substances for specific health effects. The data
collected under this test rule will be used in new or updated dose-response assessments for
placement on IRIS. This regulatory mechanism will assist EPA in filling data gaps for other
HAPs through future development of additional test rules. Improving the completeness of
toxicity testing data sets used in HAP dose-response assessments assists in reducing the
uncertainty in those assessments and any resultant risk assessments.
When chronic non-cancer toxicity criteria are not available from IRIS, several other
sources may be consulted to obtain values for use in residual risk assessments. Some of these
sources and criteria are summarized in Exhibit 13. These alternative sources use an approach
similar to the approach used to derive RfC and RfD values for IRIS. If appropriate criteria are
not available, the Agency may develop a provisional RfC or RfD using published EPA
methodology.
* * * March 1999 Page 58 * * *
-------
Residual Risk Report to Congress
EXHIBIT 13
EXAMPLES OF CHRONIC TOXICITY CRITERIA
Organization
Value
Definition and Basis
EPA/ORD
Integrated Risk
Information
System (IRIS)
Reference
Concentration
(RfC)/Reference
Dose (RiD) (EPA
1998i)
An RfC is an estimate (with uncertainty spanning perhaps an order of
magnitude) of a continuous inhalation exposure to the human population
(including sensitive subgroups) that is likely to be without an appreciable
risk of deleterious non-cancer effects during a lifetime. Similarly, an RiD
is an estimate (with uncertainty spanning perhaps an order of magnitude)
of a daily oral exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of deleterious
non-cancer effects during a lifetime. The RfC/RfD values in IRIS have
undergone rigorous review and received Agency-wide approval.
EPA/OSWER
Health Effects
Assessment
Summary Tables
(HEAST)
Reference
Concentration
(RfC)/Reference
Dose (RiD) (EPA
1997J)
The RfC/RfD definitions are identical to those for the IRIS RfCs/RfDs.
The HEAST is a comprehensive listing consisting almost entirely of
provisional risk assessment information for oral and inhalation routes for
chemicals of interest to Superfund, the Resource Conservation and
Recovery Act (RCRA), and EPA in general. Although the values in
HEAST have undergone review and have the concurrence of individual
Agency program offices, they have not had enough review to be
recognized as Agency-wide consensus information.
Agency for Toxic
Substances and
Disease Registry
(ATSDR)
Chronic Minimal
Risk Level (MRL)
(ATSDR 1998)
An MRL is an estimate of the daily human exposure (inhalation or oral)
to a hazardous substance that is likely to be without appreciable risk of
non-cancer health effects over a specified duration of exposure. The
intermediate exposure duration is 15-364 days, and the chronic exposure
duration is 365 days and longer. MRLs are derived similarly to RiDs and
RfCs; however, the ATSDR protocol uses different endpoints than EPA.
MRLs are developed by ATSDR as substance-specific health guidance
(i.e., screening) levels to identify contaminants of concern at hazardous
waste sites. The data undergo a rigorous review process, including
internal ATSDR reviews, peer reviews, and public comment periods.
NOTE: Criteria are available from other sources, including State agencies such as the California Environmental Protection
Agency, and may be considered as needed.
Acute Non-cancer Effects Assessment. EPA efforts are underway to develop acute
toxicity criteria with a consistent and sound scientific basis, including the AREs being developed
by EPA's ORD (EPA 1998g). The methodology was reviewed by EPA's SAB in June 1998 and
is being revised to address comments received. When they become available, AREs will be the
preferred values to be used for residual risk assessments. AEGLs are being developed by the
National Advisory Committee for AEGLs for Hazardous Substances (NAC/AEGL Committee), a
discretionary federal advisory committee. The NAC/AEGL committee follows procedures
consistent with NRC guidelines (NRC 1993). Proposed AEGL values for the first 12 chemicals
have been published for public comment (EPA 1997h). Acute toxicity criteria known as
emergency response planning guidelines (ERPGs) have been developed by the American
Industrial Hygiene Association (AJHA) for various severities of effects (AIHA 1998). In the late
* * *
March 1999 Page 59
* * *
-------
Residual Risk Report to Congress
1980s, EPA developed LOCs (levels of concern) for extremely hazardous substances (EHSs)
regulated under section 302 of the Emergency Planning and Community Right-to-Know Act
(EPA et al. 1987). These and selected other acute toxicity criteria are summarized in Exhibit 14.
EXHIBIT 14
EXAMPLES OF ACUTE TOXICITY CRITERIA
Organization
Value
Definition and Basis
EPA/ORD
Acute Reference
Exposure (ARE)
(EPA 1998g)
Exposure (concentration and duration of 1-24 hours) that is not likely to
cause adverse effects in the general population. Based on
NOAEL/LOAEL or surrogate and UFs. Exposure levels at which
increased mild (adverse effects level [AELJ-1), moderate/severe (AEL-2),
or frank (FEL) effects occur also considered. Method under
development.
Federal
Interagency Group
(includes EPA)
Acute Exposure
Guidance Level
(AEGL) (NRC
1993, EPA 1997h)
Under development by Federal Advisory Committee Act (FACA)
committee. First 12 proposed AEGLs recently published (EPA 1997h).
Concentrations for 1-8 hour exposure of the general population. Levels
that are expected to protect from discomfort (AEGL-1), disability
(AEGL-2), or life-threatening effects or death (AEGL-3). Based on
NOAEL/LOAEL or surrogate and uncertainty factors (UFs).
American
Industrial Hygiene
Association
(AIHA)
Emergency
Response
Protective
Guideline (ERPG)
(AIHA 1998)
Concentrations for exposure of the general population for durations up to
1 hour. Levels expected to protect individuals from other than mild,
transient (ERPG-1), irreversible or serious (ERPG-2), or life-threatening
(ERPG-3) effects. Based on weight of evidence and professional
judgment.
Agency for Toxic
Substances and
Disease Registry
(ATSDR)
Minimal Risk
Level (MRL)
(ATSDR 19xx)
For inhalation or oral exposure of the general population for up to 14
days, value at which adverse health effects not expected. Derived using
NOAEL/LOAEL and UFs, similar to RfCs/RfDs.
National Research
Council (NRC)
Short-term Public
Emergency
Guidance Level
(SPEGL) (NRC
1986)
Ceiling concentration for an unpredicted single exposure (1-24 hours)
designed to protect the general population. Based on professional
judgment.
EPA/OPPT
Level of Concern
(LOC) (EPA et al.
1987)
Concentration that may result in serious irreversible health effects or
death in the general population after exposure for a relatively short (1-
hour) period. Based on 0.1 x the IDLH (immediately dangerous to life
and health) level or surrogates. (Note: The LOC is no longer preferred
for emergency planning (EPA 1996e); AEGLs or ERPGs should be used
if available.)
NOTE: Criteria are available from other sources, including State agencies such as the California Environmental Protection
Agency, and may be considered as needed.
As for the chronic criteria, consensus values are preferred when available. If a suitable
consensus value is not available, the Agency may derive a provisional value from acute toxicity
data.
* * *
March 1999 Page 60
* * *
-------
Residual Risk Report to Congress
Cancer Assessment. As in the case of chronic non-cancer assessments, IRIS is the
primary source of Agency consensus criteria. The derivation of these values was discussed in
detail in the dose-response section above. The values in IRIS have undergone internal peer
review, and, for recent assessments, external peer review, and have been approved Agency-wide.
The toxicological basis for the values is provided, as well as other supporting data and
information regarding the uncertainty in the assessment. As the IRIS assessments for some
HAPs are less current than others, the Agency will evaluate the appropriateness of some
assessments in light of more recent credible and relevant information. The EPA HEAST
(described in Exhibit 13), as well as outside sources including State agencies, will also be
consulted as needed.
The cancer criterion may be qualitative, in the form of a classification regarding the
strength of the evidence concerning a chemical's carcinogenicity. Under the 1986 cancer
guidelines, this classification might be "B2, probable human carcinogen based on sufficient
evidence from animal studies." Under the proposed 1996 cancer guidelines, a chemical might be
classified as "likely to be a human carcinogen by any route of exposure." These classifications
represent the hazard identification phase. A dose-response assessment is also needed for any
quantitative risk assessment. For cancer, this is typically expressed as the cancer risk per unit
dose, or slope factor. If a consensus cancer criterion is not available from the hierarchy of
sources, a provisional value may be derived. In order to derive a cancer slope factor, data are
needed from a well-conducted lifetime carcinogenicity study, in which an adequate number of
tissues were evaluated histopathologically, and treatment-related cancer was observed. A
sufficient number of animals should have been used (generally 50/sex/dose), and the incidence
and type of tumor and other histopathologic lesions should have been reported. Using the cancer
incidence data, a linear extrapolation to zero from a point of departure is then used to calculate
the cancer risk per unit dose. Data on a chemical's pharmacokinetics, its genotoxicity, and other
information on its possible mode of action can be used to refine the assessment.
As is described previously, cancer dose-response assessments are not currently available
(within or outside EPA) for all HAPs. We have activities underway to increase the HAP
coverage in IRIS and to collect the toxicity data for these assessments.
3.4.2 Ecological Effects
In ecological effects characterization, risk assessors evaluate the relationship between
HAP exposure and adverse effects on the ecological assessment endpoints which might have
been identified at the population, community, or ecosystem level. A variety of sources of
ecological effects data can be used, such as field studies, laboratory studies, and SARs (see
Exhibit 15). The ecological effects characterization identifies causal information linking
exposure to the HAP with relevant observed ecological effects and determines the nature and
intensity of the effects and, if appropriate, the time scale for recovery after exposure ceases. The
effects estimates can be either point estimates of a specified effect level (e.g., a 20 percent
response level) or probabilistic estimates describing the entire stressor-response curve.
* * * March 1999 Page 61 * * *
-------
Residual Risk Report to Congress
EXHIBIT 15
SOURCES OF INFORMATION FOR ECOLOGICAL EFFECTS
Various types of original data are used for ecological effects characterization, some of which are common to the human
health effects data base.
> Human Health Data Base. With the exception of epidemiological data and controlled human exposures, the
lexicological data which are used in the hazard identification and dose-response steps of human health assessment are
also relevant to ecological effects, specifically for mammalian wildlife (see Exhibit 9).
> Laboratory Studies. Due to the limitations and expense of field studies and microcosm studies, most risk assessors
rely on laboratory ecotoxicology studies. These studies are typically easier to conduct, and effects can be directly
linked to exposure to a single HAP. There is uncertainty, however, in extrapolating the results from standard
laboratory species to the wide array of species in the environment. Additionally, in most cases, laboratory studies are
not designed to assess effects on populations, communities, and ecosystems.
> Field Studies. Studies of wildlife, populations, communities, and ecosystems exposed to HAPs in natural settings can
provide valuable information on the effects of HAPs. Field data can be valuable in demonstrating the presence or
absence of a cause-effect relationship that can provide a basis for prioritization or for recognizing the efficacy of a risk
reduction action. In many cases, however, wildlife are exposed to numerous types of stressors (chemical and non-
chemical), and the effects of individual HAPs can be difficult to isolate. In addition, field studies are conducted
infrequently due to the significant time and resources required.
> Microcosm Studies. Studies on the exposure of multi-species and multi-media enclosed experimental systems to
HAPs can control some of the uncertainty associated with multiple stressor exposure in field studies. These studies
can provide information about food web dynamics and the interactions of populations of organisms. As with field
studies, microcosm studies are time and resource intensive and, therefore, are relatively uncommon.
> SARs. In the absence of adequate ecotoxicology studies, scientists may rely on SARs. By using SARs, the toxic
effects of a HAP can be inferred based on the similarity of its chemical structure to a chemical whose ecotoxicity is
better understood. Types of SARs include: quantitative SARs (QSARs), qualitative SARs, and best analog SARs.
In the case of air toxics, ecological impacts can result from exposure to airborne HAPs
(e.g., via inhalation) or exposure to HAPs deposited or transferred to other environmental media
(e.g., water, soils). The HAP emissions can be assessed for both primary and secondary effects.
Primary effects (e.g., lethality, reduced growth, neurological/behavioral and impaired
reproduction) result from exposure of aquatic and terrestrial organisms to HAPs. An extreme
example of a primary effect might be deaths of waterfowl caused by an accidental release of an
extremely toxic chemical. HAPs which accumulate in plant and animal tissue provide a well
known example of a direct harmful effect on wildlife. During the 1950s and 1960s, DDT built
up in the wild food chain such that it caused thinning of eggshells of top predators such as bald
eagles and brown pelicans, which dramatically reduced the birds' hatching success. The
populations of these birds plummeted, driving them to the brink of extinction.
Secondary effects are the result of HAP action on supporting components of the
ecosystem (e.g., habitat destruction, loss of prey, and nutrient imbalances). These secondary
effects occur through biological interaction of one or more species' populations with individuals
or populations which have been primarily affected. For example, exposure to a toxic air
* * * March 1999 Page 62** *
-------
Residual Risk Report to Congress
pollutant may adversely effect one or more species of microscopic algae, bacteria, or fungus,
which can adversely affect an ecosystem's nutrient cycling and primary production. This can
lead to an alteration in the abundance, distribution, and age structure of a species or population
dependent on these microscopic organisms which can then lead to changes in competition and
food web interactions in other species. These ecosystem effects can be propagated to still other
populations, affecting their presence or representation within the ecosystem. A relatively simple
example of secondary effects involves the aerial application of pesticides in Canada which
dramatically reduced the population of an aquatic insect. This impact to the insect population
indirectly affected wild ducklings in the ecosystem which depend on the insects as a food supply
(Sheehan et al. 1987).
Both primary and secondary effects may occur within the same time frame of exposure,
but secondary effects tend to be long lasting and can persist well after the direct effects have been
eliminated because of the interrelationships among species in an ecosystem.
The HAP emissions also can be assessed for both local and regional impacts. Local
impacts, which apply to most HAPs, may be short-term or long-term and affect receptors near the
source. Regional impacts, which apply primarily to persistent and bioaccumulative HAPs, are
most often long-term and generally affect organisms both near to and distant from the source.
In assessing the potential for estimated exposures to pose environmental risks, the
available data relevant to the chosen assessment endpoints are reviewed and a measure of effect
is determined. Criteria (e.g., point estimates of thresholds for ecological effects) may be
calculated for site-specific ecological receptors depending on the importance of those receptors to
the local ecosystem, or for an endpoint not previously evaluated. For example, while some
criteria may be based on survival, growth, and reproductive success of a population, criteria
protective of a threatened or endangered species, a valuable game species (e.g., trout), or an
ecologically key species (e.g., wolf) might be based on an endpoint that is relevant to individual
organism health (e.g., a neurological deficit) rather than to population maintenance. On the other
hand, criteria based on higher effect levels (e.g., 20 to 50 percent or higher of the population is
affected) might be appropriate for species for which great functional redundancy exists in the
ecosystem (e.g., different herbaceous plants; see Lawton and Brown 1994). The "scaling up"
approach to analysis, inherently assumes that data evaluated at the individual or population level
are applicable to higher scales (e.g., community, ecosystem) or broader scales (e.g., landscape,
watershed, or ecosystem). As we develop more fully our methods for ecological risk assessment,
we will be carefully considering this issue.
Criteria may be developed for each combination of environmental medium and ecological
community described by the generic assessment endpoints in the conceptual model. For a
persistent HAP that might partition into all environmental media, criteria may be needed for all
of the following media/receptor combinations:
* * * March 1999 Page 63 * * *
-------
Residual Risk Report to Congress
Air/terrestrial animals exposed via inhalation;
Air/plants with their foliage exposed to the air;
Water/aquatic biota exposed via direct contact with water;
Sediments/benthic aquatic biota exposed via direct contact with sediments;
Soil/soil macro- and micro-invertebrates; and
Soil/plants.
For each medium/receptor combination identified above, the criteria are usually expressed as a
concentration of the HAP in the environmental medium. EPA ambient water quality criteria
(AWQC) for the protection of aquatic life are an example used by the Agency's Office of Water
in implementing the water quality protection sections of the CWA.
For a persistent HAP that might also bioaccumulate in plants or animals, a RfD
considered protective of wildlife that feed on those plants or animals would be needed along with
information on food ingestion rates for sensitive and most exposed animal species and
information on the degree of bioaccumulation in appropriate trophic components. Examples of
that approach for aquatic systems can be found in the Great Lakes Water Quality Initiative
(GLWQI) for mercury, DDT, PCBs, and 2,3,7,8-TCDD (EPA 1995d,e) and for terrestrial
systems in the EPA methods of assessing exposures to combustor emissions (EPA 1993b).
Development of stressor-response curves, instead of point estimates of effect, can provide
more information for and flexibility in evaluating risks. For example, stressor-response curves
can allow a description of the areal extent of a community that might be affected to differing
degrees (e.g., 40 percent mortality of soil invertebrates over 10 acres, 20 percent mortality over
the surrounding 100 acres, and less than 10 percent mortality of soil invertebrates in areas beyond
those 110 acres).
Data Availability, Limitations, and Closing Data Gaps
EPA's identification of appropriate criteria for use in the air toxics program and
specifically in residual risk analyses is an ongoing effort. Currently available criteria are being
evaluated to determine their applicability in residual risk analysis. The screening level of
analysis may use conservative criteria derived from no-observed-adverse-effect levels (NOAELs)
for a most sensitive species for the community in question. This reliance on a 'bottom up'
approach, which is similar to that relied upon in derivation of EPA water quality criteria for the
protection of aquatic life, is assumed to be more likely to overestimate rather than underestimate
risk. Other options are available for more refined analyses. And analyses for risk
management/risk reductions under residual risk would also take into account costs, safety,
energy, and other relevant factors, as specified under the CAA.
If appropriate ecotoxicity criteria are not available for a specific HAP, criteria may be
developed, if adequate toxicity data are available (types of data are described in Exhibit 15). The
* * * March 1999 Page 64 * * *
-------
Residual Risk Report to Congress
most appropriate laboratory tests are those that measure effects on survival, growth, and
reproduction.
Although some of the animal toxicity data used for human health assessment provide data
for mammalian effects assessment, it should be stated that data are lacking for effects endpoints,
especially for plants, birds, and wildlife. Data from field studies are also not widely available.
Additionally, there is a paucity of established criteria for environmental effects. There are no
data sets comparable to the IRIS or HEAST data bases for human health values. As part of our
tool and methodology development, we intend to identify an appropriate methodology for
development of ecological criteria. An example of ecological criteria the Agency has developed
are the ambient water quality criteria for the protection of aquatic life derived under the Clean
Water Act. Until we identify the appropriate criteria or criteria methodology for air toxics
assessments, the available effects data (e.g., EPA's AQUIRE, TERRETOX, and PHYTOTOX
data bases (EPA 1998J)) are considered appropriate for use in screening-level assessments, while
more refined assessments may require completion of more refined tools and the collection or
compilation of additional data.
3.5 Risk Characterization
The final step in the risk assessment process is the risk characterization, in which the
information from the previous steps is integrated and an overall conclusion about risk is
synthesized that is complete, informative, and useful for decision-makers. The nature of the risk
characterization will depend on the information available, the regulatory application of the risk
information, and the resources (including time) available. In all cases, however, major issues
associated with determining the nature and extent of the risk should be identified and discussed.
Further, EPA's March 1995 Policy for Risk Characterization (EPA 1995f) specifies that a risk
characterization "be prepared in a manner that is clear, transparent, reasonable, and consistent
with other risk characterizations of similar scope prepared across programs in the Agency."
EPA's 1995 Guidance for Risk Characterization (EPA 1995a) lists several guiding principles for
defining risk characterization in the context of risk assessment. The three principles with respect
to the information content and uncertainty aspects of risk characterization are as follows (EPA
1995a).
(1) The risk characterization integrates the information from the hazard identification,
dose-response, and exposure assessments, using a combination of qualitative
information, quantitative information, and information regarding uncertainties. A
good characterization should include different kinds of information from all portions of
the foregoing assessment, carefully selected for reliability and relevance.
(2) The risk characterization includes a discussion of uncertainty and variability. The
risk assessor must distinguish between variability (arising from true heterogeneity) and
uncertainty (resulting from a lack of knowledge).
* * * March 1999 Page 65 * * *
-------
Residual Risk Report to Congress
(3) Well-balanced risk characterizations present risk conclusions and information
regarding the strengths and limitations of the assessment for other risk assessors,
EPA decision-makers, and the public. "Truth in advertising" is an integral part of the
characterization, discussing all noteworthy limitations while taking care not to become
mired in analyzing factors that are not significant.
3.5.1 Human Health Effects
The 1995 Guidance for Risk Characterization (EPA 1995a) identifies several guiding
principles, shown in Exhibit 16, with respect to descriptions of risk.
EXHIBIT 16
GUIDING PRINCIPLES WITH RESPECT TO RISK DESCRIPTORS
Information about the distribution of individual exposures is important to communicating the results of a
risk assessment. Both high-end and central tendency descriptors are used to convey the variability in risk
levels experienced throughout the population.
Information about population exposure leads to another important way to describe risk. Both a
probabilistic number of cases (or environmental impacts) and an expected percentage of the exposed population
(or ecological resource) with risk greater than a certain level are valuable ways to present information.
Information about the distribution of exposure and risk for different subgroups of the population are
important components of a risk assessment. Highly susceptible individuals or areas should be identified as
well as those highly exposed, when possible.
Situation-specific information adds perspective on possible future events or regulatory options.
Consideration of alternative scenarios when conducting risk assessment can aid in risk management decisions.
An evaluation of the uncertainty in the risk descriptors is an important component of the uncertainty
discussion in the assessment. Both quantitative and qualitative evaluations of uncertainty can be useful to
users of the assessment.
Integration of Exposure and Effects Analyses
Risk assessments are intended to address or provide descriptions of risk to: (1)
individuals exposed at average levels and those in the high-end portions of the risk distribution;
(2) the exposed population as a whole; and (3) important subgroups of the population such as
highly susceptible groups or individuals (e.g., children), if known.
Individual Risk. Individual risk predictions are intended to estimate the risk borne by
individuals within a specified population or subpopulation. These predictions are used to answer
questions concerning the affected population, the risk levels of various groups within the
population, and the average or maximum risk for individuals within the populations of interest.
* * * March 1999 Page 66 * * *
-------
Residual Risk Report to Congress
Central Tendency Estimates of Risk are intended to give a characterization of risk for the
typical situation in which an individual is likely to be exposed. This may be either the
arithmetic mean risk (average estimate) or the median risk (median estimate), either of
which should be clearly labeled (EPA 1992a).
High-end Estimates of Risk are intended to estimate the risk that is expected to occur in a
small but definable segment of the population. The intent is to "convey an estimate of
risk in the upper range of the distribution, but to avoid estimates which are beyond the
true distribution. Conceptually, high-end risk means risk above about the 90th percentile
of the population distribution, but not higher than the individual in the population who
has the highest risk" (EPA 1992a).
Population Risk. Population risk predictions are intended to estimate the extent of risk
for the population as a whole. This typically represents the sum total of individual risks within
the exposed population.
Sensitive or Susceptible Subpopulations. Risk predictions for sensitive subpopulations
are a subset of population risks. Sensitive subpopulations consist of a specific set of individuals
who are particularly susceptible to adverse health effects because of physiological (e.g., age,
gender, pre-existing conditions), socioeconomic (e.g., nutrition), or demographic variables, or
significantly greater levels of exposure (EPA 1992a). Subpopulations can be defined using age,
race, gender, and other factors. If enough information is available, a quantitative risk estimate
for a subpopulation can be developed. If not, then any qualitative information about
subpopulations gathered during hazard identification should be summarized as part of the risk
characterization.
Because cancer and non-cancer dose-response assessment methods are currently quite
different, risk characterizations also differ and are discussed separately.
Non-cancer Effects. Unlike cancer risk characterization, non-cancer risks typically are
not expressed as a probability of an individual suffering an adverse effect. Instead, the potential
for non-cancer effects is evaluated by comparing an estimated exposure level over a specified
period of time (e.g., lifetime) with a reference
level such as an RfC (described in Section
3.4.1).
"Risk" for non-cancer effects
typically is quantified by comparing the
exposure to the reference level as a ratio.
The resultant HQ can be expressed as an
equation, where HQ = exposure/reference
level. Exposures or doses below the
reference level (HQ<1) are not likely to be
HAZARD QUOTIENTS AND HAZARD INDICES
The hazard quotient (HQ) is the ratio of the estimated
exposure to the health criterion level for a given chemical.
For example, for chronic inhalation exposure, the health
criterion could be the RfC. If the HQ is less than 1, the
RfC is not exceeded and health effects are unlikely. The
hazard index (HI) is the sum of the HQs for each chemical
considered to have a similar mechanism of action in a
mixture. The HI (for a mixture of i compounds) may be
calculated as: HI = HQ; + HQ2 + ...+ HQj. If the HI is <1,
health effects are unlikely.
* * *
March 1999 Page 67
* * *
-------
Residual Risk Report to Congress
associated with adverse health effects. With exposures increasingly greater than the reference
level (i.e., HQs increasingly greater than 1), the potential for adverse effects increases. The HQ,
however, should not be interpreted as a probability. Comparisons of HQs across substances may
not be valid, and the level of concern (LOG) does not increase linearly as exposures approach or
cross the reference level. This is because of the differences among reference levels in their
derivation and the fact that the slope of the dose-response curve above the benchmark can vary
widely depending on the substance and type of effect.
While some potential environmental hazards may involve significant exposure to only a
single compound, exposure to a mixture of compounds that may produce similar or dissimilar
non-cancer health effects is more common. In a few cases, reference levels may be available for
a chemical mixture of concern or for a similar mixture. In such cases, risk characterization can
be conducted on the mixture using the same procedures used for a single compound. However,
non-cancer health effects data are usually available only for individual compounds within a
mixture. In screening-level assessments for such cases, a conservative HI approach is sometimes
used (see text box above). This approach is based on the assumption that even when individual
pollutant levels are lower than the corresponding reference levels, some pollutants may work
together such that their potential for harm is additive and the combined exposure to the group of
chemicals poses greater likelihood of harm. Some groups of chemicals can also behave
antagonistically, such that combined exposure poses less likelihood of harm, or synergistically,
such that combined exposure poses harm in greater than additive manner. The assumption of
dose additivity is most appropriate to compounds that induce the same effect by similar modes of
action (EPA 1986c). As with the HQ, the HI should not be interpreted as a probability of risk,
nor as strict delineation of "safe" and "unsafe" levels (EPA 1986c; EPA 1989c). Rather the HI is
a rough measure of potential for risk and needs to be interpreted carefully. Although the HI
approach encompassing all chemicals in a mixture may be appropriate for a screening-level study
(EPA 1989c), it is important to note that application of the HI equation to compounds that may
produce different effects, or that act by different mechanisms, could overestimate the potential
for effects. Consequently, in a refined assessment, it is more appropriate to calculate a separate
HI for each non-cancer endpoint of concern when mechanisms of action are known to be similar
(EPA 1986c).
Cancer. Risks for cancer are generally expressed as either individual risks or population
risks. The distribution of exposures and individual risks within a given population can also be
presented, providing an estimate of the number of people exposed to various predicted levels of
risk. The Agency's risk characterization guidelines recommend that risk assessments describe
individual risk, population risk, and risk to important subgroups of the population such as highly
exposed or highly susceptible groups (EPA 1995a). For air toxics emissions, individual or
population cancer risks can be calculated by multiplying the corresponding exposure estimate by
the unit risk estimate (URE). Cancer risk is defined as the upper-bound probability of
contracting cancer following exposure to a pollutant at the estimated concentration over a 70-
year period (assumed human lifespan). This predicted risk focuses on the additional risk of
cancer predicted from the exposure being analyzed, beyond that due to any other factors.
* * * March 1999 Page 68 * * *
-------
Residual Risk Report to Congress
Estimates of risk are usually expressed as a probability represented in scientific notation as a
negative exponent of 10. For example, an additional risk of contracting cancer of 1 chance in
10,000 (or one additional person in 10,000) is written as IxlO"4. Because UREs are typically
upper-bound estimates, actual risks may be lower than predicted.
Population risk is an estimate that applies to the entire population within the given area of
analysis. Each estimated exposure level is multiplied by the number of people exposed to that
level and by the URE. For the great majority of HAPs for which the unit risk estimate is an
"upper confidence level" value, this provides an upper-bound prediction of cancer risk for that
group after a 70-year exposure to that level. The risks for each exposure group are summed to
provide the excess cancer cases predicted in the entire exposed population. This 70-year
population risk estimate is sometimes divided by 70 to obtain an upper-bound prediction of the
number of cancer cases per year.
When calculating individual or population risk, it is important to check the consistency
and validity of key assumptions, such as the averaging period for exposure, the exposure route,
absorption adjustments, and spatial consistency.
People are often exposed to multiple chemicals rather than a single chemicals. In those
few cases where cancer potency values and UREs are available for the chemical mixture of
concern or for a similar mixture, risk characterization can be conducted on the mixture using the
same procedures used for a single compound. However, cancer dose-response assessments and
UREs are usually available only for individual compounds within a mixture. Consequently, in
screening-level assessments of carcinogens for which there is an assumption of a linear dose-
response, the cancer risks predicted for individual chemicals may be added to estimate total risk.
This approach is based on an assumption that the risks associated with individual chemicals in
the mixture are additive. The assumption of additivity is generally considered conservative. In
more refined assessments, the chemicals being assessed need to be evaluated for this concern.
The following equation estimates the predicted incremental individual cancer risk, assuming
additivity, for simultaneous exposures to several carcinogens:
RiskT = Riskj + Risk2 + ....+ Riskj
where:
Rj _ the total cancer risk (expressed as an upper-bound risk of contracting
cancer over a lifetime)
Rj = the risk estimate for the ith substance.
A variation of the additivity approach is used for some mixtures of structurally similar
carcinogens for which cancer slope factors (i.e., measures of potency) are not available for all
mixture components. For carcinogenic dioxins and furans, for example, a toxic equivalency
factor (TEF) approach is used as described in EPA's dioxin reassessment document (EPA
* * * March 1999 Page 69 * * *
-------
Residual Risk Report to Congress
1994f). In this approach, which has an underlying assumption of additivity across mixture
components, the cancer potency of certain dioxin and furan congeners is estimated relative to
2,3,7,8-TCDD based on other toxicity information that is available for all the congeners (e.g.,
LD50). Then, TEFs based on these relative cancer potencies are used to adjust the exposure
concentrations of mixture components, which are subsequently summed into a single exposure
concentration for the mixture. That exposure concentration based on TEFs is then used, along
with the 2,3,7,8-TCDD slope factor, to estimate cancer risks for the mixture.
For carcinogens being assessed based on the assumption of nonlinear dose-response, the
MOE approach may be considered, consistent with the proposed revision of EPA's cancer
guidelines (EPA 1996b). As described in Section 3.4.1, the MOE approach leaves the decision
about the appropriate reduction in exposure compared to the point of departure (i.e., the
observable toxicity data) up to the risk manager. An in-depth MOE analysis would be made in
consideration of factors that could include the steepness of the dose-response curve, persistence
of the compound in the body, known human variability in response, or demonstrated human
sensitivity as compared with experimental animals. In a typical case, the point of departure
derived from modeling the observable data would be a tumor incidence of 10 percent (e.g., risk
of 1 in 10). If the chemical fits a linear mode of action, a reduction in the dose of 1,000 would
result in an estimated risk of 1 in 10,000. For a nonlinear mode of action, a reduction of the
same magnitude would lead to a much lower risk because of the nonlinearity in the dose-
response slope. If the mode of action includes a threshold below which there is no risk of cancer,
such a reduction could lead to a zero cancer risk.
Since neither thresholds nor risk are explicitly estimated, there is no analogous form of
the simple dose addition approach that is amenable to assessment of mixtures of nonlinear
carcinogens. Since the MOE analysis is done on a case-by-case basis, the determination of the
appropriate "acceptable" MOE for each component would be required before a mixtures
assessment could be performed. It is also not clear how the MOE approach should handle effects
in different target organs or with different modes of action. A consideration of the mode of
action that leads to the conclusion that the nonlinear dose-response evaluation is appropriate can
also provide information relevant to whether nonlinear carcinogens should be considered
additive. While the Agency's current mixtures guidelines (EPA 1986c) do not address nonlinear
carcinogens, they generally recommend the assumption of additivity for carcinogens unless
contrary information is available. Carcinogenic substances showing nonlinear modes of action
through unrelated mechanisms or in different tissues would not generally be combined.
Interpretation and Presentation of Risks
In the risk characterization step of final assessments under residual risk, the estimates of
health risk will be presented in the context of uncertainties and limitations in the data and
methodology. Additionally, information relevant to public health context of the residual risk will
be presented. This may include, as available, information on relevant health effects occurring in
the study population. Available epidemiological studies or other human health data will be
* * * March 1999 Page 70 * * *
-------
Residual Risk Report to Congress
discussed and presented along with a summary of the hazard identification and dose-response
information for the HAPs being assessed. Uncertainties and limitations related to the hazard
identification and dose-response assessment may also be discussed. Uncertainty analyses and the
presentation of uncertainties is discussed in more detail in Section 4.2.3.
The degree to which all types of uncertainty need to be quantified and the amount of
uncertainty that is acceptable varies. For a screening-level analysis, a high degree of uncertainty
is often acceptable, provided that conservative assumptions are used to bias potential error
toward protecting human health. Similarly, a region-wide or nationwide study will be more
uncertain than a site-specific one. In general, the more detailed or accurate the risk
characterization, the more carefully uncertainty needs to be considered.
On May 15, 1997, EPA issued a document entitled Policy for Use of Probabilistic
Analysis in Risk Assessment (EPA 1997k). It also issued an accompanying document entitled
Guiding Principles for Monte Carlo Analysis (EPA 1997c). The policy and guiding principles
are designed to support the use of various quantitative techniques for characterizing variability
and uncertainty, a critical part of a complete risk characterization. The policy establishes
conditions that are to be satisfied by risk assessments that use probabilistic techniques. These
conditions relate to the good scientific practices of clarity, consistency, transparency,
reproducibility, and the use of sound methods. Exhibit 17 provides the conditions for an
acceptable risk assessment that uses probabilistic analyses techniques. EPA's position, as stated
in these documents, is "that such probabilistic analysis techniques as Monte Carlo analysis, given
adequate supporting data and credible assumptions, can be viable statistical tools for analyzing
variability and uncertainty in risk assessments."
Data Availability, Limitations, and Closing Data Gaps
The NRC, in its recent review of EPA's risk assessment methodology for HAPs (NRC
1994), recommended that uncertainty and variability should be quantified and the distinction
between uncertainty and variability maintained throughout the assessment. A model under
development by EPA for air toxics risk assessments, TRIM, will do this explicitly. In the
interim, a Monte Carlo assessment is sometimes conducted on the risk estimates produced by
HEM or other methods. At present, such assessments primarily address variability, while
uncertainty is largely described qualitatively. The variability assessment considers variation in
such factors as the number of years residents occupy their primary residences, number of hours
per day people are at home, breathing rates across the exposed population, the amount of ambient
pollution that infiltrates to the indoor microenvironment, and certain meteorological variables.
Thus, the results of the assessment may be expressed in probabilistic terms, potentially providing
the risk manager and the affected public with more information than was previously provided.
However, care must be taken in the interpretation of such analyses, as they are only as reliable as
the underlying data and assumptions. Uncertainty in risk assessment is discussed further in
Section 4.2.3.
* * * March 1999 Page 71 * * *
-------
Residual Risk Report to Congress
EXHIBIT 17
CONDITIONS FOR AN ACCEPTABLE RISK ASSESSMENT THAT USES
PROBABILISTIC ANALYSIS TECHNIQUES
> The purpose and scope of the assessment should be clearly articulated in a "problem formulation" section that includes
a full discussion of any highly exposed or highly susceptible subpopulations evaluated (e.g., children, the elderly, etc.).
The questions the assessment attempts to answer are to be discussed and the assessment endpoints are to be well
defined.
> The methods used for the analysis (including all models used, all data upon which the assessment is based, and all
assumptions that have a significant impact upon the results) are to be documented and easily located in the report. This
documentation is to include a discussion of the degree to which the data used are representative of the population under
study. Also, this documentation is to include the names of the models and software used to generate the analysis.
Sufficient information is to be provided to allow the results of the analysis to be independently reproduced.
> The results of sensitivity analyses are to be presented and discussed in the report. Probabilistic techniques should be
applied to the compounds, pathways, and factors of importance to the assessment, as determined by sensitivity analyses
or other basic requirements of the assessment.
> The presence or absence of moderate to strong correlations or dependencies between the input variables is to be
discussed and accounted for in the analysis, along with the effects these have on the output distribution.
> Information for each input and output distribution is to be provided in the report. This includes tabular and graphical
representations of the distributions (e.g., probability density function and cumulative distribution function plots) that
indicate the location of any point estimates of interest (e.g., mean, median, 95th percentile). The selection of
distributions is to be explained and justified. For both the input and output distributions, variability and uncertainty are
to be differentiated where possible.
> The numerical stability of the central tendency and the higher end (i.e., tail) of the output distributions are to be
presented and discussed.
> Calculations of exposures and risks using deterministic (e.g., point estimate) methods are to be reported if possible.
Providing these values will allow comparisons between the probabilistic analysis and past or screening-level risk
assessments. Further, deterministic estimates may be used to answer scenario-specific questions and to facilitate risk
communication. When comparisons are made, it is important to explain the similarities and differences in the
underlying data, assumptions, and models.
> Because fixed exposure assumptions (e.g., exposure duration, body weight) are sometimes embedded in the toxicity
metrics (e.g., reference doses, reference concentrations, unit cancer risk factors), the exposure estimates from the
probabilistic output distribution are to be aligned with the toxicity metric.
Source: EPA 1997c
Information on health status of local study populations is not usually readily available.
With regard to cancer prevalence and incidence, yearly estimates are available on a national basis
from the National Cancer Institute's Surveillance Epidemiology and End Results Project (e.g.,
Ries et al. 1998). Additionally, many States now maintain cancer registries consistent with
National Cancer Institute recommendations. In order to provide some public health context for
predicted cancer risks, relevant information from these sources will be accessed. Less
information is available on the prevalence or incidence of other health effects. Federal public
health agencies such as the Centers for Disease Control will be consulted. Rates for diseases as
causes of death are available from the National Center for Health Statistics. Many States have
* * * March 1999 Page 72 * * *
-------
Residual Risk Report to Congress
surveillance requirements beyond those for CDC reporting (e.g., certain birth defect registries).
Information on the proportion of cancer and other health effects that may be associated with
environmental exposures would need to be identified to put overall incidence data in the
appropriate perspective.
3.5.2 Ecological Effects
Integration of Exposure and Effects Analyses
Risk characterization is the final phase of an ecological risk assessment in which risks are
described and estimated by integrating the estimates of exposure and effects developed in the
analysis phase. As described in EPA's guidelines (EPA 1998d), and implied in the residual risk
decision framework described in Section 5.3, this process requires comparison of the exposure
and stressor-response profiles developed during the analysis. In this step exposure
concentrations are compared to (1) published background concentrations in media and biota and
(2) the levels estimated to cause adverse effects on the assessment endpoints. Generally, there
are two ways to quantitatively estimate risks - point estimates and probabilistic estimates - and
each has its advantages and disadvantages. One example of a quantitative ecological risk
assessment is presented in Exhibit 18. Another example is the EPA Region 5 risk assessment
for a hazardous waste incinerator in East Liverpool, Ohio (EPA 19971). Additional case studies
of quantitative ecological risk assessments are presented in Paustenbach (1989) and Maughan
(1993).
The point estimate approach, which has been used in numerous EPA ecological risk
assessments, uses single values (usually upper-bound estimates) to represent key variables in the
assessment (Finley and Paustenbach 1994). The approach is relatively simple and
straightforward; however, there are several major limitations. The repeated use of upper-bound
point estimates can lead to unrealistically conservative risk estimates. In addition, point
estimates provide a limited amount of information to the risk manager and the public. Therefore,
the point estimate approach is most useful as a screening approach that approximates a plausible,
worst case situation for some potentially exposed receptors.
In contrast, the probabilistic approach uses a distribution of data rather than a single point
to represent key variables in the assessment (Finley and Paustenbach 1994). This method makes
much greater use of the available exposure and toxicity data than the point estimate approach and
provides more information to the risk manager. Instead of yielding a single point estimate of
risk, the probabilistic approach provides a range of potential risks as well as their likelihood of
occurrence. In addition, a probabilistic assessment is more conducive to sensitivity and
quantitative uncertainty analysis. Major disadvantages of probabilistic assessments are that they
require more time and resources and are more difficult to communicate or "sell" to some
stakeholders. Another difficulty is that information on the distribution of input values is often
lacking or uncertain.
* * * March 1999 Page 73 * * *
-------
Residual Risk Report to Congress
EXHIBIT 18
AN ECOLOGICAL RISK ASSESSMENT CASE STUDY: OZONE RISKS TO AGROECOSYSTEMS
The case study summarized here provides an example of how EPA has assessed environmental risks from an air pollutant
(ozone) under the National Ambient Air Quality Standards (NAAQS) program (EPA 1993a; EPA 1996f). In 1997, EPA
set a new NAAQS for ozone (EPA 1997m). The new secondary standard was set at a level judged by the Administrator to
"provide increased protection against adverse effects to public welfare ...," including "... against ozone-induced effects on
vegetation, such as agricultural crop loss, damage to forests and ecosystems, and visible foliar injury to sensitive species."
This example highlights ecological risk assessment concepts and methods.
> Problem Formulation. Under the CAA, EPA is required to set NAAQS for "any pollutant which, if present in the
air, may reasonably be anticipated to endanger public health or welfare and whose presence in the air results from
numerous or diverse mobile and/or stationary sources." EPA develops public health (primary) and welfare
(secondary) NAAQS. According to section 302 of the CAA, the term welfare "includes ... effects on soils, water,
crops, vegetation, manmade materials, animals, wildlife, weather, visibility, and climate, damage to and deterioration
of property, and hazards to transportation, as well as effects on economic values ...". A secondary standard, as
defined in section 109(b)(2) of the CAA, must "specify a level of air quality the attainment and maintenance of which
in the judgment of the Administrator, based on such criteria, is requisite to protect the public welfare from any known
or anticipated adverse effects associated with the presence of such air pollutant in the ambient air."
This case study focuses on an assessment endpoint for agricultural crops (e.g., the prevention of an economically
adverse reduction in crop yields). Yield loss is defined as an impairment of, or decrease in, the value of the intended
use of the plant. This concept includes a decrease in the weight of the marketable plant organ, reduction in aesthetic
values, changes in crop quality, and/or occurrence of foliar injury when foliage is the marketable part of the plant.
These types of yield loss can be directly measured as changes in crop growth, foliar injury, or productivity, so they
also serve as the measures of effect for the assessment.
> Exposure Analysis. The EPA used ambient ozone monitoring data across the U.S. and a Geographic Information
System (GIS) model to project national cumulative, seasonal ozone for the maximum three month period during the
summer ozone season. This allowed EPA to project ozone concentrations for some rural parts of the country where
no monitoring data were available but where crops were grown, and to estimate the attainment of alternative NAAQS
scenarios. The USDA's national crop inventory data were used to identify where ozone-sensitive crop species were
being grown and in what quantities. This information allowed the Agency to estimate the extent of exposure of
ozone-sensitive species under the different scenarios.
> Ecological Effects Analysis. Stressor-response profiles describing the relationship between ozone and growth and
productivity for 15 crop species representative of major production crops in the U.S. (e.g., crops that are economically
valuable to the U.S., of regional importance, and representative of a number of crop types) had already been
developed from field studies conducted from 1980 to 1986 under the National Crop Loss Assessment Network
(NCLAN) program. The NCLAN studies also included secondary stressors (e.g., low soil moisture and co-exposure
with other pollutants like sulfur dioxide), which helped EPA interpret the environmental effects data for ozone.
> Risk Characterization. Under the different NAAQS scenarios, the Agency estimated the increased protection from
ozone-related effects on vegetation associated with attainment of the different NAAQS scenarios. Monetized
estimates of increased protection associated with several alternative standards for economically important crops were
also developed. This analysis focused on ozone effects on vegetation since these public welfare effects are of most
concern at ozone concentrations typically occurring in the U.S. By affecting commercial crops and natural
vegetation, ozone may also indirectly affect natural ecosystem components such as soils, water, animals, and wildlife.
Mixtures. As with non-cancer assessments of human health risks, when ecological
toxicity data for complex mixtures are unavailable, the HI approach may be used, as scientifically
appropriate, to integrate the ecological risks of multiple chemical stressors (EPA 1996d). HQs
for the individual constituents in a mixture are derived by dividing each
* * * March 1999 Page 74 * * *
-------
Residual Risk Report to Congress
constituent's exposure level by a corresponding criterion for ecological effects. The resulting
quotients would then be added together to generate an HI for the mixture for each media/receptor
combination (e.g., air/terrestrial animals or water column/aquatic organisms). Use of the HI
approach assumes that the toxicities of the mixture constituents are additive or close to additive.
This assumption is likely to be true for mixtures of chemicals that have similar modes of action;
however, it may be unrealistic to default to a molecular mechanism of toxicity for ecological risk
analyses.
Screening-level risk assessment may use the HI approach to estimate the risks of mixtures
of HAPs to ecological receptors, but the assumptions and associated limitations concerning HAP
interactions should be clearly stated in the assessment's documentation. It may often be the case
that a single chemical is responsible for the HI exceeding 1, and the assessment can then move
forward with focus on that chemical. In more refined assessments, assumptions inherent in the
use of the HI will need to be carefully evaluated with regard to scientific appropriateness.
A major limitation of the HI approach is that it provides a point estimate of the risk and is
clearly a one dimensional model that relies on concentration (Suter 1993). Additionally, given
the lack of fundamental knowledge of effects at the molecular level for most pollutants, it may be
unrealistic to assume a molecular mechanism of toxicity as a means of addressing mixtures of all
HAPs. In the future, we may need to consider how chemicals affect critical processes governing
fitness of the ecosystem (e.g., photosynthesis in plants, reproduction) in our ecological risk
assessments.
Interpretation and Presentation of Risks
The previous discussion on interpretation and presentation of risk in Section 3.5.1 is also
applicable with regard to ecological risk characterization. As previously mentioned, the risk
characterization phase should include a summary of the strengths, limitations, assumptions, and
major uncertainties associated with the risk estimates. Uncertainty analysis in risk assessment is
also discussed further in Section 3.5.1 and Section 4.2.3.
As with presentation of human health risks, assessments of environmental risk from air
toxics should be presented in context of available information regarding other risks in addition to
a summary of the exposure and effects characterizations and their integration. Depending on the
problem formulation and analysis plan for the ecological risk assessment, social and economic
concerns may need to be incorporated into the more refined assessments. In residual risk
management decisions, various other factors must be considered along with the information
presented in the characterization of risk of adverse environmental effect. These include "costs,
energy, safety, and other relevant factors." These considerations will be documented with the
risk management decision.
* * * March 1999 Page 75 * * *
-------
Residual Risk Report to Congress
EXAMPLES OF CONSIDERATIONS FOR
DETERMINING ECOLOGICAL SIGNIFICANCE
How large is the area where ecological criteria have
been exceeded?
What proportion of the habitat is affected at local,
county, State, and national levels?
Are the exposure concentrations and ecological
criteria above background levels for the area of
interest?
What types of ecological impacts have been associated
with this pollutant or similar pollutants in the past?
Is the criterion or stressor-response curve based on
high quality data (i.e., is there a high degree of
confidence in the criterion)?
What are the costs, energy, safety, and other relevant
considerations required for decision-making?
Without calibrated or validated
population models, professional judgment is
needed to estimate the ecological significance
of contaminant concentrations that exceed
levels associated with varying magnitudes of
effect on different species or communities.
Unless an endangered or threatened species is
at issue, society is generally not concerned
with the death of individual plants or animals.
For other species, it is unlikely that a few
percent additional mortality of individuals
could result in population-level effects that
might impair ecosystem structure and
function. However, it is extremely difficult to
estimate how much additional contaminant-
induced mortality or reduced reproductive
success a population can compensate for
before population levels begin to decline,
particularly if the population is subject to
other stresses. These issues, which should be
considered in the development of assessment endpoints in the problem formulation phase, should
then be confirmed and described in the risk characterization.
Data Availability, Limitations, and Closing Data Gaps
Although our development of tools, data, and methods for ecological risk assessment of
air toxics is in its early stages, the Agency has some experience in ecological risk assessment for
air toxics (e.g., EPA 19971) and other air pollutants (see Exhibit 18). A lack of certain types of
criteria (e.g., for wildlife inhalation) and of criteria of any type for many of the HAPs may
handicap our analyses, especially in the early stages. As part of data development for air toxics
assessment, the Agency is in the process of identifying and assessing the available data and data
bases for various ecological receptors.
As the Agency refines its tools, there are many issues we will try to address. For
example, the issue of chemical residence times in the environment and the scale of ecological
analysis is important (e.g., if a chemical has a residence time of a month or more, then the
distribution of the chemical can approach hemispheric proportions). Longer residence times in
the atmosphere will lead to global distributions and in order to more comprehensively address
this issue, risk assessment methods may need the ability to scale appropriately.
* * *
March 1999 Page 76
* * *
-------
Residual Risk Report to Congress
4. Other Statutory Report Requirements of Section 112(f)(1)
The preceding chapter describes the methods and general process that will be used for
performing human and ecological risk assessment under residual risk and other components of
the air toxics program. The general analysis framework that the Agency is currently evaluating
for use in the residual risk program is described in Chapter 5. The remaining elements required
by statute to be covered in the section 112(f)(l) Report to Congress are addressed in this chapter.
Additional aspects of some of these topics are also covered in other parts of this Report.
4.1 Section 112 (f)(1)(B)
Section 112(f)(l)(B) of the Clean Air Act directs EPA to investigate and report on "the
public health significance of such estimated remaining risk and the technologically and
commercially available methods and costs of reducing such risks." These topics are presented in
the following two sections.
4.1.1 Public Health Significance
This section addresses the directive in CAA section 112(f)(l)(B) that EPA investigate and
report on "the public health significance of such estimated remaining risk." At present, the data
are not available to conduct an analysis to determine the public health significance for residual
risk from air toxics. Given the legislatively mandated schedules for MACT implementation and
for performing residual risk assessments, analyses have not yet been completed on any source
categories for the purposes of estimating potential residual risks. Without these analyses, it is not
possible to determine at this time what the public health significance of any residual risks may
be.
As residual risk assessments are completed for individual source categories, information
relevant to public health context, as available, will be presented in the risk characterization step
(see Section 3.5.1) of the final analysis. This information will include, for each source category
or source, the estimated risks to public health remaining after MACT is in place, health effect
information, and the attendant uncertainties. Additional available public health information
relevant to the risks predicted may also be presented. For example, in the case of estimates of
cancer risk, available relevant information on cancer incidence or prevalence may be presented
with whatever specificity (e.g., cancer type relevant to HAP cancer hazard information,
geographic unit relevant to the source or source category) is feasible. Estimates of non-cancer
risk may be presented with a discussion of the health effects of concern and presentation of
readily available information regarding prevalence of those health effects, as appropriate. The
Agency recognizes, however, that availability of information on the health status of populations,
especially on a local basis, is currently quite limited. While this is improving in some areas, such
as in states that maintain cancer registries in accordance with National Cancer Institute
* * *
March 1999 Page 11***
-------
Residual Risk Report to Congress
specifications, among the general population there are many other health effects for which HAPs
pose potential risks that are not well tracked.
The available public health information will be considered along with estimated risks and
uncertainties in the application of the ample margin of safety framework as part of the decision-
making process of the risk management step (Section 5.3.6).
The Agency considers the ample margin of safely concept as introduced in the 1970 CAA
Amendments, and as applied in the benzene standard (EPA 1989a), a reasonable approach to
evaluate public health significance and to manage residual risks under CAA section 112. Such
an approach is consistent with the Congressional language in section 112(f)(2) (see Appendix A).
The 1989 benzene NESHAP presented a structure for applying ample margin of safety to setting
standards for carcinogens. This two-step structure included an analytical first step to determine
an "acceptable risk" after considering all health information, including risk estimation
uncertainty. In the case of benzene, a linear carcinogen, this included a presumptive limit on
maximum individual lifetime cancer risk of approximately 1 in 10 thousand. In the second step,
the standard is set at a level that provides an ample margin of safety in consideration of all health
information, including the number of persons at risk levels higher than approximately 1 in 1
million, as well as other factors such as costs and economic impacts, technological feasibility,
and factors relevant to the particular decision.
4.1.2 Available Methods and Costs of Reducing Residual Risks
Section 112(f)(l)(B) of the CAA directs EPA to investigate and report on "the
technologically and commercially available methods and costs of reducing [residual] risks" from
HAPs. This section of the Report provides a broad characterization of post-MACT emissions,
an overview of control strategies, and a discussion of key factors that will influence the available
methods and costs.
Two general types of strategies can be used to reduce the human health and
environmental risk associated with HAP exposure. One is to limit releases into the atmosphere.
These "pre-release" strategies employ various control technologies and pollution prevention
methods developed by industry to comply with regulations requiring them to reduce HAP
emissions. A second approach, applicable primarily to protecting public health, is through the
adoption of "post-release" strategies to keep people out of HAP exposure pathways - that is, to
eliminate or minimize contact between people and HAP-contaminated media. Measures of this
type can include institutional and regulatory approaches such as zoning controls and advisories,
which limit public access to areas that contain unhealthful HAP concentrations, fishing
restrictions and fish consumption advisories, and provision of alternate drinking water supplies.
These strategies are used most often in cases where unregulated sources already have emitted
large quantities of pollutants, or as emergency response measures to protect the public from
pollution caused by accidents or spills.
* * *
March 1999 Page 78 * * *
-------
Residual Risk Report to Congress
Pre-release strategies have traditionally been the preferred method to protect the public
from exposure to harmful pollutants because they minimize the impact on the environment and
place the burden of managing wastes on the source itself. Pre-release methods are consistent
with our environmental management philosophy of encouraging pollution
prevention/recycling/treatment first, and pollution disposal/release only as a last resort. Hence,
this section focuses on the technologically and commercially available pre-release strategies that
can be used to reduce residual risk.
Given the site-specific and HAP-specific nature of control technology and cost
determinations, combined with the fact that there are 188 HAPs and more than 170 source
categories and that no post-MACT risk assessments for source categories have been completed,
an in-depth discussion of the specific methods and costs of controlling post-MACT HAP
emissions is beyond the scope of this Report. Instead, the remainder of this section presents a
brief review of some of the emissions control strategies employed under the MACT requirements
and discusses how these strategies will influence the available options for further reducing the
risks of HAP emissions to the general public. A discussion of general MACT requirements is
followed by an overview of currently available control strategies, with an emphasis on ways that
industries can go beyond the requirements of MACT and other existing air regulations. Topics
addressed include site-specific parameters needed to select appropriate controls for a specific
facility and available options for reducing emissions, including add-on control equipment,
process/work practice modifications, pollution prevention techniques, and voluntary/incentive
based programs that encourage facilities to further reduce HAP emissions. Finally, a general
discussion of the key factors that influence the costs of these various strategies is provided.
MACT Emission Standards
MACT emission standards typically require one or more of the following control
requirements in order to reduce emissions: meeting a numerical or percent efficiency control
target, or a design, equipment, work practice, or operational standard. For several MACT
emission standards finalized as of October 1996, Tables I through IV of Appendix E summarize
the control standard established for several types of emission sources (i.e., process vents,
equipments leaks, coating operations, and solvent cleaning operations). The percent or level of
control established in a MACT standard usually represents a certain type(s) of control
technology. For example, the 98 percent control level shown in Table I for process vents usually
translates to the use of thermal incineration as the control technology. However, the selection
and exact specification of controls is a site-specific determination, as discussed further in the
section below entitled "Available Control Strategies."
The MACT determinations, like other broadly applicable emissions control standards, are
based on decisions about the most effective, feasible, and reliable controls available. However,
MACT standards in a particular source category do not necessarily represent the most stringent
state-of-the-art controls available to that industry. Cost and other considerations may result in
* * *
March 1999 Page 79 * * *
-------
Residual Risk Report to Congress
the most stringent controls not being selected as the national MACT standard. This is because
the CAA states that MACT standards for existing sources:
". . . shall require the maximum degree of reduction in emissions of
the hazardous air pollutants... that the Administrator, taking into
consideration the cost of achieving such emission reduction, and
any non-air quality health and environmental impacts...determines
is achievable . . ."
Accordingly, controls capable of achieving greater HAP reductions may have been ruled
out at the time of the MACT determination because of cost or other considerations. However,
such costs may later be determined to be reasonable if analysis indicates significant residual
risks. It is also possible that, over time, market conditions or technological improvements in
certain control technologies could reduce the cost of currently expensive controls to less
expensive levels, making their adoption more feasible.
Available Control Strategies
The most effective and feasible HAP control technology for a particular application must
be determined on a case-by-case basis after careful consideration of many site-specific issues,
such as the design of the facility, the overall manufacturing process, the chemicals being used,
the emission stream characteristics, the desired control efficiency, and the cost-effectiveness of
the various control options. Even within a particular industry, the methods used to control a
specific type of HAP from a certain industrial process will vary from facility to facility. Because
of this considerable variation in the types of controls used, a detailed discussion of specific
strategies is beyond the scope of this Report. Instead, a review of the general types of methods
available for control of post-MACT emissions is provided.
For the purpose of evaluating available control strategies, it is likely that emissions from
source categories regulated by MACT emission standards will fall into two basic types:
(1) Controlled sources, which are emission sources where some degree of reduction has
already taken place; or
(2) Uncontrolled sources, which are emission sources that emit directly to the atmosphere
without constraints.
For both types of emission sources, a MACT determination was made to require either
add-on controls or implementation of a work practice or an operational restriction, or not to
require controls. Residual (post-MACT) emissions are emissions associated with both controlled
and uncontrolled sources within the source category.
Residual emissions from controlled sources are generally streams of low HAP
concentration because the original emission stream has already been subjected to a MACT level
* * *
March 1999 Page 80 * * *
-------
Residual Risk Report to Congress
of control. As a result, the range of available control strategies for further reductions from these
low concentration streams is limited, especially for emission streams already controlled to 90
percent or higher.
Residual emissions from uncontrolled sources may range from low to high HAP
concentration, but generally are of a lower magnitude of emissions than emissions from the
sources subject to some level of control. Accordingly, controls capable of reducing HAP
emissions from uncontrolled streams may exist, but at the time of the MACT determination there
may have been no MACT floor, and controlling above the MACT floor may have been ruled out
because of cost or other considerations. However, costs may later be determined to be
reasonable if residual emissions are determined to present significant residual risks.
Potentially effective strategies for controlling HAP emissions - some of which will be
applicable to further controlling sources already subject to MACT - include:
Pollution prevention (P2) techniques, such as replacing hazardous substances with less
harmful substitutes;
Adding a technological control, either to a previously uncontrolled source or as a
supplement to existing controls;
Replacing existing controls with a more effective control technology; and
Changing work practices.
Methods range from the complex and costly (e.g., redesigning the manufacturing process or
retrofitting stacks with sophisticated technological controls) to less costly P2 approaches (e.g.,
substituting less toxic alternatives for hazardous substances or modifying work practices to
reduce emissions). Facilities can be further encouraged to reduce HAP emissions through the use
of voluntary/incentive based programs. This range of control options is discussed further below.
Add-on Controls. Different add-on control technologies are required for point and
fugitive emission sources. Fugitive source emissions can be captured with hoods, enclosures, or
closed vent systems and then transferred to a control device, such as those noted below.
Improved equipment (e.g., pumps, valves, seals) may also be used to prevent fugitive HAP
emissions. Different add-on technologies are used to control emissions of organic vapor,
inorganic vapor, and particulate HAPs. Add-on devices used to control organic vapor emissions
include combustion devices (i.e., thermal incinerators, catalytic incinerators, flares, boilers, and
process heaters) and recovery devices (i.e., condensers and absorbers). The two most common
methods available for controlling inorganic vapor emissions are absorption (scrubbing) and
adsorption. A third technique, combustion, may be used for some inorganic HAPs (e.g., carbonyl
sulfide). The three types of devices typically used to control particulate HAP emissions are
fabric filters (baghouses), electrostatic precipitators, and venturi scrubbers. The applicability of
each device depends on the physical and/or chemical/electrical properties of the HAP particle
* * *
March 1999 Page 81 * * *
-------
Residual Risk Report to Congress
under consideration in addition to the specific gas stream characteristics and parameters. Table
V of Appendix E provides a summary of typical control devices currently used to reduce
emissions from some source categories.
Process/Work Practice Modifications. Process modification refers to any strategy that
seeks to reduce emissions by changing the operating practices of the facility or making internal
equipment changes. Examples include the re-design of a system to recover and recycle the
emissions stream. Some firms choose to make internal equipment changes by implementing
cleaner processing technologies through equipment modifications and modernization. Many of
these strategies overlap with the P2 tactics that are being used with increasing frequency by
industry (discussed below). Operating practice changes include re-designing industrial processes
to be more efficient, or instituting alternative work practices to reduce emissions. Work practice
changes may include a wide variety of activities such as changing the ways that employees apply
industrial solvents or reducing the amount of solvents used and allowed to evaporate. Also,
where workers are directly involved in a manufacturing process there may be ways to change
worker practices to reduce HAP emissions. Another example is increasing maintenance of
process equipment. Implementing a leak monitoring program to detect and repair leaking
components is an effective work practice to reduce fugitive emissions.
Pollution Prevention. Pollution prevention is the term used to describe a set of control
strategies designed to minimize waste generation through cleaner production. The Pollution
Prevention Act of 1990 defines P2 as any source reduction practice that "reduces the amount of
any hazardous substance, pollutant, or contaminant entering any waste stream or otherwise
released into the environment (including fugitive emissions) prior to recycling, treatment, or
disposal." The potential benefits of P2 strategies include improving plant efficiency, saving
money, and enhancing the quality and quantity of natural resources for production. In addition,
P2 can be more cost-effective than traditional add-on HAP controls. While there is much
discussion and debate about what exactly constitutes P2, the following general characteristics are
typical:
Reduction of substance volumes;
Substitution for toxic substances;
Implementation of clean technology; and
Installation of in-process recovery equipment (recycling).
Reducing the amount of toxic chemicals used in the production process generally results
in cleaner production and the generation of less waste, including HAPs. Product substitution
involves replacing hazardous substances used in the production process with alternatives that
result in lower hazardous substance emissions. A common example is the replacement of VOC-
laden solvents and lubricants with water based formulations. Many hazardous chemicals used in
manufacturing have environmentally safe substitutes that can be used in their place. In some
cases there may be effectiveness and cost trade-offs to using an alternative product, but for many
* * *
March 1999 Page 82 * * *
-------
Residual Risk Report to Congress
industrial substances cost-effective alternatives exist. Ultimately, each of these P2 programs
reduces the amount of wastes that is generated in the production process. Because the
combustion of industrial wastes is a major source of HAP emissions, designing facilities to
produce less waste will result in direct air quality benefits.
Voluntary and Incentive Based Approaches More industries than ever before are
voluntarily controlling emissions. This is due in part to the many federal pollution prevention
programs that have been established to encourage self-regulation by industry, as well as to
liability considerations, community pressures, and the desire to be a "good citizen." For several
years EPA has been experimenting with voluntary partnerships between government and industry
as a means to more rapidly achieve environmental goals. The Agency's 33/50, Energy Star,
Green Lights, and Green Chemistry programs have succeeded in gaining commitments from
thousands of industrial sources to reduce air emissions, including HAPs. Industries have
responded positively to these programs because of their voluntary nature and the positive public
recognition they receive for participation. Their success in achieving environmental results
demonstrates that voluntary programs can be an effective way to encourage companies to adopt
control strategies for reducing HAP emissions and residual risks.
Incentive based policies may be another way to reduce the total HAP emissions released
into the atmosphere beyond currently mandated MACT levels. These policies allow sources the
flexibility not only to choose what technologies to use for their reductions, but how extensive
their reductions will be.
Control Strategy Cost
Just as specific control technologies cannot be examined until the specific source
category and HAP or HAPs have been identified, the specific cost to reduce any residual risk that
may remain following MACT implementation cannot be determined at this time. Cost analyses
are critically dependent on numerous and various conditions, including individual source stream
characteristics, HAP characteristics, site conditions at a particular facility, level of control
necessary, and the various control options that may be considered. After MACT has been
promulgated and a source category and particular HAP (or HAPs) have been identified for
residual risk reduction, a detailed cost analysis can be performed.
Factors that may be considered in assessing the cost-effectiveness of a particular control
strategy include:
Capital costs (e.g., the cost of the equipment, estimated costs for site preparation and
installation, and cost of ancillary modifications and upgrades to monitoring and process
control equipment);
Cost of capital for the affected industry;
Fuel costs;
* * *
March 1999 Page 83 * * *
-------
Residual Risk Report to Congress
Chemical costs;
Incremental labor costs to operate equipment;
Production penalties associated with the equipment, and other opportunity costs;
Control efficiency for various streams;
Expected performance degradation over the life of the equipment;
Expected equipment life;
Lost producer surplus; and
Lost consumer surplus.
With this information, capital costs can be annualized; operating costs can be
disaggregated into fixed and variable costs; life cycle, annual emission estimates can be derived;
and costs and emission reductions can be estimated for a variety of operating scenarios. These
data are typically entered into an existing model, such as the EPA model HAP-PRO, to determine
control cost-effectiveness in terms of cost per mass of pollutant reduced.
4.2 Section 112 (f)(1)(C)
4.2.1 Epidemiological and Other Health Studies
Section 112(f)(l)(C) requires EPA to assess and report on "the actual health effects with
respect to persons living in the vicinity of sources, any available epidemiological or other health
studies ..." Information on actual health effects on neighboring populations resulting from HAP
emissions from source categories is limited. This section presents a summary discussion of
epidemiological, laboratory, and other exposure studies, then briefly describes how EPA intends
to use these data and actual source category-specific health effects data that may become
available in the context of section 112(f) residual risk assessments.
Current State of Knowledge
The earliest efforts to investigate the relationship between air pollution and ill health were
focused on characterizing the relationship between obvious and acute effects (respiratory
irritation, exacerbation of asthma, other respiratory and cardiovascular disease and death) and
short-duration incidents ("air pollution episodes") of high exposures to combustion products. In
extreme cases (such as the episodes occurring in Donora, Pennsylvania in 1948 and London,
England in 1952) noticeable increases in acute mortality have been seen. In less serious
episodes, increased incidence of respiratory diseases often occurs. Beginning in the late 1980s,
studies of adverse health effects near hazardous waste disposal sites began to appear, including
U.S. studies such as those conducted by the Agency for Toxic Substances and Disease Registry
(ATSDR) (Dayal et al. 1995), as well as a number of foreign studies (Klemans et al. 1995).
While it has been reported that individuals who live or work in the vicinity of sources of air
toxics emissions were, in some cases, found to have higher exposures than the general population
(EPA 1995g), most health effects studies, generally, do not focus on populations near sources of
* * *
March 1999 Page 84 * * *
-------
Residual Risk Report to Congress
HAPs. Therefore, information on potential health effects of air toxics is primarily based on
laboratory animal and occupational studies. These types of studies are suggestive of potential
adverse effects, but usually evaluate chemicals at higher exposures than normally expected for
the general human population. Human epidemiological data can give evidence of potential
effects, but are often limited by lack of actual exposure conditions, lack of statistical power, or
confounding factors.
Besides laboratory and occupational studies to assess health effects, investigators have
employed techniques such as follow-up studies of geographic patterns of disease (particularly
cancer), emissions inventories, exposure and risk assessment studies, and biomarker studies of
selected pollutants (see accompanying text box). These studies generally have focused on the
following major types of health effects - cancer, respiratory irritation and other respiratory
toxicity, neurobehavioral toxicity, hepatic effects, renal effects, and reproductive and
developmental effects - attributed to air pollutants, and investigators have evaluated associations
between exposures and health effects. For example, epidemiologic studies of air toxics have
focused on the cancer endpoint because (1) there are established and easily accessible data bases
of cancer mortality and, to a lesser extent, incidence at national and regional levels, and (2) many
toxic air pollutants are suspect or confirmed human carcinogens. Some of these carcinogenic
pollutants also are convenient subjects for environmental studies because they are persistent in
air and soil-water systems, and exposures can thus can be more readily measured and estimated.
Focused studies of particular classes of toxic air pollutant sources to assess effects of
adverse exposures have also been performed. Initially, attention was given to the well-studied
and common metallic pollutants such as cadmium and lead, other criteria pollutants, or other
general indicators of air quality. Some of the toxic metals represent special cases, each having its
own unique pattern of non-cancer effects. The renal effects of cadmium exposures (ATSDR
1993a), neurodevelopmental impacts of lead (ATSDR 1993b), and reproductive toxicity of
mercury exposures (ATSDR 1994) are the most well-studied examples. In addition, a few
studies use total mortality, or cause specific mortality, as endpoints. Individually, these various
studies have provided data that contribute to an understanding of the relationship between air
pollution exposure and adverse effects, on both the qualitative and quantitative level.
The Agency has recently surveyed the published literature on the actual human health
effects of outdoor air toxics exposures at ambient levels (EPA 1995g), and some information
from this study is summarized in this section and provides examples of the difficulties inherent in
making causal connections between exposure and effects. One of the most extensively
investigated connections between exposure to air pollutants and health effects is that between
lung cancer and exposure of populations near smelters to arsenic. Several studies have addressed
this relationship (Brown et al. 1984; Frost et al. 1987; Pershagen 1985). These studies tend to
show increased risk associated with exposure (or exposure surrogates, such as distance from the
smelter), although the apparent increase was not statistically significant in all cases. For
example, Frost et al. (1987) found that lung cancer patients were more likely to live close to an
* * *
March 1999 Page 85 * * *
-------
Residual Risk Report to Congress
SOME APPROACHES TO ESTABLISH RELATIONSHIP
BETWEEN AIR TOXICS EXPOSURE AND HEALTH EFFECTS
Laboratory Studies. Adverse health effects of exposures to specific pollutants are often evaluated in studies with
laboratory animals or human volunteers. In these studies, the pollutant concentrations are likely to be higher than
the exposures to the general population, and with animal studies, extrapolation of the observed effects to humans
must be considered.
Studies of Geographic Patterns of Disease Incidence or Mortality. Studies of vital statistics, disease incidence,
or mortality may disclose geographic patterns of adverse health effects that are suggestive of a relationship to
specific pollutants or pollutant sources. If such studies are not supplemented by exposure data, and are not
controlled for confounding factors other than pollutant exposures, it is not possible to support inferences of
causation associated with pollutant exposures.
Studies of General Population Exposures, Exposure Indices, and Biomarkers. These types of studies have been
used to estimate human exposures to pollutants and draw inferences about potential adverse effects. The collected
information is often used, in conjunction with toxicity data, to conduct risk assessments. In some instances,
measurable indices of exposures (biomarkers of exposures), such as body burdens or tissue concentrations of
pollutants, can be used to document exposures and evaluate the potential for adverse effects.
Occupational Exposure/Epidemiology Studies. Health effects of specific pollutants are often first discovered
through observations of adverse effects in workers exposed to high levels of the pollutants. These studies,
however, do not directly address the potential for adverse effects occurring in the general population at lower
exposure levels.
Formal Environmental Epidemiology Investigations. A "formal" environmental epidemiology study involves
systematic investigation of the relationship between an observed pattern of adverse health effects and exposures to
one or more agents. The analysis of actual (as opposed to estimated) health outcome information is what
distinguishes an epidemiological study from a risk assessment or a biomarkers study. Systematic efforts to control
for confounding factors (factors other than exposures to the toxic substances of interest which may be responsible
for the observed effects) are what distinguish a formal ("analytical") epidemiologic study from a simple
"descriptive" summary of geographic patterns of disease incidence. Often, formal epidemiologic studies are not a
powerful enough tool to discern relatively small increases in disease.
Risk Assessments. In a risk assessment, information about exposures (which may reflect actual measured
exposures or exposures estimated using emissions and environmental models) is combined with toxicity
information (from occupational or laboratory studies) to develop predictive estimates of the frequency or severity
of occurrence of adverse effects in human populations. There is a high degree of uncertainty due to imprecision in
exposure estimates and uncertainties in dose-response information, especially at low doses.
arsenic-emitting smelter (borderline statistical significance) in a case control study that was
conducted with women to reduce confounding from occupational exposure. However, there was
no control for smoking and no effect was seen in the cross-sectional phase of their study.
Pershagen (1985) analyzed lung cancer data near an arsenic-emitting smelter, with the data
stratified by smoking status and occupational exposure. In the group that was not occupationally
exposed, there was an increased relative risk with proximity to the smelter for both nonsmokers
and smokers, but the increase reached statistical significance only among the smokers. Hughes
et al. (1988) reviewed more than 10 studies investigating health effects (primarily lung cancer) in
communities near arsenic-emitting industries. They noted that about half of the studies reported
significant increases in adverse effects while about half of them reported no effect or decreased
* * *
March 1999 Page 86 * * *
-------
Residual Risk Report to Congress
risk in the exposed populations. However, these authors noted that many of the studies
(particularly those that observed no statistically significant effect) lacked sufficient statistical
power to detect the small increases in risk that would be expected, and suggested that some small
increase in risk is likely.
With respect to other effects, Nordstrom et al. (1978) found decreased birth weight in
babies born to mothers who lived close to an arsenic-emitting smelter. However, it is unclear if
the magnitude of the decrease was clinically significant (Hughes et al. 1988).
Several studies have attempted to show an association between vinyl chloride emissions
and central nervous system birth defects (Edmonds et al. 1978; Rosenman et al. 1989; Theriault
et al. 1983). While all of these studies reported some association between potential exposure and
disease, each was limited by uncertainties in the exposure estimates, implausible results, or
potential confounding factors such as smoking or drinking. Overall, these studies provide
insufficient data to conclude that there is a causal relationship between ambient air exposure to
vinyl chloride and central nervous system birth defects.
An overall view of the epidemiologic literature on exposure to air toxics in the
environment is consistent with the notion that concern is warranted. However, understanding of
the risks to individuals living near sources and exposed daily to these air toxics is limited or
confounded by other factors. Except for a few well-known cases (the sudden release of a large
volume of methyl isocyanate in Bhopal, India, for example) where extremely high exposures to
accidental releases of industrial chemicals resulted in severe acute health effects, the adverse
effects of exposures to airborne hazardous chemicals are generally very difficult to detect.
Because of the difficulties in the extent and usability of epidemiology data, EPA has
looked into other types of data that may help bridge the gap between cause and effect. In this
context, the state-of-the-art in exposure monitoring and the use of biomarkers has become an
expanding field of research. For example, the existing literature on neurobehavioral effects of
toxic air pollutants is dominated by discussions of the adverse effects of lead on intellectual and
behavioral indices in children. These studies generally describe decrements in performance as a
function of biomarkers of lead exposure, such as blood lead concentrations or heme metabolite
levels. There is, however, little information available from these studies on the sources of lead
exposures, and lead from deteriorating paint and in pipes and solders used for drinking water
distribution can contribute significantly to total exposures.
In a study by Binkova et al. (1995), PAH DNA adducts were measured in a group of
women in the Czech Republic who worked outdoors for about eight hours per day. Personal
exposure monitoring was used, allowing both indoor and outdoor exposure to PAHs to be
evaluated; exposure to respirable particles (<2.5 jim) and PAHs was measured. Levels of DNA
adducts in white blood cells were increased immediately after days of high PAH exposure. This
study demonstrated that DNA adducts can be used as biomarkers of exposure, reflecting short-
term exposure levels. In addition, DNA adducts can be used as biomarkers of effect, because, if
unrepaired, they can lead to gene mutations, which in some cases can ultimately lead to cancer.
* * *
March 1999 Page 87 * * *
-------
Residual Risk Report to Congress
However, due to the multiple steps from gene mutation to cancerous cell, DNA adducts and gene
mutations are best viewed as indicating carcinogenic potential rather than indicating actual risk
of cancer.
Blood or tissue concentrations of metals such as cadmium are also occasionally used as
indicators of exposure and potential adverse effects for airborne toxics. Among the studies that
use biomarkers of exposure are evaluations of tissue, hair, and urine cadmium levels in a
population near heavily industrialized cities in Russia (Busteva et al. 1994). Urinary cadmium is
a reliable indicator of recent cadmium exposure, as shown by several occupational studies. The
presence of the protein p-2-microglobulin in urine (termed proteinuria) is also considered a
reliable indicator of cadmium exposure. Busteva et al. (1994) reported that the percentage of
factory workers having elevated levels of this protein in their urine (>250 ug/1) was highly
correlated with the air content of cadmium. Although no significant effect was seen in the
general population, this may have been due to the small sample size and resulting low statistical
power. Collecting biological samples and conducting laboratory testing, as in this study, is more
labor-intensive than doing epidemiological investigations using disease registries. However,
because proteinuria is a well-characterized effect of cadmium exposure, and both exposure and
effect biomarkers can be monitored by urinalysis, this technique has applicability where high
exposure to cadmium is expected.
Another potential source of information may be nationally standardized and
comprehensive disease registries or data bases for adverse effects of toxics exposures, such as
birth defects and reproductive outcomes (Shy 1993), but again, there are limitations in its use.
Currently, studies that use these sources require investigators to obtain access to local or State
health status information, whose availability is highly variable from State to State, or to obtain
information from hospital or other medical records where confidentiality may become an issue.
This difficulty is less of a concern for case control studies, but can severely limit the ability to do
large-population cohort analyses or cross-sectional studies.
Acute effects such as seen in occupational settings are less likely to be seen in studies of
the general population exposed to toxic air pollutants at ambient levels, with the possible
exception of chemicals that have specific irritant properties. In addition, the effects of usually
low chronic exposures to toxic air pollutants may be subtle, and may develop slowly over time in
response to cumulative exposures (chronic effects), or may not develop until long after exposures
occur (latent effects). Information on exposure levels to toxic air pollutants near sources, as well
as to "background" pollutants that may be confounding the results of air pollutant epidemiology
studies, is also generally limited. Thus, it is not easy to directly estimate the risks associated
with general population exposures to toxic air pollutants under conditions of chronic low-level
exposures. Nonetheless, it is currently assumed for prudent public health reasons that such
effects may be occurring because, for example, many toxic air pollutants are suspected or known
human carcinogens and even low levels of exposure could theoretically cause increased cancer
risks. In a smaller number of cases, animal or controlled human studies indicate that
noncarcinogenic effects might be expected to occur at exposures near ambient levels. In some
instances, allergic sensitization may result in adverse effects in a small, especially sensitive
* * *
March 1999 Page 88 * * *
-------
Residual Risk Report to Congress
subset of the exposed population. There is presently no national monitoring system for air toxics
that can provide even general information on the urban and rural concentration patterns of these
pollutants in ambient air.
Other issues to consider in trying to assess the actual health effects of air toxics include
(1) the lack of indoor exposure data and (2) the often observed coincidence between exposures to
toxic air pollutants and exposures to criteria air pollutants. Information on indoor exposure data
is useful since the majority of individuals spend most of their time (usually 80 percent or more)
indoors. Because concentrations of some air toxics in indoor air tend to be quite different from
(and often higher than) those outdoors, studies which do not take indoor air quality into account
will have difficulty in elucidating the true relationship between these air toxics exposures and
effects. Both toxic air pollutants and criteria pollutants are associated with areas of high
population density and industrial development, and many epidemiologic studies simply use
measures of one or a few criteria pollutants as the sole measure of exposure, and use it as a proxy
for all "air pollution." For example, in many studies that assess the relationship between
particulate exposures and acute and chronic health effects (usually where there is no clearly
identified dominant source of particulate air pollutants), it is not known which chemical or
physical constituents of particulates contribute to the observed increases in risk, and it is
therefore not possible to attribute any given fraction of these effects to toxic air pollutants.
Strategy for Considering Epidemiology/Other Health Information in Residual Risk
Analyses
Early in the data gathering stage of a residual risk analysis, the Agency will search the
scientific literature for published epidemiological studies related to the specific source categories,
HAPs, and/or locations studied. These reports will be evaluated for quality, with preference
given to those covering emissions from the source categories of concern at environmentally
relevant concentrations over long periods. Where published epidemiological studies are
unavailable, the Agency may also consider, as part of its refined analysis, examining other types
of available human health data for possible correlations between exposure and adverse effects.
Potential sources of health effects information include State or national disease registries (e.g.,
the Centers for Disease Control's Birth Defects Monitoring data base), hospital and other
medical records, death certificates, and questionnaires. The EPA intends to coordinate the
identification, collection, and review of such data with the Public Health Service and other
federal, State, and local public health officials. Examples of widely reported outcomes include
cancer incidence or mortality, birth defects, and respiratory symptoms. Information on pollutant
specific biomarkers - biological measurements associated with exposure to certain pollutants -
may also be available. Exposure to HAPs may be estimated in several ways, including ambient
monitors, mathematical modeling, or personal air monitors. The Agency recognizes the
difficulties that exist in obtaining actual health effects data. However, EPA believes that it may
be useful to incorporate some kinds of health effects/epidemiology data in the residual risk
assessments for selected air pollutants and source categories and intend to use existing data
wherever scientifically appropriate. The Agency will consider any such available public health
information in the risk characterization step, and will present and discuss the risk estimates in the
* * *
March 1999 Page 89 * * *
-------
Residual Risk Report to Congress
context of such information. Clearly, any actual health effects data can generally only be used to
help establish current or past conditions, and cannot be used directly in the prediction of post-
MACT risks that may occur in the future (i.e., residual risks).
4.2.2 Risks Posed by Background Concentrations
Section 112(f)(l)(C) also requires EPA to assess and report on "risks presented by
background concentrations of hazardous air pollutants ..." This section of the Report discusses
general information on background levels and presents a definition of background concentrations
for residual risk purposes. It describes approaches used by other EPA programs and includes
examples of rules and guidance that consider the issue of background. It also presents a
discussion of the difficulties in addressing background concentrations in residual risk analyses
and identifies data needs to assess background. The section concludes by describing options to
analyze and consider background concentrations in residual risk analyses. It describes how EPA
will assess available monitoring data for individual source categories under study, and how
background concentrations will be evaluated in residual risk assessments and treated in decision-
making.
Background concentrations may be considered to be the levels of contaminants that
would be present in the absence of contaminant releases from the source(s) under evaluation.
Background concentrations come from contaminants that either may occur naturally in the
environment or originate from anthropogenic sources. Background contamination can be
localized or ubiquitous. An example of localized contamination is the presence of high
concentrations of trace metals in dust from geologic formations naturally high in trace metals.
An example of ubiquitous contamination is the widespread presence of low concentrations of
polyaromatic hydrocarbons in soil and dust in areas near forest fires.
The EPA's Science Policy Council is developing a cumulative risk policy with the goal
of developing a framework for conducting cumulative risk assessments. While Part 1 of the
Guidance on Cumulative Risk Assessment released in August 1997 (EPA 1997n) does not
provide an explicit definition of cumulative risk or background, in general cumulative risk is
considered to include risks from multiple sources, pathways, and pollutants. The cumulative risk
guidance identifies elements that must be considered in a cumulative risk assessment such as the
cumulative effects of mixtures on different and the same target organs from multiple sources by
direct and multipathway exposures. Cumulative risk is therefore broader than the "incremental
* * *
March 1999 Page 90 * * *
-------
Residual Risk Report to Congress
risk" (or "excess risk") attributable to a given source/pathway/pollutant combination under
evaluation.
The general approach in risk assessments and risk management decisions has been to
assess incremental risk of a particular source or activity and compare that risk to an "acceptable
risk" criterion (or set of criteria). Various EPA programs, however, have taken specific
approaches to considering background risks, some of which are summarized below.
EPA Programs and Rules that Consider Background Concentrations and Risks
Site risk assessments under Superfund and the RCRA corrective action program require
the collection of background samples at or near hazardous waste sites in areas not influenced by
site contamination, but that have the same basic characteristics as the medium of concern.
Generally, comparison of background and source-related contamination is used to identify areas
affected by the source and contaminants attributable to the source. Incremental risks are then
assessed for contaminants in media demonstrated by comparison with background concentrations
to have originated from the source. The level of risk reduction is generally set by cleanup levels
based on achieving an acceptable risk or reducing contaminants to background concentrations,
whichever is least stringent. However, in some cases where anthropogenic background levels
exceed cleanup goals, EPA may determine that a response action under Superfund is necessary
and feasible, and a comprehensive plan may be developed to address area-wide contaminated
media not originating from the site source. In such cases, reduction of anthropogenic
background risks becomes an additional goal of the remediation program.
In 1993, EPA's Office of Wastewater Management developed a comprehensive risk-
based rule, known as the "Part 503" rule, to protect public health and the environment from the
anticipated adverse effects of pollutants that may be present in sewage sludge that is applied to
land. Using the results of the rule's multipathway risk assessment that considered soil
background metal concentrations in the calculations of risk-based pollutant concentration limits,
EPA set pollutant concentration limits above which sludge could not be applied. The limits were
derived by calculating the increment of pollutant from sewage sludge that could be added to the
total background receptor intake or plant uptake without exceeding a threshold dose. For human
receptors, the threshold dose was set for noncarcinogens at the chronic effects RfD, and for
carcinogens, at an incremental individual lifetime cancer risk of 10"4. For non-human and plant
receptors, background soil concentrations were subtracted from reference adverse effect
concentrations to calculate the increment of a pollutant from sewage sludge that could be applied
to soil without adverse impact. In short, soil-related background concentrations and risks were
directly and quantitatively considered in this risk management decision.
The Office of Water has developed methods to set maximum contaminant level goals
(MCLG) at concentrations at which no known or anticipated adverse health effects occur.
Drinking water equivalent levels (DWEL) are calculated from RfDs by assuming a specific
* * *
March 1999 Page 91 * * *
-------
Residual Risk Report to Congress
receptor body weight and consumption rate. The MCLG is set by multiplying the DWEL by the
percentage of the total daily exposure expected to be contributed by drinking water (i.e., the
"non-background" portion), called the relative source contribution (RSC). Generally, the Agency
assumes that the RSC from drinking water is 20 percent of the total exposure, unless specific
exposure data for a chemical is available, and that 80 percent of exposure comes from other
sources. The RSC may be as high as 80 percent. The Agency also is using this approach of
reserving a portion of risk to background in setting pollutant limits covered by the Food Quality
Protection Act (FQPA) and in the Office of Pesticide Program's re-registration decisions.
EPA has not addressed in detail the issue of background risks or cumulative risks in
RCRA hazardous waste listing determinations. In a recent hazardous waste listing determination
for petroleum refining process wastes, analyses were conducted that considered multiple wastes
disposed in land units (wastes with similar constituents from other sources) and multiple units at
a facility, thus accounting for the impact of certain other background sources.
Difficulties in Addressing Background Risk
The Agency's lack of a generalized approach to considering background risk in its risk
assessments and risk management decisions is demonstrated by the absence of discussion of
background risks in many of its major rules and the simplified approaches used in rules that
consider background concentrations. This may be due to mandates of environmental laws and
the fact that accounting for all possible sources and routes of exposure to pollutants with similar
toxic mechanisms is a complex and expensive task with many variables requiring much input
data. Methods used to assess risk are evolving and new, more sophisticated models and
strategies to assess multiple pathways of exposure are being developed. These models require
many variables to accurately account for all sources of background risk, at least some of which
are not likely to be available. Lack of data and funds required to collect the extensive data
needed to assess multiple direct and indirect pathways has often resulted in the use of simplified
assumptions and models such as limiting assessments to direct exposure pathways and regulatory
decisions that set background contributions to conservative default values. What is considered
background risk is also affected by the approach taken to define a "source" (e.g., whether the
assessment of risk is performed on a source category basis or a point source basis).
Background concentrations are not static. The half-lives of contaminants are wide
ranging and must be considered when assessing risks over a period of time. Persistent and
bioaccumulating contaminants moving along the foodchain alter background concentrations over
time. The exchange of contaminants between media (e.g., particulate deposition in surface
water) also introduces a time-related background change. In addition, regulatory changes that
reduce releases of contaminants from sources will, over time, alter background concentrations of
those contaminants. For example, if drinking water standards (or other standards affecting
exposure) are lowered for certain pollutants, exposures and any resultant risks from those
pollutants are also lowered. Similarly, residual risk reductions in the incremental risk of some
HAPs will ultimately reduce any associated background risk and consequently, overall risk of
those pollutants. However, given the considerable uncertainties in risk assessment generally, it is
* * *
March 1999 Page 92 * * *
-------
Residual Risk Report to Congress
not clear that a thorough consideration of background, even if possible, would greatly improve
the overall conclusions of the assessment. An additional issue raised by the long residence time
of certain HAPs is the relationship between the amount of emission reductions and the amount of
risk reduction.
Defining Background for Residual Risk Analyses
Given the complexities associated with assessing cumulative risk from all chemicals and
sources, background concentrations and risks for residual risk analyses will be assessed
whenever possible on a chemical-by-chemical basis for the particular HAPs under evaluation.
Although other chemicals may contribute to the cumulative background risk because of
interactions or effects on the same target organ, the data needed to evaluate cumulative risks
from multiple chemicals is quite extensive and difficult to collect. Thus, background
concentration of a particular HAP for either an affected source or source category under
evaluation is defined as the concentration of that particular HAP in environmental media
attributable to natural and anthropogenic sources - both on-site and off-site - other than the
source being evaluated. As described above, background concentrations may change over time,
and analysis of background risks would be more accurate if these changes in background
concentrations were accounted for. However, because of analytical complexity (e.g., data needs,
modeling difficulty, high uncertainty), background concentrations generally will be based on a
given point in time when taken into account for residual risk analyses.
Therefore, for the residual risk program, background concentrations will be considered
from two perspectives: the contribution of HAPs from natural sources, and the contribution of
HAPs from all anthropogenic sources other than the source under evaluation. For a particular
point source at a facility, for example, the contaminants present in air in the absence of the source
under evaluation may originate from natural sources as well as from other on-site and off-site
emissions sources. It follows that the background risk is the cumulative risk from all possible
natural and anthropogenic sources of a HAP other than the particular source or source category
under evaluation. Residual risk may be assessed in the context of both kinds of background
when the sources can be identified and their contributions measured and compared.
Strategy for Considering Background in Residual Risk Analyses
Residual risk analyses will assess incremental risk above background risk, and then
assess the significance of these risk estimates using acceptable risk criteria developed and used
historically for judging incremental risk. As described in this Report, residual risk will be
addressed in a two-tiered approach. In the relatively simple screening tier of analysis, the
residual risk analysis generally is performed without considering background at all. At most,
local or regional scale estimates of background concentrations based on statistical analyses of
monitoring data or screening-level modeling analyses (such as air concentration estimates
developed in our cumulative exposure project) may be considered. This screening analysis is
typically conducted using conservative methods and assumptions and results are compared to
acceptable risk criteria. Where residual risk estimates exceed the criteria, a more refined analysis
* * *
March 1999 Page 93 * * *
-------
Residual Risk Report to Congress
is conducted. In general, an in-depth modeling analysis of background concentrations will be
beyond the scope of the refined analysis, although available background concentration data or
other relevant information would be considered. As discussed above, a detailed analysis of
background concentrations typically would require extensive data gathering and modeling
beyond that required for the incremental risk analysis. For example, numerous nearby (and
possibly distant) HAP sources of varying types would need to be characterized in sufficient detail
to support release and exposure modeling. In some cases, background risks from HAPs
potentially could be considered to play a critical role in evaluation of the need for further
reduction of the incremental risk. Thus, for some source categories, or some individual sources,
it may be determined that detailed analysis of background concentrations is warranted.
In such cases, the relative contribution of background to the total risk from HAPs would
be considered in decisions for more stringent regulation and may influence the level of
reductions required to obtain an "ample margin of safety." If the relative contribution of
background risk is high compared to the incremental residual risk, additional source risk
reduction may provide relatively negligible benefit. Alternatively, a high relative contribution to
total risk by the incremental risk might strengthen the rationale for requiring more stringent
regulation. As described above, EPA has reserved part of the "risk burden" for background risk
in other regulatory programs (e.g., drinking water and pesticide programs), and this kind of
approach will be considered in residual risk decision-making for HAPs. In the risk
characterization step, EPA will consider and present the risk estimates in the context of the
available information on background.
The data needs for assessment of background concentrations may differ depending on
whether a source category or a specific source is under evaluation. For a specific source,
identifying the background concentrations from other natural and anthropogenic emissions
sources within a specified radius of the source will usually be considered sufficient to
demonstrate the relative contribution of background to overall risk and the impact of the single
source relative to other sources surrounding it.
4.2.3 Uncertainties in Risk Assessment Methods
This section responds to the CAA section 112(f)(l) requirement to address "any
uncertainties in risk assessment methodology or other health assessment technique," with a focus
on uncertainty in residual risk assessments. Uncertainty, when applied to the process of risk
assessment, is defined as "a lack of knowledge about specific factors, parameters, or models"
(EPA 1997c). When applied to the results of risk assessment, the term "uncertainty" refers to
the lack of precision in the risk estimate due to uncertainties in the input assumptions, models,
* * *
March 1999 Page 94 * * *
-------
Residual Risk Report to Congress
and parameter values. Examples of uncertainty relevant to the estimation of residual risks
include a lack of knowledge about the nature of a dose-response relationship for a given HAP or
a lack of data about pollutant emissions over time. Such uncertainties affect the precision and
reliability of any risk estimates that were developed for individuals exposed to the substances
(EPA 1988b). Even using the most accurate data with the most sophisticated models, uncertainty
is inherent in risk assessment. Uncertainty is usually present in all stages of risk assessment.
Although other taxonomies are sometimes used, sources of uncertainty in risk assessment are
often described by the following categories (Finkel 1990):
Uncertainty related to the conditions and circumstances of exposure (scenario
uncertainty);
Uncertainty in the structure of models used to estimate risks (model uncertainty);
Uncertainty in the input values used in risk assessment models (parameter uncertainty);
and
Inherent heterogeneity (variability).
Uncertainty can be introduced into a health risk assessment at every step in the process. It occurs
because risk assessment is a complex process, requiring integration of the:
Fate and transport of pollutants in a variable environment by processes that are often
poorly understood or too complex to quantify accurately;
Potential for adverse health effects in humans as extrapolated from animal toxicity tests;
and
Probability of adverse effects in a human population that is highly variable genetically, in
age, in activity level, and in life styles.
The presence of uncertainty in risk assessment does not necessarily imply that the results
of the risk assessment are biased, only that the risks cannot be estimated beyond a certain degree
of precision. One of the key purposes of uncertainty analysis is to estimate the degree of
precision in risk estimates derived from uncertain scenarios, models, and parameters. In
addition, uncertainty importance analysis can be used to identify the factors that contribute the
most to the overall uncertainty in risk estimates. Efforts to refine scenarios and models or to
gather more data can then be prioritized to provide the greatest reduction in risk uncertainty at the
lowest cost.
Evaluating these different kinds of uncertainty in risk assessment may require different
methods, as discussed in more detail later in this section. An important general property of
uncertainty is that it can be reduced by gathering information. Where directly relevant data are
not available, appropriately selected surrogate data may serve to reduce uncertainty.
The other important part of the general problem of "uncertainty analysis" is the need to
characterize the potential variability of scenarios, models, and parameters and how such
* * *
March 1999 Page 95 * * *
-------
Residual Risk Report to Congress
variability affects risk estimates. In contrast to uncertainty, variability has nothing to do with
data quality or a lack of knowledge of fundamental relationships, but instead "refers to observed
differences attributable to true heterogeneity" in the variables (EPA 1997c). Examples might
include variations in hourly wind velocity or in the body weights among an exposed population.
Because variability is an intrinsic property of the quantities being evaluated, it cannot be reduced
by data gathering or refinements in models. Analyses of variability are still important, however,
to assure that inputs to risk models are specified appropriately. For example, it may be found
that certain HAP emission sources or exposed populations are heterogeneous, and more reliable
estimates of risk can be developed by stratifying them and estimating risks separately for each
group.
In the context of residual risks, uncertainty analysis has important implications both for
risk assessment methods and for risk management. The following are among the key
methodological issues that arise in the context of residual risk.
Have all the important sources of uncertainty and variability in the scenarios, models, and
input variables to the risk assessment been identified?
What are the appropriate methods to evaluate uncertainty and variability, given the needs
of the decision-making process, the capabilities of available models, and the data and
resources that are available?
What additional data or model refinements can be used to reduce uncertainty in the risk
estimates?
How can information about uncertainty be summarized and presented to decision-
makers?
From the risk management perspective, important issues associated with uncertainty
analysis may include the following:
What are the most useful measures of uncertainty in risk estimates (from a risk
management standpoint)?
What is a reasonable range over which the risk estimate might vary?
What is the level of certainty that the residual risk estimate is actually greater than zero or
less than a defined LOG?
How reliably can the relative risks be compared? How well can risks be ranked?
What is the overall reliability of a specific risk estimate applied to a given decision?
* * *
March 1999 Page 96 * * *
-------
Residual Risk Report to Congress
Clearly, risk assessment and risk management issues overlap. In the discussions that
follow, the importance of adequate communication between the risk assessors and EPA risk
managers is stressed.
Approaches to Addressing Uncertainty and Variability in the Estimation of
Residual Risks
Systematic uncertainty and variability analyses have been used in support of risk
assessment in a number of fields, most notably nuclear engineering, for over three decades. The
use of uncertainty analysis in health risk assessment for exposure to chemical agents did not
become widespread until the 1980s (Bogen and Spear 1987). Since then, a wide range of
techniques for quantitative uncertainty analysis have been developed and applied to risk-related
policy analysis (e.g., Morgan and Henrion 1990; Frey 1992; Hoffman and Hammonds 1994;
McKone 1994; Hattis and Barlow 1996). In its 1994 report, Science and Judgment in Risk
Assessment, NRC recommended that, when possible, uncertainty and variability should be
quantified and the distinction between them maintained throughout risk assessment (NRC 1994).
As discussed below, a number of techniques are available that allow the separate analysis of the
impacts of uncertainty and variability on the overall dispersion in risk estimates.
The EPA has long recognized the need to consider uncertainty and variability in risk
assessment. Agency guidance on these issues has gradually evolved over more than a decade,
with major documents including:
Initial set of risk assessment guidance documents (e.g., EPA 1986f,b);
Risk Assessment Council (RAC) guidance ("the Habicht Memorandum," EPA 1992e);
Guidelines for Exposure Assessment (EPA 1992a);
Policy and guidance for risk characterization ("the Browner Memorandum," EPA
1995a,f);
Summary Report of the Workshop on Monte Carlo Analysis (EPA 1996g); and
Policy for Use of Probabilistic Analysis in Risk Assessment (EPA 1997k) and Guiding
Principles for Monte Carlo Analysis (EPA 1997c).
Among these documents, the 1992 exposure assessment guidance, the 1997 Policy for
Use of Probabilistic Analysis in Risk Assessment, and 1997 Guiding Principles for Monte Carlo
Analysis provide the most detailed recommendations for uncertainty and variability analysis.
The former document primarily provides technical guidance on uncertainty evaluation in the
context of exposure assessment, while the latter two provide refined technical guidance, as well
as recommendations on presentation of uncertainty information to decision-makers. The 1997
Policy also documents EPA's judgment that probabilistic methods should be used wherever the
circumstances justify these approaches. Thus, the Agency is committed to carefully considering
use of quantitative methods for evaluating uncertainty and variability in its residual risk
assessments. The Agency has also recently released a revised version of the Exposure Factors
* * *
March 1999 Page 97 * * *
-------
Residual Risk Report to Congress
Handbook (EFH) that supports probabilistic approaches to the treatment of a number of
commonly employed risk assessment input variables (EPA 1997g). In April 1998, the EPA Risk
Assessment Forum convened a workshop on uncertainty analysis in which the problems
associated with defining probability distributions for uncertainty and variability analyses were
discussed.
As techniques for uncertainty analysis have matured, the Agency has come to endorse a
tiered approach to such analyses. In residual risk and other air toxics analyses, EPA plans on
addressing uncertainty in a tiered approach. In this way, EPA can efficiently utilize resources,
mirroring the level of uncertainty analysis to the overall level of analysis. In the Policy for the
Use of Probabilistic Risk Analysis in Risk Assessment (EPA 1997k), four general steps (tiers) in
the recommended approach to quantitative uncertainty analysis are identified:
Single-value estimates of high-end and mid-range risk;
Qualitative evaluation of model and scenario sensitivity;
Quantitative sensitivity analysis of high-end or mid-point estimates; and
Fully quantitative characterization of uncertainty and uncertainty importance.
This approach starts with simple assessments of potential risks using both representative
and more conservative scenarios, models, and input values, using point estimates of the major
parameters. This approach may provide sufficient information for the policy question being
addressed in some cases. For example, if risks for a suitably defined high-end receptor are far
below levels of concern, then no additional uncertainty analysis (or risk analysis) may be needed
to support a risk management decision. Such screening analyses will probably be appropriate as
the first step in the analysis of residual risk uncertainty for all of the source categories.
Where the single-value high-end and mid-range estimates do not provide sufficient
information about residual risk, additional analyses can be conducted to determine the likely
range of uncertainty in these estimates, and the major factors that contribute to the uncertainty of
the estimates. The sensitivity of the high-end and mid-point estimates to the specification of
scenarios and models can usually be evaluated by conducting a manageable number of case
studies using different model specifications and observing the resulting changes in risks. If
scenario or model specification turns out to strongly affect risk estimates, a more refined analysis
(see below) may be necessary.
In addition to the evaluation of scenario and model uncertainty, it may be desirable to
evaluate the sensitivity of the point estimates of risks to variability and uncertainty in model
input parameters. This may be done through sensitivity analysis or through the use of more
detailed probabilistic methods. If sensitivity analyses are used, care must be taken to insure that
the combinations of parameter values that have the greatest impact on risks are identified. For
example, the greatest contributions to uncertainty may arise where two or more variables take
* * *
March 1999 Page 98 * * *
-------
Residual Risk Report to Congress
values that are only moderately different from their mean values, rather than where either one of
them takes an extreme value.
For some source categories, systematic sensitivity analyses would provide sufficient
information regarding residual risks, and the uncertainties associated with these risks. If they do
not, the next step is explicit probability modeling, most likely Monte Carlo or related simulation
methods. Using such approaches, uncertainty and variability distributions can be defined for the
major parameter values used in the derivation of the mid-range and high-end risk estimates.
These distributions would then be used to develop Monte Carlo estimates of risk and risk
uncertainty. There are many precedents for the application of such methods (Frey and Rhodes
1996) in the evaluation of potential risks from HAP sources.
Whether sensitivity analysis or simulation modeling is used, it is important to consider
both uncertainty and variability at this stage of the analysis. Very often, key parameters in the
residual risk assessment will be highly uncertain. Experience to date indicates that the emission-
related parameters with a particularly high degree of uncertainty include measurements of
emission rates, emissions inventories, ambient levels, and facility operating patterns that affect
HAP releases. On the risk side, uncertainties in dose-response models, dose-response
parameters, populations exposed, and behavior patterns associated with exposures seem to
contribute significantly to the overall uncertainties in population risk estimates.
Where data are lacking or limited, it may be necessary to extrapolate beyond the range of
available information, or use surrogate data where direct observations are not available, in order
to develop estimates of parameter variability and uncertainty. The Agency is currently exploring
a number of promising techniques in this area. Where relatively few data are available, statistical
techniques such as bootstrap analysis may be used to develop variability and uncertainty
distributions. Where important data are lacking, techniques for eliciting expert opinion (Morgan
and Henri on 1990) may be useful in developing estimates of the uncertainty and variability of
key parameters.
While these techniques can be very helpful in characterizing uncertainty, it is important
that all assumptions and methods be fully documented, and that the available data sources be
fully exploited before extrapolation or surrogate data are used. Decisions regarding the
appropriate methods to be used in developing uncertainty distributions must be made on a case-
by-case basis, carefully considering the specific needs of the analysis.
The final step in the analysis is a fully quantitative analysis of uncertainty and uncertainty
importance. This approach is basically a more comprehensive extension of the previously
described methods. In this case, however, rather than starting from pre-defined central-tendency
and high-end risk estimates, all scenarios and models (to the extent possible) and all parameters
are included in the modeling process as uncertainty and variability representations. Using
standard two-dimensional Monte Carlo simulation methods, the effects of variability and
* * *
March 1999 Page 99 * * *
-------
Residual Risk Report to Congress
uncertainty on the overall dispersion in risk estimates can be separated and quantified. In
addition, the relative importance of individual sources of uncertainty can be evaluated through
partial correlation coefficients, regression methods, contributions to variance, or related methods.
However, the data requirements of such an analysis often limit its ability to be truly
comprehensive.
Within the residual risk program, this option will be appropriate for sources or source
categories where potential risks may indicate the need for a risk management action. The
importance analysis could be used to guide data gathering to parameters where uncertainty is the
greatest, or to define conditions (e.g., average emissions or operating conditions) for which risk
estimates would not exceed levels of concern with a high degree of confidence.
Uncertainty and the Management of Residual Risks
It is important to recall that the underlying purpose of the evaluation of uncertainty is to
improve the quality of the decisions that are made regarding the management of risks. In the
context of residual risks, the primary purpose of the assessment is to support decisions about
whether additional controls are needed, over and above initial MACT standards, to reduce risks
to acceptable levels. Thus, at a minimum, the uncertainty analysis needs to supply risk managers
with a defensible technical basis for decisions. The important questions to be addressed include:
What is the risk? How reliable is the risk estimate? What is the expected reasonable range of
outcomes if a specific decision is acted upon? To these might be added two other key
"threshold" question, namely: Is there enough information to support a decision and, if not, what
kinds of data are needed to reduce uncertainty to acceptable levels?
A well-conducted uncertainty analysis can provide defensible and well-qualified answers
to all of these questions. If it is to do so, however, a substantial degree of interaction between
risk assessors and risk managers is required. Preferably, this interaction begins early in the risk
assessment process, when risk managers clearly articulate their information needs to the
assessors, and assessors present options for meeting those needs. The interaction continues
throughout the assessment process and into the risk communication phase, when the results of
the analysis are formally presented to risk managers. The Agency has made efforts to explore the
nature of the interaction that needs to occur and the nature of the informational needs of risk
managers (Bloom 1993), and will continue to do so to assure that uncertainty analysis makes a
constructive contribution to risk management decisions.
A second key purpose of the uncertainty analysis is to provide information useful to
stakeholders involved in the decision process. As the federal government pursues its goals of
expanded stakeholder involvement in risk management decisions (CRARM 1997a,b), a premium
is being placed, as it should be, on providing information that is useful and intelligible to non-
technical audiences. If support is to be secured for decisions, the decision rationale must
be"transparent" and understandable to affected parties.
* * *
March 1999 Page 100 * * *
-------
Residual Risk Report to Congress
The complexity of uncertainty evaluation, and particularly of probabilistic methods, may
pose a significant barrier to understanding (and thus to the utility of the analysis). In the past,
regulatory decisions have been evaluated primarily in terms of point estimates of risk and simple
dichotomous decision rules. (If the point estimate of risk is above a certain level, take a certain
action. If not, take another action.) In contrast, it may not be intuitively obvious, even to
relatively sophisticated audiences, how to relate the outputs of quantitative uncertainty evaluation
to a particular decision. For example, important aspects of the regulatory decision may rest on
relatively subtle statistical distinctions (e.g., between a 95th percentile risk estimate and an upper
95th percentile confidence limit on a risk estimate), and the challenges in presenting such
information can be formidable. In its recent guidance, the Agency has begun to define concrete
approaches to the presentation of risk and uncertainty information to decision-makers and
stakeholders. A promising approach involves relying heavily on narrative descriptions of
uncertainty and simple diagrammatic presentations of risk information. These efforts will need
to be continued and elaborated in the course of the Agency's residual risk assessments.
The question of how to present the results of uncertainty analyses overlaps with the more
general problem of risk communication. As noted in Section 4.1.1, the Agency is required to
report on the "public health significance" of residual risks. This level clearly has a probabilistic
component; e.g., how certain does the Agency need to be that a risk is or is not "significant"? Is
there some intermediate combination of risk and uncertainty that indicates the need for more data
gathering, rather than immediate management? How can uncertain risks be compared and
prioritized? The answers to these questions depend not only on the magnitude of the risks being
evaluated and the magnitude of uncertainty associated with the risk estimate, but also on the
specific control options available and their economic impacts. It will be important for the
Agency to develop consistent approaches to defining the need for uncertainty evaluation for
residual risk management and the larger air toxics program.
4.2.4 Negative Health or Environmental Consequences
This section addresses the CAA section 112(f)(l)(C) requirement to investigate and
report on "... any negative health or environmental consequences to the community of efforts to
reduce such [residual] risks." Pollution control technologies targeted at a single pollutant (e.g., a
specific HAP) and single medium (e.g., air), especially conventional end-of-the-pipe treatment
technologies, can inadvertently transfer pollutants and risks to different media, different
locations, and different receptors, and can unintentionally create new and different risks in the
process of controlling the targeted risk. Few control technologies, when viewed from a holistic,
multimedia, life cycle perspective, are without health and environmental risks of their own. In
the context of HAP residual risk, for example, a technology that removes a HAP from an air
emission stream can produce contaminated water and/or solid waste, can require additional
energy (which consumes resources and produces other pollutants), and in some cases may create
new safety risks, especially for workers. Health or environmental consequences can be
* * *
March 1999 Page 101 * * *
-------
Residual Risk Report to Congress
secondary to other consequences, such as the example of increased energy usage that may have
environmental consequences.
EPA recognizes the possibility of creating or transferring risks as an unintended
byproduct of actions that may be taken to reduce residual risks of HAPs. Thus, as part of the
section 112(f) standard-setting process, the Agency will consider significant negative health and
environmental consequences and the risk-risk tradeoffs associated with any future standards.
One of the Agency's primary goals is to ensure that measures taken to reduce risk under section
112(f) authorities do not create other risk problems.
A key step in the residual risk process for HAP source categories determined to need
additional risk reduction beyond the MACT standards in place will be the development and
analysis of a range of risk management options. Ultimately, a risk management approach will be
selected for the source category and a standard developed under section 112(f) to reduce risks to
acceptable levels. As part of the analysis of risk management options - which will include
evaluation of the effectiveness, reliability, emission and risk reduction, and cost of each option -
EPA will consider the broad range of positive and negative impacts of each risk management
option under consideration, rather than focusing simply on one criterion, such as control
efficiency or cost. Information describing and, where practicable, quantifying potential negative
consequences will be presented along with the other critical information to decision-makers
responsible for selecting the risk management strategy. The Agency also plans to assess and
consider, to the extent practicable, the uncertainty associated with its estimates of negative health
and environmental effects, and also the uncertainty associated with its evaluation of
effectiveness, reliability, and cost of risk management options.
In contrast to conventional air pollutant removal and treatment technologies, many
pollution prevention approaches to reducing residual risks have fewer negative health and
environmental consequences. This is primarily because pollution prevention approaches
eliminate pollutants (and thus emissions) at the front end of a process rather than attempting to
treat and dispose of them at some downstream step of the process. Thus, the Agency intends to
identify pollution prevention approaches as risk management options and considers them in the
standard-setting process. There will be a strong preference for selecting feasible and cost-
effective pollution prevention approaches to reduce the residual risks of HAPs, in large part
because they generally have fewer negative health and environmental consequences than other
options.
4.3 Section 112 (f)(1)(D): Legislative Recommendations
Section 112(f)(l)(D) gives EPA the opportunity to make "recommendations as to
legislation regarding such remaining risk" that may be identified during the analysis for residual
risk.
The Agency is not proposing any legislative recommendations to Congress in this Report.
At this time, EPA believes the legislative strategy embodied in the 1990 CAA Amendments
* * *
March 1999 Page 102 * * *
-------
Residual Risk Report to Congress
provides the Agency with adequate authority to address residual risks and provides a complete
strategy for dealing with a variety of risk problems. The strategy recognizes that not all
problems are national problems or have a single solution. National emission standards will be
promulgated to decrease the emissions of HAPs from stationary sources. The authority is also
provided to look at smaller scale problems such as the urban environment or the deposition of
HAPs to water bodies in order to address specific concerns, to focus or prioritize efforts to meet
specific needs such as a concern for a class of toxic and persistent HAPs, and to allow for
partnerships among EPA, States, and local programs in order to address problems specific to
these regional and local environments. Congress developed a strategy that, when taken as a
whole, provides EPA with the flexibility to identify and deal with a wide range of air toxics
problems. As the EPA gathers data, performs risk assessments, and develops standards, EPA
may reevaluate the adequacy of the CAA strategy.
Residual risk will play a major role as EPA moves into the risk-based phase of the CAA
strategy. Using information gathered from a variety of sources, including Congressionally
mandated studies, the residual risk program will provide part of the "safety net" that will insure
that the public and the environment will be protected. The following chapter describes this
program's strategy in more detail.
* * *
March 1999 Page 103 * * *
-------
Residual Risk Report to Congress
This page intentionally left blank
* * *
March 1999 Page 104 * *
-------
Residual Risk Report to Congress
5. The Residual Risk Analysis Framework
The remainder of section 112(f) - sections 112(f)(2) through (6) - describes the authority
and schedule for setting residual risk standards. Section 112(f)(2) requires EPA to promulgate
residual risk standards where necessary to provide an "ample margin of safety" to protect the
public health and to prevent, taking into consideration costs, energy, safety, and other relevant
factors, an "adverse environmental effect." This chapter describes EPA's overall goals and
framework for conducting residual risk analyses in response to sections 112(f)(2) through (6).
5.1 Legislative Context
5.1.1 The Context for the Analyses
Section 112(f) defines the context for residual risk standards to be the list of source
categories or their subcategories that have been subjected to emission standards under section
112(d) of the CAA. On December 3, 1993, EPA established the promulgation schedule for
technology-based (MACT) emission standards for 174 listed source categories (EPA 1993d).
The source categories were divided into four groups, or bins, based on their expected
promulgation date: 1992, 1994, 1997, and 2000 (also referred to as 2-year, 4-year, 7-year, and 10-
year bins). MACT regulations are intended to identify and control air emissions from those
major sources that emit HAPs listed pursuant to section 112(b) of the CAA. For existing sources
in most source categories or subcategories, the minimum level of emissions reduction to be
achieved is determined by establishing the current level of control of the best controlled 12
percent of the sources of emissions and establishing a "floor level" of emissions that is the
average emissions limitation achieved by the sources in that 12 percent group. MACT emission
reductions are based on source and technology analyses and do not consider risks presented by
potential HAP exposures.
Congress intended risks to be considered eventually, however, as evidenced by the fact
that most of the CAA-mandated air toxics programs other than MACT involve risk analyses and
strategies to reduce risk to the public and environment. Congress stated in section 112(f)(2) that
if a 112(d) standard does not reduce estimated lifetime excess cancer risk to the "individual most
exposed" to less than one in a million, then the Administrator shall promulgate residual risk
standards for the source category to protect the public health. EPA does not consider the one in a
million individual additional cancer risk level as a "brightline" mandated level of protection for
establishing residual risk standards, but rather as a trigger point to evaluate whether additional
reductions are necessary to provide an ample margin of safety to protect public health. This
interpretation is supported by the guidance provided in the September 14, 1989 Federal Register
notice promulgating national emissions standards for benzene (i.e., the benzene NESHAP),
which was cited by Congress in section 112(f) (see Section 2.1 for more discussion of the
benzene NESHAP, and Appendix B for excerpts from the preamble to the final regulation). EPA
* * *
March 1999 Page 105 * * *
-------
Residual Risk Report to Congress
plans to continue to use this guidance for making final risk management decisions under section
112(f) for carcinogens rather than adopting any single "brightline."
Residual risk is one of the air toxics programs that begins to shift the emphasis from
control technologies toward the receptors being exposed (i.e., the human populations or the
particular environments). While the source category defines the range or scope of the data that
will be required for performing residual risk analyses, the receptor defines the context for the
characterization of the risk. The HAPs emitted, the routes of exposure, and the nature of the
populations or environments being exposed become very important to the risk assessment
outcome.
5.1.2 Compliance Schedule and Effective Date
According to section 112(f)(2), residual risk standards must be promulgated within eight
years of the promulgation date of the MACT standard for that category unless the source category
MACT was scheduled for promulgation within the first two years after the date of enactment of
the 1990 CAA Amendments. In the latter case, residual risk standards must be promulgated
within nine years. Therefore, for purposes of any residual risk standards, the eight-year limit
applies to all source categories listed in the 4-, 7-, and 10-year bins, and the nine-year limit
applies to categories listed in the 2-year bin, regardless of the actual promulgation date. This
means that the 2-year bin standards promulgated under the residual risk program are due to be
finalized in the year 2002 (earliest MACT promulgation for a category in the 2-year bin was
1993). Appendix C contains tables of the source category MACT standards, organized according
to their promulgation schedule, and the actual promulgation dates of those that have been issued.
Section 112(f)(3) establishes that residual risk standards will become effective upon
promulgation, although section 112(f)(4) provides existing sources subject to residual risk
standards a 90-day time period after promulgation to comply, unless the Administrator grants a
compliance waiver of up to two years. Actions must be taken during the waiver period to assure
that "the health of persons will be protected from imminent endangerment."
5.1.3 Area Sources (CAA Section 112(f)(5))
Area sources are defined as sources that have the potential to emit less than 10 tons/year
of a single HAP or 25 tons/year of HAPs in aggregate. Section 112(f)(5) provides that the
Administrator shall not be required to conduct a residual risk review of any category or
subcategories of listed area sources for which an emission standard, referred to as Generally
Available Control Technology (GACT), is promulgated under section 112(d)(5). The EPA
interprets this statutory language to mean that any area source for which the emission standard is
based on MACT will be included in the residual risk analyses according to its specific schedule
of promulgation, but an area source for which GACT was the basis of the standard will be
reviewed under the residual risk program only if deemed necessary by EPA. Area sources to
which MACT has been applied are identified in Appendix C.
* * *
March 1999 Page 106 * * *
-------
Residual Risk Report to Congress
In an effort to utilize our resources wisely and maximize the information gained from the
residual risk analysis process, source category analyses may include area sources not subject to
MACT or GACT. The results of those analyses, with regard to such area sources, would then be
considered under the relevant components of our overall air toxics program, such as the Urban
Air Toxics Strategy.
5.1.4 Unique Chemical Substances (CAA Section 112(f)(6))
There are 17 HAPs listed under section 112(b) that are not specific individual compounds
and for which no CAS numbers are given (see Exhibit 19). Eleven of these are classes of metal
compound HAPs, and the rest cover a variety of other HAP classes. Congress has directed in
section 112(f)(6) that in setting residual risk standards applicable to sources that emit any of
these HAPs, the Administrator should consider information on the HAP that is actually emitted.
Each of these HAP classes may contain hundreds of individual compounds for which there may
be very limited or no toxicity, emissions, or other risk-related data.
In the screening tier of analysis, we may default to relying on data from unspeciated
HAPs in this category of "non-CAS number HAPs" as the basis for evaluating risks, or use data
for one member of a class as a surrogate for other members of the class that have data gaps. In
the absence of toxicity, emissions, and other risk-related information about the specific "non-
CAS number HAPs" that may be emitted by a source under study, we will continue to use
information that is available on any of the constituents, including the elemental compounds, as
scientifically appropriate. Where substance-specific data are available, we will use those data. In
analyses that may form the basis for risk reduction/risk management decisions, assumptions
about a group or members of a group will be carefully evaluated for scientific appropriateness.
An additional requirement of section 112(f)(6) is that any direct transformation
byproducts resulting from the emissions of any of these classes of HAPs should be the basis for
setting standards.
5.2 Objectives
The objectives for residual risk activities under section 112(f)(2) are two-fold.
(1) Assess any risks remaining after MACT standard compliance; and
(2) Set standards for the identified source categories, if additional HAP emission reductions
are necessary to provide an ample margin of safely to protect public health or, taking into
account cost, energy, safety, and other relevant factors, to prevent an adverse
environmental effect.
* * *
March 1999 Page 107 * * *
-------
Residual Risk Report to Congress
EXHIBIT 19
17 HAP CLASSES LISTED UNDER CAA SECTION 112(b)
Antimony Compounds Lead Compounds
Arsenic Compounds (inorganic Manganese Compounds
including arsine)
Beryllium Compounds Mercury Compounds
Cadmium Compounds Fine Mineral Fibers0
Chromium Compounds Nickel Compounds
Cobalt Compounds Polycyclic Organic Matter4
Coke Oven Emissions Radionuclides (including radon)6
Cyanide Compounds3 Selenium Compounds
Glycol Ethersb
X'CN where X = FT or any other group where a formal dissociation may occur. For example, KCN or Ca(CN)2
Includes mono-and di-ethers of ethylene glycol, diethylene glycol, and triethylene glycol R-(OCF£2CH)n-OR'
where:
n= 1,2, or 3
R = alkyl or aryl groups
R' = R, H, or groups which, when removed, yield glycol ethers with the structure:
R-(OCH2CH)n-OH.
Polymers are excluded from the glycol category.
Includes mineral fiber emissions from facilities manufacturing or processing glass, rock, or slag libers (or other
mineral derived libers) of average diameter 1 micrometer or less.
Includes organic compounds with more than one benzene ring, and which have a boiling point greater than or
equal to 100°C.
A type of atom which spontaneously undergoes radioactive decay.
We will evaluate source categories for which MACT standards are promulgated under
section 112(d) using the direction provided in section 112(f) and the risk assessment methods
described in Chapter 3. The general framework for the risk analysis process is described in
Section 5.3.
The MACT program is achieving substantial emissions reductions across many HAPs and
industries. In doing so, it is reducing risks and also leveling the emissions playing field within
industry types. The residual risk framework is intended to provide the Agency flexibility in its
decisions while ensuring that public health and the environment are protected. Our objectives
also include continuing the partnership with State and local programs in the sharing of data and
expertise, and including groups who may be affected by residual risk decisions as part of the
process, when it appears feasible and appropriate to do so.
* * *
March 1999 Page 108 * * *
-------
Residual Risk Report to Congress
5.3 Residual Risk Assessment Strategy Design
Using the context provided by Congress in section 112(f) and the methodologies, data,
and assessment process for air toxics described in more detail in previous sections of this Report,
EPA has developed a residual risk framework. The framework for residual risk analysis may be
described in several steps: identifying management goals that reflect the legal requirements,
problem formulation, data collection, exposure and toxicity assessment, risk characterization, and
risk management/risk reduction. Exhibit 20 presents a flowchart of the general residual risk
analysis process. In short, the framework calls for an iterative, tiered assessment of the risks to
humans and ecological receptors through both direct and multipathway exposures to HAPs,
leading ultimately to a decision on whether additional emission reductions are needed for
individual source categories. This type of iterative or tiered approach is consistent with the NRC
(NRC 1994) and Risk Commission (CRARM 1997a,b) reports written pursuant to the 1990 CAA
Amendments.
The first component of the residual risk framework is that EPA state its risk management
goals, which are identified at a broad level in the CAA legislation:
to achieve a level of emissions that ensures that the public health is protected with an
ample margin of safety; and
to ensure, taking into account cost, energy, safety, and other relevant factors, that the
above level of emissions do not result in an adverse environmental effect.
EPA may decide to translate those legislative objectives into more specific management goals.
Those management goals help direct the problem formulation phase of both the human health
and ecological risk assessments.
For both the human health and ecological risk assessments, the basic premise of the tiered
approach is that the early analysis is generally screening in nature. This analysis is designed to
be relatively simple, inexpensive, and quick, use existing data and defined decision criteria, and
rely on models with simplifying, conservative assumptions as inputs. These simple default
assumptions are conservative in nature to ensure that a lack of data does not result in overlooking
a source category that may pose significant risk. A more refined analysis requires more resources
and data, but the results are more certain and less likely to overestimate risk. While the strategy
is represented generally as having two tiers (screening and refined), additional analyses might be
performed within one or both tiers. The key point is that the additional analyses of increasing
complexity (and resource requirements) will be performed in a manner EPA determines is cost-
effective for a given source category. Where the available information indicates the potential for
substantial risks, a more refined analysis might be implemented at the start.
In using this approach, EPA will follow the recommendation of the NRC (1994) which
stated "EPA should use bounding estimates for screening assessments to determine whether
* * *
March 1999 Page 109 * * *
-------
Residual Risk Report to Congress
EXHIBIT 20
OVERVIEW OF RESIDUAL RISK FRAMEWORK
ITERATIVE APPROACH
Human Health Risk Assessment Ecological Risk Assessment
Problem Formulation
Exposure
Analysis
Risk Characterization
Is human
health risk
acceptable?
Are information
and analysis sufficient
to evaluate
management
options?
No further action
under Residual Risk
Strategy
Evaluation of
Risk Management Options
* * *
March 1999 Page 110 * * *
-------
Residual Risk Report to Congress
further levels of analysis are necessary. For further analysis, the committee supports EPA's
development of distributions of exposures based on actual measurements, results from modeling,
or both." The EPA believes that the analysis being evaluated for use in screening-level
assessments does, in most cases, produce bounding estimates. However, if this iteration is so
conservative that source categories will not be screened out for further consideration under the
residual risk program, an additional iteration that uses less conservative assumptions will be
evaluated and used. In the refined analysis, the exposure assessment will provide distributions of
exposures and a probabilistic distribution of risk will be estimated.
As shown in Exhibit 20, the human health and ecological risk assessments for a source
category are organized into three phases: (1) the problem formulation phase, in which the context
and scope of the assessments are specified; (2) the analysis phase, in which the HAPs' toxicity
and exposure to humans or ecological receptors are evaluated; and (3) the risk characterization
phase, in which the toxicity and exposure analyses are integrated to assess the nature, magnitude,
and uncertainty of any risks. Also as illustrated in Exhibit 20, the problem formulation and
analysis phases of the human health and ecological risk assessments will partially "overlap" in
that certain pathways of concern for humans (e.g., inhalation of outdoor air, consumption of
contaminated fish) will in some cases also be pathways of concern for some ecological receptors
(e.g., terrestrial wildlife, fish-eating wildlife). The development and conduct of risk assessments
by this three-phased approach are described more fully in the Agency's ecological risk
assessment framework (EPA 1992b) and guidelines (EPA 1998d). Although described in those
documents in the context of ecological risk assessment, the basic phased approach is also
appropriate for human health risk assessment.
Following the risk characterization phase of each assessment, a decision step occurs.
How much the risk estimates can be improved by refining the analysis is an important
consideration at this step. If no unacceptable risks have been identified for human health or
environmental effects and the analyses are adequate to support those conclusions (i.e., risks are
acceptable), then no further action is required under this process, and the results of the risk
assessment should be documented. If human health or environmental risks appear unacceptable,
and if sufficient information is available to evaluate management options considering risks, costs,
economic impacts, feasibility, energy, safety, and other relevant factors, the risk assessment is
complete (i.e., no additional iterations are needed), and the process moves to risk management
decision-making. If the information from the risk characterization is insufficient to fully evaluate
risk management options, the residual risk assessment should proceed to a still more refined
analysis.
5.3.1 Stakeholder Involvement
As the federal government pursues its goals of expanded stakeholder involvement in risk
management decisions, consistent with recent recommendations of the Risk Commission
(CRARM 1997a,b) and the NRC (NRC 1996), EPA is committed to involving stakeholders, as
appropriate, at various stages throughout the residual risk analysis process. The NRC's
* * *
March 1999-Page 111 * * *
-------
Residual Risk Report to Congress
Understanding Risk presents a risk assessment/risk management model that also emphasizes
extensive interaction and involvement of stakeholders. Thus, an important component of this
process will be the establishment of interactive discussions with the parties involved. In the
residual risk analysis process, EPA expects the level of stakeholder involvement to vary for the
different source categories, depending on the complexity of the analysis and the potential risks
involved. For source categories with the potential for higher risks and more complex analyses,
stakeholder involvement is likely to occur more frequently throughout the process.
The stakeholders in this case are State and local public health and air toxics agencies,
Tribal groups, the affected industries, and public interest groups. The purpose of these
interactions may be to identify available data, to discuss the results of the risk assessments, to
determine the nature and the scope of the potential risks, to hear concerns and perceptions about
the level of risk, to discuss the next steps in the process (e.g., need for refinements to the
analysis), and to discuss the options available to reduce risk if necessary. Stakeholder
involvement adds another dimension by allowing affected parties to have input and to be given
the opportunity to understand the views of other participants. Feedback from stakeholders,
including those whose concerns may extend beyond the technical capabilities of modeling to
better discern the complete problem, may assist in our evaluation of results. For example, while
the scope of the residual risk analyses will be national, it is possible that local, State, or regional
level problems would only be brought to light by groups at that level. As noted above,
stakeholder involvement may not be the same for all analyses. The level of stakeholder
involvement may be driven by the complexity of the analyses and the expected impacts of
decisions that will result from the analyses. With regard to ecological risk assessments,
stakeholder input can also be valuable in characterizing the societal importance of the ecosystems
at risk.
At important points in the process, the Agency will make information available to State
and local public health and air toxics agencies, Tribal groups, affected industries, and concerned
public interest groups, and may take other steps to facilitate meaningful stakeholder participation.
Those with concerns, specific interests, or information about the specific source category are
encouraged to provide input and assist in the process by pointing out source categories or HAPs
of concern, or by identifying issues to consider. In addition, the Agency expects that
stakeholders will bring valuable new data on HAP toxicity, emissions, or exposure to its
attention. In the problem formulation phase and more extensive data collection step of refined
risk assessments, involvement of stakeholders, specifically affected industries and State and local
agencies, is especially important. As the process for a source category moves closer to risk
reduction/risk management decisions, stakeholder involvement is considered more critical. The
opening of a stakeholder dialogue, consistent with legal limitations such as the Federal Advisory
Committee Act, provides the opportunity for all groups to be involved early in the risk
management process and for the implementation of a rational risk reduction strategy that
proceeds from mutual understanding rather than a one-sided argument.
* * *
March 1999-Page 112* * *
-------
Residual Risk Report to Congress
5.3.2 Priority Setting
Priority setting among the large number of source categories to be reviewed - that is,
determining the order in which residual risk assessments for specific source categories will be
conducted - also is a critical part of the overall strategy. EPA intends to set priorities based on a
number of considerations, including the actual MACT promulgation dates for source categories
(which determines the statutory time period for residual risk determinations) and any available
information bearing on the level of residual risks attributable to various source categories. While
meeting statutory deadlines, EPA will, to the extent possible and based on the available data, set
priorities aimed at achieving the largest, most cost-effective risk reductions first. Priority setting
also will be iterative; priorities are likely to be revised during the course of the residual risk
program as new information becomes available and initial analyses are performed on various
source categories.
Prioritization may occur at many stages of the process. For example, information
collected in the initial problem formulation step will help in setting priorities for a screening-
level analysis. Results of the screening analyses will aid in determining the need for and setting
priorities for a refined analysis. It is also noted that results of screening and refined analyses are
expected to contribute to our priority setting with regard to new research, data collection, and
tool development.
As discussed in Section 5.1.2, the MACT promulgation dates, which determine the
statutory time period for residual risk determinations, fall into four "bins" (2-year, 4-year, 7-year,
and 10-year). Section 112(f)(2) requires standard-setting to address residual risks within eight or
nine years of the promulgation of MACT standards. As a practical matter, this establishes a tight
timeframe in which to develop the information necessary for conducting and refining screening
analyses and in using this information for priority setting. The later two bins, the 7-year and 10-
year, contain many more source categories than the earlier ones. Given the greater number of
source categories in these later bins, priority may be largely driven by the residual risk statutory
deadlines. The Agency's intention is to consider other factors as described above. The extent to
which this is feasible may vary for the later bins and will be determined as we initiate the process
for those source categories.
5.3.3 Problem Formulation and Data Collection
Residual risk analysis for a given source category will begin by describing the context and
scope of the problem to be evaluated. As much data as are readily available will be used at this
stage of the assessment, and stakeholders with interest in this category may be encouraged to
provide input. Information from State, local, or Tribal entities may help the planning process by
pointing out source categories or HAPs of concern, or by identifying issues to consider. It would
be at this stage that key decisions about the HAPs of concern would be made and reassessed in
any subsequent iteration of analysis. For example, do the HAPs being emitted trigger the need
for human health or ecological assessments of pathways other than inhalation? What are the
* * *
March 1999-Page 113 * * *
-------
Residual Risk Report to Congress
endpoints of concern, and what populations may be most affected by the HAPs being emitted?
These evaluations may be largely at a qualitative level, but they will inform the design of the
analysis to follow, in either a screening or refined level.
As discussed in the previous section, the timing of the MACT promulgation schedule, as
well as the need for efficient utilization of resources, will require some prioritization of work. A
number of source categories may be scheduled for analyses during the same time period. The
problem formulation phase will help to prioritize which source categories need earlier attention.
It also will help to determine what data are needed to support certain decisions and whether those
data are available.
Designing the risk assessments during problem formulation involves the following main
activities:
Characterize key sources of HAP release;
Characterize environmental behavior of HAPs and determine for which, if any,
multipathway analyses might be required;
Identify need for ecological assessment;
Identify receptors that are potentially at risk;
Select assessment endpoints; and
Identify exposure pathways of concern.
Many types of data from a wide variety of data sources are needed to assess the residual
risks of source categories. Data collection is expected to occur throughout the residual risk
assessment process. Some data collection is needed even before any screening analyses are
begun on individual source categories, to serve as a basis for setting priorities and ordering the
source categories for residual risk assessment. Because the screening assessment is intended to
be based on readily available data, data collection for this step generally will involve gathering
and organizing the existing data (e.g., health and environmental effects of HAPs, post-MACT
source emission rates for HAPs, previously performed risk assessments of source emissions),
generally from EPA sources (e.g., MACT rulemaking docket, MACT data base) and State and
local air toxics agencies.
The data available will, in part, determine whether an analysis is done on specific
facilities in a source category or on model plants of the type developed during MACT rule
development. EPA anticipates that the amount of information available about facilities within a
source category may be more extensive after the Agency promulgates a MACT standard versus
what was known during MACT rule development. Some of the additional information
anticipated is increased knowledge of the HAPs being emitted, the regulatory level or estimated
emission reductions for these HAPs, the locations of the facilities subject to a MACT rule, and
whether a specific facility is in compliance with the rule. This type of information could narrow
the scope of the analysis to those facilities that appear most likely to be a residual risk concern.
* * *
March 1999 Page 114***
-------
Residual Risk Report to Congress
Problem formulation, including establishment of the conceptual model, sets the context
and scope of human health and ecological risk assessments. For the initial assessment, it also
includes an evaluation of the potential for specific HAPs to accumulate in the environment,
which influences the need for multimedia analyses.
Information on the potential for HAPs to accumulate in the environment can be used to
narrow a comprehensive set of assessment endpoints in the ecological risk screen. Given that
HAPs are initially released to the air, the most important question for the initial problem
formulation is the degree to which the HAPs might persist and partition into other environmental
media. If a HAP is unlikely to accumulate in the environment, then only those ecological
communities that come into direct contact with HAPs in the air need be considered. The
question of whether a multipathway analysis is needed is also asked during problem formulation
in the human health risk assessment.
To identify HAPs that are likely to accumulate in the environment, and thus potentially
pose risks (ecological and/or human health) via food chains and other environmental media, the
most important HAP characteristics are environmental persistence and bioaccumulation
potential.
environmental
persistence
bioaccumulation
If field data, chemical property data, or inference from chemical structure
suggest that the HAP will persist in the environment for several weeks to
several years (or longer), then a multimedia analysis might be necessary.
For persistent and non-volatile HAPs, it is likely that the HAP will be
deposited and accumulate over time in aquatic and terrestrial systems
downwind of the source.
If field data, laboratory data, models (e.g., food web), and/or the log Kow
suggest that the HAP might accumulate in plant or animal tissues, then a
food chain analysis might also be needed. Various cutoff values for
screening bioaccumulation potential have been used. For example, the
Final Water Quality Guidance for the Great Lakes System (EPA 1995e)
used a bioaccumulation factor (BAF) in fish of 1,000 to identify
bioaccumulative chemicals, and log Kow values from 3.0 to 5.0 have been
used to identify constituents likely to bioaccumulate in aquatic and
terrestrial ecosystems (e.g., Connell 1988; Garten and Trabalka 1983;
Suter 1993).
Where possible in the screening assessment, environmental characteristics that influence
the behavior of a HAP in different media (e.g., persistence in water versus air) and thus their
potential exposure to different ecosystems will be identified. For example, if a HAP is readily
degraded by hydrolysis in surface water, aquatic life might not be at risk even if the HAP is toxic
and persistent in air and deposits to surface waters, into which it readily partitions. In a refined
* * *
March 1999-Page 115 * * *
-------
Residual Risk Report to Congress
ecological risk assessment, a literature search and review of studies that describe ecological
impacts that have been clearly attributed to the HAP, or field measurement studies that indicate
environmental "sinks" for the pollutant (i.e., in what environmental compartment(s) the pollutant
is likely to accumulate), can be useful.
For ecological risk assessment, the screening step may also include selection of HAPs for
analysis based on their relative toxicity. For some source categories, several HAPs might be
released. It is possible that the environmental behavior of several HAPs is such that they are
expected to partition into the same environmental medium. If information is available to indicate
that one or a few of those HAPs are much more toxic to ecological communities in contact with
that medium than the remaining HAPs, then it might be possible to focus the ecological
screening assessment on the most toxic of those HAPs. If, in the screening analysis, the most
toxic of those HAPs indicate no risks, then the less toxic HAPs may not need to be evaluated
further.
Developing the Conceptual Model
The conceptual model for a residual risk assessment includes a description of the sources
of HAP releases, information on emission rates, and a description of exposure pathways,
assessment endpoints, and the measures that will be used to evaluate the assessment endpoints.
Multimedia analyses are likely to be needed for many of the persistent HAPs, whereas only the
air pathway may need to be considered for some short-lived HAPs. For those HAPs that are not
expected to accumulate in the environment, either locally or regionally, the conceptual model is
relatively simple, and can be assumed to involve inhalation of air by humans and terrestrial
animals and direct exposure of plant foliage to the air. For those HAPs that might accumulate in
other environmental media (e.g., in water, sediments, soil, or plants), a multimedia exposure
model with the appropriate receptor communities will be needed.
In ecological risk assessments, the various environmental communities need to be
carefully considered. For HAPs that are likely to partition into sediments and soils, receptors of
concern include the benthic aquatic community, the soil macro- and microinvertebrate
community, and plants. For HAPs that are likely to partition into water, the benthic and free-
swimming aquatic communities should be included. For HAPs that might bioconcentrate or
bioaccumulate in aquatic organisms, the animals that feed on those organisms should be
considered (e.g., piscivorous wildlife). For HAPs that might bioaccumulate in terrestrial plants,
herbivorous animals should be included in the conceptual model.
5.3.4 Screening Analyses
Screening-level analyses will often be applied as a first step in the assessment of both
human health and ecological risks, and may include other pathways in addition to inhalation as
appropriate (see discussion in Section 5.3.3). When a screening assessment is complete, EPA
will assemble the information it has collected, as well as the results of the screening analysis, to
* * *
March 1999-Page 116* * *
-------
Residual Risk Report to Congress
prepare a characterization of the source category that would describe any potential public health
or environmental concerns. This information may include both quantitative and qualitative data
and results; at this level, any quantitative exposure and risk estimates will generally be point
estimates (not probabilistic estimates). The screening assessment results will typically be used to
eliminate low-risk source categories from further consideration, to prioritize the remaining
source categories as to the need for a refined assessment, and also to focus any refined
assessment so that it is done more efficiently.
While the screening analysis can serve as a basis for a decision to pursue additional
analyses or to eliminate low-risk source categories from further consideration under section
112(f), it may not be adequate to serve as a basis for establishing additional emission reduction
requirements under section 112(f). These analyses are typically conservative in nature and
specifically designed to more likely overestimate than underestimate risks (yielding a certain
level of false positives). Their results should not be misinterpreted to provide a realistic
prediction of risk. That is, the purpose of a screening analysis is to identify those situations or
HAPs for which no further action is needed and those for which further analysis is needed.
When a subsequent analysis is performed, those aspects of the analysis that are thought to
influence risk most or contain the greatest uncertainty are refined.
The screening analysis will rely largely on readily available data, use simple approaches
to estimate emissions, use simple fate and transport models, use simple multimedia models (with
simple conservative bioaccumulation factors and models of transfer of HAPs from air and soils
to plants, or from air and water to biota), and incorporate readily available toxicity values. The
approximate physical locations of the HAP emission sources are determined from available
information such as emissions profiles derived from the development of MACT source
categories, the Background Information Documents for proposed MACT standards, and MACT
model plants data.
Human Health
Screening analyses will rely largely on readily available data and incorporate readily
available toxicity values. The general methods to be followed are described in Chapter 3.
Depending on the expected magnitude of risk and ready availability of appropriate data,
the maximum off-site modeled concentration may be used to estimate the most exposed
individual in screening-level risk assessments. Where risks are expected to be elevated, in order
to conserve resources, we may pass over this conservative assumption step and move to a refined
assessment that incorporates population data in order to derive the MIR (maximum individual
risk) for areas that people are believed to occupy. Because screening-level risk assessments will
be used for the purpose of determining whether or not further analysis and concern are warranted,
the MEI estimate may be used for risk management decisions that result in the judgment not to
regulate a given source category, but will not be used for risk management decisions that call for
additional controls or regulatory actions.
* * *
March 1999-Page 117* * *
-------
Residual Risk Report to Congress
When a screening assessment has been conducted for a source category, the risk
characterization will typically be used by EPA managers to decide if a more refined risk
assessment should be conducted or if nothing more needs to be done under the residual risk
program. As described in Section 5.3.1, stakeholder involvement at this point may be valuable.
Criteria for Evaluating Screening Analysis Results. Exhibit 21 summarizes human
health risk assessment assumptions and criteria for the screening level of analysis and for the
more refined analysis. EPA will consider a wide range of available toxicity values in
determining if the continued emission of HAPs poses a risk to the public or the environment.
When EPA-verified toxicity values are not available, other sources of toxicity values may be
used (see Section 3.4.1).
Cancer. In the assessment of cancer risks, dose-response assessments developed in a
manner consistent with the direction of the 1996 proposed cancer guidelines (EPA 1996b), which
utilize information on the mechanism of action more than the previous guidelines (EPA 1986b),
are preferred. For early screening analyses, a linear mechanism will be assumed (unless an EPA
assessment is complete which assumes otherwise). Screening analyses may assume additivity of
individual HAP associated cancer risks. Where the screening risk results are below a 10"6 level
of risk, excess cancer risks will usually be considered acceptable and no further action will be
necessary under this process.
Non-cancer effects. Acute and chronic exposures will be assessed separately. For
chronic exposures, long-term exposure estimates (e.g., annual average) will be used. For acute
risks, a similar analysis will occur except that short-term exposure estimates (e.g., one-hour
averages) will be used. In early iterations of the screening analysis, the health criterion for all
non-cancer assessments (acute and chronic) may be based on the hazard index (HI) calculated by
assuming additivity of HAPs in a mixture, where plausible. For each HAP emitted from a source
category's facilities, the toxicity value will be compared with the upper-end HAP exposure level,
as determined in the exposure screen, resulting in a hazard quotient (upper-end HAP exposure
level + toxicity value (such as the RfC)). In a screening analysis, the hazard quotients for each
HAP in the mixture may be added regardless of endpoints, resulting in an HI value. This will
result in a more conservative outcome than looking at HAPs individually, or than looking at
different endpoints separately. In a more refined analysis, the assumption of additivity may be
reviewed and limited to HAPs for which the assumption has a plausible basis or for which no
data are available to support its rejection. A more refined risk assessment will likely be
conducted when the HI exceeds 1 in the screening analysis (i.e., when exposure estimates exceed
toxicity reference levels).
Ecological
Not all HAPs will automatically be considered in ecological risk analyses. Consistent
with EPA guidelines (EPA 1998d), priority will be given to certain HAPs based on their
environmental behavior and toxicity. As discussed in section 5.3.3, HAPs with the potential for
* * *
March 1999 Page 118 * * *
-------
Residual Risk Report to Congress
EXHIBIT 21
SUMMARY OF ASSUMPTIONS AND CRITERIA FOR EVALUATING PUBLIC HEALTH RISKS
Component of the
Risk Assessment
Screening Level3
Refined"
Problem
Formulation
From readily available information, identify
HAPs for analysis
Identify HAPs that require multipathway
analysis
Use generic multimedia conceptual model
simplified based on HAP characteristics and
likely exposure pathways,
Screening analysis results or other information
used to identify HAPs and exposure scenarios
for assessment
Screening analysis results or other information
used to identify multipathway HAPs of concern
More site-specific multimedia model
Analysis Phase
Simple conservative assumptions and
screening-level exposure models are used
In early iterations, assume additivity for all
HAPs; refine this assumption as scientifically
appropriate in later iterations
Variety of sources relied upon for toxicity
values
Conservative individual exposure estimate
(may use theoretical MEI in early iterations)
Size and nature of potentially exposed
population not necessarily considered
Simple analysis of uncertainty
Where scientifically appropriate, assume
additivity for HAPs
More careful consideration of toxicity value
basis and source
Evaluate population distributions of exposure
and risk
More refined uncertainty analyses
Criteria
Upper-end individual cancer risk <10"6
generally considered acceptable
Upper-end individual cancer risk > 10"6 may
lead to refined analysis
HI < 1 generally considered acceptable
HI > 1 leads to reexamination of additivity
assumptions and if HI still greater than 1, may
lead to refined analysis
Upper-end individual cancer risk <10"6 generally
considered acceptable
Upper-end individual cancer risk of roughly 1 in
10,000 is ordinarily considered the upper end of
the range of acceptability
Decisions on unacceptable risk will be made on
a case specific basis, considering information
including confidence in the risk estimate,
population size, distribution of risk within the
population, presence of sensitive subpopulations
at various risk levels, the effects of concern,
uncertainties in the effects information, and other
factors
Screening assessment may be based on upper-end estimated HAP exposure at the location of either the hypothetical MEI or the
MIR in locations people are believed to occupy. Available toxicity values will be considered.
bRefined assessment based on more detailed and site-specific, and less conservative, estimated HAP exposures at the MIR
location and throughout the spatial area of impact. EPA consensus toxicity values, or equivalent, reviewed in light of any
additional credible and relevant information, are typically used.
* * *
March 1999 Page 119***
-------
Residual Risk Report to Congress
adverse environmental effects due to a particular ability to persist, bioaccumulate, or exhibit
acute toxicity will be considered high priority in analyses for environmental risks. It is likely that
this will result in the identification of only a small minority of HAPs that will entail quantitative
risk analyses.
For both screening and refined assessments, the analysis phase of the ecological risk
assessment involves two main steps: estimating HAP concentrations in the environment
(including biota, where appropriate) and evaluating exposure-response profiles. In the initial
screening assessment, point estimates for both the HAP concentrations in the environment and
for ecological effects will generally be used.
A main purpose of the screening-level ecological risk assessment is to screen out those
HAPs and sources of HAPs that are unlikely to pose threats to ecological receptors based on
readily available information. Because information on the habitats and ecosystems surrounding
individual facilities of a source category generally is not readily available, for purposes of the
screen, EPA generally assumes the presence of generic ecological systems and receptors. The
simple multipathway analysis is employed to estimate if, and to what extent, generic ecological
receptors may be exposed to HAPs. Using the approximate source locations, a generic
ecosystem model including representative environmental and ecological receptors for the sites at
risk is developed. The exposure and potential impact are then modeled and predicted
concentrations in the various environmental media are compared to available ecotoxicity criteria
(i.e., point estimates of thresholds for ecological effects). Ecotoxicity criteria are described in
Section 3.4.2.
EPA assumes, for purposes of screening, that if the most sensitive species known to occur
within an ecological community is protected from adverse effects caused by a HAP, the structure,
and therefore the function, of the community also will be protected. Protection of the ecosystem
as a whole is inferred from the protection of its component communities. These assumptions are
consistent with those made by the Office of Water in developing ambient water quality criteria
for the protection of aquatic life and with those made by the Office of Solid Waste in developing
a variety of screening ecotoxicity criteria. These assumptions will need to be carefully evaluated
as the ecological risk assessment methodology for residual risk is developed.
Criteria for Evaluating Screening Analysis Results. The results of the screening
exposure and ecological effects assessments are integrated to characterize risk. In the screening-
level ecological risk characterization, the maximum HAP concentrations estimated for the
various environmental media are compared to the appropriate screening-level ecotoxicity criteria
for each ecological community specified in the conceptual model. The ratio of the estimated
environmental concentration to the ecotoxicity criteria is called the hazard quotient. When the
hazard quotient exceeds 1, a more refined assessment may be needed. Exhibit 22 summarizes
the assumptions and criteria used to evaluate environmental risks for the screening analysis and
for the more refined analyses.
* * *
March 1999 Page 120 * * *
-------
Residual Risk Report to Congress
EXHIBIT 22
SUMMARY OF ASSUMPTIONS AND CRITERIA FOR EVALUATING ENVIRONMENTAL RISKS
Component of the
Risk Assessment
Screening Level
Refined3
Problem
Formulation
Based on generic aquatic and terrestrial
ecosystems assumed to be near source category
facilities
HAPs screened for those that might require
multipathway analyses
Generic multimedia conceptual model
simplified based on HAP characteristics and
likely exposure pathways
Generic assessment endpoints of maintaining
ecological community structure and function
are used for the communities that might be
exposed
Based on more site-specific information on
ecosystems, habitats, and species near the
facilities of concern
Results of screening analysis or other
information used to identify HAPs and exposure
pathways of concern
More site-specific conceptual model developed
based on results of screening analysis or other
information and site-specific data
Correspondingly more refined assessment
endpoints are developed
Analysis Phase
Simple conservative assumptions and
screening-level exposure models are used
Conservative values from the literature are
assumed for factors such as bioavailability and
bioaccumulation
Locations with maximum estimated HAP
concentration are used to estimate exposure
Screening-level ecotoxicity benchmarks are
identified or developed as point estimates of
no-observed-effect levels for the most sensitive
species in the generic communities
More refined assumptions, site-specific data, and
refined exposure models are used
More representative values from the literature or
actual measurements from the field are used for
factors such as bioavailability and
bioaccumulation
Spatial and temporal extent and magnitude of
contamination are estimated
Refined ecotoxicity benchmarks are identified or
developed as point estimates of low-observed-
effect levels for the assessment endpoints
identified under problem formulation
As data permit, full stressor-response curves
might be developed
Actual field evaluation of ecological condition
near some facilities might be performed
Criteria
HI <1 acceptable; >1 leads to a reexamination
of conservative assumptions and, if the HI
continues to exceed 1, to a more refined
analysis
Consideration of potential environmental
significance of effects limited to benchmark
selection and prioritization
HI <1 acceptable; >1 may be acceptable
depending on ecological significance
Potential environmental significance of effects is
evaluated based on a number of factors,
including area! extent and magnitude of
estimated effects on assessment endpoints and
local, State, Tribal, regional, or national
significance of the assessment endpoints
"Refined assessment based on more detailed and site-specific, and less conservative, estimated HAP exposures at the MIR
location and throughout the spatial area of impact. EPA consensus toxicity values, or equivalent, reviewed in light of any
additional credible and relevant information, are typically used.
* * *
March 1999 Page 121
* * *
-------
Residual Risk Report to Congress
At the end of the screening-level risk characterization, if none of the estimated
environmental concentrations are greater than the corresponding criteria, the conservative risk
screen indicates that the source category does not pose a risk of "an adverse environmental
effect." The results of the screening analysis should be documented, and the ecological risk
assessment process would stop. On the other hand, there might be one or more HAPs and
combinations of exposure media and ecological communities for which the exposure
concentration is greater than the screening ecotoxicity criteria (i.e., the hazard quotient is greater
than 1) or for which the sum of the hazard quotients that apply to the same communities exceeds
1. If any sources or HAPs result in exposures in excess of the appropriate ecotoxicity screening
criteria, further analysis may be warranted.
If estimated levels are only slightly greater than screening-level ecotoxicity criteria (e.g.,
less than an order of magnitude), it is worth reexamining all of the conservative assumptions
used in the screening analyses to see if a more realistic combination of fate and transport
parameters or more realistic values for other key parameters would change the result. Common
conservative assumptions that should be reexamined at this point include, among others, use of
conservative bioaccumulation factors from the literature, assuming that bioavailability is 100
percent, or assuming that 100 percent of a metal is present in its most toxic form (e.g., methyl
mercury instead of elemental mercury). The basis for the criteria may also be reexamined at this
point with regard to underlying uncertainties.
If estimated environmental concentrations are substantially greater than screening-level
ecotoxicity criteria (e.g., more than an order of magnitude) and remain so after selected less
conservative assumptions are used, then a more refined risk assessment may be indicated. If only
one or a few of the facilities within a source category are likely to be causing the result, then a
more refined assessment for those individual facilities using site-specific information might be
appropriate. If several facilities are likely to be at issue, a more refined analysis for the source
category might be needed.
5.3.5 Refined Analyses
For source categories that proceed from screening to refined risk assessments, additional
data collection will be required, with a greater emphasis on site-specific data for affected
facilities. As mentioned previously, some assessments may begin at the refined level. In some
cases, this data collection effort may be relatively extensive, although it should be able to be
focused based on the results of the screening assessment, when done, on the HAPs, types of
effects (i.e., endpoints), sources, locations, exposure pathways, and receptors of most concern.
Data collection to support the refined assessment may involve more detail about data elements
used in the screening assessment (e.g., HAP emission rates, source characteristics) as well as
information about additional data elements (e.g., exposed populations and subpopulations,
epidemiology and disease registry information, actual ecosystems and endangered and threatened
species that might be exposed). This data collection step is also more likely to include collection
* * *
March 1999 -Page 122 * * *
-------
Residual Risk Report to Congress
of data from industry sources and possibly other stakeholders, in addition to more extensive data
collection from State and local agencies.
The sources of this additional information for the refined assessment will vary. It is
assumed that State, local, and EPA Regional offices should have information that is more site-
specific, especially about which facilities are subject to a particular MACT rule, which have
applied for operating permits, and which are in compliance at a particular time. Other facility-
specific information that is needed to conduct the more detailed exposure and risk analysis may
have to be obtained from the information request mechanisms that were used to gather data for
the MACT process. Other information needed may come from existing data bases, such as U.S.
Census data, geographic information systems (GIS), or other types of data bases that may provide
needed inputs for modeling. EPA may also work together with industry to obtain needed data.
Considerable professional judgment is required to carry out and interpret a more refined
residual risk assessment, and the steps taken and approaches used may vary from one source to
the next, even within the same source category. As noted earlier, refinement might be necessary
for some or all components of the analysis. Evaluating the sensitivity of the risk results to
different components of the risk analysis can help identify which components are most important
and allow us to preferentially refine the more sensitive components or assumptions.
Human Health
The refined analyses will be based on the methods and approaches described in Chapter 3
and will incorporate more site-specific data, fewer simple default assumptions, and more
comprehensive and complex models (e.g., ISCST3 for atmospheric dispersion and deposition).
In general, these analyses will be probabilistic and will produce estimates of risk distributions (in
addition to point estimates). The theoretical MEI risk estimate will not be used in refined
assessments; instead, the MIR estimate for areas that people are believed to occupy will be used
to provide input for risk management decisions that may call for additional controls or regulatory
actions.
Criteria for Evaluating Refined Analysis Results. The refined analysis, like the
screening analysis, may be iterative with increasing complexity at each iteration. General
assumptions and criteria are summarized in Exhibit 21. In refined risk assessment, the level of
confidence is increased through the use of EPA or comparable consensus toxicity values that
reflect currently available information. This ensures that toxicity criteria of consistently high
quality and derived by a consistent methodology are used in the assessment. At this level of
analysis, additional available credible and relevant data for all toxicity values used will be
considered by the Agency. In the exposure assessment, more site-specific data and more refined
models are used to estimate exposure concentrations and intakes. In addition, the refined
analysis considers the number of people exposed at different levels.
* * *
March 1999-Page 123 * * *
-------
Residual Risk Report to Congress
Carcinogens subject to benzene NESHAP. In assessing cancer risk in the refined
analysis, multiple HAP exposures are treated as additive where scientifically appropriate or in the
absence of information to the contrary (consistent with EPA policy), and the numbers of people
exposed in various subpopulation groups may be considered. This is to allow the
characterization of risks to specific populations that may need a greater degree of protection. The
Agency will evaluate results consistent with the benzene NESHAP, which states that "an MIR of
approximately [10"4] should ordinarily be the upper end of the range of acceptability." In
addition, EPA would attempt to provide protection to the greatest number of people possible at
an excess individual lifetime risk of cancer no higher than one in a million (10"6), taking into
account additional factors relating to the appropriate level of control (e.g., costs, economic
impacts, feasibility).
Carcinogens for which a margin of exposure analysis is appropriate. For HAPs that EPA
has identified as carcinogens with a nonlinear mode of action, consistent with the guidance in
EPA's proposed revised cancer guidelines (EPA 1996b) or subsequent final revised guidelines,
when available, an MOE analysis may be undertaken.10 The MOE analysis may take into
consideration the number of people exposed, especially sensitive subpopulations, at the various
exposure levels. Individual chemical assessments of the "appropriate" MOE may be made,
considering factors specific to the individual assessment, which could include any or all of the
following: the steepness of the dose-response curve, persistence of the compound in the body,
known human variability in response, and demonstrated human sensitivity as compared with
experimental animals. In addition, the chemical-specific MOE evaluation should provide
information on the appropriate combination or segregation of the chemicals in the mixture. The
use of additivity will be maintained, where scientifically appropriate. The methodology for
combining chemical-specific MOE values across mixture components has not yet been
developed by the Agency. One way this might be done is by first calculating the ratios of
individual HAP exposure levels to the corresponding departure point divided by the chemical-
specific "appropriate" MOE.11 These ratios could be summed for multiple chemicals, and a sum
of ratios (i.e., total ratio) greater than 1 might be considered indicative of a potential hazard. This
is roughly analogous to treating the MOE as a UF and calculating a hazard index.
Non-cancer effects. An RfC that reflects currently available credible and relevant
information is preferred for the calculation of an HQ, at this level of analysis. For chemicals
10 EPA recognizes that the use of an HI approach for non-cancer health effects and a MOE approach for
nonlinear carcinogens presents challenges to the economist in performing economics benefits analysis. This
concern was raised in the CRARM report, which also discussed a general approach to address the issue (CRARM
1997b). In the coming years, the scientific community will need to work with economists to devise defensible
methodologies for economic analyses of these types of effects.
For example, if the departure point for a given chemical is 5 /wg/m , the chemical-specific "acceptable"
MOE is determined to be 1,000, and the exposure level is 0.0005 //g/m3, the ratio for that chemical would 0.0005 +
(5/1,000) = 0.1.
* * *
March 1999 Page 124 * * *
-------
Residual Risk Report to Congress
with no RfC or if the RfC is not verifiable, a scientifically appropriate alternate value with
comparable basis may be used.
For mixtures of HAPs, the HI is calculated based on target organ effects, where adequate
data exist to allow such calculations (EPA 1986c; EPA 1997d). For each chemical in the
mixture, a thorough review of the toxicity literature may be required to determine which organ
systems are affected (e.g., liver, respiratory, central nervous system). It is expected that an HI
less than 1 that is derived using target organ specific hazard quotients would ordinarily be
considered acceptable. If the HI is greater than 1, then the amount by which the HI is greater
than 1, the uncertainty in the HI, the slope of the dose-response curve, and a consideration of the
number of people exposed would be considered in determining whether the risk is acceptable.
Evaluation of the acceptable value for an HQ or an HI of 1 also would consider the values
of UFs and the confidence in the RfCs that are used in the calculation of the HI. In general, it is
considered that each UF is somewhat conservative; because all factors are not likely to
simultaneously be at their most extreme (highest) value, a combination of several factors can lead
to substantial conservatism in the final value. Larger composite UFs lead to more conservative
RfCs. Conversely, lower composite UFs are less conservative and usually indicate a higher level
of confidence in the RfC. Intermediate UF values or a mixture of high and low UFs would
require an examination of the relative contribution of various chemicals to the HI. Thus, an HI or
HQ greater than 1 may be considered acceptable based on consideration of other factors.
The non-cancer acute HQ should be calculated based on estimates of exposure for the
appropriate short duration. The ARE, when available, should be used as the chemical-specific
health criterion in the calculation of an acute HQ. For chemicals with no ARE, a provisional
ARE may be developed from other acute toxicity criteria (see Exhibit 14) or from the available
health effects data. For HAP mixtures, the non-cancer acute HI should be calculated, as
appropriate, based on estimates of related effects (e.g., in the same target system). On a case-by-
case basis, HQs or His greater than 1 may be considered acceptable based on consideration of the
factors described above for chronic HQs and His.
Ecological
For the more refined ecological assessments, spatial and temporal patterns of HAP
contamination of the environment and more complete exposure-response profiles will likely be
considered. Also, more sophisticated models can be used to simulate the fate and transport of
contaminants in the ecosystem of concern, or concentrations in environmental media might
actually be measured in the field and mapped to depict the contamination pattern at the specific
site.
Natural populations and communities usually can compensate for some degree of loss in
survivorship or reproduction. The ability for populations to compensate for some loss depends
on species' characteristics (e.g., longevity, growth rate, reproductive rate) and characteristics of
* * *
March 1999-Page 125 * * *
-------
Residual Risk Report to Congress
the ecosystem and communities in which the species exists (e.g., food abundance, presence of
competitors, natural stress levels). Plants tend to be very resilient and able to tolerate or
compensate for a wide range of natural (e.g., drought) and anthropogenic stressors. All "natural"
populations and communities undergo changes on at least a seasonal basis, and ecosystems can
exist in many different states, all of which might be "healthy" and likely to persist over time.
These issues will be important to consider in the development of residual risk methodology for
identifying "adverse environmental effects."
Evaluating the sensitivity of the risk results to different components of the risk analysis
can help identify which components are most important and allow the assessors to refine the
more sensitive analyses or assumptions sequentially. If it appears that some site-specific
information will need to be collected in the field (e.g., identify and evaluate the ecosystems
surrounding a facility and the pattern of contamination around the facility), the problem
formulation step and conceptual model will need to be refined as thoroughly as possible, and an
analysis plan should be developed for the field data collection and assessment. During this
problem formulation, assessment endpoints may need to be defined on a site-specific basis. It
might be possible to identify species that require a higher level of protection (e.g., game fish)
than species for which greater functional redundancy exists (e.g., forage fish, for which many
species can play a similar functional role in the ecosystem). Moreover, on a site-specific basis,
endpoints other than direct toxicological effects might be considered, such as a change in algal
species composition in response to a chemical stressor that results in a decline in water quality.
If a refined analysis is needed, more realistic (i.e., less generic) approaches can be used to
characterize risks. General assumptions and criteria are summarized in Exhibit 22. For example,
in early iterations of the refined analysis, an ecotoxicity criterion may be compared to an average
instead of maximum estimated HAP concentration, using an ecologically relevant area over
which to average the concentrations. A refined assessment may involve comparing a series of
isopleths (i.e., lines of constant concentration) of estimated HAP concentrations in the
environment to stressor-response curves. For a refined analysis of a specific site, mapping the
overlap of isopleths of estimated or measured HAP concentrations with the location of ecological
receptors can be helpful in evaluating the significance of the risks. For example, population-
level models might be adapted for an ecological risk assessment application to delineate the
impact of a chemical stressor on population dynamics over space and time. Such tools have
already been used successfully in ecological risk assessments, particularly for fish populations
(see Suter 1993). Information to be included in such refined risk characterizations would also
include the local, State, Tribal, regional, and/or national ecological value or significance of the
ecological entities at risk.
5.3.6 Risk Management/Risk Reduction Decisions
Prior to a decision on the need for a standard and specifically what that standard needs to
accomplish, there are risk management decision points within the residual risk assessment
strategy after the risk characterization step in each of the risk assessments (see Exhibit 20). To
* * *
March 1999 -Page 126 * * *
-------
Residual Risk Report to Congress
consider a source category to be of no further concern under the residual risk program, the health
criteria ("ample margin of safety") and, considering costs and other factors, the environmental
criteria (no "adverse environmental effect") would need to be satisfied. Where the available
information is too limited to make a "no further action" determination, those components of the
source category responsible for the uncertainty would be subject to more data collection and
more refined analysis. If the decision is made not to continue the analysis of a source category
(i.e. that source category is eliminated from further consideration under section 112(f) in this
process), then the information supporting that decision would be made available to stakeholders.
While the screening analyses can serve as a basis for a decision to pursue additional
analyses or to eliminate low-risk source categories from further consideration under section
112(f), early iterations at the screening tier of analysis are not adequate to serve as a basis for
establishing additional emission reduction requirements under section 112(f).
In addition to the results of the risk analysis/characterization based on human health and
environmental data, EPA is also required by CAA section 112(f) to consider other factors before
the establishment of additional risk standards. In determining whether further regulation is
warranted in order to protect public health with an ample margin of safety and/or to prevent an
adverse environmental effect, the risk manager will evaluate the level of risk and the risk
reduction achievable against costs, feasibility, and other factors and, in the case of environmental
risks, against costs, energy, safety, and other relevant factors. The Agency recognizes that
because of location (or other factors) there may be cases where, after application of MACT
standards, only a subset of facilities within a source category poses risks of concern. In
determining the need for additional standards, EPA would look at all federal, State, and local
regulations for that particular category. The proposed integrated air toxics budget initiative for
fiscal year 2000 is intended to be a significant tool that could be used to achieve additional air
toxics reduction beyond MACT control through available authority and approaches prior to
residual risk determination. EPA will then evaluate the remaining risk and consider ample
margin of safety as discussed below. In those cases where it is determined to be necessary, EPA
will use CAA section 112(f)(2) residual risk authority to set national standards but focus the
applicability of standards only on those portions of the source category.
The EPA will apply the ample margin of safety framework to public health risks in the
context of the tiered risk assessment and management approach for air toxics' residual risks. For
carcinogens, EPA will apply a two-step ample margin of safety approach, as described here and
in Section 2.1. EPA developed the benzene risk management framework, which forms the basis
for human health risk management in the residual risk program, in response to a 1987 DC Circuit
Court decision on the Vinyl Chloride national emission standard, also taking into consideration
public comment on several alternative risk management approaches it had proposed for benzene
(see Section 2.1 for more historical background on the benzene national emission standard).
According to the benzene framework, EPA would develop national emission standards for HAPs
in two steps: (1) first determine a "safe" or "acceptable risk" level, considering only public health
factors, and (2) then set an emission standard that provides an "ample margin of safety"
* * *
March 1999 -Page 127 * * *
-------
Residual Risk Report to Congress
considering relevant factors in addition to health such as costs, economic impacts, and feasibility.
In establishing the acceptable risk level, EPA would consider the extent of the estimated risk if
an individual were exposed to the maximum level of a pollutant for a lifetime, i.e., maximum
individual risk (MIR). Although an MIR for cancer of approximately 1 in 10 thousand should
ordinarily be the upper-end of the range of acceptability under this approach, EPA would
consider other health and risk factors (e.g., projected overall incidence of cancer or other serious
health effects within the exposed population, the number of people exposed within each
individual lifetime risk range, the science policy assumptions and estimation uncertainties
associated with the risk measures). In the second step, EPA would attempt to provide protection
to the greatest number of people possible at an excess individual lifetime risk of cancer no higher
than 1 in 1 million (10"6), taking into account additional factors relating to the appropriate level
of control (e.g., costs, economic impacts, feasibility). The acceptable risk established in the first
step would not be exceeded by the standards EPA adopts based on the second step. This
approach is consistent with risk management approaches taken by other EPA programs intended
to broadly protect public health. For example, other EPA programs use a risk management range
of 10"6 to 10"4 under their reasonable maximum exposure scenario to guide their decision-making
for carcinogens.
The EPA has not yet implemented the ample margin of safety approach as interpreted by
the Vinyl Chloride decision with respect to non-cancer effects or carcinogens for which the MOE
analysis is appropriate, though EPA believes that the 1989 benzene NESHAP could provide
important guidance for residual risk decisions in these areas. The Agency does not yet have
applications of the benzene NESHAP two-step approach to specifically address non-cancer
public health risks and public health risks posed by carcinogens with non-linear risk assumptions,
but such risk management framework applications are being developed. In applying the benzene
NESHAP approach, the EPA would first determine an "acceptable" level of such risk, again
without taking into consideration the cost of achieving such protection or other, non-health
factors. As a second step, EPA would set standards sufficient to provide an "ample margin of
safety," and these other factors would be weighed in such standard-setting. Under this approach,
the Agency would have the discretion under Vinyl Chloride to identify both the "acceptable risk"
level and methods of arraying factors for consideration in the "ample margin of safety" step.
Section 112(f) also gives EPA the authority to promulgate more stringent controls as
necessary to protect against an adverse environmental effect. In promulgating such controls,
EPA must, according to the statute, take into consideration costs, energy, safety, and other
relevant factors. The EPA is currently developing a policy for how it will implement this
authority and make residual risk management decisions regarding prevention of adverse
environmental effects.
5.3.7 Comparison to CRARM Recommendations
In formulating its strategy for assessing residual risks under the CAA, EPA has
conformed to many of the specific recommendations articulated by CRARM in their 1997 final
report (CRARM 1997a,b). EPA's overall consistency with the tiered approach advocated by the
* * *
March 1999 Page 128 * * *
-------
Residual Risk Report to Congress
Commission (see Exhibit 4) is evident throughout this Report in the methods and strategies
described (see, for example, Exhibit 20). In addition, five specific recommendations of the
Commission (see Section 3.1.2) are listed here along with a short explanation of how EPA is
fulfilling each.
Characterize and articulate the scope of the national, regional, and local air toxics
problems and their public health and environmental contexts.
We are in the process of defining an Air Toxics Strategy that will assess what we know
about these problems and will identify how the provisions in section 112 can best address
them. As part of the air toxics program directed by Congress in the CAA, we have and
continue to characterize specific issues such as mercury emissions (EPA 1997a),
emissions from utilities (EPA 1998b), and deposition of air pollutants to the Great Waters
(EPA 1997b). The integrated Urban Air Toxics Strategy (EPA 1998a), which is focused
on risks posed by cumulative emissions in urban areas, and the residual risk program
(described in this Report), through which post-MACT risks from industrial source
categories are assessed, are two major elements of EPA's characterization of the air
toxics problem as part of the air toxics program.
Use available data and default assumptions to perform screening-level risk assessments
to identify sources with the highest apparent risks.
This is the underlying strategy of EPA's residual risk approach described throughout this
Report and illustrated in the flow chart in Exhibit 20. The flow chart is an adaptation of
the approach proposed by the Commission in their 1997 final report.
Conduct more detailed assessments of sources and facilities with the highest risks,
providing guidance and incentives to regulated parties to either conduct these risk
assessments or reduce emissions to below screening thresholds.
EPA is currently evaluating the potential for both EPA and regulated parties to carry out
detailed risk assessments, when appropriate based on screening assessment results, using
the methods described in detail in Chapter 3 of this Report. EPA will develop guidance
for such assessments as necessary.
EPA will consider incentives to industry to reduce residual risks, as described in Section
4.1.2.
At facilities that have incremental lifetime upper-bound cancer risks greater than one in
100,000 persons exposed or that have exposure concentrations greater than reference
standards, examine and choose risk reduction options in light of total facility risks and
public health context.
* * *
March 1999 Page 129 * * *
-------
Residual Risk Report to Congress
In accordance with CAA section 112(f)(2), EPA will consider the estimated cancer risks
for facilities and implement management options that ensure an "ample margin of safety"
as defined in the 1989 benzene NESHAP. The two-step benzene approach, described in
detail in Section 2.1, is generally consistent with the Commission's recommendation,
although it does not incorporate a "flexible bright line" of 10"5 (CRARM 1997b). As
discussed in Section 5.3.6, the Agency is developing risk management frameworks for
non-cancer effects and carcinogens analyzed by an MOE approach.
EPA may consider total facility risks and public health context in risk management
decisions when doing so will ensure that the concept of ample margin of safety is
maintained.
Consider reduction of residual risks from source categories of lesser priority.
EPA interprets this statement to say that the Agency should address highest risk source
categories first, and then consider additional risk reductions from the lower priority (i.e.,
lower risk) source categories. The Agency will prioritize source categories for evaluation
under the residual risk program to the extent possible, given data limitations and
legislative time constraints. The goal of prioritizing will be to address source categories
with higher risk first. EPA will use information from the Agency's overall air toxics
program and data gathered in the problem formulation part of the risk assessments to help
prioritize source categories.
An alternative interpretation of this statement is that lesser priority risk sources should
not be ignored in the implementation of risk reduction actions. While these sources may
not be identified for additional risk reduction requirements under residual risk, they will
receive attention, as appropriate, under our broader programs aimed at pollution
prevention and waste minimization nationwide.
5.4 Summary
Following the CAA section 112(f), EPA has developed a framework to identify, assess,
and manage the residual risks associated with air toxics emissions following the application of
MACT standards to source categories. We will be relying on the general methodology and
process illustrated by the framework described in this document in our risk assessment activities
throughout the air toxics program. The framework is guided by sections 112(f)(2) through (6)
and influenced by the recent recommendations made by the NRC (NRC 1994) and the Risk
Commission (CRARM 1997a,b), and it incorporates EPA's current risk assessment and risk
management policies, published guidelines, and methods. In short, the residual risk analysis
framework consists of a tiered, iterative assessment of the human health and environmental risks
resulting from both inhalation and non-inhalation exposures to HAPs following MACT
implementation, leading ultimately to decisions on whether additional emission reductions are
needed. Key steps in the process include problem formulation, data collection, risk analysis, and
* * *
March 1999 Page 130 * * *
-------
Residual Risk Report to Congress
risk management/risk reduction decision-making. The human health risk management decision
criteria are based on the "ample margin of safety" principles, first laid out in EPA's 1989 national
emission standard for benzene and affirmed in the 1990 CAA Amendments, and the
environmental decision criteria are based on the "prevent, taking into consideration costs, energy,
safety, and other relevant factors, an adverse environmental effect" language in the statute. This
framework is intended to provide EPA appropriate flexibility in its decisions while ensuring that
public health and the environment are protected from air toxics as envisioned by Congress in the
CAA.
* * *
March 1999-Page 131 * * *
-------
Residual Risk Report to Congress
This page intentionally left blank
* * *
March 1999-Page 132* *
-------
Residual Risk Report to Congress
References
Agency for Toxic Substances and Disease Registry (ATSDR). 1993a. Toxicological profile for
cadmium. Atlanta: U.S. Department of Health and Human Services, Public Health Service.
Agency for Toxic Substances and Disease Registry (ATSDR). 1993b. Toxicological profile for
lead. Atlanta: U.S. Department of Health and Human Services, Public Health Service.
Agency for Toxic Substances and Disease Registry (ATSDR). 1994. Toxicological profile for
mercury. Atlanta: U.S. Department of Health and Human Services, Public Health Service.
Agency for Toxic Substances and Disease Registry (ATSDR). 1998. Agency for Toxic
Substances and Disease Registry: Minimal risk levels (MRLs) for hazardous substances at
http://atsdrl.atsdr.cdc.gov:8080/mrls.html. Updated January 5, 1998.
Agency for Toxic Substances and Disease Registry (ATSDR). 19xx. Toxicological profile for
[various substances]. Atlanta: U.S. Department of Health and Human Services, Public Health
Service.
American Industrial Hygiene Association (AJHA). 1998. Emergency response planning
guidelines and workplace environmental exposure level guides. Fairfax, VA.
Baird, S.J., J.T. Cohen, J.D. Graham, A.I. Shlyakhter, and J.S. Evans. 1996. Non-cancer risk
assessment: A probablistic alternative to current practice. Human and Ecological Risk
Assessment 2(1):79-102.
Binkova, B., J. Lewtas, I. Miskvova, J. Lenicek, and R. Sram. 1995. DNA adducts and personal
air monitoring of carcinogenic polycyclicaromatic hydrocarbons in an environmentally exposed
population. Carcinogenesis (England) 16(5): 1037-1046.
Bloom, D.L., D.M. Byrne, and J.M. Andresen. 1993. Communicating risk to senior EPA policy
makers: A focus group study. Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC.
Bogen, K.T. and R.C. Spear. 1987. Integrating uncertainty and interindividual variability in
environmental risk assessment. Risk Analysis 15(3): 411-419.
Brown, L.M., L.M. Pottern, and WJ. Blot. 1984. Lung cancer in relation to environmental
pollutants emitted from industrial sources. Environ. Res. 34:250-261.
* * *
March 1999-Page 133 * * *
-------
Residual Risk Report to Congress
Bustueva, K.A., B.A. Revich, and L.E. Bezpalko. 1994. Cadmium in the environment of three
Russian cities and in human hair and urine. Arch. Environ. Health 49(4):284-288.
Commission on Risk Assessment and Risk Management (CRARM). 1996. Risk assessment and
risk management in regulatory decision-making. Draft report. Washington, DC.
Commission on Risk Assessment and Risk Management (CRARM). 1997a. Framework for
environmental health risk management. Final report, Volume 1. Washington, DC.
Commission on Risk Assessment and Risk Management (CRARM). 1997b. Risk assessment
and risk management in regulatory decision-making. Final report, Volume 2. Washington, DC.
Connell, D.W. 1988. Bioaccumulation behavior of persistent organic chemicals with aquatic
organisms. Rev. of Environ. Contamin. and Toxicol. 101:118-154.
Dayal, H., S. Gupta, N. Trieff, D. Maierson, and D. Reich. 1995. Symptom clusters in a
community with chronic exposure to chemicals in two Superfund sites. Archives of
Environmental Health 50(2): 108-111.
Driver, L. and A. Pope. 1998. The 1996 National Toxics Inventory and its role in the
Government Performance and Results Act. AWMA/EPA Emission Inventory Conference, New
Orleans, LA. December 1998.
Edmonds, L.D., C.E. Anderson, J.W. Flynt Jr., and L.M. James. 1978. Congenital central
nervous system malformations and vinyl chloride monoma exposure: A community study.
Teratology 17:137-142.
Finkel, A.M. 1990. Confronting Uncertainty in Risk Management: A Guide for Decision-
Makers. Center for Risk Management, Resources for the Future. Washington, DC.
Finley, B. and D. Paustenbach. 1994. The benefits of probabilistic exposure assessment: Three
case studies involving contaminated air, water, and soil. Risk Analysis 14(l):53-73.
Frey, H.C. 1992. Quantitative analysis of uncertainty and variability in environmental policy
making. Prepared for the American Association for the Advancement of Science and the U.S.
Environmental Protection Agency.
Frey, H.C. and D.S. Rhodes. 1996. Characterizing, simulating, and analyzing variability and
uncertainty: an illustration of methods using an air toxics emissions example. Human and
Ecological Risk Assessment 2(4):762-797.
* * *
March 1999 Page 134 * * *
-------
Residual Risk Report to Congress
Frost, F., L. Harter, S. Milham, R. Royce, A. Smith, J. Hartley, and P. Enterline. 1987. Lung
cancer among women residing close to an arsenic emitting copper smelter. Arch. Environ.
Health 42:148-152.
Garten, C.T., Jr. and J.R. Trabalka. 1983. Evaluation of models for predicting terrestrial food
chain behavior of xenobiotics. Environ. Sci. Technol. 17(10):590-595.
Hattis, D. and K. Barlow. 1996. Human interindividual variability in cancer risks Technical
and management challenges. Human and Ecological Risk Assessment 2(1): 194-220.
Hoffman, F.O. and J.S. Hammonds. 1994. Propagation of uncertainty in risk assessments: the
need to distinguish between uncertainty due to lack of knowledge and uncertainty due to
variability. Risk Analysis 14(5): 707-712.
Hughes, J.P., L. Polissar, and G. Van Belle. 1988. Evaluation and synthesis of health effects
studies of communities surrounding arsenic producing industries. Int. J. Epidemiol. 17:407-413.
Klemans, W., et al. 1995. Cytogenetic biomonitoring of a population of children allegedly
exposed to environmental pollutants. Phase I, SCE analysis. Mutation Research 319(4):317-
323.
Lawton, J.H. and V.K. Brown. 1994. Redundancy in ecosystems: Biodiversity and ecosystem
function. Springer-Verlag, Berlin Heidelberg, Germany, pp. 255-270.
Maughan, J.T. 1993. Ecological assessment of hazardous waste sites. Van Nostrand Reinhold,
New York, NY.
McKone, T.E. 1994. Uncertainty and variability in human exposures to soil contaminants
through home-grown food: A Monte Carlo assessment. Risk Analysis 14(4):405-419.
Morgan, G. and M. Henri on. 1990. Uncertainty: A guide to dealing with uncertainty in
quantitative risk and policy analysis. Cambridge University Press.
National Academy of Sciences (NAS). 1973. Water quality criteria 1972 (the "Blue Book").
National Research Council (NRC). 1983. Risk assessment in the federal government:
Managing the process. National Academy Press, Washington, DC.
National Research Council (NRC). 1986. Criteria and methods for preparing emergency
exposure guidance level (EEGL), short-term public emergency guidance level (SPEGL), and
continuous exposure guidance level (CEGL) documents. National Academy Press, Washington,
DC.
* * *
March 1999-Page 135 * * *
-------
Residual Risk Report to Congress
National Research Council (NRC). 1993. Guidelines for developing community emergency
exposure levels for hazardous substances. National Academy Press, Washington, DC.
National Research Council (NRC). 1994. Science and judgment in risk assessment. National
Academy Press, Washington, DC.
National Research Council (NRC). 1996. Understanding risk. National Academy Press,
Washington, DC.
Natural Resources Defense Council (NRDC), Inc. v. EPA. 1987. 824 F.2d at 1146.
Nordstrom, S., L. Beckman, and I. Nordenson. 1978. Occupational and environmental risks in
and around a smelter in northern Sweden, variations in birthweight. Hereditas 88:43-46.
Paustenbach, DJ. 1989. The risk assessment of environmental and human health hazards: A
textbook of case studies. John Wiley and Sons, New York, NY.
Pershagen, G. 1985. Lung cancer mortality among men living near an arsenic emitting smelter.
Am. J. Epidemiol. 122:684-694.
Ries, L.A.G, C.L. Kosary, B.F. Hankey, B.A. Miller, and B.K. Edwards (eds). 1998. SEER
cancer statistics review, 1973-1995. National Cancer Institute, Bethesda, MD.
Rosenman, K.D., I.E. Rizzo, M.G. Conomos, and GJ. Halpin. 1989. Central nervous system
malformations in relation to polyvinyl chloride production facilities. Arch. Environ. Health
44(5):279-282.
Sheehan, P.J., A. Baril, P. Mineau, O.K. Smith, A. Harfenist, and W.K. Marshall. 1987. The
impact of pesticides on the ecology of prairie-nesting ducks. Technical Report Series, No. 19.
Canadian Wildlife Service, Ottawa.
Shy, C.M. 1993. Epidemiological studies of neurotoxic, reproductive, and carcinogenic effects
of complex mixtures. Environ Health Perspect 101(Suppl. 4):183-186.
STAPPA/ALAPCO. 1989. Toxic air pollutants: State and local regulatory strategies.
Suter, G.W., II. 1993. Ecological risk assessment. Lewis Publishers, Chelsea, MI.
Theriault, G., H. Iturra, and S. Gingras. 1983. Evaluation of the association between birth
defects and exposure to ambient vinyl chloride. Teratology 27:359-370.
U.S. EPA. 1976. Quality criteria for water (the "Red Book"). Office of Water, Washington,
DC.
* * *
March 1999-Page 136* * *
-------
Residual Risk Report to Congress
U.S. EPA. 1980. Notice of water quality criteria documents. Federal Register 45:79318.
November 20.
U.S. EPA. 1984. Risk assessment and management: Framework for decision making. Office of
Policy, Planning, and Evaluation, Washington, DC. EPA-600/9-85-002.
U.S. EPA. 1986a. Guidelines for mutagenicity risk assessment. Federal Register 51:34006-
34012. September 24.
U.S. EPA. 1986b. Guidelines for carcinogen risk assessment. Federal Register 51:33992-
34003. September 24.
U.S. EPA. 1986c. Guidelines for the health risk assessment of chemical mixtures. Federal
Register 51:34014-34025. September 24.
U.S. EPA. 1986d. Guidelines for deriving numerical water quality criteria for the protection of
aquatic organisms and their uses. Office of Water Regulations and Standards, Washington, DC.
U.S. EPA. 1986e. Standard evaluation procedure for ecological risk assessment. Office of
Prevention, Pesticides, and Toxic Substances and Office of Pesticide Programs, Washington,
DC. EPA-540/9-85-001.
U.S. EPA. 1986f. Guidelines for exposure assessment. Federal Register 51:34042-34054.
September 24.
U.S. EPA. 1986g. Users manual for the human exposure model (HEM). OAQPS, Research
Triangle Park, NC. EPA-540/5-86-001. June.
U. S. EPA, Federal Emergency Management Agency, and Department of Transportation. 1987.
Technical guidance for hazards analysis, emergency planning for extremely hazardous
substances. EPA-OSWER-88-001.
U.S. EPA. 1988a. Proposed guidelines for exposure-related measurements. Federal Register
53:48830-48853. December2.
U.S. EPA. 1988b. National emission standards for hazardous air pollutants. Federal Register
53(145):28496-28056, Proposed Rule and Notice of Public Hearing. July 28.
U.S. EPA. 1989a. National emission standards for hazardous air pollutants; Benzene. Federal
Register 54(177):38044-38072, Rule and Proposed Rule. September 14.
U.S. EPA. 1989b. Risk assessment guidance for Superfund, Volume II: Environmental
evaluation manual. Office of Emergency and Remedial Response.
* * *
March 1999-Page 137* * *
-------
Residual Risk Report to Congress
U.S. EPA. 1989c. Risk assessment guidance for Superfund, Volume I: Human health
evaluation manual. Office of Emergency and Remedial Response.
U.S. EPA. 1990. Methodology for assessing health risks associated with indirect exposure to
combustor emissions. Office of Research and Development and Office of Health and
Environmental Assessment, Washington, DC. EPA-600/6-90-003.
U.S. EPA. 1991. Guidelines for developmental toxicity risk assessment. Federal Register
56:63798-63826.
U.S. EPA. 1992a. Guidelines for exposure assessment. Federal Register 57:22888-22938.
May 29.
U.S. EPA. 1992b. Framework for ecological risk assessment. Risk Assessment Forum, Office
of Research and Development, Washington, DC. EPA-630/R-92-001. February.
U.S. EPA. 1992c. A tiered modeling approach for assessing the risks due to sources of
hazardous air pollutants. Office of Air Quality Planning and Standards, Research Triangle Park,
NC. EPA-450/4-9-001.
U.S. EPA. 1992d. Draft report: A cross-species scaling factor for carcinogen risk assessment
based on equivalence of mg/kg3/4/day. Federal Register 57:24152-24173. June 5.
U.S. EPA. 1992e. Guidance on risk characterization for risk managers and risk assessors
("Habicht Memorandum"). Risk Assessment Council, Washington, DC. February 26.
U.S. EPA. 1993a. A review of ecological assessment case studies from a risk assessment
perspective. Risk Assessment Forum, Office of Research and Development, Washington, DC.
EPA-630/R-92-005. May.
U.S. EPA. 1993b. Addendum to the methodology for assessing health risks associated with
indirect exposure to combustor emissions. Office of Research and Development, Washington,
DC. EPA-600/AP-93-003.
U.S. EPA. 1993c. A descriptive guide to risk assessment methodologies for toxic air pollutants.
Office of Air Quality Planning and Standards, Research Triangle Park, NC. EPA-453/R-93-038.
U.S. EPA. 1993d. National emission standards for hazardous air pollutants schedule for the
promulgation of emission standards under section 112(e) of the Clean Air Act Amendments of
1990. Federal Register 58:63941-63954. Decembers.
U.S. EPA. 1994a. Deposition of air pollutants to the Great Waters, First Report to Congress.
EPA-453/R-93-055. May.
* * *
March 1999 Page 138 * * *
-------
Residual Risk Report to Congress
U.S. EPA. 1994b. A review of ecological assessment case studies from a risk assessment
perspective, Volume n. Risk Assessment Forum, Office of Research and Development,
Washington, DC. EPA-630/R-94-003. July.
U.S. EPA. 1994c. Exposure assessment guidance for RCRA hazardous waste combustion
facilities. Office of Solid Waste and Emergency Response, Washington, DC. EPA-530/R-94-
021.
U.S. EPA. 1994d. National Human Activity Pattern Survey (NHAPS) - Use of nationwide
activity data for human exposure assessment (W.C. Nelson, Project Officer, EPA/ORD, Research
Triangle Park, NC). Presented at American Waste Management Association meeting.
Cincinnati, OH. Paper #94-WA75A.01. June.
U.S. EPA. 1994e. Methods for derivation of inhalation reference concentrations and application
of inhalation dosimetry. Washington, DC.
U.S. EPA. 1994f. Estimating exposure to dioxin-like compounds (three volumes). External
review draft. EPA-600/6-88-005Ca.
U.S. EPA. 1994g. Methods for exposure-response analysis and health assessment for acute
inhalation exposure to chemicals: Development of the acute reference exposure. Draft Working
Paper. Office of Health and Environmental Assessment, Research Triangle Park, NC.
U.S. EPA. 1995a. Guidance for risk characterization. Science Policy Council, Washington, DC.
February.
U.S. EPA. 1995b. SCREENS model user's guide. Office of Air Quality Planning and
Standards, Research Triangle Park, NC. EPA-454/B-95-004.
U.S. EPA. 1995c. User's guide for the industrial source complex (ISC3) dispersion models.
Office of Air Quality Planning and Standards, Research Triangle Park, NC. EPA-454-/B-95-
003a.
U.S. EPA. 1995d. Great Lakes water quality initiative criteria documents for the protection of
wildlife: DDT, Mercury, 2,3,6,8-TCDD, PCBs. Office of Water. EPA-820/B-95-008.
U.S. EPA. 1995e. Final water quality guidance for the Great Lakes System. Federal Register
60:15366, Final Rule. March 23.
U.S. EPA. 1995f. Policy for risk characterization ("Browner Memorandum"). Office of the
Administrator, Washington, DC. March.
* * *
March 1999 Page 139 * * *
-------
Residual Risk Report to Congress
U.S. EPA. 1995g. Summary and analysis of available air toxics health effects data. Final draft.
Prepared by ICF Incorporated for Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency. September.
U.S. EPA. 1995h. Proposed guidelines for neurotoxicity risk assessment. Federal Register
60(192):52032-52056. Office of Research and Development, Research Triangle Park, NC.
U.S. EPA. 1995L Technical support document for the Hazardous Waste Identification Rule:
Risk assessment for human and ecological receptors. Office of Solid Waste. August.
U.S. EPA. 1996a. Hazardous air pollutant list, modification. Federal Register 61:30816-30823,
final rule. June 18.
U.S. EPA. 1996b. Proposed guidelines for carcinogen risk assessment. Office of Research and
Development, Washington, DC. EPA-600/P-92-003C.
U.S. EPA. 1996c. Guidelines for reproductive toxicity risk assessment. EPA-630/R-96-009.
September.
U.S. EPA. 1996d. Proposed guidelines for ecological risk assessment. Federal Register
61:47552. September 9, 1996. Risk Assessment Forum, Office of Research and Development,
Washington, DC. EPA-630/R-95-002B. August.
U.S. EPA. 1996e. Accidental release prevention requirements. Federal Register 61:31667-
31730. June 20.
U.S. EPA. 1996f. Review of the national ambient air quality standards for ozone: Assessment of
scientific and technical information. Office of Air Quality Planning and Standards, Research
Triangle Park, NC. EPA-452/R-96-007
U.S. EPA. 1996g. Summary report for the workshop on Monte Carlo analysis. Risk
Assessment Forum, Washington, DC. EPA-630/R-96-010.
U.S. EPA. 1997a. Mercury study report to Congress. EPA-452/R-97-0003. December.
U.S. EPA. 1997b. Deposition of air pollutants to the Great Waters, Second report to Congress.
EPA-453/R-97-011. June.
U.S. EPA. 1997c. Guiding principles for Monte Carlo analysis. Risk Assessment Forum,
Washington, DC. EPA-630/R-97-001. March.
U.S. EPA. 1997d. Draft guidelines for risk assessment of chemical mixtures. Office of
Research and Development, Washington, DC.
* * *
March 1999 Page 140 * * *
-------
Residual Risk Report to Congress
U.S. EPA. 1997e. Ecological risk assessment guidance for Superfund: Process for designing
and conducting ecological risk assessments. Environmental Response Team, Edison, NJ.
U.S. EPA. 1997f. Methodology for assessing health risks associated with multiple exposure to
combustor emissions. Office of Research and Development, Cincinnati, OH. NCEA 0238
(Update to EPA/600/6-90/003).
U.S. EPA. 1997g. Exposure factors handbook. Office of Research and Development,
Washington, DC.
U.S. EPA. 1997h. National Advisory Committee for acute exposure guideline levels for
hazardous substances. Federal Register 62:58839-58851, Notice. October 30.
U.S. EPA. 19971. Amended proposed test rule for hazardous air pollutants; Extension of
comment period. Federal Register 62:67465-67485. December 24.
U.S. EPA. 1997J. Health effects assessment summary tables: FY 1997 update. Office of Solid
Waste and Emergency Response, Washington, DC. EPA-540-R-97-036.
U.S. EPA. 1997k. Policy for use of probabilistic analysis in risk assessment. Office of the
Administrator, Washington, DC. May 15.
U.S. EPA. 19971. EPA Region 5 risk assessment for the Waste Technologies Industries (WTI)
hazardous waste incinerator East Liverpool, Ohio. 8 volumes. Chicago, Illinois. PB97-174486.
May.
U.S. EPA. 1997m. National Ambient Air Quality Standards for Ozone. Federal Register
62(138):38856-38896. July 18.
U.S. EPA. 1997n. Guidance on cumulative risk assessment, Part 1, Planning and scoping.
Science Policy Council, Washington, DC.
U.S. EPA. 1998a. Draft integrated urban air toxics strategy to comply with section 112(k),
112(c)(3) and section 202(1) of the Clean Air Act. Federal Register 63:49240. September 14.
U.S. EPA. 1998b. Study of hazardous air pollutant emissions from electric utility steam
generating units - Final Report to Congress. EPA-453/R-98-004. February.
U.S. EPA. 1998c. Guidelines for neurotoxicity risk assessment. Federal Register 63: 26926.
May 14.
U.S. EPA. 1998d. Guidelines for ecological risk assessment. EPA/630/R-95-002f April 30.
* * *
March 1999 Page 141 * * *
-------
Residual Risk Report to Congress
U.S. EPA. 1998e. Revised draft user's guide for the AMS/EPA regulatory model - AERMOD.
Office of Air Quality Planning and Standards, Research Triangle Park, NC.
U.S. EPA. 1998f Human health risk assessment protocol for hazardous waste combustion
facilities, Volume I. Office of Solid Waste and Emergency Response. EPA-530/D-98-001 A.
U.S. EPA. 1998g. Methods for exposure-response analysis for acute inhalation exposure to
chemicals: Development of the acute reference exposure. Review draft. Office of Research and
Development, Washington, DC. EPA/600/R-98/051.
U.S. EPA. 1998h. Integrated Risk Information System (IRIS); Announcement of 1998
Program; Request for Information. Federal Register 63:75-77. January 2.
U.S. EPA. 1998L U.S. Environmental Protection Agency: Integrated Risk Information System
(IRIS) at http://www.epa.gov/iris. Updated October 5.
U.S. EPA. 1998J. ECOTOXDatabase (AQUIRE, PHYTOTOX, and TERRETOX). (Database
is available to EPA and contractors through on-line connection; updated regularly). Office of
Research and Development, National Health and Environmental Effects Research Laboratory,
Mid-continental Ecology Division, Duluth, MN.
U.S. EPA. 1999 (in press). National air quality and emissions trends report, 1997. Office of Air
Quality Planning and Standards, Research Triangle Park, NC.
* * *
March 1999 Page 142 * * *
-------
Residual Risk Report to Congress
Appendix A
Full Text of Clean Air Act Section 112(f)
-------
Residual Risk Report to Congress
Appendix A
Full Text of Clean Air Act Section 112(f)
(f) Standard to Protect Health and the Environment. (1) Report. Not later than 6
years after the date of enactment of the Clean Air Act Amendments of 1990 the Administrator
shall investigate and report, after consultation with the Surgeon General and after opportunity for
public comment, to Congress on
(A) methods of calculating the risk to public health remaining, or likely to remain, from
sources subject to regulation under this section after the application of standards under
subsection (d);
(B) the public health significance of such estimated remaining risk and the
technologically and commercially available methods and costs of reducing such risks;
(C) the actual health effects with respect to persons living in the vicinity of sources, any
available epidemiological or other health studies, risks presented by background concentrations
of hazardous air pollutants, any uncertainties in risk assessment methodology or other health
assessment technique, and any negative health or environmental consequences to the community
of efforts to reduce such risks; and
(D) recommendations as to legislation regarding such remaining risk.
(2) Emission Standards. (A) If Congress does not act on any recommendation
submitted under paragraph (1), the Administrator shall, within 8 years after promulgation of
standards for each category or subcategory of sources pursuant to subsection (d), promulgate
standards for such category or subcategory if promulgation of such standards is required in order
to provide an ample margin of safety to protect public health in accordance with this section (as
in effect before the date of enactment of the Clean Air Act Amendments of 1990) or to prevent,
taking into consideration costs, energy, safety, and other relevant factors, an adverse
environmental effect. Emission standards promulgated under this subsection shall provide an
ample margin of safety to protect public health in accordance with this section (as in effect before
the date of enactment of the Clean Air Act Amendments of 1990), unless the Administrator
determines that a more stringent standard is necessary to prevent, taking into consideration costs,
energy, safety, and other relevant factors, an adverse environmental effect. If standards
promulgated pursuant to subsection (d) and applicable to a category or subcategory of sources
emitting a pollutant (or pollutants) classified as a known, probable or possible human carcinogen
do not reduce lifetime excess cancer risks to the individual most exposed to emissions from a
source in the category or subcategory to less than one in one million, the Administrator shall
promulgate standards under this subsection for such source category.
* * *
March 1999 Page A-l * * *
-------
Residual Risk Report to Congress
(B) Nothing in subparagraph (A) or in any other provision of this section shall be
construed as affecting, or applying to the Administrator's interpretation of this section, as in
effect before the date of enactment of the Clean Air Act Amendments of 1990 and set forth in the
Federal Register of September 14, 1989 (54 Federal Register 38044).
(C) The Administrator shall determine whether or not to promulgate such standards and,
if the Administrator decides to promulgate such standards, shall promulgate the standards 8 years
after promulgation of the standards under subsection (d) for each source category or subcategory
concerned. In the case of categories or subcategories for which standards under subsection (d)
are required to be promulgated within 2 years after the date of enactment of the Clean Air Act
Amendments of 1990, the Administrator shall have 9 years after promulgation of the standards
under subsection (d) to make the determination under the preceding sentence and, if required, to
promulgate the standards under this paragraph.
(3) Effective date. Any emission standard established pursuant to this subsection shall
become effective upon promulgation.
(4) Prohibition. No air pollutant to which a standard under this subsection applies may
be emitted from any stationary source in violation of such standard, except that in the case of an
existing source
(A) such standard shall not apply until 90 days after its effective date, and
(B) the Administrator may grant a waiver permitting such source a period of up to 2 years
after the effective date of a standard to comply with the standard if the Administrator finds that
such period is necessary for the installation of controls and that steps will be taken during the
period of the waiver to assure that the health of persons will be protected from imminent
endangerment.
(5) Area sources. The Administrator shall not be required to conduct any review under
this subsection or promulgate emission limitations under this subsection for any category or
subcategory of area sources that is listed pursuant to subsection (c)(3) and for which an emission
standard is promulgated pursuant to subsection (d)(5).
(6) Unique Chemical Substances. In establishing standards for the control of unique
chemical substances of listed pollutants without CAS numbers under this subsection, the
Administrator shall establish such standards with respect to the health and environmental effects
of the substances actually emitted by sources and direct transformation byproducts of such
emissions in the categories and subcategories.
* * *
March 1999 Page A-2 * * *
-------
Residual Risk Report to Congress
Appendix B
Preamble Excerpts from 1989 Benzene NESHAP
-------
Residual Risk Report to Congress
Appendix B
Preamble Excerpts from 1989 Benzene NESHAP
[Full Text of Preamble Sections 1, 2, and 3 Only]
ENVIRONMENTAL PROTECTION AGENCY (EPA)
40CFRPart61
National Emission Standards for Hazardous Air Pollutants;
Benzene Emissions from Maleic Anhydride Plants,
Ethylbenzene/Styrene Plants, Benzene Storage Vessels,
Benzene Equipment Leaks, and Coke By-product Recovery Plants
[AD-FRL-3620-4]
RIN2060-AC41
54 FR 38044
September 14, 1989
ACTION: Final rule
* * *
March 1999 Page B-l * * *
-------
Residual Risk Report to Congress
I. Summary of Decisions
Overview
Background
Selection of Approach
Maleic Anhydride Process Vents
Ethylbenzene/Styrene Process Vents
Benzene Storage Vessels
Coke By-Product Recovery Plants
Benzene Equipment Leaks
II. Background
Regulatory Background
Public Participation
Legal Framework Under Vinyl Chloride
III. Application of Policy to Benzene Source Categories
Introduction
Ethylbenzene/Styrene Process Vents
Benzene Storage Vessels
Coke By-Product Recovery Plants
Benzene Equipment Leaks
I. Summary of Decisions
Overview
This section provides a description of the EPA's approach for the protection of public
health under section 112. In protecting public health with an ample margin of safety under
section 112, EPA strives to provide maximum feasible protection against risks to health from
hazardous air pollutants by (1) protecting the greatest number of persons possible to an
individual lifetime risk level no higher than approximately 1 in 1 million and (2) limiting to no
higher than approximately 1 in 10 thousand the estimated risk that a person living near a plant
would have if he or she were exposed to the maximum pollutant concentrations for 70 years.
Implementation of these goals is by means of a two-step standard-setting approach, with an
analytical first step to determine an "acceptable risk" that considers all health information,
including risk estimation uncertainty, and includes a presumptive limit on maximum individual
lifetime risk (MIR) of approximately 1 in 10 thousand. A second step follows in which the actual
standard is set at a level that provides "an ample margin of safety" in consideration of all health
information, including the number of persons at risk levels higher than approximately 1 in 1
million, as well as other relevant factors including costs and economic impacts, technological
* * *
March 1999 Page B-2 * * *
-------
Residual Risk Report to Congress
feasibility, and other factors relevant to each particular decision. Applying this approach to the
five benzene source categories in today's notice results in controls that protect over 99 percent of
the persons within 50 kilometers (km) of these sources at risk levels no higher than
approximately 1 in 1 million.
A principle that accompanies these numerical goals is that while the Agency can establish
them as fixed numbers, the state of the art of risk assessment does not enable numerical risk
estimates to be made with comparable confidence. Therefore, judgment must be used in
deciding how numerical risk estimates are considered with respect to these goals. As discussed
below, uncertainties arising from such factors as the lack of knowledge about the biology of
cancer causation and gaps in data must be weighed along with other public health
considerations. Many of the factors are not the same for different pollutants, or for different
source categories.
Background
On July 28, 1988, EPA proposed decisions on standards under Section 112 for five
source categories of benzene. A principal aspect of the proposal, and the basis for the proposed
decisions on the source categories, were four proposed approaches for decisions under Section
112 as mandated by the DC Circuit's decision in NRDC v. EPA, 824 F.2d at 1146 (1987) (the
"Vinyl Chloride" decision). The Vinyl Chloride decision required the Administrator to exercise
his judgment under Section 112 in two steps: first, a determination of a "safe" or "acceptable"
level of risk considering only health factors, followed by a second step to set a standard that
provides an "ample margin of safety," in which costs, feasibility, and other relevant factors in
addition to health may be considered.
The four proposed approaches were designed to provide for consideration of a variety of
health risk measures and information in the first step analysis under the Vinyl Chloride decision
- the determination of "acceptable risk." Included in the alternative approaches were three that
consider only a single health risk measure in the first step: (1) Approach B, which considers only
total cancer incidence with 1 case per year (case/year) as the limit for acceptability; (2) Approach
C, which considers only the maximum individual risk ("MIR") with a limit of 1 in 10 thousand
for acceptability; and (3) Approach D, which considers only the maximum individual risk with 1
in 1 million as the limit. The fourth approach, Approach A, was a case-by-case approach that
considers all health risk measures, the uncertainties associated with them, and other health
information.
In the second step, setting an "ample margin of safety," each of the four approaches
would consider all health risk and other information, uncertainties associated with the health
estimates, as well as costs, feasibility, and other factors which may be relevant in particular
cases. The proposal solicited comment on each of the approaches as well as other approaches for
implementing the Vinyl Chloride decision (53 FR 28511-28532). The Agency received many
public comments on the approaches from citizen's groups, companies and industry trade groups,
* * *
March 1999 Page B-3 * * *
-------
Residual Risk Report to Congress
State and local governments, and individuals. Most of the comments supported either Approach
A or D, with little comment in support of Approach B or C.
Selection of Approach
Based on the comments and the record developed in the rulemaking, EPA has selected an
approach, based on Approaches A and C but also incorporating consideration of incidence from
Approach B and consideration of health protection for the general population on the order of 1 in
1 million from Approach D. Thus, in the first step of the Vinyl Chloride inquiry, EPA will
consider the extent of the estimated risk were an individual exposed to the maximum level of a
pollutant for a lifetime ("MIR"). The EPA will generally presume that if the risk to that
individual is no higher than approximately 1 in 10 thousand, that risk level is considered
acceptable and EPA then considers the other health and risk factors to complete an overall
judgment on acceptability. The presumptive level provides a benchmark for judging the
acceptability of maximum individual risk ("MIR"), but does not constitute a rigid line for making
that determination.
The Agency recognizes that consideration of maximum individual risk ("MIR") - the
estimated risk of contracting cancer following a lifetime exposure at the maximum, modeled
long-term ambient concentration of a pollutant - must take into account the strengths and
weaknesses of this measure of risk. It is an estimate of the upperbound of risk based on
conservative assumptions, such as continuous exposure for 24 hours per day for 70 years. As
such, it does not necessarily reflect the true risk, but displays a conservative risk level which is
an upperbound that is unlikely to be exceeded. The Administrator believes that an MIR of
approximately 1 in 10 thousand should ordinarily be the upper end of the range of acceptability.
As risks increase above this benchmark, they become presumptively less acceptable under
section 112, and would be weighed with the other health risk measures and information in
making an overall judgment on acceptability. Or, the Agency may find, in a particular case, that
a risk that includes MIR less than the presumptively acceptable level is unacceptable in the light
of other health risk factors.
In establishing a presumption for MIR, rather than a rigid line for acceptability, the
Agency intends to weigh it with a series of other health measures and factors. These include the
overall incidence of cancer or other serious health effects within the exposed population, the
numbers of persons exposed within each individual lifetime risk range and associated incidence
within, typically, a 50 km exposure radius around facilities, the science policy assumptions and
estimation uncertainties associated with the risk measures, weight of the scientific evidence for
human health effects, other quantified or unquantified health effects, effects due to co-location of
facilities, and co-emission of pollutants.
The EPA also considers incidence (the numbers of persons estimated to suffer cancer or
other serious health effects as a result of exposure to a pollutant) to be an important measure of
the health risk to the exposed population. Incidence measures the extent of health risk to the
exposed population as a whole, by providing an estimate of the occurrence of cancer or other
* * *
March 1999 Page B-4 * * *
-------
Residual Risk Report to Congress
serious health effects in the exposed population. The EPA believes that even if the MIR is low,
the overall risk may be unacceptable if significant numbers of persons are exposed to a hazardous
air pollutant, resulting in a significant estimated incidence. Consideration of this factor would
not be reduced to a specific limit or range, such as the 1 case/year limit included in proposed
Approach B, but estimated incidence would be weighed along with other health risk information
in judging acceptability.
The limitations of MIR and incidence are put into perspective by considering how these
risks are distributed within the exposed population. This information includes both individual
risk, including the number of persons exposed within each risk range, as well as the incidence
associated with the persons exposed within each risk range. In this manner, the distribution
provides an array of information on individual risk and incidence for the exposed population.
Particular attention will also be accorded to the weight of evidence presented in the risk
assessment of potential human carcinogenicity or other health effects of a pollutant. While the
same numerical risk may be estimated for an exposure to a pollutant judged to be a known
human carcinogen, and to a pollutant considered a possible human carcinogen based on limited
animal test data, the same weight cannot be accorded to both estimates. In considering the
potential public health effects of the two pollutants, the Agency's judgment on acceptability,
including the MIR, will be influenced by the greater weight of evidence for the known human
carcinogen.
In the Vinyl Chloride decision, the Administrator is directed to determine a "safe" or
"acceptable" risk level, based on a judgment of "what risks are acceptable in the world in which
we live." 824 F.2d at 1165. To aid in this inquiry, the Agency compiled and presented a "Survey
of Societal Risk" in its July 1988 proposal (53 FR 28512-28513). As described there, the survey
developed information to place risk estimates in perspective, and to provide background and
context for the Administrator's judgment on the acceptability of risks "in the world in which we
live." Individual risk levels in the survey ranged from 10"1 to 10"7 (that is, the lifetime risk of
premature death ranged from 1 in 10 to 1 in 10 million), and incidence levels ranged from less
than 1 case/year to estimates as high as 5,000 to 20,000 cases/year. The EPA concluded from the
survey that no specific factor in isolation could be identified as defining acceptability under all
circumstances, and that the acceptability of a risk depends on consideration of a variety of factors
and conditions. However, the presumptive level established for MIR of approximately 1 in 10
thousand is within the range for individual risk in the survey, and provides health protection at a
level lower than many other risks common "in the world in which we live." And, this
presumptive level also comports with many previous health risk decisions by EPA premised on
controlling maximum individual risks to approximately 1 in 10 thousand and below.
In today's decision, EPA has selected an approach based on the judgment that the first
step judgment on acceptability cannot be reduced to any single factor. The EPA believes that the
level of the MIR, the distribution of risks in the exposed population, incidence, the science policy
assumptions and uncertainties associated with the risk measures, and the weight of evidence that
a pollutant is harmful to health are all important factors to be considered in the acceptability
* * *
March 1999 Page B-5 * * *
-------
Residual Risk Report to Congress
judgment. The EPA concludes that the approach selected best incorporates all of this vital health
information, and enables it to weigh them appropriately in making a judgment. In contrast, the
single measure Approaches B, C, and D, while providing simple decision making criteria,
provide an incomplete set of health information for decisions under section 112. The
Administrator believes that the acceptability of risk under section 112 is best judged on the basis
of a broad set of health risk measures and information. As applied in practice, the EPA's
approach is more protective of public health than any single factor approach. In the case of the
benzene sources regulated here, more than 99 percent of the population living within 50 km
would be exposed to risks no greater than approximately 1 in 1 million; and, the total number of
cases of death or disease estimated to result would be kept low.
Under the two-step process specified in the Vinyl Chloride decision, the second step
determines an "ample margin of safety," the level at which the standard is set. This is the
important step of the standard-setting process at which the actual level of public health protection
is established. The first step consideration of acceptability is only a starting point for the analysis,
in which a floor for the ultimate standard is set. The standard set at the second step is the legally
enforceable limit that must be met by a regulated facility.
Even though the risks judged "acceptable" by EPA in the first step of the Vinyl Chloride
inquiry are already low, the second step of the inquiry, determining an "ample margin of safety,"
again includes consideration of all of the health factors, and whether to reduce the risks even
further. In the second step, EPA strives to provide protection to the greatest number of persons
possible to an individual lifetime risk level no higher than approximately 1 in 1 million. In the
ample margin decision, the Agency again considers all of the health risk and other health
information considered in the first step. Beyond that information, additional factors relating to
the appropriate level of control will also be considered, including costs and economic impacts of
controls, technological feasibility, uncertainties, and any other relevant factors. Considering all
of these factors, the Agency will establish the standard at a level that provides an ample margin
of safety to protect the public health, as required by section 112. Application of this approach to
the five source categories under consideration in this rulemaking is summarized in the following
discussions.
Maleic Anhydride Process Vents
Summary of Decision: Benzene is no longer used in the manufacture of maleic anhydride
because all plants in the industry have converted their process equipment to the more economical
n-butane feed process. Thus, all benzene exposure from this industry has been eliminated, and no
Federal regulation is needed. Maleic anhydride plants are, therefore, not discussed in the
remaining sections of this notice.
Ethylbenzene/Styrene Process Vents
Summary of Decision: The existing level of control is judged to provide an ample
margin of safety. Under existing State requirements, overall current emissions have been reduced
* * *
March 1999 Page B-6 * * *
-------
Residual Risk Report to Congress
98 percent or more from uncontrolled levels. The present level of emissions are estimated to
present an MIR of 2 in 100 thousand and a total nationwide incidence of about 1 case every 300
years (0.003 case/year). Levels of benzene reported to produce noncancer health effects are at
least three orders of magnitude above the exposures comparable to the MIR.
Most people exposed to benzene from these sources are exposed to very low risk levels.
Specifically, the risk estimates show: (1) About 600 people are exposed to risk levels of about 1
in 100 thousand reflecting 1 cancer case every 5,000 years (0.0002 case/year) and (2) at least 90
percent of the population modeled to 20 km (about 400,000 people) is exposed to risk levels of
less than 1 in 1 million, reflecting about 1 cancer case every 300 years (0.003 case/year). It is
anticipated that if modeling were conducted to a 50 km radius, the percentage of the exposed
population at risks of less than 1 in 1 million would be at least 99. Further reductions would
provide only negligible additional risk and emission reductions (less than 1 percent additional
control) and would cost approximately $0.2 million per year (1982 dollars), which would be
about the same in 1988 dollars.
Benzene Storage Vessels
Summary of Decision: In providing an ample margin of safety for this source category,
the final standards require effective controls on storage vessels not already controlled. The final
standards would reduce nationwide benzene emissions by an estimated additional 20 to 60
percent beyond the baseline level, which already includes emission reductions for most storage
vessels. The MIR after application of the standards is estimated to be 3 in 100 thousand. This
reflects a reduction from an MIR range of between 4 in 100 thousand and 4 in 10 thousand
without the standards. The estimated cancer incidence would be reduced from the range without
the standards of 1 case every 10 to 20 years (0.1 to 0.05 case/year) to 1 case every 25 years (0.04
case/ year). Levels of benzene reported to produce noncancer health effects are at least three
orders of magnitude above the exposure level after an ample margin of safety is provided by
EPA.
Most people exposed to benzene from this source category would be exposed to very low
levels. The standards are estimated to result in an emission level where: (1) No people are
exposed to a risk level greater than 1 in 10 thousand, (2) about 100,000 people would be exposed
to a risk level between 3 in 100 thousand and 1 in 1 million, and (3) a majority of the modeled
population (70 million people, or greater than 99 percent) is exposed to a risk level of less than 1
in 1 million. While EPA was unable to estimate the cancer incidences associated with various
risk levels for this source category, the cancer incidences for the higher risk levels would occur
very infrequently and for the lower risk levels would occur about once every 25 years (0.04
case/year). To reduce these exposures further, the next most effective level of control would cost
an additional estimated $1.2 million per year (1982 dollars) or roughly $1.3 million in 1988
dollars, but it was not chosen because it would not reduce the MIR and would reduce the cancer
incidence by only 1 case every 100 years (0.01 case/year).
* * *
March 1999 Page B-7 * * *
-------
Residual Risk Report to Congress
Summary of the Standards: The final standards require control of all new and existing
vessels with capacities greater than or equal to 38 cubic meters (m3) (10,000 gallons) used to
store benzene. The standards do not apply to storage vessels used for storing benzene at coke
by-product recovery facilities because they are considered under the coke by-product recovery
plant standards. The standards require use of certain kinds of equipment and work practices for
each type of benzene storage vessel. The standards require the use of internal floating roofs
(IFR's) with continuous primary seals on fixed roof vessels, and improvements to fittings (e.g.,
gaskets). For external floating roof (EFR) vessels, secondary seals are required. The standards
also require periodic inspections of the vessel roofs, seals, and fittings. Detailed summaries of the
regulation and changes since proposal are contained in sections IV and V of this notice.
Coke By-product Recovery Plants
Summary of Decision: In providing an ample margin of safety for this source category,
the final standards reduce benzene emissions by about 97 percent for affected facilities
nationwide. The MIR after application of the standards is estimated to be 2 in 10 thousand and
the cancer incidence is about 1 cancer incidence every 20 years (0.05 case/year). This reflects
significant risk reduction from the MIR of 7 in 1 thousand and the cancer incidence of 1 cancer
incidence every 6 months (about 2 case/year) that are estimated to occur without the standards.
Given estimating uncertainties in this case, the MIR level after the standards is comparable to the
EPA's benchmark of approximately 1 in 10 thousand. As discussed in Section III of this
preamble, EPA views this level as an overstatement of the actual MIR because the emission
estimates associated with this level are likely to be overstated. Levels of benzene reported to
produce noncancer health effects are at least three orders of magnitude above the exposure level
expected after an ample margin of safety is provided by EPA.
Most people exposed to benzene from this source category would be exposed to very low
levels. The standards reduce emissions to a level where: (1) Approximately 100 people would be
exposed to a risk level between the estimated MIR and about 1 in 10 thousand reflecting about 1
cancer incidence every 5,000 years (0.0002 case/year), (2) about 300,000 people would be
exposed to a risk level between 1 in 10 thousand and 1 in 1 million reflecting about 1 cancer
incidence every 100 years (0.01 case/year), and (3) a majority of the modeled population (70
million people, or greater than 99 percent) would be exposed to a risk level of less than 1 in 1
million, reflecting about 1 cancer incidence every 25 years (0.04 case/year). To reduce these
exposures to the level associated with the next most effective level of control would cost an
additional estimated $6 million per year (1984 dollars), which would be roughly $6.6 million in
1988 dollars. Furthermore, it would involve the use of a control technology that may not be
technically feasible, and would only provide a small overall risk reduction of about 1 percent,
reflecting an estimated cancer incidence of 1 in every 33 years (0.03 case/year). Additionally,
there would be no change in the MIR of about 2 in 10 thousand.
Summary of Standards: The final standards require that process vessels and tar storage
tanks in furnace and foundry coke by-product recovery plants be enclosed and the emissions
ducted to an enclosed point in the by-product recovery process where they will be recovered or
* * *
March 1999 Page B-8 * * *
-------
Residual Risk Report to Congress
destroyed. This requirement is based on the use of a gas blanketing system. The same
requirements also apply to storage tanks for benzene, benzene-toluene-xylene (BTX) mixtures,
and light oil in furnace coke by-product recovery plants. To ensure proper operation and
maintenance of the system, the standards require semiannual visual inspections and monitoring
to detect and repair leaks as well as annual maintenance inspections. The final standards also
require that light-oil sumps be completely enclosed; this requirement is based on the use of a
permanent or removable cover equipped with a gasket. Semiannual visual inspections and
monitoring for leak detection and repair are also required for this source.
The final standards establish a zero emissions limit applicable to naphthalene processing,
final coolers, and the associated final-cooler cooling towers at both furnace and foundry plants.
The limit is based on the use of a wash-oil final cooler, although other types of systems that
achieve the emissions limit can also be used.
The final standards also contain provisions for the control of equipment in benzene
service, including pumps, valves, exhausters, pressure-relief devices, sampling connections, and
open-ended lines. The leak detection and repair requirements are the same as the requirements in
40 CFR 61 subpart V, and additionally include quarterly leak detection and repair requirements
for exhausters. A detailed summary of the regulation can be found in section V of this notice.
Benzene Equipment Leaks
Summary of Decision: The existing standards for this source category (Subpart J of part
61) are judged to provide an ample margin of safety, especially considering the overstatement of
emissions. When these standards were issued in 1984, EPA estimated it would reduce emissions
by about 70 percent from the level that would occur without the standards. Using these emission
estimates (which overstate emissions as discussed in the next paragraph), the MIR was estimated
to be 6 in 10 thousand and the incidence was estimated to be 1 case every 5 years (0.2 case/year).
Based on information received in the past year, EPA considers the present level of
emissions associated with the existing standards to be substantially lower than previously
estimated. Thus the available risk estimates are substantially overstated. The EPA has reached
this conclusion after reviewing information demonstrating compliance with the existing
standards and new information about emissions from equipment leaks. However, because the
changes in the control of equipment leaks, especially leaks of air toxics, and the changes in the
analytical tools needed for determining emissions from these sources have occurred very
recently, EPA has not been able to develop better estimates of benzene emissions from
equipment leaks. If EPA were to roughly estimate emissions based on this information, the
resulting MIR would be comparable to the benchmark of approximately 1 in 10,000. (This is
discussed further in sections III and IV of this preamble). Levels of benzene reported to produce
noncancer health effects are at least three orders of magnitude above current levels of exposure.
Most people exposed to benzene emissions from this source category are exposed to very
low risk levels. Even at the estimated emission levels, the existing standards result in: (1)
* * *
March 1999 Page B-9 * * *
-------
Residual Risk Report to Congress
About 1 million people at a level between 1 in 10,000 and 1 in 1 million with an incidence of 1
case every 25 years (0.04 case/year) and (2) the vast majority of the modeled population (200
million people or greater than 99 percent) is exposed at risks of less than 1 in 1 million with an
incidence of 1 case every 5 years (0.2 case/year). If the actual emission rates were known, the
exposures would be lower than these estimates. To reduce these exposures further to the next
most effective level of emission control would require the use of control technologies that may
not be technically feasible at an estimated cost of $52.4 million per year (1979 dollars), which
would be roughly $75 million in 1988 dollars.
II. Background
Regulatory Background
In 1977, the Administrator announced his decision to list benzene as a hazardous air
pollutant under section 112 of the CAA (42 FR 29332, June 8, 1977). Benzene was determined
to be a hazardous air pollutant because of its carcinogenic properties, evidenced by elevated
leukemia incidence in populations occupationally exposed. Detailed information about the
hazard identification, dose/response assessment, exposure assessment and risk characterization
for benzene were presented in the preamble to the policy approaches and standards proposed in
July 1988 (53 FR 28496), and will not be repeated in today's notice.
The listing of benzene as a hazardous air pollutant was followed by proposal of standards
for benzene emissions from maleic anhydride process vents, EB/S process vents, benzene storage
vessels, and benzene equipment leaks in 1980 and 1981 (45 FR 26660, April 18, 1980; 45 FR
83448, December 18, 1980; 45 FR 83952, December 19, 1980; and 46 FR 1165, January 5,
1981). On June 6, 1984, after receipt of comments from industry and members of the public,
EPA published a final rule setting emission standards for benzene equipment leaks (49 FR
23498) and published proposed standards for benzene emissions from coke by-product recovery
plants (49 FR 23522). On that date, EPA also withdrew its proposed standards for maleic
anhydride process vents, EB/S process vents, and benzene storage vessels (49 FR 23558). The
withdrawal was based on the conclusion that both the benzene health risks to the public from
these three source categories, and the potential reductions in health risks achievable with
available control techniques were too small to warrant Federal regulatory action under section
112 of the CAA.
On August 3, 1984, the Natural Resources Defense Council (NRDC) filed a petition for
review in the United States Court of Appeals for the District of Columbia Circuit, seeking review
of the EPA's three withdrawals of proposed benzene emission standards, and the EPA's final
standards for benzene equipment leaks (Natural Resources Defense Council, Inc. v. Thomas, No.
84-1387). On October 17, 1984, NRDC petitioned EPA under section 307(d)(7)(B) of the CAA
to reconsider its decisions to withdraw standards for maleic anhydride process vents, EB/S
process vents, and benzene storage vessels, and to reconsider the promulgated standards for
benzene equipment leaks. The EPA denied this petition on August 23, 1985 (50 FR 34144).
* * *
March 1999 Page B-10 * * *
-------
Residual Risk Report to Congress
On July 28, 1987, the court handed down an en bane decision in a case concerning the
national emission standards under Section 112 for vinyl chloride (Docket No. OAQPS 79-3, Part
I, Item X-I-4). The court concluded in Vinyl Chloride that EPA had acted improperly in
withdrawing a proposed revision to the standards for vinyl chloride by considering costs and
technological feasibility without first determining a "safe" or "acceptable" emission level. In
light of the Vinyl Chloride opinion, EPA requested a voluntary remand to reconsider its June 6,
1984, benzene decisions. In an order dated December 8, 1987, the court granted the EPA's
motion and established a schedule under which EPA was to propose its action on
reconsideration within 180 days of the order and take final action within 360 days of the order.
This order was subsequently modified to extend the time for proposal by 45 days and then to
establish August 31, 1989, as the deadline for final action. The EPA also decided to reconsider
the proposed standards for benzene emissions from coke by-product recovery plants in light of
the Vinyl Chloride decision and to publish a supplemental proposal. All of these actions were
proposed on July 28, 1988 (53 FR 28496).
Public Participation
A public hearing was held in Washington, DC, on September 1, 1988, and was attended
by about 90 people. Oral testimony was presented by 12 organizations and individuals. The
public comment period closed on October 3, 1988, with over 200 comments received among the
four dockets. The public comment period was reopened from December 15, 1988, to January 30,
1989, based on the EPA's review of the comments and the number of requests for an extension
of the comment period. Additional comments were received, raising the combined number of
comments to more than 275.
Legal Framework Under Vinyl Chloride
The EPA considers the Vinyl Chloride decision to further define the legal framework for
setting NESHAP under Section 112 of the CAA. The court set out a two-step process for EPA to
follow in making these judgments: first, determine a "safe" or "acceptable risk" level, and then
set standards at the level which may be equal to or lower, but not higher than, the "safe" or
"acceptable" level that protects public health with an ample margin of safety. It should be
noted that the Vinyl Chloride court acknowledged that EPA could employ a single step analysis
under certain circumstances provided cost and feasibility were excluded from consideration.
Vinyl Chloride, 824 F.2d at 1165, n. 11.
In Vinyl Chloride, the court acknowledged that judgments by EPA concerning scientific
uncertainty are a relevant part of the process for establishing NESHAP. As the court noted,
Congress, in directing EPA to set NESHAP, recognized that uncertainties over the health effects
of the pollutants complicate the task. Vinyl Chloride, 824 F.2d at 1152. These same
uncertainties, according to the court, mean that the Administrator's "decision in this area 'will
depend to a greater extent upon policy judgments' to which we must accord considerable
deference." Id., 824 F.2d at 1162 (citations omitted).
* * *
March 1999 Page B-l 1 * * *
-------
Residual Risk Report to Congress
"Safe" or "Acceptable" Level: The first step is for the Administrator to determine what
level of risk to health caused by emissions of a hazardous air pollutant is "safe" or "acceptable."
(The court used these terms interchangeably.) The court in Vinyl Chloride explicitly declined to
determine what risk level is "acceptable" or to set out the method for determining the "acceptable
risk" level. Instead, the court stated that these determinations are within the Administrator's
discretion.
The court did, however, provide some guidance on the "safe" or "acceptable risk"
determination. To make this judgment, "the Administrator must determine what inferences
should be drawn from available scientific data and decide what risks are acceptable in the world
in which we live." Id., at 1165. However, the court emphasized that "safe" does not require
elimination of all risk. To support these propositions, the court cited Industrial Union Dept,
AFL-CIO v. American Petroleum Inst, 448 U.S. 607, 642 (1980) and its statement that "[tjhere
are many activities that we engage in every day - such as driving a car or even breathing city air
- that entail some risk of accident or material health impairment; nevertheless, few people would
consider those activities 'unsafe'." Vinyl Chloride, 824 F.2d at 1165. As a final matter, the court
said that the Administrator cannot consider costs or technological feasibility in this step.
Ample Margin of Safety: Once an "acceptable risk" level is determined, the second step
under Vinyl Chloride is to determine whether the emission levels accompanying that
determination should be reduced further in providing an "ample margin of safety." Noting that
the purpose of the ample margin of safety requirement is to protect against incompletely
understood dangers, uncertainties, and variabilities, the court stated that EPA "may * * * decide
to set the level below that previously determined to be safe." The court reiterated that because
the assessment of risk is uncertain, "the Administrator must use his discretion to meet the
statutory mandate." The court added that it is at this stage of the standards-setting process that
EPA may consider costs and technological feasibility and other relevant factors: "Because
consideration of these factors at this stage is clearly intended to 'protect the public health,' it is
fully consistent with the Administrator's mandate under section 112." Vinyl Chloride, 824 F.2d
at 1165.
Uniqueness of Decision: The effect of the Vinyl Chloride decision is to require a
decision making process for public health protection decisions unique to section 112, and unlike
any other regulatory decision faced by EPA. This is the result of the court's prescription of two
separate steps for decision making, the first in which only health factors can be considered in
setting an acceptable risk level, and the second in which additional factors including cost,
technological feasibility, and other relevant factors may be considered in providing an ample
margin of safety. This scheme is unlike any other under the CAA itself, or any of the other
statutes administered by EPA because the acceptable risk that EPA adopts in the first step cannot
be exceeded by the standards EPA adopts in the second step. Thus, the EPA's approach to
regulating hazardous air pollutants under section 112 is not applicable to regulatory decisions
under other statutes or other sections of the CAA. Regulatory decisions under other statutes or
other sections of the CAA will continue to be made using individual deliberative processes
pursuant to those distinct statutory mandates.
* * *
March 1999 Page B-12 * * *
-------
Residual Risk Report to Congress
In contrast to section 112, other EPA statutes have very different structures and legal
requirements for decision making on public health standards. For example, while the Safe
Drinking Water Act provides for two separate decisions, the first is a purely health-based goal
toward which to work, but not necessarily meet; the second is an enforceable standard that is
based on cost and feasibility considerations. Under both the Toxic Substances Control Act
(TSCA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the balancing of
health concerns and benefits of continued chemical use, and control costs are explicitly provided
for in decision making. The Resource Conservation and Recovery Act (RCRA) and the
Comprehensive Environmental Response, Compensation, and Liability Act both require statutory
decision making very different from the bifurcated process mandated by the court for Section
112.
Prior to issuance of Vinyl Chloride decision by the DC Circuit Court, the EPA's recent
judgments under section 112 were made in integrated approaches that considered a range of
health and risk factors, as well as cost and feasibility in certain cases. However, the Vinyl
Chloride decision has required a change in the EPA's approach to section 112, since the
previously employed integrated approaches did not partition consideration of health factors into a
first step separate from consideration of the other relevant factors. Thus, the Vinyl Chloride
decision requires EPA to consider whether a risk is acceptable without at the same time
considering benefits of the activity causing risk, feasibility of control, or other factors that EPA
(or anyone) would normally consider in determining whether a risk was "acceptable."
III. Application of Policy to Benzene Source Categories
Introduction
This section of the preamble explains the application of the EPA's policy for the
regulation of the benzene source categories discussed in the July 28, 1988, proposal (53 FR
28496). For each source category, the following are provided: (1) Background information
particularly noting any changes to the EPA's risk assessment since the July 1988 proposal, (2) the
decision on the acceptable risk noting the health-related factors and uncertainties associated with
the EPA's decision, and (3) the decision on the ample margin of safety noting health-related
impacts, technological feasibility, and cost information associated with this decision. For those
sources for which EPA made decisions that result in additional regulatory requirements, the
requirements are explained in Section V of this notice.
Ethylbenzene/Styrene Process Vents
Background: This source category covers process vents of plants manufacturing
ethylbenzene, styrene, or both. (Benzene emissions from equipment leaks and storage vessels at
EB/S plants have been considered separately and are not included in this source category). As of
1985, there were 13 plants in this source category. Information received during the public
* * *
March 1999 Page B-13 * * *
-------
Residual Risk Report to Congress
comment period indicates that emissions have declined since 1985 and emissions are now
estimated to be 135 megagrams per year (Mg/yr) or less.
Decision on Acceptable Risk: The baseline MIR of 2 X 10"5 is below the presumptive
benchmark of approximately 1 X 10"4 (which is 1 in 10 thousand expressed in scientific
notation). In estimating these risk levels, EPA has not found that co-location of EB/S plants
significantly influences the magnitude of the MIR or other risk levels. The nationwide incidence
of cancer from exposure to emissions from these facilities is estimated to be about 1 case every
330 years (0.003 case/year) or lower. The majority (more than 90 percent) of the population
within 20 km of these sources is exposed to risk levels lower than 1 X 10"6. For exposures to risk
levels greater than 1 X 10"6, the incidence is estimated to be 1 case every 10,000 years (0.0001
case/year). Benzene concentrations reported to produce noncancer health effects are at least three
orders of magnitude above the exposures predicted from these sources. After considering all
these factors, EPA judged the emission level associated with an MIR of 2 X 10"5 is acceptable.
Decision on Ample Margin of Safety: The EPA considered selecting a control level more
stringent than the level associated with the acceptable risks. This option would require control of
the few remaining uncontrolled intermittent emission sources using 98-percent efficient
combustion devices (e.g., boilers and flares). In comparing this control option and the existing
level of control, EPA found that they provide essentially the same level of safety. Both control
levels reflect a significant reduction in risks and emissions from the uncontrolled level. Control
of these sources would further reduce benzene emissions by approximately 70 to 90 Mg/yr at
most and would reduce the estimated MIR from 2 X 10"5 to 1 X 10"5. The annual incidence would
be reduced by about 1 case every 500 years (0.002 case/year).
The number of people exposed at risks greater than 1 X 10"6 is essentially the same
between these two control levels. For the total population exposed to these sources, the incidence
would change from 1 case every 330 years (0.003 case/year) to 1 case every 1,000 years (0.001
case/year). Essentially all (95 percent) of this additional reduction in incidence occurs in the
population exposed to risks lower than 1 X 10"6. The proportion of the population at risk levels
below 1 X 10"6 is not changed by this emission reduction. In addition, benzene concentrations
reported to produce noncancer health effects are at least three orders of magnitude above the
exposures predicted for these sources.
As noted above, this control option will reduce benzene emissions by 70 to 90 Mg/yr,
which represents less than an additional 1 percent reduction over the uncontrolled level. The
cost of this additional emission reduction (and consequent risk reduction) would be about
$200,000/yr (1982 dollars). While this additional cost is small, it is disproportionately large in
comparison to the small additional emission and risk reduction achieved.
After considering all of these factors, EPA judged that the existing level of controls
provides an ample margin of safety. In addition, EPA decided not to set standards to mandate the
existing level of controls. Existing controls in the EB/S industry are in the form of product
recovery devices or the routing of emissions to the process unit's boilers or other boilers onsite to
* * *
March 1999 Page B-14 * * *
-------
Residual Risk Report to Congress
conserve energy (less fuel would be required due to the energy content of the waste stream).
Thus, there is no incentive for removal of existing controls.
Additionally, there is no incentive for new sources to waste product or energy, and major
new sources would be subject to other EPA requirements (e.g., new source review [NSR],
prevention of significant deterioration [PSD]). Thus, less effective controls are not expected in
the future. For these reasons, EPA has concluded that Federal standards mandating these controls
are not warranted.
Benzene Storage Vessels
Background: This source category covers vessels used to store benzene. These vessels
are typically located at petroleum refineries, chemical plants, and bulk storage terminals. As of
1984, 126 facilities with benzene storage vessels had been identified. As noted in the July 28,
1988, Federal Register notice, nationwide baseline (i.e., no NESHAP) emissions from benzene
storage vessels are estimated to be about 620 to 1,290 Mg/yr. The range of emissions reflects
uncertainty about the presence of shingled seals versus continuous seals on existing vessels with
IFR's; the lower end of this range reflects the assumption that all storage vessels have continuous
seals, while the upper end is based on the assumption that some vessels (17 percent of the
existing IFR vessels) are equipped with shingled seals, which emit more benzene than
continuous seals. The baseline incidence associated with these emission estimates is estimated to
be 1 case every 10 to 20 years (0.1 to 0.05 case/year). The baseline MIR ranges from 4 X 10"5 to
4 X 10'4.
Decision on Acceptable Risk: The baseline MIR (4 X 10"5 to 4 X 10"4), while ranging
above the presumptive risk of approximately 1 X 10"4, is judged to be within the acceptable range
after consideration of the following factors.
First, the upper end of the range (4 X 10"4 ) is very likely an overestimate of the MIR
because it assumes that all storage vessels have shingled seals at the plants that would also have
the highest MIR's if all vessels in the industry had continuous seals. Based on information
received from industry in 1978, EPA estimated that 12 percent of the nationwide benzene storage
capacity was in vessels with shingled seals. This was estimated to be only about 17 percent of
the existing IFR vessels that store benzene. The EPA believes that shingled seals have not been
installed on new vessels for the past several years as general industry practice. Accordingly, the
number of vessels equipped with shingled seals is decreasing over time; consequently the
associated risk is also decreasing as existing vessels are replaced by new vessels. Therefore, the
assumption that all vessels in the worst-case plant have shingled seals for the upper end of the
MIR range is a unique conservative assumption for this source category. In addition, the
emission estimate for storage vessels equipped with shingled seals is overstated for the following
reason. The only test series of IFR vessels with shingled seals had testing irregularities, resulting
in inaccurately high emission estimates. These test irregularities are described in detail in the
EPA document "Benzene Emissions from Benzene Storage Tanks Background Information for
Proposal to Withdraw Proposed Standards" (EPA-450/3-84-004, March 1984). Because there is
* * *
March 1999 Page B-15 * * *
-------
Residual Risk Report to Congress
no way to determine the proportion of emissions attributable to the use of shingled seals versus
the test methodology, the emission estimate for shingled-seal vessels continues to reflect all the
uncertainty from that test series (49 FR 23563, June 6, 1984). While EPA is unable to quantify
these uncertainties, EPA qualitatively considered the effect of these uncertainties (as well as
other uncertainties in its risk assessment) in its judgment of acceptability.
Second, even if the MIR were not overestimated, EPA estimated that only 10 people (out
of the total modeled population of 70 million) are at risks greater than or equal to 1 X 10"4, and
virtually no cancer incidence is associated with this risk level. In estimating these risk levels,
EPA has not found that co-location of plants significantly influences the magnitude of the MIR
or other risk levels. Where two or more of the model plants used for the analysis might occur at
one site (e.g., both a producer and a consumer of benzene), the risks were calculated from their
total emissions. In addition, EPA estimated that the majority of the people (about 99 percent)
exposed to benzene from this source category would be exposed to a risk level of less than 1 X
10"6, reflecting 1 cancer incidence every 12 years (0.08 case/year), and that 900,000 people would
be exposed at a risk level between 1 X 10"4 and 1 X 10"6, reflecting 1 cancer incidence every 50
years (0.02 case/year). The baseline incidence is estimated to be 1 incidence every 10 to 20 years
(0.1 to 0.05 cancer case/year). This range reflects the range of emission estimates (620 to 1,290
Mg/yr). Virtually all of the incidence is associated with the population at a risk of less than 1 X
10"5. Thus, even though one end of the range of the EPA's MIR estimate for this source category
is above 1 X 10"4, it is important to consider that almost all of the exposure to benzene from
storage vessels is associated with risks well below the benchmark of approximately 1 X 10"4.
The EPA also considered the noncancer health effects associated with benzene exposures
at levels comparable to the baseline MIR range. Noncancer health effects have been associated
with exposure to benzene, but the levels reported to produce such effects are two to three orders
of magnitude above exposures comparable to the MIR range of 4 X 10"5 to 4 X 10"4, especially
with the likely overstatement of the top end of the range.
After considering all these factors, EPA judged that the baseline emission level is
acceptable.
Decision on Ample Margin of Safety: The EPA considered selecting a level of
emissions more stringent than the level associated with acceptable risk in providing an ample
margin of safety for this source category. This would require all vessels to have emission
reduction equipment that many vessels already have. Specifically, it would require the use of an
IFR with continuous primary seals on each existing fixed roof vessel, and more effective
continuous primary seals on any new vessel with an IFR. It would also require improvements to
fittings (e.g., gaskets) on the roofs of all IFR vessels. On each vessel with an EFR, this option
would require secondary seals. These are similar controls to those that are required for volatile
organic liquid (VOL) storage vessels (including benzene vessels) in 40 CFR 60 Subpart Kb,
which affects vessels constructed or rebuilt after July 23, 1984. This level of control was labeled
Option 2 in the July 28, 1988, proposal (53 FR 28496).
* * *
March 1999 Page B-16 * * *
-------
Residual Risk Report to Congress
Control Option 2 would reduce the estimated MIR to 3 X 10"5 from the baseline range of
4 X 10"5 to 4 X 10"4. Because no facility could have vessels with shingled seals, which represent
the upper end of the baseline range, all vessels would be required to have continuous seals under
the control option and the risks are not expressed as a range. Thus, no one would be potentially
exposed to a risk of greater than or equal to 1 X 10"4. The number of people estimated to be
exposed to a risk level between 1 X 10"4 and 1 X 10"6 would be reduced from 900,000 at baseline
to 100,000 with this control option. The majority of the modeled exposed population (greater
than 99 percent) would be exposed to a risk level less than 1 X 10"6 with Option 2. While EPA
was unable to estimate the cancer incidences associated with various risk levels after control to
this option for this source category, the cancer incidences for the higher risk levels would occur
infrequently, and for the lower levels would occur about once every 25 years (0.04 case/year).
Overall, the total nationwide incidence would be reduced from a range of 1 incidence every 10 to
20 years (0.1 to 0.05 case/year) to 1 incidence every 25 years (0.04 case/year). In addition, levels
of benzene reported to produce noncancer health effects are at least three orders of magnitude
above the levels expected under Option 2.
Control Option 2 would reduce benzene emissions by a range between 20 to 60 percent
(110 to 780 Mg/yr) in comparison to the emissions without standards. To achieve this emission
reduction (and consequent risk reduction) would cost $0.1 million/yr (1982 dollars). This cost is
considered to be relatively small.
The EPA also considered a more stringent control level, which would require the controls
in Option 2 and additionally require secondary seals for IFR vessels (Option 1 in the July 28,
1988, proposal notice, 53 FR 28496). This additional control would not result in any additional
reduction in the MIR beyond that achieved by Option 2. The number of people estimated to be
exposed to a risk level greater than 1 X 10"6 is estimated to be reduced from 100,000 (Option 2)
to 80,000 (Option 1). In both cases, the vast majority of the exposed population (greater than 99
percent) is at a risk of less than 1 X 10"6. Overall, the total nationwide incidence would only be
reduced from 1 incidence every 25 years (0.04 case/year) for Option 2 to 1 incidence every 33
years (0.03 case/year) for Option 1. This additional incidence reduction is associated mainly with
the population exposed to risk levels below 1 X 10"6. Levels of exposure reported to produce
noncancer health effects are at least three orders of magnitude above the levels of exposure
expected for Option 1, just as for Option 2. The additional cost of Option 1 over Option 2 would
be $1.2 million/yr (1982 dollars).
Based on the factors discussed above, EPA decided that the level of control reflected by
Option 2 provides an ample margin of safety. Although the emissions associated with the
baseline risks are considered to be acceptable, they can be reduced further, achieving additional
risk reductions, at a reasonable cost using the control technology included in Option 2. Selecting
Option 2 also ensures that any existing shingled seals are replaced with continuous seals, thus
addressing one of the uncertainties associated with the EPA's risk assessment. In addition, EPA
concluded that additional controls beyond Option 2 are not warranted. The costs of additional
controls beyond Option 2 are disproportionately high considering the small reductions in risk and
incidence which are achievable.
* * *
March 1999 Page B-17 * * *
-------
Residual Risk Report to Congress
Coke By-product Recovery Plants
Background: The risk analysis was revised after the July 1988 proposal based on
comments that the industry's operating status should be updated. There are now 36 coke
by-product recovery plants. The nationwide baseline benzene emissions are estimated to be
17,000 Mg/yr. The revised baseline estimates of health risk indicate an MIR of 7 X 10"3 and an
annual cancer incidence of 1 case every 6 months (2 cases/year). More information regarding the
updated estimates can be found in Section IV of this preamble and in the BID.
Decision on Acceptable Risk: The baseline risk of 7 X 10"3 is unacceptable for benzene, a
known human carcinogen. In considering the decision on acceptable risk for this source category,
EPA focused on control to a level that would result in an estimated MIR of 2 X 10"4. The EPA
considers this MIR to be in the acceptable range after considering several factors.
First, the long-term emissions and, therefore, the MIR are likely to be overstated because
EPA assumed that coke batteries operate at full capacity for 70 years. In fact, presently not all
plants are continuously operating at full capacity (including some of the plants with the highest
risks). In addition, the decline in the domestic coke industry makes it likely that the EPA's
estimate overstates the long-term emissions. There is considerable uncertainty in predicting the
utilization of coke batteries. Therefore, EPA made the assumption of full capacity for 70 years,
recognizing the effect of this assumption (as well as other assumptions) on its risk assessment.
Thus, EPA believes the MIR is not likely to be much different than the benchmark of
approximately 1 X 10"4 even though EPA is unable to quantify these uncertainties and, therefore,
adjust the MIR for this source category. However, EPA considered this likely overestimation
qualitatively in its judgment of acceptability. Furthermore, over time, the residual emissions
from one group of sources in this category (equipment leaks) may decrease as operators use
better equipment (e.g., improved valve packing) in addition to the required work practice
program.
Second, EPA estimated that 100 people (out of the total modeled population of 70
million) potentially would be exposed to risks of 1 X 10"4 or greater, with 1 cancer incidence
every 5,000 years among this group of 100 people (0.0002 case/year). In estimating these risk
levels, EPA has not found that co-location of coke by-product recovery plants significantly
influences the magnitude of the MIR or other risk levels. In addition, EPA estimated that the vast
majority of the modeled population (greater than 99 percent) exposed to benzene from this
source category would be exposed to a risk level of less than 1 X 10"6 reflecting 1 cancer
incidence every 25 years (0.04 case/year), and that 300,000 people would be exposed at a risk
level between 1 X 10"4 and 1 X 10"6 reflecting 1 cancer incidence every 100 years (0.01
case/year). Of the total cancer incidence (1 cancer incidence every 20 years, i.e., 0.05 case/year),
80 percent is associated with the large population at risks of less than 1 X 10"6. Thus, even
though EPA estimates an MIR of about 2 X 10"4 for this option, it is important to consider that
almost all the exposure to benzene from this source category is associated with risks well below
the benchmark of approximately 1 X 10"4.
* * *
March 1999 Page B-18 * * *
-------
Residual Risk Report to Congress
The EPA also considered the noncancer health effects associated with benzene exposures
at levels comparable to an MIR level of 2 X 10"4. Noncancer health effects have been associated
with exposure to benzene, but the probability is unlikely of the effects occurring at exposures
comparable to an MIR level of 2 X 10"4. Levels of benzene reported to produce such effects are
three orders of magnitude higher than the concentrations comparable to an MIR of 2 X 10"4.
After considering all these factors, EPA judged the emission level associated with an
MIR of 2 X 10'4 to be acceptable.
Decision on Ample Margin of Safety: The EPA considered selecting a level of emissions
more stringent than the level associated with acceptable risks in providing an ample margin of
safety for this source category. This option (Option 1) would require additional control over the
acceptable risk level (Option 2) of storage vessels at foundry coke by-product recovery plants
and would also require use of dual mechanical seals on pumps and sealed bellows valves (i.e.,
assumed to be 100 percent control) at both furnace and foundry coke by-product recovery plants.
The control technologies and their estimated impacts are presented for each emission point in
Table 1 for Options 1 and 2. It should be noted that EPA has not concluded that leakless
valves/sealed bellows valves will always effectively eliminate emissions or that they are
available for all sizes and types of equipment in benzene service. Nevertheless, EPA evaluated
Option 1 to determine if it should be selected to reflect an ample margin of safety even though
there would be technological feasibility issues in implementing this option.
* * *
March 1999 Page B-19 * * *
-------
Residual Risk Report to Congress
Table 1 - Controls Included in Each Option"
Emission points
Final cooler, cooling tower;
napthalene processing/handling
Tar decanter, tar intercepting
sump and flushing-liquor
circulation tank
Tar storage and tar-dewatering
tanks
Light-oil condenser, light-oil
decanter, wash-oil decanter,
and wash-oil circulation tanks
Excess ammonia-liquor storage
tank
Light-oil and BTX storage
tanks
Benzene storage tanks
Light-oil sump
Pumps
Valves
Exhausters
Pressure-relief devices
Sampling connection systems
Open-ended lines
Control technology
efficiency (%)
Wash-oil final cooler
(100)
Gas blanketing (98b)
Gas blanketing (98)
Gas blanketing (98)
Gas blanketing (98)
Gas blanketing (98)
N 2 gas blanketing (98)
Cover (98)
Monthly inspections (83)
Dual mechanical seals
(100)
Monthly inspections (73)
Sealed-bellows valves
(100)
Quarterly inspections (55)
Degassing reservoir vents
(100)
Rupture disc system (100)
Closed-purge sampling
(100)
Cap or plug (100)
Option 1
Furnace
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Foundry
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Option 2
Furnace
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Foundry
X
X
X
X
X
X
X
X
X
X
X
a The control options analyzed to determine an ample margin of safety are the same as those analyzed for the July 1988 proposal
(53 FR 28496), except that control options less stringent than Option 2, the level determined to be in the acceptable range, are
not shown on the table. The impacts associated with these control options have been revised since the July 1988 proposal to
reflect updated information on the industry operating status. These revisions are explained in greater detail in Section 6 of the
BID.
b 95-percent efficiency for tar decanter.
* * *
March 1999 Page B-20 * * *
-------
Residual Risk Report to Congress
In comparing Options 1 and 2, EPA found that they provide essentially the same level of
safety. Each reflects significant risk reduction in comparison to the baseline risks. Although the
estimated number of people exposed to a risk level greater than or equal to 1 X 10"4 would be
reduced from 100 to 50 under Option 1, EPA estimates that Option 1 would not reduce the MIR
below the Option 2 level of 2 X 10"4. The number of people exposed to a risk level between 1 X
10'4 and 1 X 10'6 would be reduced from 300,000 to 200,000 under Option 1. Under both options,
the vast majority of the exposed population (greater than 99 percent) would be at risk levels of
less than 1 X 10"6. For the population exposed to a risk level between 1 X 10"4 and 1 X 10"6, the
incidence would change from 1 case every 100 years (0.01 case/year) under Option 2 to 1 case
every 140 years (0.007 case/year) under Option 1; for the population exposed to risks below 1 X
10"6, the incidence would change only from 1 case every 25 years (0.04 case/year) under Option
2 to 1 case every 33 years (0.03 case/year) under Option 1. Overall, the total nationwide
incidence would be reduced from 1 case every 20 years (0.05 case/year) to 1 case every 33 years
(0.03 case/year) or only by an additional 0.02 case/year. Most (about 80 percent) of this
additional reduction in incidence in Option 1 compared to Option 2 occurs in the population
exposed to risks in the 1 X 10"6 range or lower. In addition, levels reported to produce noncancer
health effects are about three orders of magnitude above levels expected under either option.
Option 1 reduces benzene emissions by about 98 percent, whereas Option 2 reduces
benzene emissions by about 97 percent in comparison to the emissions that would occur without
the standards. This reflects only an additional 1 percent reduction for Option 1. Also, the relative
difference between these options may be even smaller than estimated. This is due to the
uncertainty that sealed bellows valves would actually achieve the assumed 100 percent reduction
in Option 1 and the potential for higher emission reduction than estimated for the equipment leak
detection and repair program under Option 2. To achieve this emission reduction (and
consequent risk reduction), Option 1 would increase the annualized cost by about $6 million/yr
(1984 dollars). While this additional cost is relatively small overall, it is disproportionately large
in comparison to the small additional emission and health risk reductions associated with Option
1 in comparison to Option 2.
In conclusion, EPA decided that Option 2 provides an ample margin of safety. The EPA
judged the risk reductions for Options 1 and 2 to be essentially the same and the greater control
cost of Option 1 to be high in relation to the small additional emission and risk reduction
achieved. In doing so, EPA considered the likely overstatement of long-term emissions and
risks and the question of technical feasibility.
Benzene Equipment Leaks
Background: This source category covers emissions of benzene from pieces of
equipment handling process streams that contain greater than 10 percent benzene, by weight.
These equipment pieces include pumps, pipeline valves, open-ended valves, flanges,
compressors, pressure-relief valves, sampling connections, process drains, and product
accumulator vessels. In 1984, there were an estimated 131 facilities in this source category.
* * *
March 1999 Page B-21 * * *
-------
Residual Risk Report to Congress
When Subpart J of Part 61, the benzene equipment leaks NESHAP, was promulgated in
1984, EPA estimated that this regulation would reduce emissions from about 7,900 Mg/yr to
2,500 Mg/yr (a 69 percent reduction). As noted in the July 28, 1988, Federal Register notice,
EPA viewed the estimate of 2,500 Mg/yr for current emissions as being an upperbound estimate,
and recognized that actual emissions may be substantially lower. The EPA reached this
conclusion after reviewing compliance report information from facilities subject to the existing
standards and other information for facilities handling toxic compounds. Information obtained
since proposal has further substantiated this conclusion. The basis for this conclusion is
summarized below and is discussed in more detail in section IV and in the BUD.
During the consideration of the public comments, EPA examined compliance reports
from 1987 and 1988 for a randomly-selected sample of 25 facilities subject to the benzene
NESHAP. This review showed many facilities had no leaking valves or pumps (0.0 percent) and
no facilities had more than 1.5 percent leaking valves. The average leak rate for valves was 0.27
percent. This performance is better than an average expected leak rate of about 3 to 5 percent. In
addition to the compliance reports, EPA also reviewed a limited amount of comprehensive data
for a few process units with equipment in benzene service. These data show emission rates a
factor of 20 to 30 below levels predicted by the earlier EPA studies. However, these more recent
results do not provide a basis for developing new emission factors that would be generally
applicable to all facilities. To rederive the emission estimates will require additional information
and analysis of current industry practices. As this information has been received only recently,
EPA has not been able to conduct the necessary studies and analyses in time to revise the
emission estimates for benzene equipment leaks. The EPA has initiated a negotiated rulemaking
to develop a new regulatory approach that will result in quantifiable emission levels, give credit
for good original plant design, and motivate innovation (54 FR 17944, April 25, 1989). This
effort is expected to require at least 6 months to complete. Consequently, the emission and risk
estimates remain essentially as presented in the July 28, 1988, Federal Register notice.
Decision on Acceptable Risk: Based on 1984 emission estimates, the MIR is estimated
to be 6 X 10"4. However, as discussed previously under "Background" (and as discussed in detail
in section IV, in response to comments), EPA considers the emission estimates to be overstated
by roughly a factor of 5 to 20, or more. If actual emissions could be quantified and modeled in
the exposure analysis, the risk estimates would decrease proportionately to the emissions, and
would be comparable to the presumptive risk benchmark. An additional factor in this
overstatement of emissions is that the analysis was developed assuming facilities continued to
operate at the estimated emission rate for 70 years. However, EPA expects that, over time,
emissions may continue to decrease due to improved control of air toxics through use of better
design, operation, and maintenance of facilities. Given all these factors, EPA concludes that the
MIR for this category is more likely to be less than the benchmark of approximately 1 X 10"4,
and will use this in its judgment on acceptability.
The estimated annual cancer incidence (based on the overstated emission estimates) is 1
case every 5 years (0.2 case/year) in a total modeled population of 200 million. The estimated
incidence among the 2,000 people predicted to be at lifetime risks greater than 1 X 10"4 is only 1
* * *
March 1999 Page B-22 * * *
-------
Residual Risk Report to Congress
case every 200 years (0.005 case/year). In estimating these risk levels, EPA has not found that
co-location of facilities significantly influences the magnitude of the MIR. In addition, EPA
estimated the majority of the population (greater than 99 percent) exposed to benzene from this
source category would be exposed to risk levels below 1 X 10"6. The incidence predicted for the
population exposed to risks smaller than 1 X 10"6 is 1 case every 5 years (0.2 case/year), and the
incidence for the population exposed to risks greater than 1 X 10"6 is 1 case every 20 years (0.05
case/year).
The EPA also considered the noncancer health effects associated with benzene exposures
at current levels of exposure from this source category. Benzene concentrations reported to
produce noncancer health effects are two to three orders of magnitude above the exposures
predicted for these sources.
After considering all of these factors, especially the substantial overstatement of
emissions, EPA judged that the present, controlled level of emissions and risks are acceptable.
Decision on Ample Margin of Safety: The EPA considered selecting a level of emissions
more stringent than the level associated with the existing standards. The additional control of
Option 1 reflects the use of dual mechanical seals for pumps, and sealed bellows valves. For the
purpose of this analysis, this equipment is considered to be leakless (i.e., 100 percent control).
However, it is not known if leakless valves/sealed bellows valves will effectively eliminate
emissions or if they are available for all sizes and types of equipment in benzene service. Thus,
it should be noted that EPA has not concluded that leakless valves/sealed bellows valves will
effectively eliminate leaks. Information is needed on the magnitude of emissions released when
a sealed bellows valve fails, failure rates of these valves, and appropriate procedures for
monitoring valves for failures before any conclusions are made. In addition, a better
understanding of the factors affecting equipment leaks and development of new regulatory
approaches is needed before significant further reductions in exposures will be assured.
Nevertheless, EPA considered Option 1 to determine if it should be selected to provide an ample
margin of safety even though there would be technological feasibility issues in implementing this
option.
Under Option 1, the estimated MIR would be reduced by roughly a factor of three, and
the nationwide incidence would be reduced from 1 case every 5 years (0.2 case/year) under the
current NESHAP baseline to 1 case every 10 years (0.1 case/year). As discussed under the
"Decision on Acceptable Risk," EPA views the estimate of the MIR for this source category as
significantly overstated. The number of people exposed to a risk level between 1 X 10"4 and 1 X
10"6 would be reduced from about 1 million to 300,000 under Option 1. For the people exposed
to these risk levels, the incidence would change from 1 case every 200 years (0.005 case/year) to
1 case every 1,000 years (0.001 case/year) and from 1 case every 25 years (0.04 case/year) to 1
case every 100 years (0.01 case/year), respectively. The number exposed to a risk level less than
1 X 10"6 would be the same under Option 1 and the existing standards, with more than 99.5
percent of the total population of 200 million exposed to these risk levels. Most (about 90
percent) of the additional reduction in incidence in Option 1 compared to the existing standards
* * *
March 1999 Page B-23 * * *
-------
Residual Risk Report to Congress
would occur in the population exposed to risks in the 1 X 10"6 range or lower. In addition,
benzene concentrations reported to produce noncancer health effects are at least two to three
orders of magnitude above the concentrations expected under Option 1 or the existing standards.
Option 1 is estimated to reduce benzene emissions by about 50 percent from the level of
the standards. The relative difference between the two control levels may be substantially
smaller than this estimate. This is due to the uncertainty that sealed bellows valves would
actually achieve the assumed 100 percent reduction in Option 1 and the greater than predicted
reductions observed with the current standards' leak detection and repair program. Because of
the large uncertainty in the emission levels under the current standards, the likely additional
emission reduction cannot be estimated. Implementation of the requirements of Option 1 would
increase the annualized control cost by $52.4 million/yr (1979 dollars). (Docket No. A-79-27,
Item V-A-1). The majority of the estimated cost is from the cost of sealed bellows valves.
Although Option 1 shows some additional emission and risk reduction may be
achievable, the control cost is disproportionately large when compared to the small reductions in
risk which could be achieved. If the actual emission reduction were known and used, the option
would likely be even less effective. Recognizing the uncertain bias in the emission estimates, the
large proportion of the incidence associated with lifetime risks less than 1 X 10"6, the questions
regarding technical feasibility, and the costs of additional controls, EPA judged the emission
levels associated with the existing NESHAP to protect public health with an ample margin of
safety. Therefore, additional control beyond the existing NESHAP is not warranted and will not
be required.
* * *
March 1999 Page B-24 * * *
-------
Residual Risk Report to Congress
Appendix C
Schedule for Source Category MACT Standards
-------
Residual Risk Report to Congress
Exhibit C-l
EPA - Clean Air Act - Title III
2-Year MACT Standards
MACT Standard /
Source Categories
DRY CLEANING
Commercial dry
cleaning dry-to-dry
Commercial
drycleaning transfer
machines*
Commercial
drycleaning transfer
machines
Industrial drycleaning
dry-to-dry
Industrial drycleaning
transfer machines
HAZARDOUS
ORGANIC NESHAP
Number of
Source
Categories
5
1
CFR
Subparts
M
F, G, H, I
Statutory
Date
11/15/92
11/15/92
Administrator
Signed
Promulgation
09/13/93
02/28/94
Fed Register
Publication
and Citation
09/22/93
(58FR49354)
04/22/94
(59FR19402)
Initial
Compliance
Date
12/20/93
10/24/94
Key Legend:
* = denotes area source category
Admin signed date = actual date EPA Administrator signed package
* * *
March 1999 Page C-l * * *
-------
Residual Risk Report to Congress
Exhibit C-2
EPA - Clean Air Act - Title III
4-Year MACT Standards
MACT Standard / Source
Categories
AEROSPACE INDUSTRY
ASBESTOS (delisted)
CHROMIUM
ELECTROPLATING
Chromic Acid Anodizing
Chromic Acid Anodizing*
Decorative Chromium
Electroplating
Decorative Chromium
Electroplating*
Hard Chromium
Electroplating
Hard Chromium
Electroplating*
COKE OVENS
COMMERCIAL
STERILIZERS
Commercial Sterilization
Facilities
Commercial Sterilization
Facilities*
DEGREASE ORGANIC
CLEANERS
Halogenated Solvent
Cleaners
Halogenated Solvent
Cleaners*
INDUSTRIAL COOLING
TOWERS
MAGNETIC TAPE
MARINE VESSELS
OFF-SITE WASTE
TREATMENT
PETRO REFINERIES
Number
of Source
Category
1
1
6
1
2
2
1
1
1
1
1
CFR
Subparts
GG
--
N
L
0
T
Q
EE
Y
DD
CC
Statutory
Date
11/15/94
11/15/94
11/15/94
12/31/92
11/23/94
11/15/94
11/15/94
11/15/94
11/15/94
11/15/94
11/15/94
Administrator
Signed
Promulgation
07/31/95
11/14/95
11/22/94
10/23/93
11/22/94
11/15/94
07/30/94
11/22/94
07/28/95
05/28/96
07/28/95
Fed Register
Publication and
Citation
09/01/95
(60FR45948)
11/30/95
(60FR61550)
01/25/95
(60FR49848)
10/27/93
(58FR57898)
12/06/94
(59FR62585)
12/02/94
(59FR61801)
09/08/94
(59FR46339)
12/15/94
(59FR64580)
09/19/95
(60FR48388)
07/01/96
(61FR34139)
08/18/95
(60FR4344)
Initial
Compliance
Date
09/01/98
11/30/95
01/25/96 decor;
01/25/97 others
11/15/93
12/02/97
03/08/96
12/15/96
09/19/99
07/01/99
08/18/98
* * *
March 1999 Page C-2 * * *
-------
Residual Risk Report to Congress
Exhibit C-2 (continued)
EPA - Clean Air Act - Title III
4-Year MACT Standards
MACT Standard / Source
Categories
PRINTING/PUBLISHING
POLYMERS & RESINS I
Butyl Rubber
Epichlorohydrin Elastomers
Ethylene Propylene Rubber
Hypalon (TM) Production
Neoprene Production
Nitrile Butadiene Rubber
Polybutadiene Rubber
Polysulfide Rubber
Styrene-Butadiene Rubber &
Latex
POLYMERS & RESINS II
Epoxy Resins Production
Non-Nylon Polyamides
Production
POLYMERS & RESINS IV
Acrylonitrile-Butadiene-
Styrene
-Methyl Methacrylate-
Acrylonitrile+
Methyl Methacrylate-
Butadiene++
Polystrene
Styrene Acrylonitrile
Polyethylene Terephthalate
SECONDARY LEAD
SMELTERS
SHIPBUILDING MACT
STAGE I GASOLINE
DISTRIBUTION
WOOD FURNITURE
total sources
Number
of Source
Category
1
9
2
6
1
1
1
1
40
CFR
Subparts
KK
U
W
JJJ
X
II
R
JJ
Statutory
Date
11/15/94
11/15/94
11/15/94
11/15/94
11/15/94
11/15/94
11/15/94
11/15/94
Administrator
Signed
Promulgation
05/15/96
07/15/96
02/28/95
05/15/96
5/31/95
11/14/95
11/23/94
11/14/95
Fed Register
Publication and
Citation
05/30/96
(61FR27132)
09/05/96
(61FR46906)
03/08/95
(60FR12670)
09/12/96
(61FR48208)
06/23/95
(60FR32587)
12/15/95
(60FR64330)
12/14/94
(59FR64303)
12/07/95
(60FR62930)
Initial
Compliance
Date
05/30/99
03/05/97
03/03/98
03/12/97
06/23/97
12/16/97
12/15/97
11/21/97
* * *
March 1999 Page C-3 * * *
-------
Residual Risk Report to Congress
Exhibit C-2 (continued)
EPA - Clean Air Act - Title III
4-Year MACT Standards
Table Legend:
* area source categories
+ Methyl Methacrylate-Acrylonitrile-Butadiene-Styrene
++ Methyl Methacrylate-Butadiene-Styrene Terpolymers
Admin signed date = actual date EPA Administrator signed package
* * *
March 1999 Page C-4 * * *
-------
Residual Risk Report to Congress
Exhibit C-3
EPA - Clean Air Act - Title III
7-Year MACT Standards
Statutory date - 11/15/97 (42 Source Categories)
7- YEAR STANDARDS
Source Category
Pesticide Active IngredientsAAA
Acrylic/Modacrylic Fibers (GMACT)
Manuf. of TetrahydrobenzaldehydeAA
Chlorine Manuf.
Chromium Chemicals Manuf.
Cyanide Chemicals Production (3)*
EAF: Stainless & Non-Stainless Steel
(2)
Ferroalloys Production
Flexible Polyurethane Foam Prod.
Mineral Wool
Nylon 6 Production
Oil & Natural Gas Production
Petroleum Refineries
Pharmaceuticals Production
Polycarbonates Production
(GMACT)
Polyether Polyols Production
Polymers & Resins III (2)*
Portland Cement
Publicly Owned Treatment Works
(POTW)
Primary Aluminum
Primary Copper
Primary Lead Smelting
Pulp & Paper (non-combust) MACT
IA
Pulp & Paper (combustion) MACT
IIA
Pulp & Paper (non-chem) MACT IIIA
Reinforced Plastic Composites Prod.
Secondary Aluminum Prod.
Steel Pickling
Wood Treatment MACT
PROPOSE
Administrator
signature
10/27/97
9/16/98
8/15/97
11/99
--
11/99
--
7/23/97
12/09/96
4/29/97
11/23/97
8/25/98
03/20/97
9/16/98
8/15/97
9/30/98
3/9/98
11/12/98
08/22/96
4/9/98
4/9/98
12/17/93
11/14/97
2/29/96
10/99
3/98
8/28/97
Actually
proposed in
FR
11/10/97
10/14/98
8/4/98
12/27/98
5/8/97
2/6/98
9/11/98
4/2/97
10/14/98
9/4/97
3/24/98
12/1/98
9/26/96
4/20/98
4/17/98
4/15/98
9/18/97
FR citation
for proposed
rule
62FR60566
63FR55178
63FR41509
61FR68408
62FR25370
63FR6288
63FR48890
62FR15754
63FR55178
62FR48804
63FR14182
63FR66085
63FR19582
63FR19201
63FR18754
62FR49052
PROMULGATE
Administrator
signature
3/99
12/98
5/1/98
11/2000
delisted
5/17/96
11/2000
delisted
5/17/96
8/98
9/15/98
4/98
Actually
promulgated
inFR
10/7/98
FR citation:
promulgated
rule
63FR53980
to be delisted
10/98
3/99
7/30/98
12/98
9/98
7/99
9/98
1/99
9/19/97
6/98
8/98
11/14/97
7/98
11/97
11/2000
3/99
4/98
9/21/98
10/7/97
4/15/98
4/15/98
63FR50280
62FR52384
63FR18504
delisted 5/17/96
* * *
March 1999 Page C-5 * * *
-------
Residual Risk Report to Congress
Exhibit C-3 (continued)
EPA - Clean Air Act - Title III
7-Year MACT Standards
7- YEAR STANDARDS
Source Category
Wool Fiberglass
Acetal Resins (GMACT)
Natural Gas Transmission and
Storage
PROPOSE
Administrator
signature
2/25/97
9/16/98
11/23/97
Actually
proposed in
FR
3/31/97
10/14/98
2/6/98
FR citation
for proposed
rule
62FR15228
63FR55178
63FR6288
PROMULGATE
Administrator
signature
3/98
Actually
promulgated
inFR
FR citation:
promulgated
rule
Key Legend:
* = Standards with more than one Source Category (see below for breakdown)
AAA = formeriy known as Agriculture Chemicals Production
AA = formerly known as Butadiene Dimers Production
A = projects are part of the Pulp and Paper rule
7 YEAR STANDARD: BREAKDOWN OF SOURCE CATEGORIES
CYANIDE CHEMICALS PRODUCTION:
Sodium Cyanide Production
Hydrogen Cyanide Production
Cyanuric Chloride Production
POLYMERS & RESINS III:
Amino Resins
Phenolic Resins
PULP & PAPER:
MACT I - non-combustion
MACT II - combustion (kraft, soda, sulfite)
MACT III - non-chemical
NESHAP for Combustion Sources in the Semichemical Pulping Industry
* * *
March 1999 Page C-6 * * *
-------
Residual Risk Report to Congress
Exhibit C-4
EPA - Clean Air Act - Title III
10-Year MACT Standards
Statutory date - 11/15/00 (87 Source Categories)
10- YEAR STANDARDS
Source Category
Aerosol Can-Filling Facilities
Alumina Processing
Ammonium Sulfate Production
Antimony Oxides
Manufacturing
Asphalt Concrete Manufacturing
Asphalt Roofing & Processing
Asphalt/Coal Tr Application-
Metal Pipes
Auto & Light Duty Truck
(surface ctg.)
Boat Manufacturing
Carbon Black
Carbonyl Sulfide (COS)
Production via Carbon Bisulfide
Clay Products Manufacturing
Coke By-Products
Coke Oven: Pushing,
Quenching...
Dry Cleaning (Petroleum
Solvent)
Engine Test Facilities
Ethylene Processes
Flat Wood Paneling
Flexible Poly Foam Fabrication
Operations
Friction Products Manufacturing
Fume Silica Production
Hydrogen Chloride Production
Hydrogen Fluoride Production
(GMACT)
Industrial Combustion Coord.
Rule +
Integrated Iron & Steel
Iron & Steel Foundries
PROPOSE
Administrator
Signature
potential
11/99
11/99
potential
11/99
08/98
11/99
11/99
12/99
11/99
11/99
11/99
Actually
proposed in FR
covered by 40CFR61 sub
11/99
potential
11/99
11/98
11/99
03/99
05/99
11/99
11/99
9/16/98
11/99
11/99
11/99
10/14/98
FR citation for
proposed rule
)artL
63FR55178
PROMULGATE
delisting
11/2000
11/2000
delisting
11/2000
08/99
11/2000
11/2000
12/2000
11/2000
11/2000
11/2000
10/2000
delisting
11/2000
11/99
11/2000
06/2000
04/2000
1 1/2000
11/2000
12/98
11/2000
11/2000
11/2000
* * *
March 1999 Page C-7 * * *
-------
Residual Risk Report to Congress
Exhibit C-4 (continued)
EPA - Clean Air Act - Title III
10-Year MACT Standards
10- YEAR STANDARDS
Source Category
Lead Acid Battery
Manufacturing
Leather Tanning & Finishing
Operations
Lime Manufacturing
Manufacuring of Nutritional
Yeast
Marine Vessel Loading
Operations
Metal Can
Metal Coil
Metal Furniture
Miscellaneous Cellulose +
Miscellaneous Metal Parts
Municipal Landfills
Misc. Organic NESHAP (MON)
+
Nitrile Resins Production AA
Non-Clay Refractories Manuf.
Organic Liquids Distribution
(Non-Gas)
Paint Strippers
Paper & Other Webs (Surface
Ctg)
Phosphoric Acid/ Phosphate
Fertilizers A
Plastic Parts & Products
Plywood/Particle Board Manuf.
Polyvinyl Chloride &
Copolymers Prod
Primary Magnesium
Printing, Coating, & Dyeing of
Fabrics
Quaternary Ammonium Comp.
Prod.
Rocket Engine Test Firing
Rubber Tire Production
Secondary Lead Smelters
Semiconductor Manuf.
PROPOSE
Administrator
Signature
-
11/99
4/99
10/7/98
-
11/99
11/99
7/99
12/99
11/99
11/99
11/99
5/99
11/99
11/99
11/99
11/21/96
11/99
11/99
11/99
5/99
11/99
11/99
11/99
3/99
11/99
Actually
proposed in FR
10/19/98
12/27/96
FR citation for
proposed rule
63FR55183
PROMULGATE
delisted 5/17/96
11/2000
04/2000
06/99
7/28/95
11/2000
11/2000
11/2000
11/2000
11/2000
11/2000
11/2000
05/15/97
05/2000
11/2000
11/2000
11/2000
12/97
11/2000
11/2000
11/2000
05/2000
11/2000
11/2000
1 1/2000
12/99
5/31/95
1 1/2000
* * *
March 1999 Page C-8 * * *
-------
Residual Risk Report to Congress
Exhibit C-4 (continued)
EPA - Clean Air Act - Title III
10-Year MACT Standards
10- YEAR STANDARDS
Source Category
Sewage Sludge Incinerators
Spandex Production
Taconite Iron Ore Processing
Uranium Hexafluoride Prod.
Vegetable Oil Production
PROPOSE
Administrator
Signature
4/99
11/99
11/99
11/99
11/99
Actually
proposed in FR
FR citation for
proposed rule
PROMULGATE
05/2000
11/2000
11/2000
11/2000
11/2000
Table Legend:
+ = standards with more than one source category (see below for breakdown)
A = two source categories being worked on together as one project
AA=Part of Polymers & Resins IV
BREAKDOWN OF SOURCE CATEGORIES FOR 10 YEAR MACT
MISCELLANEOUS CELLULOSE MACT
Carboxymethylcellulose Production
Cellulose Ethers Production
Cellulose Food Casing Manufacturing
Cellophane Production
Methylcellulose Production
Rayon Production
INDUSTRIAL COMBUSTION COORDINATING RULEMAKTNG
Industrial Boilers
Institutional/Commercial Boilers
Process Heaters
Stationary Internal Combustion Engines
Stationary Turbines
MISCELLANEOUS ORGANIC NESHAP (MON)
Alkyd Resins Production
Benzyltrimethylammonium Chloride Production
Carbonyl Sulfide Production
Chelating Agents Production
Chlorinated Paraffins Production
Ethyllidene Norbomene Production
Explosives Production
Hydrazine Production
Maleic Anhydride Copolymers Production
Manufacture of Paints, Coatings, & Adhesives
OBPA/l,3-diisocyanate Production
Photographic Chemicals Production
Phthalate Plasticizers Production
Polyester Resins Production
Polymerized Vinylidene Chloride Production
Polymethyl Methacrylate Resins Production
Polyvinyl Acetate Emulsions Production
Polyvinyl Alcohol Production
Polyvinyl Butyral Production
Rubber Chemicals Production
Symmetrical Tetrachloropyridine Production
* * *
March 1999 Page C-9 * * *
-------
Residual Risk Report to Congress
Appendix D
Summary of Response to
Science Advisory Board's (SAB) Review of
EPA's April 14,1998 Draft Residual Risk Report to Congress
-------
Residual Risk Report to Congress
Appendix D
Summary of Response to
Science Advisory Board's (SAB) Review of
EPA's April 14,1998 Draft Residual Risk Report to Congress
Introduction
This appendix includes a summary of EPA's response to the Science Advisory Board
(SAB) comments to EPA's April 14, 1998 draft Residual Risk Report to Congress (Report). The
SAB is a public advisory group, comprised of non-EPA scientists, that provides extramural
scientific information and advice to EPA. At EPA's request, the Residual Risk Subcommittee of
SAB convened on August 3, 1998 to review the Report. The SAB found the Report to be overall
a good draft of a strategy document; however, the Subcommittee indicated that certain areas of
the Report should be strengthened before it can be applied to actual residual risk assessments.
The Subcommittee was highly supportive of the Agency's plan to inform the SAB in 1999 with
examples in which the Report's strategy has been applied to specific areas. The SAB endorsed
the underlying risk assessment (RA)/risk management (RM) approach described in the Report.
However, the SAB added that the following issues needed to be addressed more directly and
explicitly before finalizing the Report.
(1) The Report should more carefully convey the limitations of the data, models, and
methods that are described or that would be needed to carry out the residual risk
assessment activities.
(2) The Report should contain or cite specific examples to clarify what some of the
bold, but vague, language is intended to convey.
(3) There needs to be a more clearly described screening approach that will prioritize
stressors for assessment and will husband (i.e., conserve) Agency resources.
(4) The Report should be more explicit about how the residual risk assessments will
be used to make risk management decisions.
Executive Summary of SAB's Review
The following is the full text of the executive summary of SAB's review of EPA's draft
Residual Risk Report to Congress.
Section 112(f)(l) of the Clean Air Act (CAA), as amended, directs EPA to prepare a
Residual Risk Report to Congress (Report) that describes the methods to be used to assess the
risk remaining, (i.e., the residual risk) after maximum achievable control technology (MACT)
* * * March 1999Page D-l * * *
-------
Residual Risk Report to Congress
standards, applicable to emissions sources of hazardous air pollutants (HAPs), have been
promulgated under Section 112(d). The Report presents EPA's proposed strategy for dealing
with the issue of residual risk and reflects consideration of technical recommendations in reports
by the National Research Council ["Science and Judgment"] (NRC, 1994) and the Commission
on Risk Assessment and Risk Management (CRARM, 1997). As a strategy document, the
Agency's Report describes general directions, rather than prescribed procedures. The announced
intent is to provide a clear indication of the Agency's plans while retaining sufficient flexibility
that the program can incorporate changes in risk assessment methodologies that will evolve
during the 10-year lifetime of the residual risk program.
In June, 1998, the Science Advisory Board (SAB) was asked to review the Agency's
April 14, 1998 draft Report to Congress on Residual Risk. The Board was asked to focus
primarily on the five specific charge questions that are addressed in the report:
a) Has the Residual Risk Report to Congress (Report) properly interpreted and considered
the technical advice from previous reports, including:
(1) The NRC's 1994 report "Science and Judgment in Risk Assessment", and
(2) The 1997 report from the Commission on Risk Assessment and Risk
Management, in developing its risk assessment methodology and residual risk
strategy?
b) Does the Report identify and appropriately describe the most relevant methods (and their
associated Agency documents) for assessing residual risk from stationary sources?
c) Does the Report provide an adequate characterization of the data needs for the risk
assessment methods?
d) Does the Report provide adequate treatment of the inherent uncertainties associated with
assessment of residual risks?
e) Does the Report deal with the full range of scientific and technical issues that underlie a
residual risk program?
An SAB Subcommittee of the Executive Committee met in public session on August 3,
1998 at the USEPA main auditorium in Research Triangle Park, NC. Written comments
prepared before and after the meeting by Subcommittee members form the basis for this report.
Those comments are included in Appendix A for the edification of the Agency as an illustration
of the issues identified by the Subcommittee members and the range of views expressed.
In short, the SAB found the Report to be a generally good draft of a strategy document,
but one that must be strengthened in a number of important places prior to its submission to
* * * March 1999Page D-2 * * *
-------
Residual Risk Report to Congress
Congress. The Subcommittee was highly supportive of the approach that the Agency described
in terms of coming back to the SAB in 1999 with examples in which the Report's strategy is
applied to specific cases.
Overall, the Report utilizes the risk assessment(RA)/risk management (RM) framework,
endorsed by the SAB and others. It emphasizes the dynamic and evolving nature of the RA
process by not being overly prescriptive, while also providing some bounds to the process in both
the areas of RA and RM. The Agency has clearly studied the National Research Council and
Commission on RA/RM reports that related to this topic and has addressed many of the concerns
and suggestions that they raised. At the same time, there are additional points that should be
confronted more directly, including the following:
(1) The Report gives a misleading impression that more can be delivered than is
scientifically justifiable, given the data gaps and limited resources (e.g., time, funding)
for conducting the residual risk assessments. The Subcommittee recommends that the
Report more carefully convey the limitations of the data, models, and methods that are
described or that would be needed to carry out the residual risk assessment activities.
The task of conducting so many assessments of the risks remaining after implementation
of MACT controls is daunting, but doable. While the Report describes a general strategy for
accomplishing this task, it does not address many of the outstanding, practical difficulties that
will have to be overcome in carrying out the strategy. For example, there will likely be many
situations in which the data implied in the strategy are absent. Although a number of options
exist, it is not clear what the Agency will do in such cases. Other problems that need attention
include: computer models that have had only limited independent testing for their application to a
particular problem and/or have not been adequately validated for its general applicability across a
wide array of situations, information in important toxicological databases that is outdated or has
had limited peer review, and special limitations in information and tools for ecological risk
assessment. The Congress and the public, on the basis of reading this Report, may have
unrealistically high expectations of what the Agency can, in fact, deliver in terms of the accuracy,
precision, and timeliness of residual risk assessments.
(2) The Report should contain or cite specific examples to clarify what some of the bold, but
vague, language is intended to convey.
The Report lacks any specific examples and/or citations of existing examples to illustrate
its discussion of the many complex and difficult issues involved, such as, but not limited to, the
following:
a) Involving stakeholders in the process, which is particularly important when it comes to
sharing information among the Federal and State Governments and industry.
b) Determining the criteria for when to use other than default assumptions.
* * * March 1999Page D-3 * * *
-------
Residual Risk Report to Congress
c) Addressing background contamination and competing sources of risks (e.g., mobile and
area sources).
d) Dealing with the trade-off between risks from HAPs and possible risks posed by
measures to reduce the HAPs risks.
e) Assessing risks in the face of significant limitations in the available data, the lack of
validation of existing and emerging computer models, and the need to consider
uncertainty in the results.
f) Employing screening tiers and emerging risk assessment methodologies in such a way
that scarce resources are targeted on the most important assessments and are not
expended on resource-intensive, low-information-yield analyses.
g) Providing a public health perspective to these issues.
(3) There needs to be a more clearly described screening approach that will prioritize
stressorsfor assessment and will conserve Agency resources. The Report should more
clearly present the approach by which the Agency will perform the screening and
prioritization.
There is the potential that the Residual Risk program could evolve into a large,
resource-intensive activity unless there is an appropriate and well-supported screening approach
in place to prioritize assessments among the 188 pollutants and 174 source categories. The
screening methods should be such that they avoid generating a large number of "false positives"
that would drain scarce RA resources or "false negatives" that could result in leaving high
risk situations unaddressed. Unless the Agency carefully prioritizes its assessments and
conserves its resources, the program could evolve either into a wide, but shallow, program that
fails to adequately quantify and target residual risks or into a program that fails to address a
sufficient number of pollutants and sources, due to over-analysis of just a few cases.
(4) The Report should be more explicit about how the residual risk assessments will be used
to make risk management decisions.
The Subcommittee recognizes that the Report is a description of a strategy for RA, not for
RM, per se. However, as S&J and the CRARM report each emphasize, there should be open
communication between risk assessors and risk managers at the beginning of the process, so that
it is clear how the RA will fit into the RM process. If the Residual Risk program is, indeed, to be
"science-based", then it is important that there be, even in a strategy document, some discussion
of what type of RA is needed and how its results will be factored with other legitimate risk
management factors during the final stages of decision making.
* * * March 1999Page D-4 * * *
-------
Residual Risk Report to Congress
The Subcommittee strongly encourages the Agency to implement their plan to bring to
the SAB for review in 1999 some applications of the Residual Risk strategy as specific
illustrations of how these complex issues will be addressed. This approach will permit more
detailed discussion of many of the implementation issues that members felt will arise when
residual risk assessments are made.
Considering a larger issue beyond its specific Charge, the Subcommittee expressed some
concern about the manner in which risks from HAPs are being addressed, when compared with
the risks posed by Section 109 Criteria Air Pollutants (CAPs). There are differences in the
wording of the Clean Air Act Amendments as to the level of risk avoidance that should be
provided. This incongruity is puzzling and suggests that it may be useful to reevaluate how risks
are assessed and managed for these two types of airborne pollutants. We recognize that the
current legislation requires that these two classes of pollutants be treated separately. However,
since the Agency was specifically asked to suggest changes in the legislation, there is an
opportunity to propose a more comprehensive framework upon which to build the assessment
and management of the risks from both HAPs and CAPs. Such a broader public health
perspective would result in greater improvements in health and environmental benefits for a
given expenditure of resources. The Agency has taken some steps towards a comprehensive
view of HAPs and CAPs in its Report to Congress on the Costs and Benefits of the Clean Air
Act, 1970-1990 (EPA 1997) that has been reviewed earlier by the SAB (SAB 1997, 1996) and
those steps should be continued. The contrast in relative benefits of the two programs was
revealing.
In addition, the Agency Staff should consider outlining a number of the most important
Residual Risk issues in a policy memo to top management; e.g., the limitations on what science
can deliver and the comparison between the Section 112 (HAPs) program and the Section 109
(CAPs) program. These managers should be made aware of the problems involved and be given
the opportunity to provide the kind of guidance that would clarify these matters for the benefit of
those both inside and outside of the Agency.
In summary, the Agency's Report is a useful strategic document that will help guide the
Agency as it moves ahead with the Residual Risk program. However, the Subcommittee
recommends that the Agency be more candid with Congress and the public about what can be
accomplished with existing limitations in data, models, methods, time, and resources. The
Subcommittee has pointed out many areas that will require more thought, more documentation,
and more articulation before the program is actually implemented.
* * * March 1999Page D-5 * * *
-------
Residual Risk Report to Congress
Response to SAB Comments
In this section, EPA addresses SAB's four major comments.
1. The report should more carefully convey limitations of data, models, and methods
that are described or that would be needed to carry out residual risk assessment
activities.
RESPONSE
The report has been revised to clarify the current availability of data and tools relevant to
air toxics risk assessment, the resultant limitations of the risk assessments, and plans for
data and tool development to improve this situation. The more obvious limitations
include the lack of dose-response assessments and ecological criteria for many HAPs.
This situation significantly handicaps our risk assessment for those HAPs, thus limiting
the scope of some source category risk assessments. This leads to a greater level of
uncertainty regarding residual risks than if all data gaps were filled.
Sections detailing the availability of data, methodology, or models, as appropriate, have
been included in the report following the discussion of each of the the various
components of the risk assessment process. In addition to describing the current
availability and completeness of data or methodology, and how that may affect the
limitations and uncertainties associated with risk assessments, plans to improve that
situation (i.e., data and tool development activities and priorities) are also presented.
2. The report should contain or cite specific examples to clarify what some of the
"bold, but vague language" is intended to convey.
RESPONSE
General discussion of some topics in the Report is necessary given that the Agency is in
the initial stages of the residual risk assessment process and that evaluation of the process
following initial analyses may lead to changes. However, clarifying language has been
incorporated to provide the reader with a better understanding of the methods and general
process presented.
A new subsection on stakeholder involvement has been added to highlight ways in which
stakeholders may be involved in the risk assessment process. Additional text has been
added to describe the term "default options." In the restructured chapter on the general
risk assessment framework for residual risk, differences between the screening and
refined tiers are more clearly described. A major difference between the two tiers is the
use of conservative assumptions in the screening tier. In the refined tier, additional data
or more refined modeling are relied upon to replace the conservative assumptions. That
* * * March 1999Page D-6 * * *
-------
Residual Risk Report to Congress
is, the specificity and complexity (and consequently resource intensiveness) increases
with each tier. Additionally, experience from case studies will inform the problem
formulation stage in later source category assessments.
The section describing the risk characterization step for both human health and ecological
risk assessments is strengthened regarding presentation of calculated risks in context of
uncertainties associated with the analysis and, as data are available, risk posed by
background concentrations. Additional available public health information may also be
presented in this step for final risk assessment iterations (i.e., those supporting regulatory
risk management decisions). The section of the Report addressing Clean Air Act section
112(f)(l)(B) discussion of uncertainties in the risk assessment methodology and analysis
of uncertainties in air toxics risk assessment has been substantively revised.
As risk management decisions are made regarding the need for residual risk standards,
information specific to each source category regarding risks associated with
implementation of controls can be considered.
To improve clarity of descriptions of ecological risk assessment methodology, examples
have been added to the report.
3. There needs to be a more clearly described screening approach that will prioritize
stressors for assessment and will conserve Agnecy resources.
RESPONSE
The chapter on the general framework for the residual risk risk assessment process has
been restructured to better describe the screening and refined tiers of assessment. The
screening tier provides the ability to identify those source categories or subcategories and
HAPs that may need to move into the refined assessment tier. The risk estimates derived
in the screening tier can be used in conjunction with information on available data and
other relevant information to set priorities for refined analyses. The Report is not meant
to provide a detailed description of data, assumptions, and analyses within each tier, i.e.,
the Report is not meant to be a guidance document. Rather, it provides a description of
the general framework for the risk assessment process. Use of the tiered approach allows
EPA to efficiently and effectively use resources and available data. The screening tier is
less resource intensive, and more likely overly conservative, while the refined tier
requires more resources and relies on more realistic assumptions. The decision made
with results of the screening analysis is "no further action" or "refine analysis," while the
decision made with results of the more refined analyses is "no further action" or "consider
additional emissions control."
* * * March 1999Page D-7 * * *
-------
Residual Risk Report to Congress
4. The Report should be more explicit about how the residual risk assessments will be
used to make risk management decisions.
RESPONSE
As EPA's process for conducting residual risk assessments and consideration of those
results in risk management decision is evolving, the Report is not intended to provide
details regarding risk management decisions. The Report includes general descriptions of
risk management decision points within the risk assessment framework, e.g., during
problem formulation and scoping phases and in consideration of iterative assessment
results.
* * * March 1999Page D-8 * * *
-------
Residual Risk Report to Congress
Appendix E
Summary of MACT Standards and Control Technologies
-------
Residual Risk Report to Congress
Table I - Summary of MACT for Process Vents Under Promulgated NESHAP(a)
MACT Control Level for Affected Sources
40CFR63
Subpart
SubpartG
Subpart M
Subpart O
Subpart U
Subpart W
Subpart
CC
Subpart
DD
Subpart EE
Subpart
JJJ
Industry Source
Category
HON
Perchloroethylene
Dry Cleaning
EO Sterilization
Group 1 Polymers
and Resins
Group II Polymers
and Resins
Petroleum Refineries
Off-Site Waste and
Recovery
Magnetic Tape
Manufacturing
Group IV Polymers
and Resins
HAP Emission Control
Standard
HAP control efficiency > 98%
Vent to refrigerated condenser, carbon
adsorber, or "equivalent control device" as
applicable to machine (b)
Ethylene oxide (EO) control efficiency> 99%
Continuous process HAP control efficiency >
98% and
Batch process HAP control efficiency> 90%
HAP control efficiency > 98%(c)
HAP control efficiency > 98%
HAP control efficiency > 95%(e)
HAP control efficiency > 95%
Continuous process HAP control efficiency >
98%(f)and
Batch process HAP control efficiency> 90%(f)
Alternative Standards Established by Subpart
Vent to a flare, or
Vent to control device with HAP outlet concentration < 20 ppmv
none specified
Achieve aeration room vent EO concentration < 1 ppmv
Vent to a flare, or
Vent to control device with HAP outlet concentration < 20 ppmv
Achieve mass emission limit < 5,000 Ib HAP/yr(c)
Vent to a flare, or
Vent to control device with HAP outlet concentration < 20 ppmv(d)
Vent to a flare, or
Vent to combustion control device with HAP outlet concentrations
20 ppmv
none specified
Alternative standards available for process vents in certain
subcategories under conditions selected in rule. These options
include (not all options are allowed in all cases): achieve HAP
emission limit per unit of product produced; vent to control device
with HAP outlet concentration < 20 ppmv; and vent to a flare.
* * *
March 1999 Page E-l * * *
-------
Residual Risk Report to Congress
Table I (concluded)
TABLE NOTES:
(a) This is a summary table prepared to group the MACT standards by similar HAP emission points. It is not a
comprehensive listing of the individual subpart requirements, and is not to be used to determine the applicability and
compliance requirements under 40 CFR part 63 for a specific facility location.
(b) Under Subpart M, owner/operator has the option of venting the air-perchloroethylene vapor
stream exhausted from existing dry-cleaning machine to carbon adsorber provided control
device installed before 9/22/93.
(c) Under Subpart W process vents are included in the group of emission points that must be
controlled to achieve an overall maximum emission limit standard for the resin or polyamine
manufacturing process. The standard listed in this table applies only for resin manufacturing
processes that are new sources.
(d) Under Subpart CC these emission limit standards are not explicitly stated as an alternative
standard, but is applied implicitly through the applicability provision specifying the affected
process vents requiring Organic HAP Emission Controls (see Table 6a).
(e) Under Subpart DD, an owner/operator may elect to meet this control efficiency standard by
averaging emissions from all of the affected process vents.
(f) This is the minimum control efficiency for most subcategories.
* * *
March 1999 Page E-2 * * *
-------
Residual Risk Report to Congress
Table II - Summary of MACT for Equipment Leaks Under Promulgated NESHAP
-------
Residual Risk Report to Congress
Table III - Summary of MACT for Organic Coating Application Operations Under Promulgated NESHAP
95%
Achieve HAP control efficiency >
81%
Achieve HAP control efficiency >
81%
Achieve HAP control efficiency >
81%
none
none
none
Achieve HAP control efficiency >
92%
none
* * *
March 1999 Page E-4 * * *
-------
Residual Risk Report to Congress
Table III (concluded)
TABLE NOTES:
(a) This is a summary table prepared to assist in grouping the MACT standards by similar HAP emission
points. It is not a comprehensive listing of the individual subpart requirements, and is not to be used
to determine the applicability and compliance requirements under 40 CFR part 63 for a specific
facility location.
(b) Different numerical values are specified for different types of coatings and for existing sources and
new sources.
(c) Rule distinguishes between a "printing operation" and a "coating operation," but both are included as
part of the affected sources if a press is capable of printing or coating on the same substrate.
* * *
March 1999 Page E-5 * * *
-------
Residual Risk Report to Congress
Table IV - Summary of MACT for Organic Solvent Cleaning Operations Under Promulgated NESHAP 88%
Option 2: Maintain minimum freeboard ratio of 75%.
Subpart GG
Aerospace
manufacturing
and
rework facilities
Solvent cleaning operations
Implement specific work practice requirements
Depainting operations
Existing sources achieve overall HAP control efficiency >
81%
New sources achieve overall HAP control efficiency > 95%
Implement specific work practices requirements.
* * *
March 1999 Page E-6 * * *
-------
Residual Risk Report to Congress
Table IV (concluded)
TABLE NOTES:
(a) This is a summary table prepared to assist in grouping the MACT standards by similar HAP emission points. It is not a
comprehensive listing of the individual subpart requirements, and is not to be used to determine the applicability and
compliance requirements under 40 CFR part 63 for a specific facility location.
* * *
March 1999 Page E-7 * * *
-------
TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
1. REPORT NO.
EPA-453/R-99-001
3. RECIPIENTS ACCESSION NO.
4. TITLE AND SUBTITLE
Residual Risk Report to Congress
5. REPORT DATE
1999
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Emission Standards Division
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report has been prepared in response to section 112(f)(l) of the Clean Air Act and provides the
Congress and the public with a description of the methods and general framework that EPA will use to assess
the public health and environmental risk which may remain after implementation of air toxics emissions
standards required under section 112(d) of the Clean Air Act. This remaining risk is referred to as "residual
risk." Air toxics, also known as hazardous air pollutants, are those pollutants known or suspected to cause
cancer or other adverse health effects to humans or adverse environmental effects. This report also discusses
specific issues relevant to the evaluation of residual risk and methods and costs of reducing such risk.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATT Field/Group
Residual Risk
Air Toxics
Hazardous Air Pollutants
MACT
Risk Assessment
Air Pollution control
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (Report)
Unclassified
21. NO. OF PAGES
232
20. SECURITY CLASS (Page)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION IS OBSOLETE
-------
Environmental Engineering Science, In-press, 2002.
APPENDIX
LEACHING TEST METHODS
A-l
-------
Environmental Engineering Science, In-press, 2002.
A.l. AV002.1 (Availability at pH 7.5 with EDTA)
1. Scope
1.1. This test method measures the maximum quantity, or mobile fraction of the total content, of inorganic
constituents in a solid matrix that potentially can be released into solution. An extraction fluid of 50 mM
ethylenediamine-tetraacetic acid (EDTA) is used to chelate metals of interest in solution at near neutral pH
during a single extraction.
1.2. This is a candidate screening protocol (Tier 1).
1.3. This test method is not intended for the release characterization of organic constituents.
2. Cited Protocols
2.1. ASTM (1980) "Standard Method for Water (Moisture) Content of Soil, Rock, and Soil-Aggregate
Mixtures D 2261-80", Philadelphia, PA: American Society for Testing and Materials.
2.2. pHOO 1.0 (pH Titration Pretest).
2.3. AWOO1.0 (Acid Washing of Laboratory Equipment).
2.4. PS001.1 (Particle Size Reduction).
3. Summary of the Test Method
Constituent availability is determined by a single challenge of an aliquot of the solid matrix to dilute
acid or base in deionized (DI) water with a chelating agent (Garrabrants and Kosson 2000). A solution of 50
mM ethylenediamine-tetraacetic acid (EDTA) in DI water is used to minimize liquid phase solubility limitations
for cationic constituents with very low solubility (i.e., Pb, Cu, Cd). For most materials, this test is conducted on
material that has been particle size <2 mm and a minimum sample mass of 8 g dry sample is used1. In all
extractions, a liquid-to-solid (LS) ratio of 100 mL extractant/g dry sample and a contact time of 48 hours are
used to reduce mass transfer rate limitations. Extracts are tumbled in an end-over-end fashion at 28±2 rpm at
room temperature (20±2°C). After the appropriate contact time, the leachate pH value of the extraction is
measured. The retained extract is filtered through 0.45-um pore size polypropylene filtration membranes and
analytical sample is saved for subsequent chemical analysis.
The required endpoint pH value for the optimized extraction of cations and anions is 7.5±0.5. The final
specified pH value is obtained by addition of a pre-determined equivalent of acid or base prior to the beginning
of the extraction. The amount of acid or base required to obtain the final endpoint pH value is specified by a
titration pretest of the material which follows the "pHOOl.O (pH Titration Pretest)" protocol with the
A-2
-------
Environmental Engineering Science, In-press, 2002.
modifications that the titration solution is 50 mM EDTA solution rather than DI water. The required pH range
for this pretest is limited to pH values 5 through 8. Since "AV002.1 (Availability at pH 7.5 with EDTA)" is a
batch extraction procedure used for materials that may be heterogeneous in acid neutralization capacity,
extractions at the limiting values of 7.0 and 8.0 are recommended in addition to the pH target value extraction.
The leachate with a pH value closest to 7.5 is saved for chemical analysis while the others are discarded.
4. Significance and Use
The results from this test are used to determine the maximum quantity, or the fraction of the total
constituent content, of inorganic constituents in a solid matrix that potentially can be released from the solid
material in the presence of a strong chelating agent such as ethylenediamine-tetraacetic acid. The chelated
availability, or mobile fraction, can be considered (1) the thermodynamic driving force for mass transport
through the solid material or (2) the potential long-term constituent release. Also, a mass balance based on the
total constituent concentration provides the fraction of a constituent that may be chemically bound, or immobile
in geologically stable mineral phases. The availability represents a potential for constituent release, not an
actual release measurement. This procedure measures availability in relation to the release of anions at an
endpoint pH of 7.5±0.5 and cations under enhanced liquid-phase solubility due to complexation with the
chelating agent.
5. Apparatus
5.1. Extraction Vessel - a wide-mouth container, constructed of high-density polyethylene that does not
preclude headspace (e.g. Nalgene #3120-9500 or equivalent). The vessel must have a leak-proof seal that
can sustain the required end-over-end tumbling. The container must be of sufficient volume to
accommodate both a minimum solid sample and a leachant volume based on a LS ratio of 100 mL
extractant/g dry sample. If centrifugation is to be used for gross phase separation, the extraction vessel
should be capable of withstanding centrifugation at 4000 rpm for a minimum of 10 minutes.
5.2. Extraction Apparatus - rotary tumbler capable of rotating the extraction vessels in an end-over-end fashion
at constant speed of 28±2 rpm (e.g., Analytical Testing, Werrington, PA or equivalent).
5.3. Filtration Apparatus - pressure or vacuum filtering apparatus (e.g., Nalgene #300-4000 or equivalent).
5.4. Filtration Membranes - 0.45 um pore size polypropylene filtration membrane (e.g., Gelman Sciences GH
Polypro #66548, Fisher Scientific or equivalent).
5.5. pHMeter - standard, two point calibration pH meter (e.g., Accumet 20, Fisher Scientific or equivalent).
5.6. Adjustable Pipetter - Oxford Benchmate series or equivalent with disposable tips (delivery range will
depend on material neutralization capacity and acid strength).
5.7. Centrifuge (optional) - e.g., RC5C, Sorvall Instruments, Wilmington, DE or equivalent.
1 The particle size, sample mass and contact time shown here represent a typical base case scenario. Alternate
sample masses and contact times are required for materials where particle size reduction to <2 mm is either
A-3
-------
Environmental Engineering Science, In-press, 2002.
6. Reagents and Materials
6.1. Reagent Grade Water - deionized (DI) water must be used as the major extractant in this procedure. DI
water with a resistivity of 18.2 MQ can be provided by commercially available water deionization systems
(e.g., Milli-Q Plus, Millipore Corp., Bedford, MA or equivalent).
6.2. 50 mMEDTA Solution - prepared by dissolving 18.61 g of disodium ethylenediamine-tetraacetate
dihydrate - C10H14N2O8Na2'2H2O (Sigma Chemical, St. Louis, MO or equivalent) in one liter of DI water.
6.3. 2N Nitric Acid Solution - prepared by diluting Tracemetal Grade Nitric Acid (Fisher Scientific or
equivalent) with deionized water.
6.4. IN Potassium Hydroxide Solution - reagent Grade (Fisher Scientific or equivalent).
7. Acid Washing Procedure
Because the concentrations of inorganic constituents in leachates may be very low (i.e., <10 ug/L), all
laboratory equipment that comes in contact with the material, the extraction fluid, or the leachant must be rinsed
with 10% nitric acid followed by three rinses with DI water to remove residual inorganic deposits following
"AW001.0 (Acid Washing of Laboratory Equipment)".
8. Initial Sample Preparation
8.1. Particle Size Reduction - depending on the nature of the material, a sufficient mass of the material should
be particle size reduced to <2 mm using "PS001.1 (Particle Size Reduction)" protocol.
8.2. Solids Content Determination - It is necessary to know the solids content of the material being tested so
that appropriate adjustments can be made to conduct the test under the specified LS ratio. Prior to the
initiation of the test, a moisture content determination of the "as received" material must be conducted
using ASTM Method D 2261-80, "Standard Method for Laboratory Determination of Water (Moisture)
Content of Soil, Rock, and Soil Aggregate Mixtures". The solids content is calculated as the mass of the
dried sample divided by the mass of "as received" material as in the following equation:
M
ary (Equation Al-1)
Mrec
where SC = the solids content [gdry/g],
M^ = the dry sample mass [g dry], and
MTec = the mass of the "as received" material [g].
9. AV002.1 Procedure
The AV002.1 protocol may be conducted only after the required equivalents of acid or base to reach
the three specified extraction pH values are determined. The three extraction pH values should include the pH
target value (i.e., 7.5) plus the two-pH limiting values (i.e., 7.0 and 8.0). Additionally, the volume of 50 mM
impractical or unnecessary (see accompanying text).
A-4
-------
Environmental Engineering Science, In-press, 2002.
EDTA solution required to obtain a total LS ratio of 100 mL/g dry material should be calculated. Table Al-1
shows an example schedule of HNO3 additions following the pHOOl.O protocol for a dry equivalent sample
mass of 8 g (<2 mm particle size) and a dry-basis moisture content of 10% (i.e., 0.1 mL/g dry)
Table Al-1. Example schedule of acid addition and 50 mM EDTA makeup for a dry equivalent sample
mass of 8 g dry and a dry basis moisture content of 0.1 mL/g dry for the " AV002.1 (Availability at pH 7.5
with EDTA)" protocol.
Extract no.
1 - limit
2 - target
3 - limit
Endpoint
solution
pH
7.0
7.5
8.0
Equivalents of
acid to add
[meq/g dry]
1.05
0.93
0.63
Volume of 2N
HNO3
[mL]
4.20
3.48
2.52
Volume of
moisture in
sample [mL]
0.8
0.8
0.8
Volume of 50
mMEDTA
makeup [mL]
795.00
795.72
796.68
9.1. Place the minimum dry equivalent sample mass (i.e., 8 g dry) into each of three high-density polyethylene
bottles. Label each bottle with one of the above target pH values. The required equivalent mass of "as
received" material can be calculated following Equation A1-4 if the solids content is known.
Mdrv
Mrec = ^- (Equation Al-4)
»jO
where Mrec = the mass of the "as received" material [g],
Mdry = the dry equivalent sample mass (i.e., 8 g dry for particle size <2 mm [g dry], and
SC = the solids content of the material [g dry/g].
9.2. Add the appropriate makeup volume of 50 mM EDTA solution to each bottle as specified in a schedule of
acid and base additions (e.g., Table Al-1).
9.3. Add the appropriate volume of 2N HNOs or IN KOH required to achieve the endpoint pH values to each
bottle with an automatic pipetter. Volumes of acid or base are specified by the pre-determined schedule
(e.g., Table Al-1).
9.4. Tighten the leak-proof lid for each bottle and tumble the three extracts in an end-over-end fashion at a
speed of 28±2 rpm at room temperature (20±2°C).
9.5. At the end of the equilibration period, remove the extraction vessels from the rotary tumbler.
9.6. Clarify the leachates by allowing the bottles to stand for 15 minutes. Alternately, centrifuge the bottles at
4000±100 rpm for 10±2 minutes.
9.7. Decant a minimum volume of clear, unpreserved supernatant from each bottle into suitable vessel in order
to measure final solution pH.
9.8. Save the leachate with a pH value that is both within the target pH range (i.e., 7.5±0.5) and closest to the
target pH value (i.e., 7.5). The other extracts are discarded.
A-5
-------
Environmental Engineering Science, In-press, 2002.
9.9. Separate the solid and liquid phases of the saved extract by vacuum filtration through a 0.45-um pore size
polypropylene filtration membrane. The filtration apparatus may be exchanged for a clean apparatus as
often as necessary until all liquid has been filtered.
9.10. Collect, preserve, and store the amount of leachate required for chemical analysis.
10. AV002.1 Interpretation
After chemical analysis, the chelated availability can be determined for each "constituent of potential
concern" (COPC). This availability can be calculated on a dry sample mass basis by multiplying the constituent
concentration in the leachate by the test-specific LS ratio as shown in Equation A1-5.
AVLEDTA = CEDTA LS (EquationAl-5)
where A VLEDTA = the constituent availability using 50 mM EDTA [mg/kg dry],
CEDTA = the constituent concentration using 50 mM EDTA [mg/L], and
LS = the test liquid to solid ratio (i.e., 100) [L/kg].
11. References
Garrabrants, A. C. and D. S. Kosson (2000). "Use of a chelating agent to determine the metal availability for
leaching from soils and wastes." Waste Management and Research 20(2-3): 155-165.
A-6
-------
Environmental Engineering Science, In-press, 2002.
A.2. SR002.1 (Alkalinity, Solubility and Release as a Function of pH)
1. Scope
1.1. This test method provides the acid^ase titration buffering capacity of the tested material and the liquid-
solid partitioning equilibrium of the "constituents of potential concern" (COPC) as a function of pH at a
liquid to solid (LS) ratio of 10 mL extractant/g dry sample.
1.2. This is a characterization protocol (Tier 2b) designed to obtain detailed teachability information.
1.3. This test method is not intended for the determination of the solubility profile of organic constituents.
2. Cited Protocols
2.1. ASTM (1980) "Standard Method for Water (Moisture) Content of Soil, Rock, and Soil-Aggregate
Mixtures D 2261-80," Philadelphia, PA: American Society for Testing and Materials.
2.2. pHOO 1.0 (pH Titration Pretest).
2.3. AWOO1.0 (Acid Washing of Laboratory Equipment).
2.4. PS001.1 (Particle Size Reduction).
3. Summary of the Test Method
Based on the information obtained in the "pHOOl.O (pH Titration Pretest)" protocol, an acid or base
addition schedule is formulated for eleven extracts with final solution pH values between 3 and 12, via addition
of HNO3 or KOH aliquots. The exact schedule is adjusted based on the nature of the material; however, the
range of pH values must include the natural pH* of the matrix, which may extend the pH domain (e.g., for very
alkaline or acidic materials). Depending on the natural pH and buffering capacity of the material being tested,
HNO3, and/or KOH may be required to achieve the target pH values. Additionally, if potassium is a COPC,
NaOH may be substituted for KOH in this protocol.
Using the schedule, the equivalents of acid or base are added to a combination of deionized (DI) water
and the particle size reduced material. The material is particle size reduced to <2 mm and a sample size of 40 g
dry sample is used1. The final liquid to solid (LS) ratio is 10 mL extractant/g dry sample, which includes DI
water, the added acid or base, and the amount of moisture that is inherent to the waste matrix as determined by
moisture content analysis. The eleven extractions are tumbled in an end-over-end fashion at 28±2 rpm for a
contact time of 48 hr. Following gross separation of the solid and liquid phases by centrifugation or settling,
leachate pH measurements are taken and the phases are separated by vacuum filtration through 0.45-um
* Natural pH is defined as the pH, which is obtained when the designated amount of material is contacted with
DI water for the designated period of time.
1 The particle size, sample mass and contact time shown here represent a typical base case scenario. Alternate
sample masses and contact times are required for materials where particle size reduction to <2 mm is either
impractical or unnecessary (see accompanying text).
A-7
-------
Environmental Engineering Science, In-press, 2002.
polypropylene filtration membranes. Analytical samples of the leachates are collected and preserved as
appropriate for chemical analysis.
4. Significance and Use
The SR002.1 protocol can be used (1) to create a material-specific titration curve of the acid or base
neutralization capacity of the material in contact with varying equivalents of acid or base at a liquid to solid
ratio of 10 mL/g dry and (2) to characterize the liquid-solid partitioning equilibrium behavior of COPCs as a
function of pH between the pH values of 3 and 12 at a liquid to solid ratio of 10 mL/g dry.
This protocol was modified from the Acid Neutralization Capacity Test (Environment Canada and
Alberta Environmental Center 1986) for use with materials having little acid neutralization capacity (e.g., soils
or industrial wastes). Size reduced material and low LS ratio ensure that thermodynamic equilibrium between
solid and liquid phases is obtained within the duration of the protocol for most low solubility constituents (e.g.,
Pb, As, Cu, Cd). In the case of highly soluble species (e.g., Na, K, Cl), which do not reach saturation prior to
complete solubilization of the species from the solid phase, this protocol can be used to measure the release of
the available fraction of the total constituent content.
5. Apparatus
5.1. Extraction Vessel - a wide-mouth container constructed of high-density polyethylene that does not
preclude headspace (e.g., Nalgene #3140-0250 or equivalent). The vessel must have a leak-proof seal that
can sustain the end-over-end tumbling and centrifugation required. The container must be of sufficient
volume to accommodate both the solid sample and a leachant volume based on a LS ratio of 10 mL
extractant/g dry sample. Since centrifugation may be required for gross phase separation, the extraction
vessel should be capable of withstanding centrifugation at 4000 rpm for a minimum of 10 minutes.
5.2. Extraction Apparatus - rotary tumbler capable of rotating the extraction vessels in an end-over-end fashion
at constant speed of 28±2 rpm (e.g., Analytical Testing, Werrington, PA or equivalent).
5.3. Filtration Apparatus - pressure or vacuum filtering apparatus (e.g., Nalgene #300-4000 or equivalent).
5.4. Filtration Membranes - 0.45 um pore size polypropylene filtration membrane (e.g., Gelman Sciences GH
Polypro #66548, Fisher Scientific or equivalent).
5.5. pH Meter - standard, two point calibration pH meter (e.g., Accumet 20, Fisher Scientific or equivalent).
5.6. Adjustable Pipetter - Oxford Benchmate series or equivalent with disposable tips (delivery range will
depend on material neutralization capacity and acid strength).
5.7. Centrifuge (recommended) - e.g., RC5C, Sorvall Instruments, Wilmington, DE or equivalent.
6. Reagents and Materials
6.1. Reagent Grade Water - deionized water must be used as the major extractant in this procedure. Deionized
water with a resistivity of 18.2 MQ can be provided by commercially available water deionization systems
(e.g., Milli-Q Plus, Millipore Corp., Bedford, MA or equivalent).
A-8
-------
Environmental Engineering Science, In-press, 2002.
6.2. 2N Nitric Acid Solution - prepared by diluting Tracemetal Grade Nitric Acid (Fisher Scientific or
equivalent) with deionized water.
6.3. IN Potassium Hydroxide Solution - reagent Grade (Fisher Scientific or equivalent).
7. Acid Washing Procedure
Because the concentrations of inorganic constituents in leachates may be very low (i.e., <10 ug/L), all
laboratory equipment that comes in contact with the material, the extraction fluid, or the leachant must be rinsed
with 10% nitric acid followed by three rinses with DI water to remove residual inorganic deposits following
"AW001.0 (Acid Washing of Laboratory Equipment)".
8. Initial Sample Preparation
8.1. Particle Size Reduction - depending on the nature of the material, a sufficient mass of the material should
be particle size reduced to <2 mm using "PS001.1 (Particle Size Reduction)" protocol.
8.2. Solids Content Determination - It is necessary to know the solids content of the material being tested so
that appropriate adjustments can be made to conduct the test under a specified LS ratio. Prior to the
initiation of the test, a moisture content determination of the "as received" material must be conducted
using ASTM Method D 2261-80, "Standard Method for Laboratory Determination of Water (Moisture)
Content of Soil, Rock, and Soil Aggregate Mixtures". The solids content is calculated as the mass of the
dried sample divided by the mass of "as received" material following Equation A2- 1 .
Mdrv
sc = ary_ (Equation A2-1)
M
rec
where SC = the solids content [gdry/g],
Mdiy = the dry sample mass [g dry], and
M^ = the mass of the "as received" material [g].
9. SR002.1 Procedure
The SR002. 1 protocol may be conducted only after the equivalents of acid or base required to span the
desired pH range are determined from a material specific titration curve as generated by "pHOOl.O (pH Titration
Pretest)" or equivalent. Since the pretest provides information for acid and base additions at LS of 100 mL/g dry
sample, the pH response for the SR002. 1 protocol at an LS ratio of 10 mL/g dry sample will be approximate.
The variability in endpoint pH, however, is consistent with the objective of this protocol (i.e., to measure
constituent solubility and release over a broad pH range with endpoints of approximately pH 3 and 12). Table
A2-1 shows the example schedule of acid or base additions and DI water make up volume for the SR002. 1
protocol generated from the titration information shown in Figure 1 using 40 dry g of sample with a moisture
content (dry basis) of 0. 1 mL/g dry.
A-9
-------
Environmental Engineering Science, In-press, 2002.
9.1. Place the minimum dry equivalent mass (i.e., 40g dry sample) into each of eleven high-density
polyethylene bottles. The equivalent mass of "as received" material can be calculated if the solids content is
known following Equation A2-4.
M=-;j-j- (Equation A2-4)
where Mrec = the mass of the "as received" material [g],
Mdry = the dry equivalent sample mass (i.e., 8 g dry for particle size <2 mm [g dry], and
SC = the solids content of the material [g dry/g].
9.2. Label each bottle with the extraction number or acid addition and add the volume of DI water specified in
the schedule for LS ratio makeup (e.g., Table A2-1).
9.3. Add the appropriate volume of acid or base to each extraction using an adjustable pipetter. The required
volume of acid or base is specified in the schedule for acid addition (e.g., Table A2-1).
9.4. Tighten the leak-proof lid on each bottle and tumble all extracts in an end-over-end fashion at a speed of
28±2 rpm at room temperature (20±2°C) for 48 hours.
Table A2-1. Example schedule for acid addition for 40 g dry equivalent mass samples and a moisture
content (dry basis) of 0.1 mL/g dry for the "SR002.1 (Alkalinity, Solubility and Release as a Function of
pH)" protocol.
Extract
no.
1
2
o
J
4
5
6
7
8
9
10
11
Endpoint
solution pH
12.0
11.0
10.0
9.0
8.0
Natural
6.0
5.0
4.0
3.0
2.0
Equivalents of
acid to add
[meq/g]
-1.10
-0.75
-0.58
-0.15
-0.09
0.00
0.08
0.12
0.90
1.80
3.10
Volume of 2N
HNO3 or llx
KOH [mL]
44.0
30.0
23.2
6.0
3.6
0.0
1.6
2.4
18.0
36.0
62.0
Volume of
moisture in
sample [mL]
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
Volume of DI
water makeup
[mL]
352.0
366.0
372.8
390.0
392.4
396.0
394.4
393.6
378.0
360.0
334.0
9.5. At the conclusion of the agitation period, remove the extraction vessels from the rotary tumbler and clarify
the leachates by allowing the bottles to stand for 15 minutes. Alternately, centrifuge the bottles at
4000±100 rpm for 10±2 minutes.
9.6. Decant a minimum volume of clear, unpreserved supernatant from each extraction in order to measure and
record the solution pH.
A-10
-------
Environmental Engineering Science, In-press, 2002.
9.7. For each extraction, separate the solid from the remaining liquid by vacuum filtration through a 0.45-um
pore size polypropylene filtration membrane. The filtration apparatus may be exchanged for a clean
apparatus as often as necessary until all liquid has been filtered.
9.8. Collect, preserve, and store the amount of leachate required for chemical analysis.
10. SR002.1 Interpretation
10.1. pH Titration Curve
The material response to acid or base addition at LS of 10 mL/g dry can be interpreted if a pH titration
curve is generated. Plot the pH of the sample analyzed as a function of the equivalents of acid or base
added per dry gram of material. For materials where both acid and base were required, equivalents of base
can be presented as opposite sign of acid equivalents (i.e., 5 meq/g of KOH would correspond to -5 meq/g
ofHNO3).
10.2. "Liquid-solidpartitioning" (LSP) Curve
After chemical analysis has been conducted, a constituent LSP curve can be generated for each constituent
of concern. The constituent concentration in the liquid phase of each extract is plotted as a function of
solution pH. The curve indicates the equilibrium concentration of the constituent of interest at LS of 10
mL/g over a pH range. Additionally, the constituent LSP behavior with pH is indicative of specific
constituents speciation in the solid matrix. Figure A2-1 illustrates typical LSP curve behaviors for cationic,
amphoteric, and oxyanionic constituents as a function of pH.
innn
100 -
10 -
j1 i -
i o
o "-1
C
o 0 01 -
0 001
0.0001 -
0 00001 -
^
\
^
k
\
-
4
\
\
\
\/
^\
~~
Amphote
- vjxyamon
- Highly So
/
\
\
ric
ic
luble
i i i 1 i i i 1 i
\
x
\
N
v
i i i
6 8 10 12
Leachate pH
Figure A2-1. LSP curves of cationic, amphoteric, oxyanionic, and highly soluble species from the
SR002.1 protocol
A-ll
-------
Environmental Engineering Science, In-press, 2002.
The shape of the LSP curve (i.e., general location of maxima/minima) is controlled by the equilibrium
between liquid phase constituent (e.g., Pb+2) and solid phase species (e.g., Pb(OH)2 or Pb3(PO4)2) as a
function of pH. Also, leachate ionic strength and the presence of complexing (e.g., acetate or chloride
ions) or co-precipitating (sulfate or carbonate ions) agents in the leachant solution can influence the LSP
curvature and magnitude (Kosson, van der Sloot et al. 1996).
At very low pH, the matrix often is broken down by the aggressive leachant and the measured constituent
solubility approaches a limiting value (as shown in Figure A2-1). Since much of the non-silica based
matrix can be digested at pH values =2, the corresponding release in this pH range can represent either the
release of the total constituent content or the release of only an operationally defined "available fraction"
of the total content. In order to correlate the release in this pH range to total element analyses, a release-
based curve can be developed by multiplying the measured release concentration at each pH value by the
LS ratio in L/kg.
11. References
Kosson, D. S., H. A. van der Sloot, T.T. Eighmy. (1996). "An approach for estimating of contaminant release
during utilization and disposal of municipal waste combustion residues." Journal of Hazardous Materials 47:
43-75.
A-12
-------
Environmental Engineering Science, In-press, 2002.
A.3. SR003.1 (Solubility and Release as a Function of LS Ratio)
1. Scope
1.1. This test method is used to determine the effect of low liquid to solid ratio on liquid-solid partitioning
equilibrium when the solution phase is controlled by the tested material. This is used to approximate initial
pore water conditions and initial leachate compositions in many percolation scenarios (e.g., monofills). In
this test, the pH and redox conditions are dictated by the sample matrix. The solubility as a function of
liquid to solid (LS) ratio can be determined for all "constituents of potential concern" (COPCs) over a
range of LS ratios from 10 to 0.5 mL/g dry material.
1.2. This is a characterization protocol (Tier 2b) designed to obtain detailed leachability information.
1.3. This test method is not intended for the characterization of the release of organic constituents.
2. Cited Protocols
2.1. ASTM (1980) "Standard Method for Water (Moisture) Content of Soil, Rock, and Soil-Aggregate
Mixtures D 2261-80," Philadelphia, PA: American Society for Testing and Materials.
2.2. AWOO1.0 (Acid Washing of Laboratory Equipment).
2.3. PS001.1 (Particle Size Reduction).
3. Summary of the Test Method
This protocol consists of five parallel batch extractions over a range of LS ratios (i.e., 10, 5, 2, 1, and
0.5 mL/g dry material), using deionized (DI) water as the extractant with minimum 40 g dry sample aliquots of
material that have been particle size reduced to <2 mm1. Additional material may be required at low LS ratio to
provide leachate yield sufficient for analytical methods (Table A3-1). All extractions are tumbled in an end-
over-end fashion at 28±2 rpm at room temperature (20±2°C) in leak-proof vessels for 48 hours. Following gross
separation of the solid and liquid phases by centrifugation or settling, leachate pH and conductivity
measurements are taken. The bulk phases are separated by a combination of pressure and vacuum filtration
using 0.45-um polypropylene filter membrane. In all, five leachates are collected, and preserved as appropriate
for chemical analysis.
Table A3-1. Minimum dry equivalent mass as a function of LS ratio recommended for the SR003.2 protocol.
LS 10 mL/g
40 g
LS 5 mL/g
40 g
LS 2 mL/g
50 g
LS 1 mL/g
100 g
LS 0.5 mL/g
200 g
1 The particle size, sample masses and contact time shown here represent a typical base case scenario. Alternate
sample masses and contact times are required for materials where particle size reduction to <2 mm is either
impractical or unnecessary (see accompanying text).
A-13
-------
Environmental Engineering Science, In-press, 2002.
4. Significance and Use
The SR003.1 protocol can be used to provide an estimate of constituent concentration as the extraction
LS ratio approaches the bulk porosity of the material. The solution filling the pores of the material (i.e., pore
water) locally approaches thermodynamic equilibrium with the different constituents of the material of concern.
The resulting pore water solution may be saturated with material constituents, which can result in deviations
from ideal dilute solution behavior and activity coefficients significantly different from unity. Estimation of the
activity coefficient within the pore water is necessary for accurate estimation of constituent concentration within
the pore water and coupled mass transfer rates for leaching. Thus, the use of decreasing LS ratio allows for
experimentally approaching the composition of the pore water solution of the material of concern and
determining the change in pH and species concentration in comparison to that measured at an LS ratio of 10
mL/g dry as used in the "SR002.1 (Alkalinity, Solubility and Release as a Function of pH)" protocol.
5. Apparatus
5.1. Extraction Vessel -a wide-mouth container constructed of plastic, that does not preclude headspace (e.g.,
Nalgene #3140-0250 or equivalent). The vessel must have a leak-proof seal that can sustain the end-over-
end tumbling and centrifugation required. The container must be of sufficient volume to accommodate
both a minimum solid sample mass and a leachant volume based on a maximum LS ratio of 10 mL
extractant/g dry sample. The extraction vessel should be capable of withstanding centrifugation at 4000
rpm for minimum of 10 minutes.
5.2. Extraction Apparatus - rotary tumbler capable of rotating the extraction vessels in an end-over-end fashion
at constant speed of 28±2 rpm (e.g., Analytical Testing, Werrington, PA or equivalent).
5.3. Filtration Apparatus - filtering apparatus (e.g., Nalgene #300-4000 or equivalent) capable of pressure and
vacuum filtration.
5.4. Filtration Membranes - 0.45 um pore size polypropylene filtration membrane (e.g., Gelman Sciences GH
Polypro #66548, Fisher Scientific or equivalent).
5.5. pH Meter - standard, two point calibration pH meter (e.g., Accumet 20, Fisher Scientific or equivalent).
5.6. Graduated Cylinder - determined by particle size and LS ratio, polymethyrpentene (e.g., Nalgene #3663-
0100 or equivalent) volume.
5.7. Centrifuge - e.g., RC5C, Sorvall Instruments, Wilmington, DE or equivalent.
6. Reagents and Materials
6.1. Reagent Grade Water - deionized water must be used as the major extractant in this procedure. Deionized
water with a resistivity of 18.2 MQ can be provided by commercially available water deionization systems
(e.g., Milli-Q Plus, Millipore Corp., Bedford, MA or equivalent).
A-14
-------
Environmental Engineering Science, In-press, 2002.
7. Acid Washing Procedure
Because the concentrations of inorganic constituents in leachates may be very low (i.e., <10 ug/L), all
laboratory equipment that comes in contact with the material, the extraction fluid, or the leachant must be rinsed
with 10% nitric acid followed by three rinses with DI water to remove residual inorganic deposits following
AW001.0 (Acid Washing of Laboratory Equipment).
8. Initial Sample Preparation
8.1. Particle Size Reduction - depending on the nature of the material, a sufficient mass of the material should
be particle size reduced to <2 mm using "PS001.1 (Particle Size Reduction)" protocol.
8.2. Solids Content Determination - It is necessary to know the solids content of the material being tested so
that appropriate adjustments can be made to conduct the test under a specified LS ratio. Prior to the
initiation of the test, a moisture content determination of the "as received" material must be conducted
using ASTM Method D 2261-80, "Standard Method for Laboratory Determination of Water (Moisture)
Content of Soil, Rock, and Soil Aggregate Mixtures". The solids content is calculated as the mass of the
dried sample divided by the mass of "as received" material following Equation A3 -1.
M
sc = ary_ (Equation A3-1)
where SC = the solids content [gdry/g],
Mdiy = the dry sample mass [g dry], and
Mrec = the mass of the "as received" material [g].
9. SR003.1 Procedure
9.1. Place the minimum dry equivalent mass required for each LS ratio (Table A3-1) into each of five high-
density polyethylene bottles. The equivalent mass of "as received" material can be calculated if the solids
content is known following Equation A3-2.
Mdrv
Mrec = ^- (Equation A3 -2)
»jO
where Mrec = the mass of the "as received" material [g],
Mdry = the dry equivalent sample mass (see Table A3-1) [g dry], and
SC = the solids content of the material [g dry/g].
9.2. Measure out the appropriate volume of DI water in a graduate cylinder for each of the following LS ratios
- 10, 5, 2, 1, and 0.5 mL/g dry equivalent mass. For a dry material, this volume will be the mass of the
aliquot multiplied by the desired LS ratio. However, if the material has high moisture content (e.g., > 5%),
the volume of water contained in the sample should be subtracted from the volume of DI water to be
added.
9.3. Add the DI water to the solid material and tighten the leak-proof lid.
A-15
-------
Environmental Engineering Science, In-press, 2002.
9.4. Tighten the leak-proof lid on each bottle and tumble all extracts in an end-over-end fashion at a speed of
28±2 rpm at room temperature (20±2°C) for 48 hours.
9.5. Remove the extraction vessel from the rotary tumbler at the conclusion of the agitation period.
9.6. Clarify the leachates by allowing the bottles to stand for 15 minutes. Alternately, centrifuge the bottles at
4000±100 rpm for 10±2 minutes.
9.7. Decant a minimum volume of clear, unpreserved supernatant in order to measure the solution pH.
9.8. Separate the solid from the remaining liquid by a combination of pressure and vacuum filtration through a
0.45-um pore size polypropylene filtration membrane. A non-reactive gas (e.g., nitrogen or argon) should
be used for pressure filtration. The filtration apparatus may be exchanged for a clean apparatus as often as
necessary until all liquid has been filtered.
9.9. Collect, preserve and store the amount of leachate required for chemical analysis.
10. SR003.1 Interpretation
The filtered extracts are analyzed for common ionic strength-contributing cations (i.e., sodium,
potassium, calcium) and any other constituents of interest. Conductivity, pH and concentrations of constituents
of concern as a function of the liquid to solid ratio then are extrapolated to the liquid to solid ratio for the pore
water within the matrix. The liquid to solid ratio for the pore water is defined by the porosity of the matrix as:
LS = (Equation A3-3)
Pdry
where LS = the liquid to solid ratio on a dry basis [mL/g dry],
e = the porosity [cm3/cm3] estimated by measuring the water absorption capacity of the matrix, and
pdry = the density on a dry basis [g dry/cm3].
The resulting concentrations of sodium, potassium and hydroxide (i.e., pH) then are used to estimate the pore
water ionic strength and activity coefficients.
A-16
-------
Environmental Engineering Science, In-press, 2002.
A.4. MT001.1 (Mass Transfer Rates in Monolithic Materials)
1. Scope
1.1. This protocol assesses the release rate of "constituents of potential concern" (COPCs) from
monolithic materials under mass transfer-controlled release conditions. These conditions occur when
the mode of water contact with the solid material results in a flow around a structure with low
permeability (e.g., cement treated wastes, capped granular fills, or compacted granular material).
1.2. This test method is not intended for the characterization of the release behavior of organic
constituents.
2. Cited Protocols
2.1. ASTM (1980) "Standard Method for Water (Moisture) Content of Soil, Rock, and Soil-Aggregate
Mixtures D 2261-80," Philadelphia, PA: American Society for Testing and Materials.
2.2. US Army Corps of Engineers (1970) Engineering Manual. "Engineering and Design: Laboratory Soils
Testing." EM 1110-2-1906, Washington, D.C.: Office of the Chief of Engineers.
2.3. AWOO1.0 (Acid Washing of Laboratory Equipment).
3. Summary of the Test Method
The MTOO1.1 (Mass Transfer Rates in Monolithic Materials) protocol consists of tank leaching of
continuously water-saturated monolithic material with periodic renewal of the leaching solution. The vessel
and sample dimensions are chosen so that the sample is fully immersed in the leaching solution. Cylinders
of 2 cm minimum diameter and 4 cm minimum height or 4 cm minimum cubes are contacted with
deionized (DI) water using a liquid to surface area ratio of 10 mL of DI water for every cm2 of exposed
solid surface area. Leaching solution is exchanged with fresh DI water at pre-determined cumulative times
of 2, 5 and 8 hours, 1, 2, 4 and 8 days1. This schedule results in seven leachates with leaching intervals of 2,
3, 3, 16 hours, 1, 2 and 4 days. At the completion of each contact period, the mass of the monolithic sample
after being freely drained is recorded to monitor the amount of leachant absorbed into the solid matrix. The
solution pH and conductivity for the leachate is measured for each time interval. A leachate sample is
prepared for chemical analysis by vacuum filtration through a 0.45-um pore size polypropylene filtration
membrane and preservation as appropriate. Leachate concentrations are plotted as a function of time along
with the analytical detection limit and the equilibrium concentration determined from SR002.1 protocol at
the extract pH for quality control. Cumulative release and flux as a function of time for each constituent of
interest are plotted and used to estimate mass transfer parameters (i.e., observed diffusivity).
A-17
-------
Environmental Engineering Science, In-press, 2002.
4. Significance and Use
The objective of the MT001.1 protocol is to measure the rate of COPC release from a monolithic
material (e.g., solidified waste form or concrete matrix) under leaching conditions where the rate of mass
transfer through the solid phase controls constituent release. These conditions simulate mechanisms that
occur when water (e.g., infiltration or groundwater) is diverted to flow around a relatively impermeable
material (e.g., solidified waste forms, road base material, or capped granular fills). Results of this test are
used to estimate intrinsic mass transfer parameters (e.g., observed diffusivities for COPCs) that are then
used in conjunction with other testing results and assessment models to estimate release. Results of the
MTOO1.1 protocol reflect both physical and chemical interactions within the tested matrix, thus requiring
additional test results for integrated assessment. While the recommended method is derivative of ANS 16.1
(ANS 1986), a teachability index is not assumed nor used as a decision criterion.
5. Apparatus
5.1. Extraction Vessel - a polypropylene container with an opening large enough so that the monolith can
be easily removed and replaced. The container must also have an air-tight cover to minimize the
exposure to carbon dioxide, which can lead to carbonate formation in some highly alkaline matrices.
5.2. Monolith Holder - a mesh or structured holder constructed of an inert material to leachate constituents
and acid washing liquids. At least 98% of the monolith surface area should be exposed to the leachant.
Also, the holder must orient the monolith in the center of the leaching vessel so that there is an
approximately equal amount of leachant opposing every surface. A schematic of one such design for
10-cm diameter by 10-cm cylindrical samples is presented in Figure A4-1. The dimension of this
apparatus may be scaled as appropriate for sample size.
5.3. Filtration Apparatus - pressure or vacuum filtering apparatus (e.g., Nalgene #300-4000 or
equivalent).
5.4. Filtration Membranes - 0.45 um pore size polypropylene filtration membrane (e.g., Gelman Sciences
GH Polypro, Fisher Scientific #66548 or equivalent).
5.5. pHMeter - standard, two point calibration pH meter (e.g., Accumet 20, Fisher Scientific or
equivalent).
5.6. Beaker - 100 mL borosilicate glass (e.g., Fisher Brand or equivalent).
1 This schedule may be extended for additional extractions to provide more information about longer-term
release. The recommended schedule extension would be additional cumulative times 14 days, 21 days, 28
days, and every four weeks thereafter as desired.
A-18
-------
Environmental Engineering Science, In-press, 2002.
Plastic Screws
1
h
9.5 mm dia. Polyethelene
rod with large thread
through block
10 cm dia.
Monolith
11
c
c
c
X10cm
Sample
m
-\
"
1
II H--I I-^H 1
| 9cm -
i.
6 mm'
i!
o
in
o
0
9.5 mm
Threaded
Holes
11 cm
1.2 cm
Wide Tabs
15 cm dia. x 1.2 mm Polyethylene Disk
Figure A4-1. Design schematic for monolithic sample holder for MTOO1.1 (Mass Transfer in
Monolithic Materials) protocol.
6. Reagents and Materials
6.1 Reagent Grade Water - deionized water must be used as the major extractant in this procedure.
Deionized water with a resistivity of 18.2 MQ can be provided by commercially available water
deionization systems (e.g., Milli-Q Plus, Millipore Corp., Bedford, MA or equivalent).
7. Acid Washing Procedure
Because the concentrations of inorganic constituents in leachates may be very low (i.e., <10 ug/L),
all laboratory equipment that comes in contact with the material, the extraction fluid, or the leachant must
be rinsed with 10% nitric acid followed by three rinses with DI water to remove residual inorganic deposits
following AW001.0 (Acid Washing of Laboratory Equipment).
8. Initial Sample Preparation
8.1. Preparation of Monolithic Samples
The surface area of the monolithic sample must be known in order to estimate constituent release
from the test sample in the MTOO 1.1 protocol. A representative sample of existing monolithic
materials must be obtained by coring or some other non-destructive method. Cylinders of 2-cm
minimum diameter and 4-cm minimum height or 4-cm minimum cubes are recommended.
8.2. Moisture Determination
It is necessary to know the moisture content of the material being tested so that the release of
constituents can be normalized to the dry equivalent mass of the monolith. This adds flexibility to the
A-19
-------
Environmental Engineering Science, In-press, 2002.
leaching characterization approach by allowing for comparison among treatment options of varying
moisture contents. Since moisture content procedures tend to alter the chemical and physical
properties of the solid phase, an additional sample must be prepared in exactly the same manner as the
test sample to use for moisture determination. Alternately, determination of moisture content may be
taken using material samples segregated during gross particle size reduction following the "PS001.0
(Particle Size Reduction to <300 um, <2mm or <5mm)" protocol. Moisture determination of the solid
matrix must be conducted using ASTM Method D 2261-80, "Standard Method for Laboratory
Determination of Water (Moisture) Content of Soil, Rock, and Soil Aggregate Mixtures".
9. MT001.0 Procedure
This protocol is a dynamic tank leaching procedure with leachant exchanges at cumulative
leaching times of 2, 5, and 8 hours, 1, 2, 4, and 8 days. This schedule results in seven leachates with
leaching intervals of 2, 3, 3, 16 hours, 1, 2 and 4 days. The leachant is DI water and the pH of each leachate
is measured.
9.1. Specimen Measurements
9.1.1- Measure and record the dimensions (i.e., diameter and height for a cylinder; length, width and
depth for a parallelepiped) of the monolithic specimen for surface area calculation.
9.1.2 - Measure and record the mass of the specimen. This value is monitored for each leachant
exchange.
9.1.3 - Place the specimen in the monolith holder, if a holder is used.
9.1.4- Measure and record the mass or the specimen and holder, if applicable.
9.2. Leachant Exchange
9.2.1 - Place the mesh (if a mesh is used instead or a holder), in a clean leaching vessel.
9.2.2 - Fill the clean leaching vessel with the required volume of DI water using a liquid to surface
area ratio of 10 mL of DI water for every cm2 of exposed solid surface area.
9.2.3 - Gently place the specimen or the specimen and holder in the leaching vessel so that the
leachant is evenly distributed around the specimen. Submersion should be gentle enough that
the physical integrity of the monolith is maintained and wash-off is minimized.
9.2.4 - Cover the leaching vessel with the air-tight lid.
9.2.5 - By repeating Steps 9.2.1-9.2.2 at the end of the leaching interval, prepare a fresh leachant in a
new leaching vessel.
9.2.6 - Remove the specimen or the specimen and holder from the vessel. Drain the liquid from the
surface of the specimen into the leachate for approximately 20 seconds.
9.2.7 - Measure and record the mass of the specimen or the mass of the specimen and holder. The
difference in mass between measurements is an indication of the potential sorption of leachant
by the matrix. In the case where a holder is used, moisture will condense on the holder as the
leaching intervals increase in duration and sample sorption may not be evident.
A-20
-------
Environmental Engineering Science, In-press, 2002.
9.2.8 - Place the specimen or the specimen and holder into the clean leaching vessel of new leachant
prepared in Step 9.2.2.
9.2.9 - Cover the clean leaching vessel with the air-tight lid.
9.2.10 -Decant 25-50 mL of leachate into a 100 mL beaker.
9.2.11 -Measure and record the pH of the decanted leachate.
9.2.12 -Filter the remaining leachate through a 0.45-|jm polypropylene membrane.
9.2.13 -Collect and preserved enough leachate for chemical analysis.
9.2.14 -Repeat the leachate exchange procedure (Steps 9.2.1-9.2.14) until all seven leachants are
collected.
10. MT001.0 Interpretation
10.1.Mass Transfer Coefficients
Interpretation of the release of constituents using the "MTOO 1.0 (Mass Transfer Rates in Monolithic
Materials)" protocol is illustrated using the bulk diffusion model. Other models that may also be used
to determine mass transfer coefficients and tortuosity values include the Shrinking Unreacted Core
model (Hinsenveld and Bishop, 1996) and the Coupled Dissolution-Diffusion model (Sanchez, 1996).
These models incorporate chemical release parameters into the model to better estimate release
mechanisms and predictions.
At the conclusion of the MTOO 1.0 protocol, the interval mass released is calculated for each leaching
interval as:
C- V
Mt. = - (Equation A'
where Mt. = mass released during leaching interval i [mg/m2],
Cj = the constituent concentration in interval i [mg/L],
Vt = the leachant volume in interval i [L], and
A = the specimen surface area exposed to the leachant [m2].
An observed diffusivity of COPCs can be determined using the logarithm of the cumulative release
plotted versus the logarithm of time. In the case of a diffusion-control mechanism, this plot is
expected to be a straight line with a slope of 0.5. An observed diffusivity can then be determined for
each leaching interval where the slope is 0.5+0.15 by (de Groot and van der Sloot 1992):
* ( M< T
D°bs = n =L=^- (EquationA4-2)
(2pC0 (JT,-^)}
where D°bs = observed diffusivity of the species of concern for leaching interval i [m2/s],
A-21
-------
Environmental Engineering Science, In-press, 2002.
M t. = Mass released during leaching interval i [mg/m2],
tt = Contact time after leaching interval i [s],
fa = Contact time after leaching interval i-1 [s],
C0 = Initial leachable content (i.e., available release potential) [mg/kg], and
p= Sample density [kg/m3].
The overall observed diffusivity is then determined by taking the average of the interval observed
diffusivities. Only those interval mass transfer coefficients corresponding to leaching intervals with
slopes between 0.35 and 0.65 are included in the overall average mass transfer coefficient (IAWG
1997).
10.2. Matrix Tortuosity
Tortuosity is a measure of the physical retention in the matrix and is a matrix-specific property. The
matrix tortuosity reflects the extended path length of a diffusing ion in the pore structure of a matrix
relative to a straight path through the matrix. Typically, the mass transfer release of non-interactive
components, or tracers, is measured and observed interval mass transfer coefficients are compared to
the tracer molecular diffusivity in aqueous solutions as shown in Equation A4-4.
\mol
(Equation A4-4)
ri
where T= the matrix physical retention, or tortuosity [-],
Dmol= the molecular diffusion coefficient in aqueous solution [m2/s], and
Dobs = the observed diffusion coefficient in the matrix [m2/s].
Sodium or chloride is normally selected as tracer elements under the assumption that these elements
do not react with the matrix being evaluated. The matrix tortuosity should be calculated as the average
of interval tortuosity values subject to the same interval slope criteria (0.35 - 0.65) pertaining to mass
transfer coefficients.
11. References
de Groot, G. J. and H. A. van der Sloot (1992). Determination of leaching characteristics of waste materials
leading to environmental product certification. Solidification and Stabilization of Hazardous. Radioactive.
and Mixed Wastes. 2nd Volume. ASTM STP 1123. T. M. Gilliam and C. C. Wiles. Philadelphia, PA,
American Society for Testing and Materials: 149-170.
Hinsenveld, M. & Bishop, P. L. (1996) "Use of the shrinking core/exposure model to describe the
Reachability from cement stabilized wastes." In Stabilization and Solidification of Hazardous, Radioactive,
and Mixed Wastes, 3rd Volume, ASTM STP 1240, (T. M. Gilliam & C. C. Wiles, eds.): American Society
for Testing and Materials.
IAWG (1997). Municipal Solid Waste Incinerator Residues. Amsterdam, Elsevier Science Publishers.
A-22
-------
Environmental Engineering Science, In-press, 2002.
Kosson, D. S., Kosson, T. T. & vander Sloot, H. (1993) "Evaluation of solidification/stabilization
treatment processes for municipal waste combustion residues." EPA Cooperative Agreement #CR 818178-
01-0, Cincinnati, Ohio: US Environmental Protection Agency.
Sanchez, F. (1996) "Etude de la lixiviation de milieux poreux contenant des especes solubles: Application
au cas des dechets solidifies par Hants hydrauliques," Doctoral Thesis, Lyon, France: Institut National des
Sciences Appliquees de Lyon.
A-23
-------
Environmental Engineering Science, In-press, 2002.
A.5. MT002.1 (Mass Transfer Rate in Granular Materials)
1. Scope
1.1. This protocol assesses the release rate of "constituents of potential concern" (COPCs) from compacted
granular matrices under mass transfer-controlled release conditions. These conditions occur when the
mode of water contact with the solid material results in a flow around a material structure (e.g., capped
granular fills, or low permeability compacted granular material).
1.2. This test method is not intended for the characterization of the release behavior of organic constituents.
2. Cited Protocols
2.1. ASTM (1978) "D 1557. Standard Method for Moisture-Density Relations of Soils and Soil-Aggregate
Mixtures Using 10 Ib. Rammer and 18 in. Drop," Philadelphia, PA: American Society for Testing and
Materials.
2.2. ASTM (1980) "D 2261-80. Standard Method for Water (Moisture) Content of Soil, Rock, and Soil-
Aggregate Mixtures," Philadelphia, PA: American Society for Testing and Materials.
2.4. US Army Corps of Engineers (1970) Engineering Manual. "Engineering and Design: Laboratory Soils
Testing" EM 1110-2-1906, Washington, D.C.: Office of the Chief of Engineers
2.5. AW001.0 (Acid Washing of Laboratory Equipment).
3. Summary of the Test Method
The MT002.0 (Mass Transfer Rates in Compacted Granular Materials) consists of tank leaching of
continuously water-saturated compacted granular material with intermittent renewal of the leaching solution.
This test is used when a granular material is expected to behave as a monolith because of compaction during
field placement. An unconsolidated or granular material, size-reduced to <2 mm1 is compacted into molds using
modified Proctor Compactive Effort (ASTM Method D 1557 "Standard Method for Moisture-Density Relations
of Soils and Soil-Aggregate Mixture using lOlb. Rammer and 18 in. Drop"). A 10-cm diameter cylindrical mold
is used and the sample is packed to a depth of 10 cm. The mold and sample are immersed in deionized water
(DI) such that only the surface area of the top face of the sample contacted the leaching medium. The leachant
is refreshed with an equal volume of DI using a liquid to surface area ratio of 10 mL/cm2 (i.e., LS of 10 cm) at
cumulative times of 2, 5 and 8 hours, 1, 2, 4 and 8 days2. This schedule results in seven leachates with leaching
intervals of 2, 3, 3, 16 hours, 1, 2 and 4 days. The solution pH and conductivity for the leachate is measured for
each time interval. A leachate sample is prepared for chemical analysis by vacuum filtration through a 0.45-um
1 The particle size reduction and cylindrical matrix diameter specified represents a base case scenario. Change
in the particle size specification requires alteration of the compacted sample diameter for a cylindrical matrix
such that the matrix diameter is 10 times the maximum particle diameter.
A-24
-------
Environmental Engineering Science, In-press, 2002.
pore size polypropylene filtration membrane and preservation as appropriate. Leachate concentrations are
plotted as a function of time along with the analytical detection limit and the equilibrium concentration
determined from SR002.1 protocol at the extract pH for purposes of quality control. Cumulative release and
flux as a function of time for each constituent of interest are plotted and used to estimate mass transfer
parameters (i.e., observed diffusivity).
4. Significance and Use
The objective of the MT002.1 protocol is to measure the rate of COPC release from compacted
granular materials under leaching conditions where the rate of mass transfer through the solid phase can control
constituent release. These conditions simulate mechanisms that occur when water (e.g., infiltration or
groundwater) is diverted to flow around a relatively impermeable material (e.g., compacted granular fills).
Results of this test are used to estimate intrinsic mass transfer parameters (e.g., observed diffusivities for
COPCs) that are then used in conjunction with other testing results and assessment models to estimate release.
5. Apparatus
5.1. Extraction Vessel - a polypropylene container with an opening large enough so that the monolith can be
easily removed and replaced (e.g., Cole-Parmer #AP-06083-15 or equivalent). The container must also
have an air-tight cover to minimize the exposure to carbon dioxide, which can lead to carbonate formation
in some highly alkaline matrices.
5.2. Specimen Mold - a 10 cm diameter by 10 cm high cylindrical mold constructed of an inert material to
leachate constituents and acid washing liquids (e.g., MA Industries, Inc., Peachtree City, GA or
equivalent). It must be constructed so that the exposed surface area of the test specimen is only one
circular face of the mold. If necessary, 3 mm diameter drain holes may be cut into the mold to aid in
drainage of leachate from the mold. These holes should be placed at least 10 cm above the bottom of the
mold. A schematic of one such design is presented in Figure A5-1.
5.3. Filtration Apparatus - pressure or vacuum filtering apparatus (e.g., Nalgene #300-4000 or equivalent).
5.4. Filtration Membranes - 0.45 um pore size polypropylene filtration membrane (e.g., Gelman Sciences GH
Polypro #66548, Fisher Scientific or equivalent).
5.5. pHMeter - standard, two point calibration pH meter (e.g., Accumet 20, Fisher Scientific or equivalent).
5.6. Beaker - 100 mL, borosilicate glass (e.g., Fisherbrand or equivalent).
2 This schedule may be extended for additional extractions to provide more information about longer-term
release. The recommended schedule extension would be additional cumulative times 14 days, 21 days, 28 days,
and every four weeks thereafter as desired.
A-25
-------
Environmental Engineering Science, In-press, 2002.
3 mm dia.
Drainage
Holes
1
Figure A5-1. Design schematic for compacted sample mold for MT002.1 (Mass Transfer in Granular
Materials) protocol.
6. Reagents and Materials
6.1. Reagent Grade Water - deionized water must be used as the major extractant in this procedure. Deionized
water with a resistivity of 18.2 MQ can be provided by commercially available water deionization systems
(e.g., Milli-Q Plus, Millipore Corp., Bedford, MA or equivalent).
7. Acid Washing Procedure
Because the concentrations of inorganic constituents in leachates may be very low (i.e., <10 ug/L), all
laboratory equipment that comes in contact with the material, the extraction fluid, or the leachant must be rinsed
with 10% nitric acid followed by three rinses with DI water to remove residual inorganic deposits following
"AW001.0 (Acid Washing of Laboratory Equipment)."
8. Initial Sample Preparation
8.1. Optimum Moisture Content
Optimum moisture content refers to the amount of moisture (fractional mass of water [g water/g dry
material]) in the granular sample that is present at the optimum packing density (g dry material/cm3). This
density is defined and the determination described in ASTM Method D 1557 "Standard Method for
Moisture-Density Relations of Soils and Soil-Aggregate Mixtures Using 10 Ib. Rammer and 18 in. Drop".
Modifications of this standard method are used as described below. The optimum moisture content of the
material is determined using a preliminary test consisting of determining the dry density of the compacted
material as a function of varying water contents. For this purpose, ca. 100 grams of "as received" material
compacted in a 4.8-cm diameter mold are used. Three consecutive layers of materials are compacted 25
times using a 1 kg (2 Ib) hammer and 45 cm (18 in) drop (modifications of the Proctor Compactive Effort
[ASTM D 1557 "Standard Method for Moisture-Density Relations of Soils and Soil-Aggregate Mixtures
Using 10 Ib. Rammer and 18 in. Drop"]). The height and weight of the resulting compacted material is
A-26
-------
Environmental Engineering Science, In-press, 2002.
measured. A known amount of water is then added and mixed with the same material sample and the same
procedure as for the "as received" material is followed. This step is repeated several times, and then a
curve of the dry density versus the water content, expressed as a percent of the dry mass of material, is
drawn. This curve is parabolic, with the maximum indicating the optimum water content. It is important
that the granular material be compacted at optimum moisture content in order to obtain packing densities
that approximate field conditions.
8.2. Moisture Determination
Prior to the initiation of the test, a moisture determination of the compacted granular matrix must be
conducted using ASTM Method D 2261 -80," Standard Method for Laboratory Determination of Water
(Moisture) Content of Soil, Rock, and Soil Aggregate Mixtures". The moisture content determination also
may be conducted on the unconsolidated bulk material used for the compaction at the optimum moisture
content.
9. MT002.1 Procedure
The MT002.1 procedure is a dynamic tank leaching procedure with leachant exchanges at pre-
determined cumulative times of 2, 5 and 8 hours, 1, 2, 4 and 8 days (see footnote 2). This schedule results in
seven leachates with leaching intervals of 2, 3, 3, 16 hours, 1, 2 and 4 days. The leachant is deionized water (DI
water) and the pH of each leachate is recorded.
9.1. Preparation of Test Specimens
9.1.1- Measure and record the mass of a clean sample mold.
9.1.2- Using the method described below, compact the granular material at its optimum moisture content
into the mold to a minimum height of 10 cm. It is recommended that the compacted height be
slightly under the drainage holes for best drainage of the sample.
Compaction technique: Three consecutive layers of material are compacted 25 times using a 1 kg
(2 Ib) hammer and 45 cm (18 in) drop (modifications of the Proctor Compactive Effort [ASTM D
1557 "Standard Method for Moisture-Density Relations of Soils and Soil-Aggregate Mixtures
Using 10 Ib. Rammer and 18 in. Drop"]).
9.1.3- Measure and record the mass of the sample mold and compacted sample. The difference in this
measurement and the empty mold mass (Step 9.1.1) is recorded as the mass of granular material at
optimum moisture. This value is monitored at the end of each leaching interval as an indication of
the mass of leachant that is sorbed into the matrix.
9.1.4- Measure and record the height of the compacted matrix by measuring the outer height of the mold
to the rim and subtracting the inside depth from the rim to the matrix.
9.2. Leachant Exchange
9.2.1 - Fill a clean leaching vessel with 1000 mL of DI water.
9.2.2 - At the beginning of the first leaching interval, there is no recovered leachate. The sample and mold
are gently placed in the leaching vessel so that the leachant is evenly distributed around the
A-27
-------
Environmental Engineering Science, In-press, 2002.
sample. Submersion should be gentle enough that the physical integrity of the monolith is
maintained.
9.2.3 - Cover the leaching vessel with the air-tight lid.
9.2.4 - At the end of the leaching interval, prepare a fresh leachant in a new leaching vessel (Step 9.2.1).
9.2.5 - Remove the sample and mold from the vessel. Drain the leachate from the surface of the specimen
into the leachate for approximately 20 seconds.
9.2.6 - Measure and record the mass of the sample and mold. The difference in mass between interval
measurements is an indication of the potential sorption of leachant by the matrix.
9.2.7 - Place the sample and holder into the clean leaching vessel of new leachant.
9.2.8 - Cover the clean leaching vessel with the air-tight lid.
9.2.9 - Decant 25-50 mL of leachate into a 100 mL beaker.
9.2.10 -Measure and record the pH of the decanted leachate.
9.2.11 -Filter at least 500 mL of the remaining leachate through a 0.45 mm polypropylene membrane.
After filtration, the remaining leachate is discarded.
9.2.12 -Collect and preserved enough leachate for chemical analysis.
9.2.13 -Repeat the leachate exchange procedure (Steps 9.2.1-9.2.12) until all seven leachants are
collected.
10. MT002.1 Interpretation
10.1.Mass Transfer Coefficients
Interpretation of the release of constituents using the MT002.0 (Mass Transfer Rates in Granular
Materials) protocol is illustrated using the bulk diffusion model. Other models that may also be used to
determine mass transfer coefficients and tortuosity values include the Shrinking Unreacted Core model
(Hinsenveld and Bishop 1996) and the Coupled Dissolution/Diffusion model (Sanchez, 1996). These
models incorporate chemical release parameters into the model to better estimate release mechanisms and
predictions.
At the conclusion of the MT001.0 protocol, the interval mass released is calculated for each
leaching interval as:
Mt. = -^-^- (Equation A5-1)
where Mt, = mass released during leaching interval i [mg/m2];
Q = the constituent concentration in interval i [mg/L],
Vt = the leachant volume in interval i [L], and
A = the specimen surface area exposed to the leachant [m2].
An observed diffusivity of COPCs can be determined using the logarithm of the cumulative release plotted
versus the logarithm of time. In the case of a diffusion-control mechanism, this plot is expected to be a
A-28
-------
Environmental Engineering Science, In-press, 2002.
straight line with a slope of 0.5. An observed diffusivity can then be determined for each leaching interval
where the slope is 0.5+0.15 by (de Groot and van der Sloot 1992):
> ( M* Y
D°bs = n - :4 =^ (Equation A5-2)
(2pC0 (^t~-^)j
where D°bs = observed diffusivity of the species of concern for leaching interval i [m2/s],
M t. = Mass released during leaching interval i [mg/m2],
tt = Contact time after leaching interval i [s],
ti-i = Contact time after leaching interval i-1 [s],
C0 = Initial leachable content (i.e., available release potential) [mg/kg], and
p= Sample density [kg/m3].
The overall observed diffusivity is then determined by taking the average of the interval observed
diffusivities. Only those interval mass transfer coefficients corresponding to leaching intervals with slopes
between 0.35 and 0.65 are included in the overall average mass transfer coefficient (IAWG 1997).
10. 2. Matrix Tortuosity
Tortuosity is a measure of the physical retention in the matrix and is a matrix-specific property. The matrix
tortuosity reflects the extended path length of a diffusing ion in the pore structure of a matrix relative to a
straight path through the matrix. Typically, the mass transfer release of non-interactive components, or
tracers, is measured and observed interval mass transfer coefficients are compared to the tracer molecular
diffusivity in aqueous solutions as shown in Equation A4-4.
j-\mol
T = (Equation A5 -3 )
Dobs
where T= the matrix physical retention, or tortuosity [-],
Dmol= the molecular diffusion coefficient in aqueous solution [m2/s], and
D°bs = the observed diffusion coefficient in the matrix [m2/s].
Sodium or chloride is normally selected as tracer elements under the assumption that these elements do not
react with the matrix being evaluated. The matrix tortuosity should be calculated as the average of interval
tortuosity values subject to the same interval slope criteria (0.35 - 0.65) pertaining to mass transfer
coefficients.
11. References
de Groot, G. J. and H. A. van der Sloot (1992). Determination of leaching characteristics of waste materials
leading to environmental product certification. Solidification and Stabilization of Hazardous. Radioactive, and
Mixed Wastes. 2nd Volume. ASTM STP 1123. T. M. Gilliam and C. C. Wiles. Philadelphia, PA, American
Society for Testing and Materials: 149-170.
A-29
-------
Environmental Engineering Science, In-press, 2002.
Hinsenveld, M. & Bishop, P. L. (1996) "Use of the shrinking core/exposure model to describe the teachability
from cement stabilized wastes." In Stabilization and Solidification of Hazardous, Radioactive, and Mixed
Wastes, 3rd Volume, ASTMSTP 1240, (T. M. Gilliam & C. C. Wiles, eds.): American Society for Testing and
Materials.
IAWG (1997). Municipal Solid Waste Incinerator Residues. Amsterdam, Elsevier Science Publishers.
Kosson, D. S., Kosson, T. T. & vander Sloot, H. (1993) "Evaluation of solidification/stabilization treatment
processes for municipal waste combustion residues." EPA Cooperative Agreement #CR 818178-01-0,
Cincinnati, Ohio: US Environmental Protection Agency.
Sanchez, F. (1996) "Etude de la lixiviation de milieux poreux contenant des especes solubles: Application au
cas des dechets solidifies par liants hydrauliques," Doctoral Thesis, Lyon, France: Institut National des Sciences
Appliquees de Lyon.
A-30
-------
Environmental Engineering Science, In-press, 2002.
A.6. pHOOl.O (pH Titration Pretest)
1. Scope
1.1. This protocol is used to generate a material-specific pH titration curve of a solid material at a liquid-solid
(LS) ratio of 100 mL/g dry sample. This titration curve is used to formulate an acid and base addition
schedule for the "SR002.1 (Alkalinity, Solubility and Release as a Function of pH)" protocol.
1.2. This protocol is not intended for determination of pH titration data for organic matrices.
2. Cited Protocols
2.1. ASTM(1980) "D 2261-80 Standard Method for Determination of Water (Moisture) Content of Rock, Soil
and Soil Aggregates", Philadelphia, PA: American Society for Testing and Materials.
2.2. SR002.1 (Alkalinity, Solubility and Release as a Function of pH).
2.3. AWOO1.0 (Acid Washing for Laboratory Equipment).
2.4. PS001.1 (Particle Size Reduction).
3. Summary of the Method
This protocol is used to obtain a material-specific titration curve between the pH values of 2 and 12.
From this titration curve, the required equivalents of acid or base to obtain endpoint pH values are determined
for addition to deionized water (DI water) extractions in the "SR002.1 (Alkalinity, Solubility and Release as a
Function of pH)" protocol. All procedures are conducted at room temperature (20±2°C) and at a LS ratio of 100
mL/g dry sample on material that has been size reduced to <2 mm using "PS001.1 (Particle Size Reduction)"
protocol. In the pHOOl.O protocol, a minimum equivalent sample mass of 8 g dry sample is used. The natural
pH* of the appropriate sample mass of aliquot of material in deionized (DI) water at an LS ratio of 100 mL/g
dry sample is measured in a borosilicate glass beaker using a pH meter. The natural pH of the material is used to
determine if acid (base) is required to lower (raise) the solution pH in order to cover the range from pH 3 to 12.
Next, a series of 100 to 500 uL aliquots of acid are added to this beaker containing the minimum
sample mass (i.e., 8 g dry equivalent mass) and DI water at a LS ratio of 100 mL/g. Nitric acid is used to lower
the solution pH. The volume of acid added will depend on the buffering capacity of the material. For each
addition, the solution pH is measured after 20-30 minutes of stirring using a magnetic stirrer followed by 5
minutes of settling. The cumulative acid addition and the solution pH are monitored for each addition until the
desired acidic pH range is covered. The aliquot addition procedure is repeated on a new sample aliquot using
100 to 500 uL aliquots of base, if required, until the entire pH range from values of 3 to 12 is covered. The use
of potassium hydroxide or sodium hydroxide to raise the solution pH should be based on consideration of the
constituents of interest (i.e., if potassium is a constituent of concern, NaOH must be used in the titration).
* Natural pH is defined as the pH, which is obtained when the designated amount of material is contacted with
DI water for the designated period of time.
A-31
-------
Environmental Engineering Science, In-press, 2002.
From the data collected by addition of acid and/or base, a titration curve showing the pH response as a
function of the equivalents of acid or base added per dry gram of sample is generated. Equivalents of base are
presented as negative equivalents of acid (i.e., 1 meq/g dry KOH equals -1 meq/g dry HNO3). A schedule of
volumetric acid or base additions and extraction media makeup volumes is created for the SR002.1 (Alkalinity,
Solubility and Release as a Function of pH) protocol.
4. Significance and Use
Since the release of inorganic constituents is often controlled by liquid phase pH, the endpoint pH (i.e.,
the pH of the leachate after the desired contact time) is a critical parameter, which must be controlled, in many
leaching protocols. The final pH of the liquid phase is a result of the neutralization, or titration, of the alkalinity
in the material by an acid or a base. In batch extraction procedures designed to challenge the material at specific
pH target values (e.g., SR002.1 protocol), leachate pH may be controlled by the addition of pre-determined
equivalents of acid or base according to the acid/base addition schedule and material-specific titration curve as
provided by pHOOl.O (pH Titration Pretest).
5. Apparatus
5.1. Beaker - 400 mL borosilicate glass (e.g., Fisher Brand or equivalent).
5.2. Magnetic Stirring Bar - 25 mm X 9.5 mm dia. Teflon coated (e.g., Fisherbrand #09-311-9 or equivalent).
5.3. Magnetic Stirrer - e.g., Barnstead/Thermolyne S46725 or equivalent.
5.6. Adjustable Pipetter - 100-1000 uL Oxford Benchmate or equivalent with disposable tips.
6. Reagents
6.1. Reagent Grade Water - Deionized (DI) water must be used as the major extractant in this procedure. DI
water with a resistivity of 18.2 MQ can be provided by commercially available water deionization systems
(e.g., Milli-Q Plus, Millipore Corp., Bedford, MA or equivalent).
6.2. 2NNitric Acid Solution - prepared by diluting Tracemetal Grade Nitric Acid (e.g., Fisher Scientific or
equivalent) with deionized water.
6.3. IN Potassium Hydroxide Solution - Reagent Grade (e.g., Fisher Scientific or equivalent).
7. Acid Washing Procedure
Because the concentrations of inorganic constituents in leachates may be very low (i.e., <10 ug/L), all
laboratory equipment that comes in contact with the material, the extraction fluid, or the leachant must be rinsed
with 10% nitric acid followed by three rinses with DI water to remove residual inorganic deposits following
AW001.0 (Acid Washing of Laboratory Equipment).
A-32
-------
Environmental Engineering Science, In-press, 2002.
8. pHOOl.O Procedure
The pHOOl.O protocol consists of three sections used to (1) measure the natural pH of a size reduced
material in DI water at a LS ratio of 100 mL/g dry sample, (2) determine the pH titration behavior of the
material to addition of 2N nitric acid or IN potassium hydroxide (NaOH optional), and (3) generate a schedule
of acid and/or base additions to achieve desired pH endpoints for use in the RU-SR002. 1 protocol. A detailed
procedure for each part of the pretest follows.
8.1. Natural pH of Solid Materials
8.1.1 - Place the minimum dry equivalent mass (i.e., 8 g dry sample) into an appropriate beaker. The
equivalent mass of "as received" material can be calculated if the solids content is known
following Equation A6-1.
Mrec=T (Equation A6-1)
where Mrec = the mass of the "as received" material [g],
Mdry = the dry equivalent sample mass (i.e., 8 g dry sample) [g dry], and
SC = the solids content of the material [g dry/g].
8.1.2- Using a graduated cylinder, measure out the appropriate volume of DI water based on a LS of 100
mL/g dry sample and add it to the beaker. Also, add a magnetic stirring bar to the beaker.
8.1.3- Agitate the slurry with a magnetic stirrer at medium speed for 5 minutes.
8.1.5- Make three pH measurements reading within 30 to 60 seconds after the transfer and record the
average.
8.1.6- Based on the mean natural pH value, determine if acid, base, or a combination of the two is
required to cover the range of pH from 2 to 12. For example, if the material has a natural pH of
12.4 (e.g., a material treated by solidification/stabilization), then only acid would be needed.
However, if a soil with a natural pH of 6.7 is to be tested, both reagents are required. Acid is used
to lower the solution pH and base is used to raise the solution pH.
8.2. pH Titration
8.2. 1 - To the slurry formed in Section 8. 1, add a minimum aliquot of 100 uL of 2N nitric acid and mix
for a minimum of 20 minutes at medium speed using a magnetic stirrer. In the case where only
base is required to raise the solution pH, follow Steps 8.2.1 through 8.2.3 substituting "base" for
"acid".
8.2.2 - Allow the suspension to settle for 5 minutes and perform a pH measurement of the solution.
8.2.3 - Record the cumulative volume of acid and the corresponding solution pH.
8.2.4 - Repeat the process (Steps 8.2.1 and 8.2.3) using 100 uL increment additions of the 2 N acid,
recording each addition and the subsequent pH measurement until the appropriate pH range is
A-33
-------
Environmental Engineering Science, In-press, 2002.
obtained. If it is anticipated that the material has a high amount of acid neutralization capacity,
larger aliquots (e.g., 250 uL) may be added as long as the pH shift after completed mixing is less
than three pH units.
8.2.4 - If necessary, repeat Section 8.1 and Steps 8.2.1 through 8.2.4 using IN KOH solution to obtain a
required pH range (typically between pH values of approximately 2 and 12).
9. Data Interpretation
The data from the pHOO 1.0 protocol must be analyzed in terms of the solution pH resulting from the
cumulative addition of equivalents of acid or base normalized for a gram of dry sample. The following example
data (Table A6-1) which may result from this pretest using 2N HNO3 and IN KOH for a material with near-
neutral natural pH and medium buffering capacity is used for illustrative purposes only. Equivalents and
volumes of base are presented as negative values of acid (i.e., 1 meq of base equals -1 meq of acid and 1 mL of
base equals -1 mL of acid). If the natural pH of the material is near or above 12.0, the pretest would result in
data determined only by addition of HNO3.
Table A6-1. Example pH 001.0 (pH Titration Pretest) results for a sample mass of 8 g dry sample.
Volume of 2NHNO3 or
IN KOH Added [uL]
-6400
-4800
-4000
-3200
-2400
-1600
-800
0
400
1000
1600
2000
3000
4000
6000
Equivalents of Acid
Added [meq/g] *
-0.80
-0.60
-0.50
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.25
0.40
0.50
0.75
1.00
1.50
Solution pH
12.5
12.1
11.8
11.2
10.3
8.8
7.9
6.8
5.7
4.9
4.3
3.9
3.4
2.8
2.1
* 2 N HNO3 = 2 meq/mL for 8 g sample, therefore 1000 jiL HNO3 = 1 mL HNO3 = 0.25 meq HNO3/g. dry
IN KOH = 1 meq/mL for the 8 g sample, therefore 1000 |im KOH = 1 KOH = 0.125 meq KOH/g.
Using the solution pH response to cumulative acid and base addition, a material-specific titration curve
similar to Figure A6-1 can be generated for an LS ratio of 100 mL/g dry sample. Extrapolation of this titration
curve to achieve target pH endpoints with other LS ratios (e.g., in SR002.1 protocol) will result in an
approximate pH response.
A-34
-------
Environmental Engineering Science, In-press, 2002.
9.1. SR002.1 Protocol Schedule
If a material-specific titration curve is not available, the "pHOO 1.0 (pH Titration Pretest)" protocol must be
conducted to determine the approximate equivalents of acid or base needed to achieve final pH endpoints
for extractions ranging from pH 3 to pH 12. The required equivalents of acid or base are determined by
creating a titration curve for the material, between these target pH values, and reading the equivalents from
the curve that correspond to the target pH values. The pH response to acid and base additions as
determined by this method will be approximate due to the large difference in LS ratio (i.e., LS of 100
mL/g dry for pHOOl.O and LS of 10 mL/g dry for SR002.1).
ID
6-
4-
2 -
o^
"\
; -0.58
meq/g ,
V
\
r ^
)
L
>^
°^~~cx_
0.00
r meq/g ^
o -1 1 1 1
-2.0 -1.0 0.0 1.0
Acid Added [meq/g]
1.80 ~^
meq/g
2.0 3
)
0
Figure A6-1. Example "pHOOl.O (pH Titration Pretest)" data showing schedule point selection for
"SR002.1 (Alkalinity, Solubility and Release as a Function of pH)".
9.1.1- Determine the equivalents of HNO3 or KOH per dry gram of material required to reach all of the
eleven desired endpoint pH values between 3 and 12 from the titration curve shown in Figure A6-
1. For each target pH, a horizontal line is drawn from the desired pH value to the titration curve.
Then a vertical line is drawn from the titration curve to the equivalents of acid that are required to
obtain this pH value. In this manner, the equivalents of acid or base required for all target endpoint
pH values can be determined.
9.1.2- Convert the acid or base addition for each target pH from meq/g dry sample to a volume addition
of 2N nitric acid or IN base using Equation A6-2.
(Equation A6-2)
where Va/b = the volume of acid or base to be added [mL],
A-35
-------
Environmental Engineering Science, In-press, 2002.
Aeq = the amount of acid or base expressed in equivalents [meq/g dry],
Mdry = the dry equivalent sample mass (i.e., 8) [g dry], and
Na/b = the normality of the acid (i.e., 2) or base (i.e., 1) [meq/mL].
9.1.3- Calculate the volume of makeup DI water required to provide an LS of 10 mL of extractant per
gram of dry solid sample. If the material has high moisture content, the volume of water contained
within the sample should be subtracted from the total required leachant. For example, 40 g dry
equivalent mass sample with a dry-basis moisture content of 10% (i.e., 0.1 mL/g dry) and
requiring an addition of 15 mL of 2 N Nitric Acid would also require 381 mL of DI water as a
makeup volume according to the following equation:
VDI =(Mdry -LS}-Va/b -(Mdry -MCdbasis) (EquationA6-3)
where VDI = the volume of DI water makeup [mL],
Mdry = the mass of dry solid sample (i.e., 20) [g dry],
LS = the test liquid to solid ratio (i.e., 10) [mL/g dry],
Va/t = the volume of acid or base from the titration curve [mL], and
MCdbasis = the moisture content on a dry mass basis [mL water/g dry] from
ASTMD 2261-80.
Table A2-12 shows the example schedule of acid or base additions and DI water make up volume for the
SR002.1 protocol generated from the titration information shown in Figure 1 using 40 dry g of sample
with a moisture content (dry basis) of 0.1 mL/g dry.
Table A6-2. Example schedule for acid addition for 40 g dry equivalent mass samples and a moisture
content (dry basis) of 0.1 mL/g dry for the "SR002.1 (Alkalinity, Solubility and Release as a Function of
pH)" protocol.
Extract
no.
1
2
3
4
5
6
7
8
9
10
11
Endpoint
solution pH
12.0
11.0
10.0
9.0
8.0
Natural
6.0
5.0
4.0
3.0
2.0
Equivalents of
acid to add
[meq/g]
-1.10
-0.75
-0.58
-0.15
-0.09
0.00
0.08
0.12
0.90
1.80
3.10
Volume of 2N
HNO3 or llx
KOH [mL]
44.0
30.0
23.2
6.0
3.6
0.0
1.6
2.4
18.0
36.0
62.0
Volume of
moisture in
sample [mL]
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
Volume of DI
water makeup
[mL]
352.0
366.0
372.8
390.0
392.4
396.0
394.4
393.6
378.0
360.0
334.0
A-36
-------
Environmental Engineering Science, In-press, 2002.
A.7. PS001.1 (Particle Size Reduction)
1. Scope
1.1 This protocol is used to size reduce a solid material to a particle size of either <300um, <2mm or <5mm
for subsequent characterization.
2. Cited Protocols
2.1. ASTM (1980) "Standard Method for Water (Moisture) Content of Soil, Rock, and Soil-Aggregate
Mixtures D 2261-80," Philadelphia, PA: American Society for Testing and Materials.
2.2. AWOO1.0 (Acid Washing of Laboratory Equipment).
2.3. SR002.1 (Alkalinity, Solubility and Release as a Function of pH).
2.4. SR003.1 (Solubility and Release as a Function of LS Ratio).
3. Summary of the Protocol
Depending on the nature of the solid samples, all solid samples to be subjected to equilibrium-based
leaching protocols (e.g., SROOx. 1 series protocols) must be particle size-reduced to <300um, <2mm or <5mm to
minimize mass transfer rate limitation through larger particles.
Particle size reduction to 5mm or 2mm should be accomplished by crushing with a rock hammer in a
thick (i.e., 4-8 mil), sealed plastic bag followed by sieving through either a 5mm or 2mm polyester sieve.
Alternatively, a laboratory size jaw crusher can be used for particle size reduction to <2mm or <5mm.
Prior to particle size reduction to <300um, desiccation to a maximum moisture content of 15% (w/w)
may be necessary for materials with naturally high moisture contents. Particle size reduction then is conducted
in a closed vessel using a ball mill with an appropriate aggregate or other equivalent grinding apparatus (e.g.,
mortar and pestle or centrifugal grinder). Milling is immediately followed by separation of the <300um fraction
through a 300-um (50 mesh) sieve. The jar milling/sieving process is repeated on the fraction that does not pass
the sieve until a minimum of 85% of the initial material mass has been size reduced and collected. The milled
product is stored in an air-tight polyethylene vessel until required for leach testing.
4. Significance and Use
Large particle sizes may limit the release of constituents in extraction protocols used to measure
constituent solubility or release at low liquid-to-solid (LS) ratios (i.e., SR002.1 and SR003.1). Testing protocols
such as these are designed reach equilibrium between solid and liquid phases within reasonable test duration for
material leaching characterization. Application of these protocols to materials of larger particle will necessitate
longer contact time to obtain equilibrium between solid and liquid phases.
A-37
-------
Environmental Engineering Science, In-press, 2002.
5. Apparatus
5.1. Reduction Apparatus - jar mill (e.g., US Stoneware #764 AVM) with an appropriate grinding media (e.g.,
zirconia pellets, Fisher Scientific or equivalent) or other apparatus suitable for size reducing solid
materials.
5.2. MillJar Vessel - ceramic jar (e.g., Fisher Scientific #08-382C) or polyethylene bottle (e.g., Nalgene
#2120-0005) with air-tight lid or equivalent.
5.3. Rock Hammer - e.g., Stanley Steelmaster SB24 or equivalent.
5.4. Sealable Plastic Bag - e.g., Ziploc Brand Freezer Bags or equivalent.
5.5. Jaw Crusher - e.g., ASC Scientific Laboratory Size Jaw Crusher.
5.6. Mortar - e.g., Coors #60319 or equivalent.
5.7. Pestle - e.g., Coors #60320 or equivalent.
5.8. Desiccator - e.g., Fisherbrand #08-615B or equivalent.
5.9. Desiccant - 8 mesh indicating SiO2 desiccant (e.g., EM Science, Gibbstown, NJ or equivalent).
5.10. Sieve - 5 mm high-density polyethylene US standard sieve with polyester mesh.
5.11. Sieve -1 mm (10 mesh) high-density polyethylene US standard sieve with polyester mesh (e.g., Cole
Farmer #AP-06785-20) or equivalent.
5.12. Sieve - 300 um (50 mesh) stainless steel US standard sieve with stainless steel mesh1 (e.g., Fisherbrand
#04-881-10T or equivalent).
5.13. Storage Vessel - wide mouth, polyethylene bottle with an air-tight lid (e.g., Nalgene #3120-9500 or
equivalent).
6. Acid Washing Procedure
In order to minimize cross contamination of replicates or samples, all laboratory equipment that comes
in contact with the material must be rinsed with 10% nitric acid followed by DI water to remove residual
deposits following the "AW001.0 (Acid Washing of Laboratory Equipment)" protocol. For the "PS001.1
(Particle Size Reduction)" protocol, it is mandatory that equipment is acid washed between material types and
recommended between replicates.
7. Particle Size Reduction Procedure
7.1. For particle size reduction to <5 mm or <2 mm, an initial mass of sample should be placed in a thick,
scalable plastic bag on a hard surface.
7.2. With a rock hammer, crush the monolithic or large granular material into smaller units. If the integrity of
the plastic bag is compromised during size reduction, the material may be transferred into a new bag.
7.3. As an alternative method, laboratory size jaw crusher can be used for particle size reduction to <5 mm or
<2mm.
A plastic body/ mesh (e.g., polyethylene/polyester) is recommend if available at a 300um (50 mesh) opening.
A-38
-------
Environmental Engineering Science, In-press, 2002.
7.4. When the material seems to be of a uniform particle size, sieve the material through a 5 mm sieve or a
2mm sieve, retaining both the fraction that passes and the fraction that does not pass the sieve.
7.5. Return the fraction that does not pass the sieve into the plastic bag for continued size reduction.
7.6. Repeat Steps 1.2-1 A until greater than 85% of the initial material mass has been reduced to either <5mm
or <2mm. Place the entire sample mass into an air-tight vessel until a moisture content analysis is
conducted.
7.7. Determine the moisture content of the material using ASTM method D 2261-80 "Standard Method for
Laboratory Determination of Water (Moisture) Content of Soil, Rock, and Soil Aggregate Mixtures".
7.8. For further particle size reduction to <300|jm, desiccation may be necessary if the moisture content of the
material is greater than 15% (w/w). If no desiccation is required, continue particle size reduction with Step
7.8.
7.9. Place the solid material in a porcelain milling jar or plastic milling vessel that is approximately half-filled
with milling media. The total volume of media and sample should be less than 2/3 of the bottle volume.
7.10. Place the vessel on the ball mill and tumble it until the material breaks into smaller units. The duration of
milling will vary depending on material properties. If the sample does not break down, grinding with a
mortar and pestle followed by jar milling may be required.
7.11. Sieve the material through a 300-um (50 mesh) sieve, collecting the particles that pass the sieve in an
appropriate storage container.
7.12. Return the grinding media and the fraction that does not pass the sieve to the milling jar for additional
particle size reduction. Alternately, continue to reduce the particle size using the mortar and pestle.
7.13. Repeat the milling/sieving process (Steps 7.9-7.12) until a minimum of 85% of the original mass has been
particle size reduced to less than 300 um.
7.14. Store the size-reduced material in an airtight container to prevent contamination through exchange with
the environment. Store in a cool, dark and dry place until use.
A-39
-------
Environmental Engineering Science, In-press, 2002.
A.8. AW001.0 (Acid Washing of Laboratory Equipment)
1. Scope
1.1. This procedure is used to prepare laboratory equipment for use in inorganic extraction tests.
2. Summary of the Protocol
Because concentrations of inorganic constituents in leachates may be very low (i.e., <10 ug/L), all
laboratory equipment that is exposed to the material, the extraction fluid, or the leachant must be rinsed with
10% nitric acid followed by deionized water to remove residual deposits. This equipment includes supplies,
utensils and containers or any surface that will come into direct contact with the material. After removing loose
debris with soap and tap water, all contacting surfaces are rinsed with 10% nitric acid then triple rinsed with
deionized (DI) water. The equipment is dried and stored in such a manner as to minimize contamination with
trace metals. When the equipment is used, no further preparation is required.
3. Reagents and Materials
3.1. Cleaning Brush - soft, non-damaging brush (e.g., Fisher Scientific or equivalent).
3.2. Detergent - e.g., Sparkleen, Fisher Scientific or equivalent.
3.3. Reagent Grade Water - Deionized (DI) water with a resistivity of 18.2 M£l can be provided by
commercially available deionization systems (e.g., Milli-Q Plus, Millipore, Bedford, MA or equivalent).
3.4. 10% (v/v) Nitric Acid- made by dilution of Tracemetal Grade nitric acid (e.g., Fisher Scientific or
equivalent) with DI water.
4. Acid Washing Procedure
4.1. Rinse loose debris from the surface of the object using tap water.
4.2. Wash the object thoroughly using a brush, soap and water. Triple rinse with tap water.
4.3. Using a designated laboratory squirt bottle, apply a steady stream of 10% nitric acid solution to completely
cover all contacting surfaces. Repeat the application of the 10% nitric acid three times.
4.4. Triple rinse all surfaces with DI water.
4.5. Dry the object by using direct sunlight, ovens, or forced drafts of warm air. Take care to limit exposure to
airborne particulates or any source of contamination.
4.6. Objects that are not for immediately use must be covered or stored in an area where exposure to airborne
particulates or any other source of contamination can be minimized. Alternately, all equipment can be
triple dipped into a polyethylene crock (Cole-Parmer #AP-06724-60 or equivalent) containing a 10% nitric
acid bath with a dipping basket (e.g., Cole-Parmer #AP-06717-50 or equivalent). For this approach,
however, frequent monitoring of the metals concentration and renewal of the bath solution are required to
minimize the possibility of depositing metals onto equipment surfaces.
A-40
-------
Environmental Engineering Science, In-press, 2002.
5. Safety
Caution should be taken when working with either the full strength or 10% nitric acid solutions. At a
minimum of safety precautions, the use of acid resistant gloves and eye protection are required. All equipment
should be rinsed over a tank constructed of an inert material (e.g., polyethylene tank, Nalgene #14100-0015 or
equivalent).
A-41
-------
Environmental Engineering Science, In-press, 2002.
An Integrated Framework for Evaluating Leaching in Waste
Management and Utilization of Secondary Materials
D.S. Kosson1*, H.A. van der Sloot2, F. Sanchez1 and A.C. Garrabrants1
Department of Civil and Environmental Engineering
Vanderbilt University
Nashville, Tennessee, USA
2The Netherlands Energy Research Foundation
Petten, the Netherlands
Abstract
A framework for the evaluation of inorganic constituent leaching from wastes and secondary materials is
presented. The framework is based on the measurement of intrinsic leaching properties of the material in
conjunction with mathematical modeling to estimate release under field management scenarios. Site
specific and default scenarios are considered, which may be selected based on the evaluation context. A
tiered approach is provided to allow the end-user to balance between the specificity of the release estimate,
the amount of testing knowledge required, a priori knowledge, and resources required to complete an
evaluation. Detailed test methodologies are provided for a suite of laboratory leaching tests.
Key Words: leaching, metals, waste, soil, utilization, beneficial use, secondary materials, disposal,
landfill, risk assessment, test methods
to whom communications should be addressed.
Box 1831 Station B, Nashville, TN 37235. Phone: (615) 322-1064, Email: David.Kosson@Vanderbilt.edu
-------
Environmental Engineering Science, In-press, 2002.
INTRODUCTION
Leaching tests are used as tools to estimate the release potential of constituents from waste
materials over a range of possible waste management activities, including during recycling or reuse, for
assessing the efficacy of waste treatment processes, and after disposal. They may also be used to develop
endpoints for remediation of contaminated soils and the source term1 for environmental risk
characterization. The Resource Conservation and Recovery Act (RCRA) requires the USEPA to classify
wastes as either hazardous or non-hazardous. In implementing this portion of RCRA, the USEPA asks,
"Would this waste pose unacceptable environmental hazards if disposed under a plausible, regulatorily
defined, mismanagement scenario?" This scenario typically represents "worst case" management (i.e., the
estimated highest risk, plausible, legal management option) and wastes posing such unacceptable
environmental hazards warrant classification and regulation as hazardous wastes. In developing the
Toxicity Characteristic regulation (40 CFR 261.24), the USEPA defined the plausible, worst-case
mismanagement scenario for evaluating industrial waste as co-disposal in a municipal solid waste (MSW)
landfill. The assumption of this mismanagement scenario, in turn, resulted in the development of the
Extraction Procedure Toxicity test and its successor, the Toxicity Characteristic Leaching Procedure
(TCLP; see 45 FR 33084, May 19, 1980, and 55 FR 11798, March 29, 1990), which attempts to replicate
some key leaching factors typical of MSW landfills.
The TCLP has come under criticism because of overbroad application of the test (and underlying
assumption of MSW co-disposal) in evaluating and regulating wastes, and some technical specifications of
the methodology. The Science Advisory Board of USEPA reviewed the leaching evaluation framework
being employed by the agency in 1991 and 1999 (USEPA, 1991; USEPA, 1999). In the 1999 review, the
Science Advisory Board stated:
The current state of the science supports, even encourages, the development and use of
different leach tests for different applications. To be most scientifically supportable, a leaching
protocol should be both accurate and reasonably related to conditions governing teachability under
actual waste disposal conditions.
And
1 In this context, 'source term' refers to representation of constituent release from a waste or contaminated
soil that is used in subsequent fate and transport modeling for exposure evaluation in risk assessment.
-------
Environmental Engineering Science, In-press, 2002.
The multiple uses of TCLP may require the development of multiple leaching tests. The result
may be a more flexible, case-specific, tiered testing scheme or a suite of related tests incorporating the
most important parameters affecting leaching. Applying the improved procedure(s) to the worst-case
scenario likely to be encountered in the field could ameliorate many problems associated with current
procedures. Although the Committee recognizes that these modifications may be more cumbersome to
implement, this type of protocol would better predict teachability.
The Science Advisory Board also criticized the TCLP protocol on the basis of several technical
considerations, including the test's consideration of leaching kinetics, liquid-to-solid ratio, pH, potential for
colloid formation, particle size reduction, aging, volatile losses, and co-mingling of the tested material with
other wastes (i.e., co-disposal).
In response, this paper offers an alternative framework for evaluation of waste leaching potential
that responds to many of the criticisms of the TCLP. It provides a tiered, flexible framework capable of
incorporating a range of site conditions that affect waste leaching and so can estimate leaching potential
under conditions more representative of actual waste management. The paper also addresses practical
implementation of the framework in different applications, and an example application of this approach for
evaluating alternative treatment processes for mercury contaminated soils is presented in a companion
paper (Sanchez et al., 2002). The leach testing protocols used in the framework also address technical
concerns with the TCLP. The test protocols provided here are designed only for application to inorganic
species; however, the concepts presented for the integrated framework are general, with application to both
inorganic and organic species. Applicable test methods for organic species are the subject of future
development. Complete technical specifications for the protocols are provided in the Appendix.
IS THE RIGHT QUESTION BEING ASKED?
In evaluating the leaching potential of wastes based on a single, plausible worst-case
mismanagement scenario via TCLP, the USEPA seeks to provide environmental protection for unregulated
wastes. However, wastes are managed in many different settings, and under a range of conditions that affect
waste leaching. The reliance of the USEPA on a single, plausible worst-case, management scenario for
leach testing may be generally protective, but often at the cost of over regulation. It has also proven to be
inadequately protective in some cases (see discussion of spent aluminum potliner regulation at 62 FR
41005, July 31, 1997 and 62 FR 63458, December 1, 1997). While reliance on a single waste management
scenario as the basis for leach testing may simplify implementation of RCRA, many of the wastes evaluated
using TCLP have little if any possibility of co-disposal with MS W; assessment of the release potential of
wastes as actually managed is needed to better understand the hazards posed by waste. Neither the TCLP,
3
-------
Environmental Engineering Science, In-press, 2002.
nor any other test performed under a single set of conditions, can provide an accurate assessment of waste
hazards for all waste.
From an environmental protection perspective (and setting aside the particular requirements of
RCRA), the goal of leaching testing is to answer the question "What is the potential for toxic constituent
release from this waste by leaching (and therefore the risk) under the selected management option?" For
environmentally sound waste management, the following questions result from different perspectives:
From the waste generator's prospective - Which waste management options are acceptable for a
waste?
From the waste management facility's perspective - Which wastes are suitable for disposal in a
specific disposal facility?
From the potential end-user's perspective - Is this secondary material acceptable for use in
commerce (e.g., as a construction material)?
The framework for answering these questions should be consistent across many applications, ranging from
multiple waste disposal scenarios to determination of the environmental acceptability of materials that may
be subject to leaching (e.g., construction materials). At the same time, the framework should be flexible
enough to consider regional and facility-specific differences in factors affecting leaching (e.g., precipitation,
facility design). A methodology guideline (ENV 12920, 1996) developed under European standardization
initiatives recommends that the management scenario be a central consideration in the testing and
evaluation of waste for disposal and beneficial use of secondary materials. This methodology is an
extension of the approach in the Building Materials Decree established in The Netherlands (Building
Materials Decree, 1995).
The answers to the questions posed above require several interrelated assessments including (i) the
release rate and total amount over a defined time interval of potentially hazardous constituents from the
waste, (ii) attenuation of the constituents of concern as they migrate from the waste, through groundwater,
to the receptor being considered, (iii) exposure of the receptor, and (iv) the toxicity of each specific
constituent. Considerable effort has resulted in accurate assessment techniques and data for evaluating
contaminant transport through the environment (and attenuation), and toxicity for a large number of
constituents.
In contrast to the detailed research on constituent fate, transport and risk following release,
estimation of constituent release by leaching most often assumes (i) the total content present is available for
-------
Environmental Engineering Science, In-press, 2002.
release, or (ii) the contaminant concentration in the leachate will be equal to that measured during a single
batch extraction and is constant with time2, or (iii) the fraction of the contaminant extracted during a batch
extraction is equal to the fraction that will leach (USEPA, 1986; Goumans et al., 1991). These approaches
frequently result in grossly inaccurate estimation of actual release (both over- and under-estimation).
Inaccurate release estimation, in turn, forces disposal of materials that are suitable for beneficial use,
mandates remediation of soils to levels beyond that necessary for environmental protection, unnecessarily
depletes disposal capacity, or results in groundwater contamination (if release is underestimated). In
addition, treatment processes, that may be proven to reduce the extracted concentration for a regulatory test
(TCLP), have resulted in increased release when compared to management scenarios without treatment
(Garrabrants, 1998). Thus, methodologies that result in a more accurate estimate of contaminant leaching
may both improve environmental protection through more efficient use of resources and be economically
beneficial.
In general, leaching tests can be classified into the following categories (Environment Canada,
1990): (i) tests designed to simulate contaminant release under a specific environmental scenario (e.g.,
synthetic acid rain leach test or TCLP), (ii) sequential chemical extraction tests, or (iii) tests which assess
fundamental leaching parameters.
Tests that are designed to simulate release under specific environmental scenarios are limited
because they most often do not provide information on release under environmental scenarios different
from the one being simulated. This type of limitation has led to widespread misuse and misinterpretation of
TCLP results. Reliance on simulation-based testing also results in treatment processes that are designed to
"pass the test" rather than to improve waste characteristics or reduce leaching under actual use or disposal
scenarios. For instance, it is common practice to include waste treatment additives to buffer the TCLP
leachant at a pH resulting in minimum release of target constituents. However, when the buffered material
is landfilled, the landfill leachate pH may be dominated either by the material buffering capacity (monofill
scenarios) or by other sources (co-disposal scenarios). In either case, the release scenario may differ
significantly from conditions simulated by the testing protocol and unpredicted leaching behavior may
occur.
Sequential chemical extraction tests evaluate release based on extraction of the waste with a series
of increasingly more aggressive extractants. The sequential extraction approach, originally compiled by
2 This assumption is often referred to as the "infinite source" assumption.
-------
Environmental Engineering Science, In-press, 2002.
Tessier et al. (Tessier et al., 1979), has been adapted by others (Frazer and Lum, 1983). These adapted
approaches have limitations that require case-by-case evaluation (Khebohian and Bauer, 1987; Nirel and
Morel, 1990). In addition, the operationally defined nature of sequential extraction approaches make
generalized application in a waste management framework difficult.
In addition, geochemical speciation modeling also can provide useful insights into leaching
behavior, as it provides information on possible solubility controlling mineral phases (Meima et al., 1999;
van der Sloot, 1999; Crannell et al., 2000), the role of sorption processes with Fe, Mn and Al phases
(Meima and Comans, 1998; Meima and Comans, 1999), and complexation with dissolved organic mater
(Keizer and van Riemsdijk, 1998; Kinniburgh et al., 1999; van der Sloot, 2002). However, geochemical
modeling often requires detailed solid phase identification that is either impractical or not possible for
complex materials, and needed solubility and adsorption parameters may be unavailable. Although the
information it provides can be used effectively in waste management, geochemical modeling often only
provides qualitative or semi-quantitative results and is not a tool for regulatory control.
The alternative framework described below was designed to assess intrinsic waste leaching
parameters, thereby providing a sound basis for estimation of release potential in a range of different
potential waste management scenarios. It provides a basis either for choosing acceptable management or
disposal from among several possible options or for judging whether a pre-selected management or disposal
option is in fact environmentally sound and appropriate.
AN ALTERNATIVE FRAMEWORK FOR EVALUATION OF LEACHING
Waste testing should provide information about potential contaminant release from a waste in the
context of the anticipated disposal or utilization conditions. Thus, testing should reflect the range of
conditions (e.g., pH, water contact, etc.) that will be present in the waste and at its interface with its
surroundings during the long-term, which may be significantly different than the properties of the material
immediately following production3.
Examples where the material as produced has different constituent release behavior than that during
utilization are: (i) concrete pillars immersed in surface water where release reflects the neutral pH of
surface water rather than the alkali pH of Portland cement concrete (van der Sloot, 2000), (ii) stabilized
coal fly ash exposed to seawater showing surface sealing (Hockley and van der Sloot, 1991), (iii) MSWI
bottom ash used in road base application being neutralized with a few years of field exposure (Schreurs et
al., 2000), and (iv) use of steel slag in coastal protection applications where V and Cr leaching is reduced
by the natural formation of ferric oxide coatings in the utilization environment (Comans etal, 1991).
-------
Environmental Engineering Science, In-press, 2002.
The goals of a revised framework for evaluation of contaminant leaching should be to: (i) provide
conservative4 but realistic estimates of contaminant leaching for a broad range of waste types, constituents
of concern, environmental conditions, and management options, (ii) utilize testing strategies that can be
carried out using standard laboratory practices in reasonable time frames (e.g., several hours to several
days, depending on requirements), (iii) provide for release estimates that consider site-specific conditions,
(iv) encourage improvements in waste management practices, (v) provide flexibility to allow level of
evaluation (and hence degree of over-conservatism5) to be based on the user's requirements, (vi) evolve in
response to new information and take advantage of prior information, and (vii) be cost effective.
In concert with these goals, evaluation of constituent release can be approached by a series of
steps: (i) define management scenarios and mechanisms occurring in the scenarios (e.g., rainfall infiltration)
that control constituent release, (ii) measure intrinsic leaching parameters for the waste or material being
evaluated (over a range of leaching conditions), (iii) use release models incorporating measured leaching
parameters (corresponding to anticipated management conditions) to estimate release fluxes and long-term
cumulative release, and (iv) compare release estimates to acceptance criteria. Management scenarios can
either be default scenarios that are designed to be conservative or incorporate site-specific information to
provide more-accurate estimates of release. In CEN TC 2926, such a scenario-based approach has been
described as an experimental standard (ENV 12920, 1996). This standard describes steps very similar to
those identified above.
The controlling release mechanisms most often can be described in terms of either equilibrium
controlled or mass-transfer rate controlled. Equilibrium controlled release occurs for slow percolation
through porous or granular materials. Mass transfer rate controlled release occurs when flow is
predominantly at the exterior boundary of monolithic materials or percolation is very rapid relative to mass
transfer rate of constituent release to the percolating water. Intrinsic leaching parameters that are to be
measured using laboratory testing are: constituent availability, constituent partitioning at equilibrium
between aqueous and solid phases as a function of pH and liquid-to-solid (LS) ratio, acid and base
4 In this paper, "conservative" estimates of release implies that the actual release will be less than or equal
to the estimated release during the management scenario considered.
5 For most cases, more detailed waste characterization results in more accurate estimates of actual
contaminant release, providing safety margins by reducing the degree of over-estimated release. However,
more detailed characterization requires additional testing cost and time which may not be justified because
of either the limited amount of waste to be managed, time constraints, or other reasons.
6 CEN/TC 292 is the European Standardization Organization (CEN) technical committee dealing with
characterization of waste (established in 1993). For additional information, see www.cenorm.be on the
Internet.
-------
Environmental Engineering Science, In-press, 2002.
neutralization capacities (ANC and BNC), and constituent mass transfer rates. Definition of management
scenarios and application of intrinsic parameters, release models and decision criteria are discussed in later
sections of this paper.
To achieve the desired framework goals and series of evaluation steps, a three-tiered testing
program is proposed (Figure 1). An analogous, tiered approach, developed with input from the authors of
this paper, has been recommended by Eighmy and Chesner for evaluation of secondary materials for use in
highway construction (Eighmy and Chesner, 2001). In the framework presented in this paper, each
successive tier provides leaching data that is more specific to the material being tested and possible leaching
conditions than the previous tier. Individual leaching tests are designed to provide data on intrinsic leaching
parameters for a waste or secondary material. Results from multiple tests, used in combination with either
default management scenario assumptions (more conservative, but with simpler implementation) or site-
specific information, provide more accurate release assessments. However, the results of a single test (e.g.,
the first tier availability test) can be used as the most conservative approach for management decisions
when time or economic considerations do not justify more-detailed evaluations.
Three tiers of assessment can be defined to efficiently address the above waste management
questions and criteria:
Tier 1 - Screening based assessment (availability).
Tier 2 - Equilibrium based assessment (over a range of pH and LS conditions).
Tier 3 - Mass transfer based assessment.
Progressing from Tier 1 through Tier 3 provides increasingly more realistic and tailored, and less
conservative, estimates of release, but also requires more extensive testing.
Tier 1 is a screening test that provides an assessment of the maximum potential for release under
the limits of anticipated environmental conditions, without consideration of the time frame for release to
occur. This concept of maximum potential release is often referred to as "availability." In practical
application, availability is operationally defined using a selected test method. Leaching potential is
expressed on a mass basis (e.g., mg X leached/kg waste). The basis for this bounding analysis would be
testing under extraction conditions that maximize release within practical considerations (see further
discussion below). Tier 2 testing is based on defining liquid-solid equilibrium as a function of pH and LS
(i.e., chemical retention in the matrix). Tier 3 testing uses information on liquid-solid equilibrium in
conjunction with mass transfer rate information (i.e., physical retention of constituents in addition to
-------
Environmental Engineering Science, In-press, 2002.
chemical retention in the matrix). Both Tier 2 and Tier 3 testing may use either default or site-specific
management assumptions (e.g., infiltration rates, fill depth) to estimate release as a function of time. For a
scenario, leachate concentrations based on equilibrium will always be greater than or equal to those based
on mass transfer rate. Thus, equilibrium release estimates (Tier 2) may be a conservative approximation in
the absence of mass transfer rate information (Tier 3)7.
For Tier 2 and Tier 3 assessments, three levels of testing (Levels A, B or C) are defined. Each of
the three levels of testing may be used depending on the amount of previous knowledge (test data) of the
waste, or the degree of site-specific tailoring desired. Level A (in either Tier 2 or 3) uses concise or
simplified tests. The basis for Tier 2A would be measurement of the leaching characteristics at conditions
that bound the range of anticipated field scenarios for equilibrium (e.g., use of three extractions to define
release at acidic, neutral and alkali pH conditions with consideration of the material's natural pH at LS=10
mL/g). The basis for Tier 3 A testing would be a coarse estimate of release rates (e.g., a four point, 5 day
monolithic leach test). The data from these tests would be used in conjunction with default management
scenario bounding conditions, and simplified release models, to provide a conservative assessment in the
absence of more detailed knowledge. Example applications of Level A testing (in either Tier 2 or 3) include
for routine disposal of wastes that may fail Tier 1 testing, simplified evaluations for disposal or utilization
that can be justified based on more conservative assumptions, and verification that a material being tested
exhibits characteristics similar to a class of materials that has previously been more extensively
characterized (e.g., Level B, see below).
Level B testing provides detailed characterization of the waste or secondary raw material. The
basis for Tier 2B testing would be definition of equilibrium over the full range of relevant pH and LS
conditions (i.e., pH 2-13, and LS 0.5-10 mL/g). The maximum release observed under these conditions also
is functionally equivalent to the availability measured in Tier 1, although the specific values may differ
based on the method of determination. The basis for Tier 3B testing would be a more complete definition of
mass transfer rates (e.g., 10 data points over 60 days) and verification of material integrity (e.g., strength
after leaching). These more detailed data can be used in conjunction with either default or site-specific
management scenario assumptions, and either simplified or advanced release models. For example, results
from Level B testing in conjunction with default scenarios and simplified release models can provide the
basis for comparison of treatment processes. Results from Level B testing used in conjunction with site-
Extrapolation of laboratory mass transfer test results to field conditions requires careful consideration of
-------
Environmental Engineering Science, In-press, 2002.
specific information and advanced models provide the most realistic and least conservative assessment.
Level B testing would only be carried out initially for a material or class of materials generated in large
quantities, and thereafter only if significant changes in material characteristics are indicated by periodic
Level A testing. Level B testing provides insight into the critical components for a given material and thus
providing the basis for selection of a reduced set of parameters for subsequent testing. After completion of
Level B testing, Level A testing can be used to answer the question, "Does the material currently being
tested have the same characteristics of the material that was previously characterized in more detail (Level
B)?" The frequency of testing can be related to the degree of agreement with the level B testing. Good
performance is then rewarded by reduction in test frequency. A deviation then requires initially more
frequent testing to verify the deviation, and if necessary a return to the level B testing to evaluate the cause.
Additional examples of application of Level B testing include monofill disposal of special wastes and
approvals for beneficial use of secondary materials.
Level C provides the most simplified testing for quality control purposes, and relies on
measurement of a few key indicators of waste characteristics, as identified in the level B testing. An
example of Level C testing would consist of titration of a sample to a designated pH with measurement of
the concentration of a limited number of constituents in the resulting single extract. Specific Level C testing
requirements would be defined on a case specific basis. Level C should only be used after Level B testing
has initially been completed to provide a context for quality control. One application of Level C testing
would be the routine (e.g., daily, weekly or monthly) evaluation of incinerator ash prior to disposal.
A feedback loop is provided between Tier 2C and Tier 2A within the framework (Figure 1). This
loop is provided to indicate that Tier 2 A testing can be used on a random basis to provide further assurance
of attainment of regulatory objectives when much more simplified testing is allowed on a routine basis (Tier
2C). In this case, the Tier 2A testing is compared with the more complete Tier 2B characterization testing to
verify that the batch of material being tested has not deviated significantly from the material that was
originally characterized and serves as the baseline assessment. A similar approach may be used when
quality control testing is based on mass transfer rate testing (Tier 3C) rather than equilibrium testing (Tier
2C).
While the above framework provides the specific basis only for evaluation of inorganic
constituents, an analogous set of test conditions can be described for evaluation of organic constituents.
the external surface area for water contact and the potential for external stresses.
10
-------
Environmental Engineering Science, In-press, 2002.
Additional considerations for organic constituents would include (i) the potential for mobility of a non-
aqueous phase liquid, (ii) the fact that pH dependence of aqueous partitioning is usually limited to the
indirect (although important) effect of pH on dissolved organic carbon levels from humic or similar
substances, and (iii) availability for many organic constituents is limited and may require a more complex
modeling approach.
DECISION MAKING BASED ON THE EVALUATION FRAMEWORK
Application of laboratory testing results to environmental decision-making requires linking the
laboratory data to environmental endpoints of concern (protection of human health and environment). This
is done through data or models that represent environmental processes, including groundwater transport of
released constituents, exposure to humans or animals via drinking water, and the toxicity of the released
constituents of concern.
This linkage was established for the TCLP based on assuming the test results yielded a leachate
constituent concentration that reflected anticipated field leachate that would be produced during disposal in
the bounding scenario. This leachate constituent concentration in turn would be reduced through natural
groundwater attenuation processes as it moved through the groundwater (e.g., dilution and adsorption)
before reaching a drinking water well. This "concentration-based approach" implicitly assumes an infinite
source of the constituents of concern and does not account for either the anticipated changes in release over
time (including exhaustion of the source) or the potential for cumulative effects of release over time.
Furthermore, this approach considers only the leaching behavior of the material; it does not consider the
management context (e.g., disposal vs. utilization, design of the management scenario, geographic
location). Thus, the concentration-based approach establishes a leachate concentration (as measured in the
TCLP) below which no significant impact to drinking water is anticipated. This approach also can be
misleading if the test conditions do not reasonably reflect the field conditions (e.g., with respect to pH and
LS ratio).
The proposed alternative is a performance or "impact-based approach." This approach focuses on
the release flux of potentially toxic constituents over a defined time interval. Thus, the management
scenario is evaluated based on a source term that incorporates consideration of system design, net
infiltration and the leaching characteristics of the material. Basing assessment and decisions on estimated
release allows consideration of the waste as containing a finite amount of the constituent of interest, the
11
-------
Environmental Engineering Science, In-press, 2002.
time course of release, and the ability to adapt testing results to a range of management scenarios. The
measure of release would be the mass of constituent released per affected area over time (i.e., release flux).
Knowledge of the release flux would allow more accurate assessment of impact to water resources (e.g.,
groundwater or surface water) by defining the mass input of constituent to the receiving body over time.
Results of this impact-based approach can provide direct input into subsequent risk assessment for decision
making, either based on site-specific analysis or using a generalized set of default assumptions.
Management scenarios
Waste management or utilization scenarios must be used to link laboratory assessment results to
impact assessment. Defining scenarios for this purpose requires the leaching mode controlling release
(equilibrium or mass transfer), the site-specific LS ratio, the field pH, and a time frame for assessment.
Values describing a specific waste management facility or a hypothetical default scenario could be used.
Using these site conditions with laboratory measures of constituent solubility as a function of pH and LS
ratio, a simple release model can be used to estimate the cumulative mass of the constituent released over
the time frame for a percolation/equilibrium scenario. Including laboratory measurement mass transfer rates
allows application of simple release models for mass transfer rate controlled management scenarios (e.g.,
monolithic materials).
For a hypothetical default landfill disposal scenario, parameter values may be based on national
data for different landfill types, or defined as a policy matter. Values for field pH and LS ratio may be either
measured at an actual site or estimated for the site. Measuring field pH requires collecting landfill leachate
or landfill pore water and measuring the pH before contact with the air begins to alter the pH. LS ratio
serves as the surrogate parameter for time. Good agreement has been obtained between laboratory test data
and landfill leachate based on LS (van der Sloot, 2001). Measuring field LS ratio involves measuring the
volume of leachate collected (annually) from the landfill, and comparing it with the estimated waste volume
in the landfill, or the landfill design capacity. As an alternative to measuring the LS ratio, it may be
estimated, based on defining the geometry for the management scenario and local environmental
conditions. Parameters for defining the management scenario include fill geometry (relating waste mass to
impacted area), net infiltration rates (defining amount of water contact), and time frame. For example, a
default disposal scenario may be a fill height of 10 m, 20 cm infiltration per year and 100 years
(alternatively, the total mass of waste and footprint area may be specified). The selection of the default
12
-------
Environmental Engineering Science, In-press, 2002.
management scenario is ultimately a consideration of typical waste management practices and of societal
value judgments reflected in the regulatory development process.
For discussion purposes, a 100-year interval is suggested as a hypothetical assessment period,
although other time frames could be used8. For comparison of treated wastes, a cube one meter on edge is
assumed. Laboratory test results are presented primarily as release per unit mass of waste tested (e.g., mg
X/kg waste), but also are presented and used on a concentration basis for Tier 2 testing.
Environmental Considerations
Release estimates for most cases assume that conditions influencing release are controlled by the
waste material and associated design conditions; however, properties of surrounding materials may
dominate the release conditions in some scenarios. These external stresses (e.g., pH or redox gradients,
carbonation, co-mingling effects) can lead to substantial deviation from material-driven leaching behavior.
For instance, caution must be used if large pH or redox gradients exist between the waste and the
surrounding environment or within the waste matrix. The solubility of many inorganic species may be
strongly a function of pH (e.g., Pb, Cd, Ba) or significantly altered by redox conditions (e.g., Cr, Se, As).
Large gradients in pH or redox potential can result in precipitation or rapid dissolution phenomena for some
elements as concentration gradients within the material or at the material boundary redistribute over long
time intervals (van der Sloot et al., 1994; Sanchez, 1996). The release of highly soluble species (e.g., Na, K,
Cl) is not considered a strong function of leachate conditions.
Redox gradients and reducing conditions may result from material characteristics, biological
activity or external inputs. Materials with inherent reducing properties include several types of industrial
slag, fresh sediment and degrading organic matter. Testing of these materials under air-exposed conditions
may lead to unrepresentative answers for the situation to be evaluated. For an appropriate assessment of
reducing materials, testing and release modeling that considers conditions imposed by external factors,
rather than by the waste itself, will be necessary. This is still an underdeveloped area of research.
For most alkaline wastes, the most prevalent interface reaction is absorption of carbon dioxide.
Carbonation of waste materials results in the formation of carbonate species and neutralization of alkaline
buffering capacity. For Portland cement-based matrices, the conversion of calcium hydroxide to calcium
carbonate has been noted to reduce pore water pH towards 8 (Sanchez, 2001; Garrabrants, 2001). Thus, if
13
-------
Environmental Engineering Science, In-press, 2002.
pH-dependent species are a concern, carbonation of the matrix can play a significant role in predicting long-
term release.
Currently, the proposed approach does not consider the impact of co-mingling different types of
wastes during disposal other than the impact of resulting changes in pH. In cases where a pH gradient
appears to be the most significant factor, release estimates can be accomplished using advanced modeling
approaches in conjunction with characterization data interpolated from the concentration as a function of
pH as defined under Tier 2. Test methods and release models to assess the impact of material aging under
carbonation and reducing conditions are under development (NVN 7438, 2000; Garrabrants, 2001; Sanchez
et al., 200 la). Experimental work is in progress to evaluate waste-waste interaction by quantifying
buffering of pH, dissolved organic carbon, and leaching from waste mixtures (van der Sloot et al., 200 la;
van der Sloot et al, 200Ib).
TEST METHODS FOR USE IN THE FRAMEWORK
CRITERIA FOR EQUILIBRIUM TEST METHODS
Important considerations for the design of equilibrium test methods are (i) the relationships
between particle size, sample size and contact time, (ii) definition of an appropriate LS ratio, (ii) selection
of the acid or alkali for pH modification, and (iii) practical mechanical limits. Experimental observations
with several wastes have indicated that use of a maximum particle size of 2 mm and contact time of 48
hours results in a reasonable measurement of equilibrium (Garrabrants, 1998). If diffusion is assumed to be
the rate controlling mechanism, the relationships between particle size and contact time required to
approach equilibrium can be approximated as diffusion from a sphere into a finite bath (Crank, 1975).
Critical parameters are the fraction of constituent released at equilibrium, observed diffusivity, particle
diameter and contact time. The ratio between the fraction of constituent released at a given time and the
fraction of the constituent released at equilibrium can be considered an index of the approach to
equilibrium. Results of simulations using this modeling approach are consistent with approaching
equilibrium after 48 hours for observed diffusivities less than 10"14 m2/s (Garrabrants, 1998).
The authors have found 100 years to be a useful period for release estimates. This period is typically
longer than a lifetime but short enough to be comprehendible. In addition, for many cases, a major fraction
of the long-term release is anticipated to occur during a period less than this interval.
14
-------
Environmental Engineering Science, In-press, 2002.
Equilibration times for different particle size systems, assuming all other properties remain
constant (e.g., observed diffusivity, liquid-solid ratio, fractional release at equilibrium), can be evaluated
using a dimensionless time parameter:
Dobs -t
T = (Equation 1)
r
where ris the dimensionless time parameter [-];
/ is the contact time [s];
r is the particle radius [m]; and,
Dobs is the observed diffusivity [m2/s].
Based on this approach, achieving a condition equivalent to the 2 mm/48 hr case, a particle size of 5 mm
would require extraction for 12.5 days; for a particle size of 9 mm, 40.5 days would be required. However,
most materials undergoing testing would be sized reduced or naturally have a particle size distribution with
the maximum particle size specified. Thus, a maximum particle size of 2 mm with a 48 hr minimum contact
time is specified as a base case, with alternative conditions suggested considering both equivalent
approaches to equilibrium and practical limitations (Table 1). Demonstration of approximating equilibrium
conditions for the material being tested is recommended before using alternative contact times.
Selection of sample sizes assumes testing of representative aliquots of the material being
evaluated. For the base case with a maximum particle size of 2 mm, a sample size of 40 g (equivalent dry
weight) is recommended when carrying out an extraction at an LS ratio of 10 mL/g. Heterogeneous
materials and materials with a larger particle size will require either testing of larger aliquots or
homogenization and particle size reduction prior to sub-sampling for testing. A discussion and example of
sampling of heterogeneous materials and particle size reduction followed sub-sampling for leaching tests is
provided elsewhere (IAWG, 1997).
For many test methods, an LS ratio of 10 mL/g has been selected to provide adequate extract
volumes for subsequent filtration and analysis while using standard size extraction containers (i.e., 500
mL). This liquid-to-solid ratio also provides for reasonable approach to equilibrium based on theoretical
considerations. Typically, use of an LS ratio of 10 mL/g provides solubility-controlled equilibrium over the
range of pH relevant for extrapolation to the field. The resulting solution concentration is generally only
15
-------
Environmental Engineering Science, In-press, 2002.
weakly dependent on LS ratio between LS ratio of 10 and 2 mL/g. LS ratio dependence may be verified
using an extraction at lower LS (see methods below).
In the experimental methods, pH adjustments are made using aliquots of nitric acid or potassium
hydroxide. Nitric acid was chosen to minimize the potential for precipitation (e.g., such as occurring with
sulfuric acid), complexation (e.g., with organic acids or hydrochloric acid) or analytical interferences. It is
also recognized that nitric acid is oxidizing which is a conservative selection due to the solubility behavior
of metal hydroxyl species (e.g., Pb(OH)3", Cd(OH)3") and the potential for oxidizing conditions during
management. However, oxyanions (e.g., chromate) exhibit maximum release at near neutral to slightly
alkaline conditions that typically are achievable without significant acid additions. Testing for release under
reducing conditions requires the development of additional test methods because consideration must be
given to acid selection, sample handling and establishment of reproducible reducing conditions. Potassium
hydroxide was selected to avoid interference with the use of sodium ion as an inert tracer in some
applications; however, sodium hydroxide may be substituted for cases in which potassium characterization
is a concern.
During extraction, complete mixing should be insured by end-over-end mixing. In all cases, it is
desired to test the material with the minimum amount of manipulation or modification needed prior to
extraction. Thus, it is preferable to avoid sample drying before testing, although this can be acceptable
when non-volatile constituents are of primary interest and it is necessary to achieve particle size reduction.
RECOMMENDED TEST METHODS
The following test methods are recommended for use in the proposed tiered leaching framework.
The general purpose, approach and application of these test methods are shown in Table 2. Detailed
protocols for these test methods are presented as Appendix A.
Tier 1 - Screening Tests
An ideal screening test would result in a conservative estimate of release over the broad range of
anticipated environmental conditions. In addition, this screening test would require only a single extraction
that could be completed in less than 24 hours. However, this ideal scenario is impossible to achieve. Several
approaches to measuring "availability" or maximum leaching potential have been developed or considered.
One approach is a two step sequential extraction procedure with particle size <300 |j,m, LS=100 mL/g and
16
-------
Environmental Engineering Science, In-press, 2002.
control at pH 8 and 4 (NEN 7341, 1994). Another approach uses EDTA to chelate metals of interest in
solution at near neutral pH during a single extraction (Garrabrants and Kosson, 2000). Either of these
approaches can be used as a screening test, but both approaches have practical limitations relative to
implementation. The NEN 73419 requires a small particle size, two extractions and pH control. The
approach of Garrabrants and Kosson (2000) requires a pre-titration and can have some difficulties in
controlling the pH. This approach also has been criticized as providing a release estimate that may be too
conservative.
Tier 2 - Solubility and Release as a Function of pH
The objectives of this testing is to determine the acid/base titration buffering capacity of the tested
material and the liquid-solid partitioning equilibrium of the "constituents of potential concern" (COPCs).
For wastes with high levels of COPCs, the liquid-solid partitioning equilibrium is determined by aqueous
solubility as a function of pH. For low levels of COPCs, equilibrium may be dominated by adsorption
processes. However, the concurrent release of other constituents (e.g., dissolved organic carbon, other ions)
will also impact the results by modifying the solution characteristics of the aqueous phase10. The two
approaches that have been considered for achieving the objective of measuring solubility and release as a
function of pH are (i) static (controlled) pH testing at multiple pH values through use of a pH controller at
desired set points (van der Sloot et al., 1997), and (ii) a series of parallel extractions of multiple sample
aliquots using a range of additions of acid or alkali to achieve the desired range of endpoint pH values
(Environment Canada and Alberta Environmental Center, 1986; Kosson et al., 1996; Kosson and van der
Sloot, 1997; prEN14429, 2001). Both testing approaches have been shown to provide similar results (van
der Sloot and Hoede, 1997), including determination of both the acid^ase titration buffering capacities of
the tested material and the characteristic behavior of the constituents of potential concern. The static pH
approach has the advantage of being able to achieve desired pH endpoints with a high degree of accuracy.
The parallel extraction approach has the advantage of mechanical simplicity. The range of pH examined
should include the extreme values of pH anticipated under field conditions and the pH when controlled by
the tested material (i.e., "natural" or "own" pH). Thus, while the recommended method below provides a
9 NEN is the national Dutch standardization organization, where a standardization committee has been
addressing the development of leaching tests for construction materials and waste materials since 1983.
For additional information, see www.nen.nl on the Internet.
10 For example, the dissolution of organic carbon from a waste has been shown to increase the solubility of
copper in municipal solid waste incinerator (MSWI) bottom ash and several metals in matrices containing
organic matter (van der Sloot, 2002).
17
-------
Environmental Engineering Science, In-press, 2002.
full characteristic behavior curve (i.e., for Tier 2, level B testing), an abbreviated version based on three
analysis points may be used for simplified testing (i.e., for Tier 2A). The recommended method below is
also analogous to CEN TC 292 Characterization of Waste - Leaching Behavior Test - pH Dependence Test
with Initial Acid/Base Addition (prEN14429, 2001).
SR002.1 (Alkalinity. Solubility and Release as a Function of pH)
This protocol consists of 11 parallel extractions of particle size reduced material at a liquid-to-solid
ratio of 10 mL extractant/g dry sample. An acid or base addition schedule is formulated for eleven extracts
with final solution pH values between 3 and 12, through addition of aliquots of HNO3 or KOH as needed.
The exact schedule is adjusted based on the nature of the material; however, the range of pH values
includes the natural pH of the matrix that may extend the pH domain (e.g., for very alkaline or acidic
materials). Using the schedule, the equivalents of acid or base are added to a combination of deionized (DI)
water and the particle size reduced material. The final liquid-solid (LS) ratio is 10 mL extractant/g dry
sample which includes DI water, the added acid or base, and the amount of moisture that is inherent to the
waste matrix as determined by moisture content analysis. The eleven extractions are tumbled in an end-
over-end fashion at 28±2 rpm. Contact time is a function of the selected maximum particle size, with an
extraction period of 48 hr for the base case of 2 mm maximum particle size. Following gross separation of
the solid and liquid phases by centrifugation or settling, leachate pH measurements are taken and the phases
are separated by vacuum filtration through 0.45-um polypropylene filtration membranes. Analytical
samples of the leachates are collected and preserved as appropriate for chemical analysis. The acid and base
neutralization behavior of the materials is evaluated by plotting the pH of each extract as a function of
equivalents of acid or base added per gram of dry solid. Equivalents of base are presented as opposite sign
of acid equivalents. Concentration of constituents of interest for each extract is plotted as a function of
extract final pH to provide liquid-solid partitioning equilibrium as a function of pH. Figure 2 (a-b) shows
conceptual output from the recommended SR002.1 protocol with the recognition that a broad range of
behaviors is possible. In Figure 3a, the output data of the SR002.1 protocol for a cementitious synthetic
waste matrix (Garrabrants, 2001) is compared to the total elemental content and constituent availability
(Tier 1 value).
The abbreviated version of the SR002.1-A (Alkalinity, Solubility and Release as a Function of pH)
protocol consists of three parallel extractions of particle size reduced material at a liquid-to-solid ratio of 10
mL extractant/g dry sample. The selection of the target pH values is dependent on the natural pH of the
18
-------
Environmental Engineering Science, In-press, 2002.
material. If the natural pH is <5, then natural pH, 7 and 9 are selected as the target pH values. If the natural
pH ranges between 5 and 9, then 5, 7 and 9 are selected as the target pH values, and if the natural pH is >9,
then 5, 7 and natural pH are selected as the target pH values.
Tier 2 - Solubility and Release as a Function of LS Ratio
The objective of this test is to determine the effect of low liquid-to-solid ratio on liquid-solid
partitioning equilibrium when the solution phase is controlled by the tested material. This is used to
approximate initial pore-water conditions and initial leachate compositions in many percolation scenarios
(e.g., monofills). This objective is accomplished by a series of parallel extractions using multiple aliquots of
the tested material at different LS ratio with deionized water to achieve the desired range of conditions.
When necessary, results can be extrapolated to lower LS ratio than readily achieved under typical
laboratory conditions. The range of LS ratio examined should include the condition used for solubility and
release as a function of pH testing (i.e., LS=10 mL/g) and the lowest LS practically achievable that
approaches typical pore water solutions (i.e., LS=0.5 mL/g). Thus, while the recommended method below
provides a full characteristic behavior curve (i.e., for Tier 2, level B testing), an abbreviated version based
on two analysis points may be used for simplified testing (i.e., for Tier 2A)11.
For some materials, LS <2 mL/g may be difficult to achieve with sufficient quantity of eluate for
analysis due to limitations of solid-liquid separation. In addition, the formation of leachate colloids can
result in overestimation of release for some metals and organic contaminants. Use of a column test is an
alternative to use of batch testing for measuring release as function of LS. A column test (prEN14405,
2001), similar to the Dutch standard column test (NEN 7343, 1995), has been developed within the
European Standardization Organization CEN.
SR003.1 (Solubility and Release as a Function of LS Ratio)
This protocol consists of five parallel batch extractions over a range of LS ratios (i.e., 10, 5, 2, 1,
and 0.5 mL/g dry material), using deionized (DI) water as the extractant with aliquots of material that has
been particle size reduced. The mass of material used for the test varies with the particle size of the
material. All extractions are conducted at room temperature (20±2°C) in leak-proof vessels that are tumbled
in an end-over-end fashion at 28±2 rpm. Contact time is a function of the selected maximum particle size,
with an extraction period of 48 hr for the base case of 2 mm maximum particle size. Following gross
19
-------
Environmental Engineering Science, In-press, 2002.
separation of the solid and liquid phases by centrifugation or settling, leachate pH and conductivity
measurements are taken and the phases are separated by a combination of pressure and vacuum filtration
using 0.45-um polypropylene filter membrane. The five leachates are collected, and preserved as
appropriate for chemical analysis. Figure 2 (c-d) shows conceptual output from the recommended SR003.1
protocol with the recognition that a broad range of behaviors is possible. In Figure 3b, the output data of
equilibrium-based protocols (SR002.1 and SR003.1) are compared for a cementitious synthetic waste
matrix (Garrabrants, 2001).
The abbreviated version, SR003.1-A (Solubility and Release as a Function of LS Ratio) protocol
consists of two parallel extractions of particle size reduced material using DI water at liquid-to-solid ratio of
10 and 0.5 mL extractant /g dry sample, respectively. The extraction at an LS ratio of 10 mL/g may be the
same sample as used in SR002.1-A to reduce the required number of analyses.
Tier 3 - Mass Transfer Rate (Monolithic and Compacted Granular Materials)
The objective of mass transfer rate tests is to measure the rate of COPC release from a monolithic
material (e.g., solidified waste form or concrete matrix) or a compacted granular material. Results of these
tests are to estimate intrinsic mass transfer parameters (e.g., observed diffusivities for COPCs) that are then
used in conjunction with other testing results and assessment models to estimate release. Results of these
tests reflect both physical and chemical interactions within the tested matrix, thus requiring additional test
results for integrated assessment. While the recommended methods are derivatives of ANS 16.1 (ANS,
1986), a leachability index is not assumed nor used as a decision criterion. The recommended methods
below are also analogous to NEN 7345 (NEN 7345, 1994) and methods under development by CEN/TC
292.
MT001.0 (Mass Transfer Rates in Monolithic Materials)
This protocol consists of tank leaching of continuously water-saturated monolithic material with
periodic renewal of the leaching solution. The vessel and sample dimensions are chosen so that the sample
is fully immersed in the leaching solution. Cylinders of 2 cm minimum diameter and 4-cm minimum height
or 4-cm minimum cubes are contacted with DI water using a liquid to surface area ratio of 10 mL of DI
water for every cm2 of exposed solid surface area. Larger cylinder sizes are recommended for treated
materials that have a particle size greater than 2 mm prior to solidification. Typically, the cylinder diameter
11 The abbreviated methods for testing solubility as a function of pH (three points) and solubility as a
function of LS (two points) include one common point in both tests. Thus, for integrated testing under Tier
20
-------
Environmental Engineering Science, In-press, 2002.
and height or cube dimension should be at least ten times the maximum particle size of the material
contained therein. Leaching solution is exchanged with fresh DI water at pre-determined cumulative times
of 2, 5 and 8 hours, 1, 2, 4 and 8 days12. This schedule results in seven leachates with leaching intervals of
2, 3, 3, 16 hours, 1, 2 and 4 days. At the completion of each contact period, the mass of the monolithic
sample after being freely drained is recorded to monitor the amount of leachant absorbed into the solid
matrix. The solution pH and conductivity for each leachate is measured for each time interval. A leachate
sample is prepared for chemical analysis by vacuum filtration through a 0.45-um pore size polypropylene
filtration membrane and preservation as appropriate. Leachate concentrations are plotted as a function of
time along with the analytical detection limit and the equilibrium concentration determined from SR002.1
at the extract pH for quality control to insure that release was not limited by saturation of the leachate.
Cumulative release and flux as a function of time for each constituent of interest are plotted and used to
estimate mass transfer parameters (i.e., observed diffusivity). Figure 4 shows sample output data from the
MT001.1 test for a solidified waste matrix (van der Sloot, 1999). The solubility data shown in the figure
corresponds to data derived from SR002.1.
MT002.0 (Mass Transfer Rates in Compacted Granular Materials')
This protocol consists of tank leaching of continuously water-saturated compacted granular
material with intermittent renewal of the leaching solution. This test is used when a granular material is
expected to behave as a monolith because of compaction during field placement. An unconsolidated or
granular material is compacted into molds at optimum moisture content using a modified Proctor
compactive effort (NEN 7347, 1997). A 10-cm diameter cylindrical mold is used and the sample is packed
to a depth of 7 cm. The mold and sample are immersed in deionized water such that only the surface area of
the top face of the sample contacted the leaching medium, without mixing. The leachant is refreshed with
an equal volume of deionized water using a liquid to surface area ratio of 10 mL/cm2 (i.e., LS ratio of 10
cm) at cumulative times of 2, 5 and 8 hours, 1, 2, 4 and 8 days (see footnote 12). This schedule results in
seven leachates with leaching intervals of 2, 3, 3, 16 hours, 1, 2 and 4 days. The solution pH and
conductivity for each leachate is measured for each time interval. A leachate sample is prepared for
chemical analysis by vacuum filtration through a 0.45-um pore size polypropylene filtration membrane and
2, four analysis points are recommended.
12 This schedule may be extended for additional extractions to provide more information about longer-term
release. The recommended schedule extension would be additional cumulative times 14 days, 21 days, 28
days, and every four weeks thereafter as desired. Alternately, the duration of the test may be shortened
(e.g., cumulative time of 4 days) for compliance testing.
21
-------
Environmental Engineering Science, In-press, 2002.
preservation as appropriate. Leachate concentrations are plotted as a function of time along with the
analytical detection limit and the equilibrium concentration determined from SR002.1 at the extract pH for
quality control. Cumulative release and flux as a function of time for each constituent of interest are plotted
and used to estimate mass transfer parameters (i.e., observed diffusivity).
RELEASE ASSESSMENT ESTIMATES
Release estimates may be obtained for site-specific and management scenario-specific cases when
appropriate environmental data (e.g., precipitation frequency and amounts) and design information (e.g.,
placement geometry, infiltration rates) are available. For many situations, site-specific information either
may not be readily available or may not be necessary (e.g., as in the case when the intent of testing is only
to provide uniform side-by-side comparisons of treatment processes). For these situations, default scenarios
may be defined; an application of this approach is provided in the companion paper (Sanchez et al., 2002).
These default scenarios are for illustrative purposes only, and other parameter values may be more
appropriate for different management scenarios and geographic locations.
Percolation-controlled scenario
Percolation-controlled release occurs when water flows through a permeable fill with low
infiltration rate and low liquid-to-solid ratio (Figure 5). In this case, local equilibrium at field pH is assumed
to be limiting release. The information required to estimate constituent release during this scenario is the (i)
field geometry, (ii) field density, (iii) anticipated infiltration rate, (iv) anticipated field pH, (v) anticipated
site-specific liquid-to-solid ratio, and (vi) constituent solubility at the anticipated field pH. The anticipated
site-specific liquid-to-solid (LSsite) ratio represents the cumulative liquid-to-solid ratio that can be expected
to contact the fill over the estimated time period. It is based on the infiltration rate, the contact time, the fill
density and the fill geometry and can be determined according to (Hjelmar, 1990; Kosson et al., 1996):
inf t vear
LSSJte=10 y (Equation 2)
p-Hftu
where, LSsite is the anticipated site-specific liquid-to-solid ratio [L/kg];
inf is the anticipated infiltration rate [cm/year];
tyear the estimated time period [year];
p is the fill density [kg/m3];
22
-------
Environmental Engineering Science, In-press, 2002.
Hfm is the fill depth [m]; and,
10 is a conversion factor [10 L/cm-m2].
Over an interval of 100 years or longer, LSsite values greater than 10 mL/g may be obtained for cases that
have relatively high rates of infiltration or limited placement depth (Kosson et ai, 1996; Schreurs et al,
2000). However, for many disposal scenarios, the observed LSsite has been less than 2 L/kg over a period of
ca. 10 years and for an isolated landfill site with reduced infiltration, it may take 1000 years to reach LSsite
of 1 L/kg (Johnson et al, 1998; Johnson et al, 1999; Hjelmar et al, 2001).
An estimate of the cumulative mass release per unit mass of material can then be obtained using
the anticipated site-specific LS ratio and the constituent solubility at the anticipated field pH (SfieldpH)
according to:
M 'm£s= (LSs,te ) (s 'field pH) (Equation 3)
where, M^°s is the cumulative mass of the constituent released (mass basis) at time tyear [mg/kg]; and,
is the constituent solubility [mg/L] at the pH value corresponding to field pH.
Mass transfer-controlled scenario
Mass transfer-controlled scenario occurs when infiltrating water is diverted around a low
permeability fill or prevented from percolating through the fill due to an impermeable overlay (Figure 6) or
adjacent high permeability channels. In this case, mass transport within the solid matrix is rate limiting. The
information required to estimate constituent release during such scenario are the (i) field geometry, (ii) field
density, (iii) initial leachable content and (iv) observed diffusivity of the species of concern.
The mechanisms of release under mass transfer control can be quite complex and constituent-
specific. The rate of COPC diffusion through the material can be retarded by surface reactions or
precipitation of insoluble compounds. Alternately, mass transport may be enhanced by species
complexation or mineral phase dissolution. Numerical techniques often are required to fully describe
release under complex mechanistic conditions. Sophisticated models have been developed, or are under
development, to dissolution/precipitation phenomena (Batchelor, 1990; Cheng and Bishop, 1990; Batchelor,
1992; Hinsenveld, 1992; Batchelor and Wu, 1993; Hinsenveld and Bishop, 1996; Moszkowicz et al, 1996;
Sanchez, 1996; Baker and Bishop, 1997; Moszkowicz et al, 1997; Batchelor, 1998; Moszkowicz et al,
1998), sorption/desorption phenomena, and material heterogeneity (Sanchez et al. , 2001b).
23
-------
Environmental Engineering Science, In-press, 2002.
Fickian Diffusion model
The Fickian diffusion model, based on Pick's second law, assumes that the species of interest is
initially present throughout the homogeneous porous medium at uniform concentration and considers that
mass transfer takes place in response to concentration gradients in the pore water solution of the porous
medium. The assumptions and release estimation approach shown here is most appropriate for release
scenarios for which only highly soluble species are a concern or for which external stresses (e.g., pH
gradients, carbonation, redox changes) are not significant.
In the classical representation of the diffusion model, two coupled parameters characterize the
magnitude and rate of the release: C0, the initial leachable content (e.g., available release potential, total
elemental content)13 and D°bs, the observed diffusivity of the species in the porous medium. When the
species of concern is not depleted over the time period of interest, the cumulative mass release can be
described by a one-dimensional semi-infinite geometry. Depletion is considered to occur when more than
20% of the total leachable content has been released (de Groot, 1993).
For a one-dimensional geometry, an analytical solution for Fickian diffusion is provided by Crank
(1975) with the simplifying assumption of zero concentration at the solid-liquid interface (i.e., case of a
sufficient water renewal; infinite bath assumption):
( D obs t V
M'area = 2-p-C0\ (Equation 4)
I * J
where M'area is the cumulative mass of the constituent released (surface area basis) at time t [mg/m2];
C0 is the initial leachable content (i.e., available or total elemental content) [mg/kg];
p is the sample density [kg/m3];
/ is the time interval [s]; and,
Dobs is the observed diffusivity of the species of concern [m2/s].
The test conditions for the MT series protocols (i.e., MT001.1 and MT002.1) are designed to ensure a non-
depleting matrix and approximate the zero-concentration boundary, although field conditions may not
satisfy these simplifications for many cases and the resulting release estimate may overestimate release.
Therefore, other modeling approaches may be required to more accurately extrapolate to field conditions.
24
-------
Environmental Engineering Science, In-press, 2002.
In release scenarios for which COPC depletion does not occur and Fickian diffusion is considered
the dominant release mechanism, the mass release is proportional to release time by a t172 relationship. After
a log transform, Equation 4 becomes:
^area = l°8
n
+ log / (Equation 5)
Thus, the logarithm of the cumulative release plotted versus the logarithm of time is expected to be a
straight line with a slope of 0.5. Often, initial release as observed from laboratory testing reflects wash off
or dissolution of surface-associated constituents. The apparent constituent release then may be followed by
diffusion-controlled release. Mass release over this initial time when surface phenomena are observed
would result in a line with a slope greater than 0.5. In these cases, only the data points reflecting diffusion-
controlled release are used to estimate observed diffusivity. The initial release should be verified to be
insignificant in relation to the long-term field estimate of release (see Sanchez et al, 2002 for an illustration
of this phenomena).
Estimation of observed diffusivity
Under the assumptions of the Fickian diffusion model, an observed diffusivity can be determined
for each leaching interval where the slope is 0.5+0.15 by (de Groot and van der Sloot, 1992):
D°bs = n - "r . _ (Equation 6)
where D°bs is the observed diffusivity of the species of concern for leaching interval /' [m2/s];
M^rea is the mass released (surface area basis) during leaching interval /' [mg/m2];
/, is the contact time after leaching interval /' [s]; and,
fa is the contact time after leaching interval i-1 [s].
The overall observed diffusivity is then determined by taking the average of the interval observed
diffusivities.
Release estimates
13 The value used for the initial leachable content and the determined observed diffusivity are coupled
parameters such that the same set of parameters obtained from experimental data must be used in
determining long-term release estimates.
25
-------
Environmental Engineering Science, In-press, 2002.
An estimate of the cumulative mass release for the management scenario can then be obtained
using the analytical solution (Equation 4) over the anticipated assessment interval. When COPC release per
unit mass of material is desired, conversion based on material field geometry can be applied to Equation 4.
o (nobs ,y/2
M'mass =2-C0\ (Equation 7)
V I * )
where, Mtmass is the cumulative mass of the constituent released (mass basis) at time t [mg/kg];
S is the fill surface area [m2]; and,
Fis the fill volume [m3].
In the case where initial surface wash-off is considered to provide significant contribution to the release
prediction (i.e., >5% of cumulative release), release from initial surface wash-off is added to release
estimate from diffusion-controlled phenomena. An estimate of the cumulative mass release can then be
obtained using:
r. f p.obs f\ I
M'mass = Mah-°ff -S + 2-C0 ±11 (Equations)
V I n )
where, M^"^~off is the mass of constituent released (surface area basis) from surface wash-off [mg/m2].
When depletion of the COPC is anticipated to occur over the release interval, three-dimensional analysis
using finite body models may be required to estimate cumulative release. Analytical solutions may be found
for different geometries in mass transport literature (Crank, 1975) or simplifying assumptions may be
applied to validate the above 1-D approach (Kosson et al, 1996). Alternately, numerical methods may be
used to solve the Fickian diffusion equation in three dimensions (Barna, 1994).
The above estimates represent a conservative approach for most mass transfer-controlled release
scenarios where significant external stresses are not present. A zero surface concentration assumes a
maximum gradient, or driving force, for mass transport (infinite bath assumption). In the case of slow water
flow past the surface or small liquid-to-surface area ratios, accumulation of the COPC concentration in the
leachate reduces the concentration gradient and limits leachate concentration to the mass of COPC in
equilibrium with the solid phase. Thus, the upper bound (or maximum concentration) for mass transfer-
controlled release should be estimated using release estimates obtained from equilibrium assumptions (e.g.,
Tier 2 testing in conjunction with percolation controlled release).
26
-------
Environmental Engineering Science, In-press, 2002.
Other modeling considerations
Mass transport modeling approaches (Garrabrants, 2001; Garrabrants et al., 2001; Sanchez et al.,
200la; Tiruta-Barna et al., 2001) are under development to address environmental conditions that are more
likely to be encountered in the field such as intermittent wetting under varied environmental conditions (i.e.,
relative humidity and CO2 content). Additional modeling also has been done to relate column test results to
field leaching through application of geochemical speciation (Dijkstra et al., 2001). These models can
provide more accurate release estimates, but typically require additional information (experimental and
field) and greater expertise for use. The simple modeling approach provided here is intended to be a
conservative, first-order approximation that will result in overestimation of actual release for most cases.
EXAMPLE APPLICATIONS OF THE FRAMEWORK
Important potential applications of the leaching framework defined here include (i) the
comparative assessment of waste treatment processes, such as for determinations of equivalent treatment
under RCRA, (ii) estimating environmental impacts from utilization of secondary materials in construction
applications, or (iii) estimating releases from large scale waste monofills. For these cases, Tier 2B and Tier
3B testing is recommended for initial evaluation. An example of this application is provided in the
accompanying paper (Sanchez et al., 2002). Subsequently, Tier 2A testing can be used to establish
consistency between the materials initially tested and other similar materials.
ECONOMIC CONSIDERATIONS
The more extensive testing recommended in the proposed framework will obviously increase
initial testing costs. However, these initial costs should be offset by several factors. First, detailed
characterization of a material is only necessary initially to define its characteristic leaching properties, and
only for materials that are produced in relatively large quantities. Subsequently, much less testing is needed
to verify that new samples conform to the previously established properties. Second, cost savings should be
realized through the framework by enabling alternative management strategies that are not possible under
the current rigid system. Treatment processes evaluated under this system will be better targeted to reducing
leaching under field scenarios. Reduced treatment costs may be achieved in many cases (however,
27
-------
Environmental Engineering Science, In-press, 2002.
treatment costs may increase in cases where treatment processes were only effective at meeting TCLP, but
were ineffective at reducing leaching in the field to levels consistent with risk-based endpoints). In addition,
the potential for environmental damage and future liability will be reduced because of the closer
relationship between testing and field performance. Costs for Tier 1 and Tier 2A testing should be of the
same order-of-magnitude as current TCLP testing. Reductions in costs are anticipated as the methods
become commercialized and data interpretation is automated.
CONCLUSIONS
The proposed framework presents an approach to evaluate the leaching potential of wastes over a
range of values for parameters that have a significant impact on constituent leaching (e.g., pH, LS, and
waste form) and considering the management scenario. This approach presents the potential to estimate
leaching much more accurately (than many currently used leach tests), relative to field leaching, when
conditions for leach test data are matched with field conditions. The greater accuracy of the proposed
approach makes it a useful tool for examining waste and assessing the environmental soundness of a range
of waste management options as well as for assessing the effectiveness of proposed waste treatment
methods. In addition, the proposed framework provides flexibility to the end user to select the extent of
testing based on the level of information needed and readily permits the incorporation of new testing
methods and release models as they are developed for specific applications. Appropriately used in waste
regulatory programs, this approach could make those programs substantially more cost-effective and
protective of the environment. The flexibility of the proposed approach allows for development of the
framework to provide a greater degree of tailoring to site conditions, to account for the effects of other
waste leaching parameters critical to a particular site. Reliance on a tiered approach to testing can also make
this approach more economical for smaller waste volumes and therefore more broadly feasible.
ACKNOWLEDGEMENT AND DISCLAIMER
Primary support for this research was provided by the USEPA Northeast Hazardous Substances Research
Center and the USEPA Office of Solid Waste. Limited support also was provided by (i) The Consortium for
Risk Evaluation with Stakeholder Involvement (CRESP) through U.S. Department of Energy grants DE-
FG26-OONT 40938 and DE-FG02-OOER63022.AOOO and (ii) EU DG Research funded projects. The authors
28
-------
Environmental Engineering Science, In-press, 2002.
gratefully acknowledge the thoughtful feedback from Mr. Greg Helms (USEPA), and Dr. Charles W.
Powers (Institute for Responsible Management) during the development of this manuscript and the
technical support of Ms. Teresa Kosson during the development of the test methods. The authors also
gratefully acknowledge the thoughtful comments and feedback of the anonymous reviewers and the
assistance of the Editor, Dr. D. Grasso, lead author of the USEPA Science Advisory Board Review (1999)
for which this paper is primarily in response. The viewpoints expressed in this paper are solely the
responsibility of the authors and do not necessarily reflect the view or endorsement of the USEPA.
29
-------
Environmental Engineering Science, In-press, 2002.
REFERENCES
ANS (1986). ANS 16.1. American National Standard Measurement of the Leachabilitv of Solidified Low-
Level Radioactive Wastes by a Short-Term Procedure. La Grange Park, IL, American Nuclear Society.
Baker, P.O. and P.L. Bishop (1997). "Prediction of metal leaching rates from solidified/stabilized wastes
using the shrinking unreacted core leaching procedure." Journal of Hazardous Materials 52(2-3): 311-333.
Barna, R. (1994). Etude de la diffusion des polluants dans les dechets solidifies par liants hydrauliques.
Lyon, France, Institut National des Sciences Appliquees de Lyon, 210 pp.
Batchelor, B. (1990). "Leach models: Theory and application." Journal of Hazardous Materials 24(2-3):
255-266.
Batchelor, B. (1992). "A numerical leaching model for solidified/stabilized wastes." Water Science and
Technology 26(1-2): 107-115.
Batchelor, B. (1998). "Leach models for contaminants immobilized by pH-dependent mechanisms."
Environmental Science and Technology 32: 1721-1726.
Batchelor, B. and K. Wu (1993). Effects of equilibrium chemistry on leaching of contaminants from
stabilized/solidified wastes. Chemistry and microstructure of solidified waste forms. R.D. Spence. Baton
Rouge, LA, Lewis Publishers 243-260.
Building Materials Decree (1995). Staatsblad van het Koninkrijk der Nederlanden 567.
Cheng, K.Y. and P.L. Bishop (1990). "Developing a kinetic leaching model for solidified/stabilized
hazardous wastes." Journal of Hazardous Materials 24: 213-224.
Crank, J. (1975). The Mathematics of Diffusion. London, UK, Oxford University Press.
Crannell, B.S., T.T. Eighmy, J.E. Krzanowski, J.D. Eusden, Jr., E.L. Dhaw and C.A. Francis (2000).
"Heavy metal stabilization in municipal solid waste combustion bottom ash using soluble phosphate."
Waste Management 20: 135-148.
de Groot, GJ. (1993). Detailed description of the leaching behaviour of secondary construction products.
ECN-93-085 (in Dutch).
de Groot, GJ. and H.A. van der Sloot (1992). Determination of leaching characteristics of waste materials
leading to environmental product certification. Solidification and Stabilization of Hazardous. Radioactive.
and Mixed Wastes. 2nd Volume. ASTM STP 1123. T.M. Gilliam and C.C. Wiles. Philadelphia, PA,
American Society for Testing and Materials 149-170.
Dijkstra, J.J., H.A. van der Sloot and R.N.J. Comans (2001). "Process identification and model
development of contaminant transport in MSWI bottom ash." Waste Management: (in press).
Eighmy, T.T. and W.H. Chesner (2001). Framework for evaluating use of recycled materials in the highway
environment. FHWA-RD-00-140. McLean, VA, FHWA.
ENV 12920 (1996). Methodology guideline forthe determination of the leaching behaviour of waste under
specified conditions, CEN/TC 292 WG6.
Environment Canada (1990). Compendium of Waste Leaching Tests. EPS 3/HA/7. Ottawa, Canada,
Environment Canada.
Environment Canada and Alberta Environmental Center (1986). Test methods for solidified waste
characterization, Acid Neutralization Capacity, Method #7. Ontario, Canada, Environment Canada and
Alberta Environmental Center.
30
-------
Environmental Engineering Science, In-press, 2002.
Frazer, J.L. and K.R. Lum (1983). "Availability of elements of environmental importance in incinerated
sludge ash." Environmental Science and Technology 17(1): 1-9.
Garrabrants, A.C. (1998). Development and application of fundamental leaching property protocols for
evaluating inorganic release from wastes and soils. Chemical and Biochemical Engineering. New
Brunswick, NJ, Rutgers, The State University of New Jersey, 216 pp.
Garrabrants, A.C. (2001). Assessment of inorganic constituent release from a Portland cement-based matrix
as a result of intermittent wetting, drying and carbonation. Dept. Chemical and Biochemical Engineering.
New Brunswick, NJ, Rutgers, The State University of New Jersey, 396 pp.
Garrabrants, A.C. and D.S. Kosson (2000). "Use of a chelating agent to determine the metal availability for
leaching from soils and wastes." Waste Management and Research 20(2-3): 155-165.
Garrabrants, A.C., F. Sanchez, C. Gervais, P. Moszkowicz and D. Kosson (2001). "The effect of storage in
an inert atmosphere on the release of inorganic constituents during intermittent wetting of a cement-based
material." Journal of Hazardous Materials: (accepted).
Goumans, J.J.J.M., H.A. van der Sloot and T.G. Aalbers, Eds. (1991). Waste Materials in Construction.
Studies in Environmental Science, Vol 48. Amsterdam, Elsevier Science Publishers.
Hinsenveld, M. (1992). A shrinking core model as a fundamental representation of leaching mechanisms in
cement stabilized waste. Cincinnati, OH, University of Cincinnati.
Hinsenveld, M. and P.L. Bishop (1996). Use of the shrinking core/exposure model to describe the
teachability from cement stabilized wastes. Stabilization and Solidification of Hazardous. Radioactive, and
Mixed Wastes. ASTM STP 1240. T.M. Gilliam and C.C. Wiles, American Society for Testing and
Materials. 3rd.
Hjelmar, O. (1990). "Leachate from land disposal of coal fly ash." Waste Management and Research 8:
429-449.
Hjelmar, O., H.A. van der Sloot, D. Guyonnet, R.P.J.J. Rietra, A. Bran and D. Hall (2001). Development of
acceptance criteria for landfilling of waste. An approach based on impact modelling and scenario
calculations. Proceedings of the 8th Waste Management and Landfill Symposium. T.H. Christensen, R.
CossuandR. Stegmann. 3: 711-721.
IAWG (1997). Municipal Solid Waste Incinerator Residues. Amsterdam, Elsevier Science Publishers.
Johnson, C.A., M. Kappeli, S. Brandenberger, A. Ulrich and W. Baumann (1999). "Hydrological and
geochemical factors affecting leachate composition in municipal solid waste incinerator bottom ash. Part II:
The geochemistry of leachate from landfill Losdorf, Switzerland." Journal of Contaminant Hydrology 40:
239-259.
Johnson, C.A., G.A. Richner, T. Vitvar, N. Schittli and M. Eberhard (1998). "Hydrological and
geochemical factors affecting leachate composition in municipal solid waste incinerator bottom ash. Part I:
The hydrology of landfill Losdorf, Switzerland." Journal of Contaminant Hydrology 33: 361-376.
Keizer, M.G. and W.H. van Riemsdijk (1998). ECOSAT. Department of Environmental Science,
Subdepartment Soil Science and Plant Nutrition, Wageningen Agricultural University, The Netherlands.
Khebohian, C. and C.F. Bauer (1987). "Accuracy of selective extraction procedures for metal speciation in
model aquatic sediments." Analytical Chemistry 59: 1417-1423.
Kinniburgh, D.G., W.H. van Riemsdijk, L.K. Koppal, M. Borkovec, M.F. Benedetti and M.J. Avena
(1999). "Ion binding to natural organic matter: competition, heterogeneity, stoichiometry and
thermodynamic consistency." Colloids and Surfaces A-181: 147-166.
31
-------
Environmental Engineering Science, In-press, 2002.
Kosson, D.S. and H.A. van der Sloot (1997). Integration of testing protocols for evaluation of contaminant
release from monolithic and granular wastes. WASCON '97 - International Conference on Construction
with Waste Materials, Houtham, The Netherlands, Elsevier Science Publishers.
Kosson, D.S., H.A. van der Sloot and T.T. Eighmy (1996). "An approach for estimating of contaminant
release during utilization and disposal of municipal waste combustion residues." Journal of Hazardous
Materials 47: 43-75.
Meima, I, A. van Zomeren and R.N.J. Comans (1999). "The complexation of Cu with dissolved organic
carbon in municipal solid waste incinerator bottom ash leachates." Environmental Science and Technology
33(9): 1424-1429.
Meima, J.A. and R.N.J. Comans (1998). "Application of surface complexation/precipitation modeling to
contaminant leaching from weathered MSWI bottom ash." Environmental Science and Technology 32:
683-693.
Meima, J.A. and R.N.J. Comans (1999). "The leaching of trace elements from municipal solid waste
incinerator bottom ash at different stages of weathering." Applied Geochemistry 14: 159-171.
Moszkowicz, P., R. Barna, F. Sanchez, H.R. Bae and J. Menu (1997). Models for leaching of porous
materials. WASCON '97 - International Conference on Construction with Waste Materials, Houtham St.
Gerlach, The Netherlands, Elsevier.
Moszkowicz, P., J. Pousin and F. Sanchez (1996). "Diffusion and dissolution in a reactive porous medium:
mathematical modelling and numerical simulations." Journal of Computational and Applied Mathematics
66: 377-389.
Moszkowicz, P., F. Sanchez, R. Barna and J. Menu (1998). "Pollutants leaching behaviour from solidified
wastes: A selection of adapted various models." Talanta46: 375-383.
NEN 7341 (1994). Leaching characteristics of soil, construction materials and wastes - Leaching tests -
Determination of the availability of inorganic constituents for leaching from construction materials and
waste materials. Delft, The Netherlands, NNI (Dutch Standardization Institute).
NEN 7343 (1995). Leaching characteristics of soil, construction materials and wastes - Leaching tests -
Determination of the leaching of inorganic components from granular materials with the column test. Delft,
The Netherlands, NNI (Dutch Standardization Institute).
NEN 7345 (1994). Leaching characteristics of soil, construction materials and wastes - Leaching tests -
Determination of the release of inorganic constituents from construction materials, monolithic wastes and
stabilized wastes. Delft, The Netherlands, NNI (Dutch Standardization Institute).
NEN 7347 (1997). Leaching characteristics of soil, construction materials and wastes - Leaching tests -
Compacted granular leach test of inorganic constituents. Delft, The Netherlands, NNI (Dutch
Standardization Institute).
Nirel, P.M.V. and F.M.M. Morel (1990). "Pitfalls of sequential extractions." Water Research 24(8): 1055-
1056.
NVN 7438 (2000). Leaching characteristics of soil, stony building materials and wastes - Characterization
tests - Determination of the reducing characters and reducing capacity. Delft, The Netherlands, NEN.
prEN 14405 (2001). Characterisation of waste: Leaching behavior tests - Up-flow percolation test, CEN/TC
292 WG6.
prEN14429 (2001). Characterisation of waste: Leaching behavior tests - pH dependence test with initial
acid/base addition, CEN/TC 292 WG6.
32
-------
Environmental Engineering Science, In-press, 2002.
Sanchez, F. (1996). Etude de la lixiviation de milieux poreux contenant des especes solubles: Application
au cas des dechets solidifies par Hants hydrauliques. Lyon, France, Institut National des Sciences
Appliquees de Lyon, 269 pp.
Sanchez, F., A.C. Garrabrants and D.S. Kosson (200 la). "Effects of intermittent wetting on concentration
profiles and release from a cement-based waste matrix." Environmental Engineering Science: (submitted).
Sanchez, F., I.W. Massry, T.T. Eighmy and D.S. Kosson (200Ib). "Multi-regime transport model for
leaching of heterogeneous porous materials." Waste Management: (submitted).
Sanchez, F., C. Mattus, M. Morris and D.S. Kosson (2002). "Use of a new leaching test framework for
evaluating alternative treatment processes for mercury contaminated mixed waste." Environmental
Engineering Science: (submitted).
Schreurs, J.P.G.M., H.A. van der Sloot and C.F. Hendriks (2000). "Verification of laboratory-field leaching
behavior of coal fly ash and MSWI bottom ash as a road base material." Waste Management 20(2-3): 193-
201.
Tessier, A., P.G.C. Campbell and M. Bisson (1979). "Sequential extraction procedure for the speciation of
paniculate trace metals." Analytical Chemistry 51(7): 844-851.
Tiruta-Barna, L.R., R. Barna and P. Moszkowicz (2001). "Modeling of solid/liquid/gas mass transfer for
environmental evaluation of cement-based solidified waste." Environmental Science and Technology 35:
149-156.
USEPA (1986). Hazardous Waste Management System: Land Disposal Restrictions: Final Rule, Federal
Register, Part II, Vol. 40 CFR Part 261 et seq. Washington, DC, US Environmental Protection Agency.
USEPA (1991). Leachability Phenomena. EPA-SAB-EEC-92-003. Washington, D.C., USEPA Science
Advisory Board.
USEPA (1999). Waste Leachability: The Need for Review of Current Agency Procedures. EPA-SAB-EEC-
COM-99-002. Washington, D.C., USEPA Science Advisory Board.
van der Sloot, H.A. (1999). Characterization of the leaching behaviour of concrete mortars and of cement
stabilized wastes with different waste loading for long-term environmental assessment. Waste Stabilization
and the Environment, Lyon, France.
van der Sloot, H.A. (2001). European activities on harmonisation of leaching/extraction tests and
standardisation in relation to the use of alternative materials in construction. ICMAT International
Conference on Materials for Advanced Technologies, Singapore.
EU Project SMT4-CT96-2066. Technical support to the Network Harmonization of Leaching/Extraction
tests. 2000. van der Sloot, H.A., personal communication (2002).
van der Sloot, H.A., L. Heasman and P. Quevauviller, Eds. (1997). Harmonization of Leaching/Extraction
Tests. Studies in Environmental Science, Vol 70. Amsterdam, Elsevier Science Publishers.
van der Sloot, H.A. and D. Hoede (1997). Comparison of pH static leach test with ANC test data. ECN R-
97-002. Petten, The Netherlands, ECN.
van der Sloot, H.A., D. Hoede and R.N.J. Comans (1994). The influence of reducing properties on leaching
of elements from waste materials and construction materials. Environmental Aspects of Construction with
Waste Materials. J.J.J.M. Goumans, H.A. van der Sloot and T.G. Aalbers. Amsterdam, The Netherlands,
Elsevier Science B.V 483-490.
van der Sloot, H.A., R.P.J.J. Rietra, R.C. Vroon, H. Scharff and J.A. Woelders (2001a). Similarities in the
long-term leaching behaviour of predominantly inorganic waste, MSWI bottom ash, degraded MSW and
bioreactor residues. Proceedings of the 8th Waste Management and Landfill Symposium. T.H. Christensen,
R. CossuandR. Stegmann. 1: 199-208.
33
-------
Environmental Engineering Science, In-press, 2002.
van der Sloot, H.A., A. van Zomeren, R.P. JJ. Rietra, D. Hoede and H. Scharff (200 Ib). Integration of lab-
scale testing, lysimeter studies and pilot scale monitoring of a predominantly inorganic waste landfill to
reach sustainable landfill conditions. Proceedings of the 8th Waste Management and Landfill Symposium.
T.H. Christensen, R. CossuandR. Stegmann. 1: 255-264.
34
-------
Environmental Engineering Science, In-press, 2002.
Table 1. Specifications for the base case and suggested alternative conditions for equilibrium extractions.
Maximum Particle Size [mm]
Base case Suggested alternates
5
Minimum sample size [g] 40 20 80
Minimum contact time [hr] 48 18 168 (7 days)
Container size [mL] 250 500 1000
35
-------
ts
o
o
1
1
^
1
S
1
Js
S
T3
a
1
S
o
o
o
o
to
a
S
o
O
IS
a
pplicatio
<
*j
B
6
Methodology
8
PH
1
2
.s g
Is 1> 2
fc "-1 e
8 y »
rt O S
° N M
11 1 i
§ 2 o £
g| e aa
co O
^t- oo
a a
3 3
fc" -^
H
Is Is
^
ffi ^ ^ o
^ "1 o 03
lb"Sl
y S .§ "^
£ B Jl e .§
1 ^ ^ ||
£P fl "3 O C3
PH C3 to O a
o determine the
potentially extractable
content of constituents
under environmental
conditions.
H
o
o
P>
^
££
| § "g
to *2 "Q
8 £ |
Soy
u '£ a
> -S3 g
1$ "B 2
fc ^ *
111
° 3 S
0 S M
11 1 i
S 2 o^
aa a s aa
co O
^
H
@
s
.&
1
^
^
Single extraction using 50
mM EDTA; LS ratio of 100
mL/g; contact time
dependent on particle size
o determine the
potentially extractable
content of constituents
under environmental
conditions.
H
CN
O
O
p>
^
0 o £
O H O
J 2 al
^ W a^
3 'si 'I
u .2 '> ^
° o aa I d
y g x> ss o
.5 «s § a ^
1 2 y 8 -a
c =« a u ^
" o g t« y
o CL a o 2
|8|ll
0 0
C3
O ^ ^TH
. y _u pq
^ -s -5 ^
" '-S o >;
ss & o y
^ ^ "^^ Q
^ j a-^
| TO O
1 i 8 1
S "W M '" to
-s 1-1 bo ° id
| 0 | T3 -|
"^ "§ S aa -s «
O ^~~] O [^ 'J*"t
>-H JiQ O ^ i^, c^
Q £ V g S o
^ s s § 8 "5
o o
S 1
^ y 2
CH QJ ^ ^
(D K* -"rt "^
! _^ I <£ 1 If «
0 > 3 ° ^ § o
TS -s JL C3
O PH
Semi-dynamic tank leaching
of monolithic material;
Liquid-to-surface-area ratio
of 10 [mL/cm2]
o determine mass
transfer parameters.
o estimate rate of
release under
continuously saturated
conditions.
H H
^
0
o
H
^
> -^ -M
fl c <-> T3 "to ^
° > o "o ^ I o
T3 -K JL
-------
Environmental Engineering Science, In-press, 2002.
MATERIAL
WASTE, SOIL OR PRODUCT
TIER1
TIER 2
TIERS
MANAGEMENT SCENARIO
Specific disposal or
utilization scenario
Default cases
Default Scenario
Specific or
Default (see text)
Scenario
Tier!
SCREENING
Tier2A
EQUILIBRIUM
Compliance
Tier2B
EQUILIBRIUM
Characterization
TierSA
MASS
TRANSFER RATE
Compliance
Tier2C
EQUILIBRIUM
Quality Control
(Material specific)
« Random compliance testing~-J
TierSB
MASS
TRANSFER RATE
Characterization
TierSC
MASS
TRANSFER RATE
^^1 specific)
LEVEL A
_«.Random compliance testing--'
LEVELB LEVELC
Figure 1. Alternative Framework for evaluation of leaching
37
-------
Environmental Engineering Science, In-press, 2002.
a)
14 -, , , , , , , 1000 T
19
10 -
o .
6 -
4 -
9 -
,
KOH
^
h
\
x
HNO3
^
..
Mat
X
N
\
\
"'.,
\
dx A
rixB
\
\\
x \
100 -
10 -
31 1 -
a1
^ 01-
o U'1
U 001-
0.001 -
0.0001 -
0 00001 -
\^
^
*^
\
^^-
\
\
. \
\ y
~*/"-*^
/~^n4-'.^~, '.
- Amphote
- Oxyanior
- Highly Sc
^^
X^
\
\
x^_
ric
lie
luble
_>
^ ^
/
^
^*
^
-202468
Acid Added [meq/g dry]
10
b)
10
Leachate pH
12
%
11
10
c)
2468
LS Ratio [mL/g dry]
10
rt
o
O
1,000
800
600
400
200
Constituent 1
Constituent 2 ~
d)
2 4 6 8 10
LS Ratio [mL/g dry]
Figure 2. Conceptual data obtained using equilibrium-based testing protocols: a) titration curve (SR002.1),
b) constituent release as a function of pH (SR002.1), c) pH as a function of LS ratio (SR003.1), and d)
constituent concentration as a function of LS ratio (SR003.1).
DRAFT - do not cite, quote or distribute
Framework final (in-press).doc 3/27/02
38
-------
Environmental Engineering Science, In-press, 2002.
10000
100
1
0.01
0.0001
^
\,
\
: Re
! A\
Tn
V,
\
\
\
\
\
V J»
*t
lease f(pH)
ail (pH4)
tal
1
«
/
»
a)
6 8 10 12 14
Leachate pH
g
o
b)
J .
01-
0 01 -
0001 -
: SR002.1
I ASR003.1
1
:
1
\^*
-*r^7
Cone f(pH)
Cone f(LS)
4
y7
x
>
/
/
A
A
^
10 12
Leachate pH
14
Figure 3. Actual data obtained using equilibrium-based testing protocols from a cementitious synthetic
waste: a) lead release as a function of pH compared to lead availability and total lead content and b)
comparison of SR002.1 and SR003.1 concentration data.
DRAFT - do not cite, quote or distribute
Framework final (in-press).doc 3/27/02
39
-------
Environmental Engineering Science, In-press, 2002.
ffi
6.5
20 40 60
Time (days)
00
o
O
CS
m
b)
1000
800
600
20 40 60
Time (days)
160
20 40 60
Time (days)
80
m
0.01
0.1
d)
1 10
Time (days)
100
Figure 4. Actual data obtained using MT001.1 protocol from a stabilized waste (van der Sloot, 1999): a)
leachate pH as a function of cumulative time, b) comparison of leachate barium concentration (MT001.1)
and barium solubility as a function of pH (SR002.1), c) cumulative release of barium as a function of
cumulative time, and d) barium flux as a function of mean cumulative time.
DRAFT - do not cite, quote or distribute
Framework final (in-press).doc 3/27/02
40
-------
Environmental Engineering Science, In-press, 2002.
Release scenario: Percolation
Scenario characteristics
- Granular or highly permeable material
- Low infiltration rate
- Low liquid-solid ratios [mL/g]
Site information
- Infiltration rate inf
- Fill density p
- Fill geometry H^iU
- Field pH
Local equilibrium at field pH is rate limiting
Figure 5. Release scenario: percolation.
Framework final (in-press).doc
DRAFT - do not cite, quote or distribute
3/27/02
41
-------
Environmental Engineering Science, In-press, 2002.
Release scenario: Diffusion-controlled
scenario
Scenario characteristics
- Low permeability material
- High infiltration rate
- High liquid-surface area ratios
Site information
- Fill density
- Fill geometry S, I
- Fill porosity
Mass transport within solid matrix is rate limiting
Figure 6. Release scenario: diffusion-controlled scenario.
DRAFT - do not cite, quote or distribute
Framework final (in-press).doc 3/27/02
42
-------
APPENDIX A
GLOSSARY
-------
IWEM Technical Background Document Appendix A
Glossary
Adsorption - Adherence of molecules in solution to the surface of solids (ASCE, 1985).
Adsorption isotherm - A graphical representation of the relationship between the
concentration of constituent in solution and the amount adsorbed at constant temperature.
Advection - The process whereby solutes are transported by the bulk mass of flowing
fluid. See also convective transport.
Anisotropy - The condition of having different properties in different directions.
Aquifer - A geologic formation, group of formations, or part of a formation that contains
sufficient saturated permeable material to yield significant quantities of water to wells
and springs.
Aquifer system - A body of permeable material that functions regionally as a
water-yielding unit; it comprises two or more permeable beds separated at least locally
by confining beds that impede ground-water movement but do not greatly affect the
regional hydraulic continuity of the system; includes both saturated and unsaturated parts
of permeable material.
Area of influence of a well - The area surrounding a pumping or recharging well within
which the potentiometric surface has been changed.
Breakthrough curve - A plot of concentration versus time at a fixed location.
Cancer Slope Factor (CFS) - an upper bound, approximating a 95% confidence limit,
on the increased cancer risk from a lifetime exposure to an agent. This estimate, usually
expressed in units of proportion (of a population) affected per mg/kg/day, is generally
reserved for use in the low-dose region of the dose-response relationship, that is, for
exposures corresponding to risks less than 1 in 100.
Cation exchange capacity - The sum total of exchangeable cations that a porous
medium can absorb. Expressed in moles of ion charge per kilogram of soil (or of other
exchanges such as clay).
Chronic Daily Intake (GDI) - exposure expressed as mass of a substance contacted per
unit body weight per unit time, averaged over a long period of time.
Confined - A modifier which describes a condition in which the potentiometric surface is
above the top of the aquifer.
AA
-------
IWEM Technical Background Document Appendix A
Confined aquifer - An aquifer bounded above and below by impermeable beds or by
beds of distinctly lower permeability than that of the aquifer itself; an aquifer containing
confined ground water.
Confining bed - See confining unit.
Confining unit - Means a body of impermeable or distinctly less permeable material
stratigraphically adjacent to one or more aquifers.
Darcian velocity - See specific discharge.
Darcy's law - An empirical law which states that the velocity of flow through porous
medium is directly proportional to the hydraulic gradient.
Desorption - A removal of a substance adsorbed to the surface of an adsorbent.
Desorption - The reverse process of sorption. See also sorption.
Diffusion - Spreading of solutes from regions of highest to regions of lower
concentrations caused by the concentration gradient. In slow moving ground water, this
can be a significant mixing process.
Diffusion Coefficient - The rate at which solutes are transported at the microscopic level
due to variations in the solute concentrations within the fluid phases.
Dispersion coefficient - A measure of the spreading of a flowing substance due to the
nature of the porous medium, with its interconnected channels distributed at random in
all directions. Equal to the sum of the coefficients of mechanical dispersion and
molecular diffusion in a porous medium.
Dispersion, longitudinal - Process whereby some of the water molecules and solute
molecules travel more rapidly than the average linear velocity and some travel more
slowly; spreading of the solute in the direction of the bulk flow.
Dispersion, transverse - Spreading of the solute in directions perpendicular to the bulk
flow.
Dispersivity - A geometric property of a porous medium which determines the
dispersion characteristics of the medium by relating the components of pore velocity to
the dispersion coefficient.
A-2
-------
IWEM Technical Background Document Appendix A
Distribution coefficient - The quantity of a constituent sorbed by the solid per unit
weight of solid divided by the quantity dissolved in the water per unit volume of water.
Dose-Response Relationship - The relationship between a quantified exposure (dose),
and the proportion of subjects demonstrating specific, biological changes (response).
Evapotranspiration - The combined loss of water from a given area by evaporation
from the land and transpiration from plants.
Exposure pathway - the course a chemical or physical agent takes from a source to an
exposed organism. An exposure pathway describes a unique mechanism by which an
individual or population is exposed to chemicals or physical agents at or originating from
a site. Each exposure pathway includes a source or release from a source, an exposure
point, and an exposure route. If the exposure point differs from the source, a
transport/exposure medium (e.g., water) or media (in case of intermedia transfer) also is
included.
Exposure point - A location of potential contact between an organism and a chemical or
physical agent.
Exposure point concentration - an estimate of the of the arithmetic average
concentration of a contaminant at a exposure point.
Flow, steady - A characteristic of a flow system where the magnitude and direction of
specific discharge are constant in time at any point See also flow, unsteady.
Flow, uniform - A characteristic of a flow system where specific discharge has the same
magnitude and direction at any point.
Flow, unsteady - A characteristic of a flow system where the magnitude and/or direction
of the specific discharge changes with time.
Flow velocity - See specific discharge.
Flux - See specific discharge.
Geohydrologic system - (See ground water system.) The geohydrologic units within a
geologic setting, including any recharge, discharge, interconnections between units, and
any natural or human-induced processes or events that could affect ground water flow
within or among those units.
A-2
-------
IWEM Technical Background Document Appendix A
Geohydrologic unit - (See hydrogeologic unit.) An aquifer, a confining unit, or a
combination of aquifers and confining units comprising a framework for a reasonably
distinct geohydrologic system.
Ground water - Means water below the land surface in a zone of saturation. Ground
water is the water contained within an aquifer.
Ground water, confined - Ground water under pressure significantly greater than
atmospheric and whose upper limit is the bottom of a confining unit. See also confined,
confining unit, and confined aquifer.
Ground water discharge - Flow of water from the zone of saturation.
Ground water flow - The movement of water in the zone of saturation.
Ground water flux - (See specific discharge.) The rate of ground-water flow per unit
area of porous or fractured media measured perpendicular to the direction of flow.
Ground water mound - A raised area in a water table or other potentiometric surface
created by ground water recharge.
Ground water, perched - Unconfmed ground water separated from an underlying body
of ground water by an unsaturated zone. Its water table is a perched water table. Perched
ground water is held up by a perching bed whose permeability is so low that water
percolating downward through it is not able to bring water in the underlying unsaturated
zone above atmospheric pressure.
Ground water recharge - The process of water addition to the saturated zone or the
volume of water added by this process.
Ground water system - A ground-water reservoir and its contained water. Also, the
collective hydrodynamic and geochemical processes at work in the reservoir.
Ground water travel time - The time required for a unit volume of ground water to
travel between two locations. The travel time is the length of the flow path divided by the
velocity, where velocity is the average ground water flux passing through the
cross-sectional area of the geologic medium through which flow occurs, perpendicular to
the flow direction, divided by the effective porosity along the flow path. If discrete
segments of the flow path have different hydrologic properties the total travel time will
be the sum of the travel times for each discrete segment.
A-4
-------
IWEM Technical Background Document Appendix A
Ground water, unconfined - Water in an aquifer that has a water table. Synonymous
with phreatic ground water.
Hazard quotient - the ratio of a single contaminant exposure level over a specified time
period to a reference dose for that contaminant derived from a similar period.
Head, static - The height above a standard datum of the surface of a column of water (or
other liquid) that can be supported by the static pressure at a given point. The static head
is the sum of the elevation head and the pressure head.
Health-based number (HBN) - the maximum constituent concentration in ground water
that is expected to not usually cause adverse noncancer health effects in the general
population (including sensitive subgroups), or that will not result in an additional
incidence of cancer in more than approximately one in one million individuals exposed to
the contaminant.
Heterogeneity - A characteristic of a medium in which material properties vary from
point to point.
Homogeneity - A characteristic of a medium in which material properties are identical
everywhere.
Human Health Benchmark - quantitative expression of dose-response relationships.
Hydraulic Conductivity - A coefficient of proportionality describing the rate at which
water can move through an aquifer or other permeable medium.
Hydraulic gradient - Slope of the water table or potentiometric surface.
Hydraulic Head - The height of the free surface of a body of water above a given point
beneath the surface.
Hydrodynamic dispersion - The spreading (at the macroscopic level) of the solute front
during transport resulting from both mechanical dispersion and molecular diffusion.
Hydrogeologic unit - Any soil or rock unit or zone which by virtue of its porosity or
permeability, or lack thereof, has a distinct influence on the storage or movement of
ground water.
Hydrologic properties - Those properties of a rock that govern the entrance of water and
the capacity to hold, transmit, and deliver water, such as porosity, effective porosity,
A-5
-------
IWEM Technical Background Document Appendix A
specific retention, permeability, and the directions of maximum and minimum
permeabilities.
Hydrolysis - The splitting (lysis) of a compound by a reaction with water. Example are
the reaction of salts with water to produce solutions which are not neutral, and the
reaction of an ester with water.
Hydrostratigraphic unit - See hydrogeologic unit
Immiscible - The chemical property of two or more phases that, at mutual equilibrium,
cannot dissolve completely in one another, e.g., oil and water.
Impermeable - A characteristic of some geologic material that limits its ability to
transmit significant quantities of water under the head differences ordinarily found in the
subsurface.
Infiltration - The downward entry of water into the soil or rock, specifically from a
waste management unit.
Infiltration capacity - The maximum rate at which a soil or rock is capable of absorbing
water or limiting infiltration.
Isotropy - The condition in which the property or properties of interest are the same in
all directions.
Leachate - A liquid that has percolated through waste and has extracted dissolved or
suspended materials.
Leaching - Separation or dissolving out of soluble constituents from a waste by
percolation of water.
Matrix - The solid framework of a porous system.
MCL - Maximum Contaminant Level - Legally enforceable standards regulating the
maximum allowed amount of certain chemicals in drinking water.
Mechanical dispersion - The process whereby solutes are mechanically mixed during
advective transport caused by the velocity variations at the microscopic level.
Synonymous with hydraulic dispersion.
Miscible - The chemical property of two or more phases that, when brought together,
have the ability to mix and form one phase.
-------
IWEM Technical Background Document Appendix A
Model - A conceptual, mathematical, or physical system obeying certain specified
conditions, whose behavior is used to understand the physical system to which it is
analogous in some way.
Moisture content - The ratio, expressed as a percentage, of either (a) the weight of water
to the weight of solid particles expressed as moisture weight percentage or (b) the volume
of water to the volume of solid particles expressed as moisture volume percentage in a
given volume of porous medium. See water content.
Molecular diffusion, coefficient of, - The component of mass transport flux of solutes
(at the microscopic level) due to variations in solute concentrations within the fluid
phases. Synonymous with diffusion coefficient.
Molecular Diffusion - The process in which solutes are transported at the microscopic
level due to variations in the solute concentrations within the fluid phases.
Monte Carlo Simulation - A method that produces a statistical estimate of a quantity by
taking many random samples from an assumed probability distribution, such as a normal
distribution. The method is typically used when experimentation is infeasible or when
the actual input values are difficult or impossible to obtain.
Mounding - Commonly, an outward and upward expansion of the free water table
caused by surface infiltration or recharge method.
Permeability - The property of a porous medium to transmit fluids under an hydraulic
gradient.
Pore velocity - See velocity, average interstitial.
Porosity - The ratio, usually expressed as a percentage, of the total volume of voids of a
given porous medium to the total volume of the porous medium.
Porosity, effective - The ratio, usually expressed as a percentage of the total volume of
voids available for fluid transmission to the total volume of the porous medium.
Receptor - the exposed individual relative to the exposure pathway considered.
Recharge - The process of addition of water to the saturated zone; also the water added.
In IWEM, recharge is the result of natural precipitation around a waste management unit.
Reference concentration (RFC) - an estimate (with uncertainty spanning perhaps an
order of magnitude) of a continuous inhalation exposure to the human population
-------
IWEM Technical Background Document Appendix A
(including sensitive subgroups) that is likely to be without an appreciable risk of
deleterious effects during a lifetime. It can be derived from a NOAEL, LOAEL, or
benchmark concentration, with uncertainty factors generally applied to reflect limitations
of the data used. Generally used in EPA's noncancer health assessments.
Reference Dose (RfD) - An estimate (with uncertainty spanning perhaps an order of
magnitude) of a daily oral exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of deleterious effects during a
lifetime.
Release - any spilling, leaking, pumping, pouring, emitting, emptying, discharging,
injecting, escaping, leaching, dumping or disposing of any contaminant into the
environment.
Retardation factor - The ratio of the average linear velocity of ground water to the
velocity of the retarded constituent.
Risk - the probability that a contaminant will cause an adverse effect in exposed humans
or to the environment.
Risk assessment - the process used to determine the risk posed by contaminants released
into the environment. Elements include identification of the contaminants present in the
environmental media, assessment of exposure and exposure pathways, assessment of the
toxicity of the contaminants present at the site, characterization of human health risks,
and characterization of the impacts or risks to the environment.
Saturated Zone - The part of the water bearing layer of rock or soil in which all spaces,
large or small, are filled with water
Seepage velocity - See specific discharge.
Soil bulk density - The mass of dry soil per unit bulk soil.
Soil moisture - Subsurface liquid water in the unsaturated zone expressed as a fraction of
the total porous medium volume occupied by water. It is less than or equal to the
porosity.
Solubility - The total amount of solute species that will remain indefinitely in a solution
maintained at constant temperature and pressure in contact with the solid crystals from
which the solutes were derived.
A-8
-------
IWEM Technical Background Document Appendix A
Solute transport - The net flux of solute (dissolved constituent) through a hydrogeologic
unit controlled by the flow of subsurface water and transport mechanisms.
Sorption - A general term used to encompass the process of absorption and adsorption.
Source term - The kinds and amounts of constituents that make up the source of a
potential release.
Specific discharge - The rate of discharge of ground water per unit area of a porous
medium measured at right angle to the direction of flow. Synonymous with flow rate or
specific flux.
Toxicity - the degree to which a chemical substance elicits a deleterious or adverse effect
upon the biological system of an organism exposed to the substance over a designated
time period.
Transient - See flow, unsteady.
Transmissivity - The rate at which water is transmitted through a unit width of the
aquifer under a unit hydraulic gradient. It is equal to an integration of the hydraulic
conductivities across the saturated part of the aquifer perpendicular to the flow paths.
Transport - Conveyance of dissolved constituents and particulates in flow systems. See
also solute transport and particulate transport.
Unconfined - A condition in which the upper surface of the zone of saturation forms a
water table under atmospheric pressure.
Unconfined aquifer - An aquifer which has a water table.
Unsaturated flow - The movement of water in a porous medium in which the pore
spaces are not filled to capacity with water.
Unsaturated zone - The subsurface zone between the water table and the land surface
where some of the spaces between the soil particles are filled with air.
Vadose zone - See unsaturated zone.
Volatiles - Substances with relatively large vapor pressures. Many organic substances
are almost insoluble in water so that they occur primarily in a gas phase in contact with
water, even though their vapor pressure may be very small.
A-9
-------
IWEM Technical Background Document Appendix A
Water content - The amount of water lost from the soil after drying it to constant weight
at 105 °C, expressed either as the weight of water per unit weight of dry soil or as the
volume of water per unit bulk volume of soil. See also moisture content.
Water table - The upper surface of a zone of saturation except where that surface is
formed by a confining unit. The water pressure at the water table equals atmospheric
pressure.
Water table aquifer - See unconfined aquifer.
Well - A bored, drilled or driven shaft, or a dug hole, whose depth is greater than the
largest surface dimension.
A-10
-------
APPENDIX B
LIST OF IWEM WASTE CONSTITUENTS AND DEFAULT
CHEMICAL PROPERTY DATA
-------
Constituent Chemical Properties
CAS
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
Chemical Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz {a} anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene, 1,3-
Molecular Weight
(g/mol) (a)
154.2
44.1
58.1
41.1
120.2
56.1
71.1
72.1
53.1
364.9
58.1
93.1
178.2
121.8
74.9
137.3
228.3
78.1
184.2
252.3
252.3
108.1
126.6
9.0
143.0
171.1
390.6
163.8
94.9
54.1
Solubility
(mg/L) (b)
4.24
l.OOE+06
l.OOE+06
l.OOE+06
6.13E+03
2.13E+05
6.40E+05
l.OOE+06
7.40E+04
0.18
l.OOE+06
3.60E+04
0.0434
l.OOE+06
l.OOE+06
l.OOE+06
9.40E-03
1.75E+03
500
1.62E-03
1.50E-03
4.00E+04
525
l.OOE+06
1.72E+04
1.31E+03
0.34
6.74E+03
1.52E+04
735
Log Koc
(Log(ml/g)) (c)
3.75
-0.21
-0.59
-0.71
1.26
-0.22
-0.99
-1.84
-0.089
6.18
1.47
0.60
4.21
0
0
0
5.34
1.80
1.26
5.80
5.80
0.78
2.84
0
0.80
2.39
7.13
1.77
0.76
2.06
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
0
0
31.5
0
500
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Neutral (Kn)
(1/yr)
0
0
0
0
0
6.68E+08
0.018
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
410
0
0.23
0
0
0
9.46
0
Base Catalyzed
(Kb)(l/mol/yr)
0
0
0
45
0
0
0
0
5.20E+03
0
0
0
0
0
0
0
0
0
0
0
0
0
1.40E+03
5.00E+04
0
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0426
0.0363
0.0445
0.0385
0.0397
0.0378
0.0388
0.0184
0.0319
0.0186 (i)
0.0325
0.0239
0.0208
0.0174 (i)
0.0278
0.0275
0.0233
0.0132
0.0337
0.0426
0.0325
B 1
-------
Constituent Chemical Properties
CAS
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
218019
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
Chemical Name
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro- 1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene, 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT, p,p'-
Molecular Weight
(g/mol) (a)
74.1
312.4
240.2
112.4
76.1
153.8
409.8
88.5
127.6
112.6
325.2
208.3
64.5
119.4
50.5
128.6
76.5
52.0
52.0
228.3
58.9
63.5
108.1
108.1
108.1
324.4
120.2
100.2
98.1
320.0
318.0
354.5
Solubility
(mg/L) (b)
7.40E+04
2.69
52
l.OOE+06
1.19E+03
793
0.056
1.74E+03
5.30E+03
472
11
2.60E+03
5.68E+03
7.92E+03
5.33E+03
2.20E+04
3.37E+03
l.OOE+06
l.OOE+06
1.60E-03
l.OOE+06
l.OOE+06
2.27E+04
2.60E+04
2.15E+04
2.34E+04
61
4.30E+04 (e)
5.00E+03
0.090
0.12
0.025
Log Koc
(Log(ml/g)) (c)
0.50
4.23
2.02
0
1.84
2.41
5.89
1.74
1.61
2.58
4.04
1.91
0.51
1.58
0.91
1.82
1.13
0
0
5.34
0
0
1.76
1.76
1.76
2.12
3.40
1.11
1.82
5.89
6.64
6.59
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Neutral (Kn)
(1/yr)
0
0
0
0
0
0.017
0
0
0
0
0
0
0
l.OOE-04
0
0
40
0
0
0
0
0
0
0
0
0
0
0
0
0.025
0
0.060
Base Catalyzed
(Kb)(l/mol/yr)
0
1.20E+05
0
3.15E+04
0
38
0
0
0
2.80E+06
2.50E+04
0
2.74E+03
0
0
0
0
0
0
0
0
0
0
0
2.20E+04
0
3.10E+05
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0410
0.0308
0.0172
0.0315
0.0299
0.0173
0.0334
0.0366
0.0344
0.0429
0.0299
0.0341
0.0213
0.0294
0.0311
0.0291
0.0299
0.0248
0.0295
0.0140
B2
-------
Constituent Chemical Properties
CAS
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
57976
119937
105679
84742
99650
51285
121142
606202
117840
Chemical Name
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropanel,2-
Dichlorobenzene 1 ,2-
Dichlorobenzene 1 ,4-
Dichlorobenzidine3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1 ,2-
Dichloroethylene cis-1,2-
Dichloroethylene trans- 1 ,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene l,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropene trans- 1 ,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Molecular Weight
(g/mol) (a)
270.2
278.4
236.3
147.0
147.0
253.1
120.9
99.0
99.0
96.9
96.9
96.9
163.0
221.0
113.0
111.0
111.0
111.0
380.9
222.2
268.4
229.2
0.0
256.3
212.3
122.2
278.3
168.1
184.1
182.1
182.1
390.6
Solubility
(mg/L) (b)
40
2.49E-03
1.23E+03
156
74
3.11
280
5.06E+03
8.52E+03
3.50E+03
6.30E+03
2.25E+03
4.50E+03
677
2.80E+03
2.80E+03
2.72E+03
2.72E+03
0.20
1.08E+03
0.10
2.50E+04
60
0.025
1.30E+03
7.87E+03
11.2
861
2.79E+03
270
182
0.020
Log Koc
(Log(ml/g)) (c)
4.17
6.52
1.94
3.08
3.05
3.32
2.16
1.46
1.13
1.70
1.60
1.79
2.49
0.68
1.67
1.43
1.80
1.80
5.08
1.99
4.09
0.13
1.49
6.64
2.55
2.29
4.37
1.31
-0.09
1.68
1.40
7.60
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Neutral (Kn)
(1/yr)
0.10
0
4.00E-03
0
0
0
0
0.011
9.61E-03
0
0
0
0
0
0
0
40
40
0.063
0
0
1.68
0
0
0
0
0
0
0
0
0
0
Base Catalyzed
(Kb)(l/mol/yr)
8.00E+03
0
1.20E+05
0
0
0
0
0.38
55
0
0
0
0
0
0
0
0
0
0
3.10E+05
0
4.48E+06
0
0
0
0
1.80E+06
0
0
0
0
5.20E+05
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0190
0.0281
0.0281
0.0274
0.0173 (i)
0.0341
0.0334
0.0344
0.0347
0.0307
0.0319
0.0322
0.0319
0.0190
0.0172 (i)
0.0249
B3
-------
Constituent Chemical Properties
CAS
123911
122394
122667
298044
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
Chemical Name
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine, 1,2-
Disulfoton
Endosulfan (Endosulfan I and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane, 1,2-
Ethoxyethanol 2-
Ethoxyethanol acetate, 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro- 1 ,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Molecular Weight
(g/mol) (a)
88.1
169.2
184.2
274.4
406.9
380.9
92.5
72.1
90.1
132.2
88.1
74.1
114.1
124.2
106.2
187.9
62.1
44.1
102.2
202.3
19.0
30.0
46.0
96.1
290.8
290.8
290.8
373.3
389.3
260.8
284.8
272.8
Solubility
(mg/L) (b)
l.OOE+06
36
68
16
0.51
0.25
6.59E+04
9.50E+04 (e)
l.OOE+06
2.29E+05 (g)
8.03E+04
5.68E+04
3.67E+03
6.30E+03
169
4.18E+03
l.OOE+06
l.OOE+06 (a)
6.20E+04
0.21
5.50E+05
l.OOE+06
1.10E+05
0.24
6.8
2
0.18
0.2
3.23
5.00E-03
1.8
Log Koc
(Log(ml/g)) (c)
-0.81
3.30
2.82
2.94
3.55
4.60
-0.53
0.90
-0.54
0.70
0.35
0.55
1.27
-0.27
3.00
1.42
-1.50
-1.10
0
4.63
-1.30
-2.70
0.80
3.43
3.4
3.43
5.21
4.9
4.46
5.41
4.72
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
0
0
2.50E+04
0
0
0
3.50E+03
0
0
0
0
0
0
2.90E+05
0
0
0
0
0
0
0
0
0
0
0
0
0
Neutral (Kn)
(1/yr)
0
0
0
2.30
0
0.055
31
0
0
0
4.80E-03
0
0
1.25E+03
0
0.63
0
21
0
0
0
0
0
0
1.05
0
61
0.063
0
0
25
Base Catalyzed
(Kb)(l/mol/yr)
0
0
0
5.40E+04
0
0
0
0
0
3.40E+06
0
1.10E+06
0
0
0
0
0
0
0
0
0
0
0
1.73E+06
0
0
0
0
0
0
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0331
0.0229
0.0350
0.0331
0.0308
0.0252
0.0267
0.0331
0.0429
0.0460
0.0319 (i)
0.0549
0.0337
0.0233
0.0230
0.0232
0.0180
0.0176
0.0222
0.0248
0.0228
B4
-------
Constituent Chemical Properties
CAS
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
110496
109864
78933
108101
80626
298000
1634044
56495
74953
75092
7439987
68122
91203
7440020
98953
79469
Chemical Name
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane, n-
Hydrogen Sulfide
Indeno{ l,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate, 2-
Methoxyethanol, 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
N,N-Dimethyl formamide [DMF]
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Molecular Weight
(g/mol) (a)
374.9
390.9
236.7
406.9
86.2
34.1
276.3
74.1
138.2
490.6
207.2
54.9
200.6
67.1
32.0
345.7
118.1
76.1
72.1
100.2
100.1
263.2
88.1
268.4
173.8
84.9
95.9
73.1
128.2
58.7
123.1
89.1
Solubility
(mg/L) (b)
8.25E-06 (f)
4.00E-06 (f)
50
140
12
437
2.20E-05
8.50E+04
1.20E+04
7.6
l.OOE+06
l.OOE+06
0.056 (h)
2.54E+04
l.OOE+06
0.045
l.OOE+06 (g)
l.OOE+06 (a)
2.23E+05
1.90E+04
1.50E+04
55
5.13E+04 (e)
3.23E-03
1.19E+04
1.30E+04
l.OOE+06
l.OOE+06 (e)
31
l.OOE+06
2.09E+03
1.70E+04
Log Koc
(Log(ml/g)) (c)
7.00
6.38
3.61
5.00
2.95
6.26
0.44
1.90
4.15
0
0
0.22
-1.08
4.90
0
0.95
-0.03
0.87
0.74
2.47
1.05
7.00
1.21
0.93
0
-0.99
3.11
0
1.51
0.23
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
0
0
0
0
0
0
0
0
500
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Neutral (Kn)
(1/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.69
0
0
0
0
0
2.80
0
0.017
0
l.OOE-03
0
0
0
0
0
0
Base Catalyzed
(Kb)(l/mol/yr)
0
0
0
0
0
0
0
0
0
0
5.20E+03
0
1.20E+04
0
0
0
0
0
0
0
0
0
0.60
0
0
0
0
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0133 (i)
0.0130 (i)
0.0280
0.0256
0.0164 (i)
0.0237
0.0949
0.0334
0.0520
0.0275
0.0347
0.0322
0.0264
0.0292
0.0272
0.0194
0.0394
0.0353
0.0264
0.0298
0.0322
B5
-------
Constituent Chemical Properties
CAS
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
Chemical Name
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitroso-di-n-butylamine
N-Nitroso-di-n-propylamine
N-Nitrosodiphenylamine
N-Nitrosomethylethylamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine, 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran, 2,3,7,8-
Molecular Weight
(g/mol) (a)
102.1
74.1
158.2
130.2
198.2
88.1
114.1
100.1
286.3
291.3
250.3
340.4
356.4
295.3
266.3
94.1
336.7
108.1
260.4
148.1
256.1
58.1
202.3
79.1
162.2
79.0
107.9
334.4
104.2
215.9
306.0
Solubility
(mg/L) (b)
9.30E+04
l.OOE+06
1.27E+03
9.89E+03
35.1
1.97E+04
7.65E+04
l.OOE+06
l.OOE+06
6.54
1.33
2.36E-04 (f)
1.18E-04 (f)
0.55
1.95E+03
8.28E+04
2.00E+03
2.55E+06
50
6.20E+03
0.070
33
4.05E+05 (e)
0.14
l.OOE+06
811
l.OOE+06
l.OOE+06
160.00
310
0.60
6.92E-04 (f)
Log Koc
(Log(ml/g)) (c)
-0.03
0.45
2.09
1.03
2.84
1.03
-0.02
-0.57
-0.51
3.15
5.39
4.93
6.3
4.57
3.06
1.23
0
-0.30
2.64
1.56
6.19
2.63
1.40
4.92
0.34
2.34
0
0
1.90
2.84
4.28
6.62
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
0
0
0
0
1.90E+03
0
0
0
0
0
0
0
0
0
0
0
0
59
0
0
0
0
0
0
0
0
0
0
Neutral (Kn)
(1/yr)
0
0
0
0
0
0
0
0
0
2.40
0
0
0
0
0
0
0
0
62
4.90E+05
0
0
0
0
0
0
0
0
0
0
0
0
Base Catalyzed
(Kb)(l/mol/yr)
0
0
0
0
0
0
0
0
0
3.70E+06
0
0
0
0
0
0
0
0
0
0
0
610
0
0
0
0
0
0
0
0
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0288
0.0363
0.0215
0.0245
0.0227
0.0315
0.0290
0.0319
0.0142 (i)
0.0138 (i)
0.0253
0.0325
0.0307
0.0189
0.0382
0.0344
0.0278
0.0153 (i)
B6
-------
Constituent Chemical Properties
CAS
1746016
630206
79345
127184
58902
3689245
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
Chemical Name
Tetrachlorodibenzo-p-dioxin, 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram]
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-l,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Molecular Weight
(g/mol) (a)
322.0
167.8
167.8
165.8
231.9
322.3
204.4
240.4
92.1
122.2
107.2
107.2
252.7
187.4
181.4
133.4
133.4
131.4
137.4
197.4
197.4
269.5
255.5
147.4
101.2
213.1
697.6
50.9
86.1
62.5
106.2
Solubility
(mg/L) (b)
7.91E-06 (f)
1.10E+03
2.97E+03
200
100
25
l.OOE+06
30
526
3.37E+04
1.66E+04
782
0.74
3.10E+03
170
35
1.33E+03
4.42E+03
1.10E+03
1.10E+03
1.20E+03
800
140
268
1.75E+03
5.50E+04 (e)
350
8
l.OOE+06
2.00E+04
2.76E+03
161
Log Koc
(Log(ml/g)) (c)
6.10
2.71
2.07
2.21
2.32
3.51
0
2.83
2.43
0.02
1.24
1.24
4.31
2.05
2.97
3.96
2.16
1.73
2.10
2.11
2.93
2.25
1.74
1.43
1.66
1.79
1.05
3.19
0
0.45
1.04
3.09
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Neutral (Kn)
(1/yr)
0
0.014
5.10E-03
0
0
84
0
0
0
0
0
0
0.070
0
0
0
0.64
2.73E-05
0
0
0
0
0
0
0.017
0
0
0.088
0
0
0
0
Base Catalyzed
(Kb)(l/mol/yr)
0
1.13E+04
1.59E+07
0
0
9.00E+06
0
0
0
0
0
2.80E+04
l.OOE+04
0
0
2.40E+06
4.95E+04
0
0
0
0
0
0
3.60E+03
0
0
3.00E+05
0
0
0
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0148 (i)
0.0287
0.0293
0.0298
0.0291
0.0282 (i)
0.0290
0.0173
0.0328
0.0271
0.0265
0.0303
0.0315
0.0322
0.0319
0.0255
0.0291
0.0247
0.0315
0.0378
0.0267
B7
-------
Constituent Chemical Properties
CAS
95476
106423
1330207
7440666
Chemical Name
Xylene o-
Xylene p-
Xylenes (total)
Zinc
Molecular Weight
(g/mol) (a)
106.2
106.2
318.5
65.4
Solubility
(mg/L) (b)
178
185
175
l.OOE+06
Log Koc
(Log(ml/g)) (c)
3.02
3.12
3.08
0
Hydrolysis Rate Constants (c)
Acid
Catalyzed (Ka
)(l/mol/yr)
0
0
0
0
Neutral (Kn)
(1/yr)
0
0
0
0
Base Catalyzed
(Kb)(l/mol/yr)
0
0
0
Diffusion
Coefficient in
Water (Dw)
(m2/yr) (d)
0.0270
0.0266
0.0268
Note: Data sources for chemical property values are indicated in the column headings; exceptions are noted in parentheses for individual chemical values.
Data sources:
a. http://chemfmder.cambridgesoft.com (CambridgeSoft Corporation, 2001)
b. USEPA. 1997b. Superfund Chemical Data Matrix (SCDM). SCDMWIN 1.0 (SCDM Windows User's Version), Version 1. Office of Solid Waste and Emergency Response,
Washington DC: GPO. http://www.epa.gov/superfund/resources/scdm/index.htm. Accessed July 2001
c. Kollig, H. P. (ed.). 1993. Environmental fate consultants for organic chemicals under consideration for EPA's hazardous waste identification projects. Environmental
Research Laboratory, Office of R&D, USEPA, Athens, GA.
d. Calculated based on Water 9. USEPA. 2001. Office of Air Quality Planning and Standards, Research Triangle Park, NC. http://www.epa.gov/ttn/chief/software/water/index.html.
Accessed July 2001.
e. Sycracuse Research Corporation (SRC). 1999. CHEMFATE Chemical Search, Environmental Science Center, Syracuse, NY. http://esc.syrres.com/efdb/Chemfate.htm.
Accessed July 2001.
f. Calculated based on USEPA. 2000. Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds, Part 1, Vol. 3.
Office of Research and Development, Washington, DC: GPO.
g. USNLM (U.S. National Library of Medicine). 2001. Hazardous Substances Data Bank (HSDB). http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen7HSDB. Accessed July 2001.
h. Budavari, S. (ed). 1996. The Merck Index: An Encyclopedia of Chemicals, Drugs and Biologicals. 12th edition. Whitehouse Station, NJ: Merck and Co.
i. Calculated based on USEPA. 1987. Process Coefficients and Models for Simulating Toxic Organics and Heavy Metals in Surface Waters. Office of Research and Development.
Washington, DC: US Government Printing Office (GPO).
B8
-------
APPENDIX C
TIER 1 INPUT PARAMETERS
-------
Table C.I: IWEM Tier 1 Input Parameters for Landfill, No Liner Scenario
Input
Type
8
!
Unsaturated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS11
SS12
SS13
FS1
SS15
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Duration of Leaching
Fraction of Landfill Occupied by Waste of
Concern
Depth of Waste Disposal Facility
Density of Hazardous Waste
Katio of Waste Concentration to Leachate
Concentration
Base Depth Below Grade
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsaturated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Derived
Constant
Regional Site-Based
Empirical
Constant
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
unitless
m
g/cm3
L/kg
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles2
0
40.5
6.36
1 .OOE-05
1 .OOE-05
9,340
10
486
22.0
0.0135
0.0135
48,200
25
2,430
49.3
0.0686
0.0658
94,500
50
12,100
110
0.122
0.109
199,000
75
52,600
229
0.308
0.274
521,000
90
142,000
376
0.438
0.411
1,810,000
100
3,120,000
1,770
1.15
1.08
1.20E+10
1.00
0.510
0.700
0.880
0.737
1.32
0.794
2.57
0.889
4.09
1.33
6.13
1.45
10.1
2.10
10000
0.00
0.00377
0.129
1.03
0.0106
0.410
0.305
0.0267
0.00358
1.60
0.594
0.596
1.20
0.0489
0.410
1.68
0.0570
0.0341
1.60
2.04
0.935
1.27
0.0609
0.430
3.96
0.107
0.0567
1.65
7.80
1.52
1.37
0.0746
0.450
6.10
0.154
0.1020
1.65
35.0
2.71
1.53
0.0857
0.450
15.2
0.354
0.177
1.67
169
5.90
1.82
0.0937
0.450
42.7
0.959
0.289
1.67
2,450
21.8
2.50
0.115
0.450
610
1.00
1.69
1.67
chemical-specific value
1.00
chemical-specific value
0.00
0.0004
0.0501
1.16
0.305
3.15
0.0015
0.107
1.30
4.27
174
0.00557
0.164
1.43
7.62
804
0.0191
0.236
1.56
14.3
1,890
0.0409
0.296
1.63
32.4
11,000
0.0762
0.334
1.70
91.4
31,500
0.211
0.426
1.80
914
4,290,000
1.00
0.000002
0.100
0.0009
3.15
0.002
16.3
0.0057
55.0
0.0151
321
0.0310
1,320
0.491
11,000
chemical-specific value
0.109
0.0136
0.00500
7.50
3.21
0.0000164
0.928
0.116
0.00580
7.50
5.17
0.000132
2.72
0.340
0.0170
12.5
6.05
0.000234
6.18
0.773
0.0387
12.5
6.81
0.000433
9.76
1.22
0.0610
17.5
7.41
0.000810
14.5
1.81
0.0903
22.5
7.92
0.00139
40.0
4.99
0.250
22.5
9.70
0.00984
150
0.00
0.00321
0.945
2.52
6.42
16.4
47.0
897
chemical-specific va ue
1.00
chemical-specific va ue
0.00
References
USEPA, 1986 and 1997b
Derived
ABB, 1995 and USEPA, 1997b
ABB, 1995 and USEPA, 1997b
USEPA, 2001
Policy for Tier 1
USEPA, 1986 and 1997b
Schanz and Salhotra, 1992
Policy for Tier 1
No data available
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1988
Carsel and others, 1 988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among the
three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.2: IWEM Tier 1 Input Parameters for Surface Impoundment, No Liner Scenario
Input
Type
8
!
Unsatu rated Zone
Saturated Zone
Saturated Zone (cont'd)
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS15
SS7
SS16
SS22
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Operational Life (Duration of Leaching)
Base Depth Below Grade
Waste Water Ponding Depth
Sediment Thickness (Thickness of Sludge)
Distance to Nearest Surface Water Body
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsaturated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Constant
DBGS
HZERO
DSLUDGE
DISSW
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
m
m
m
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles2
0
9.30
3.05
0.0000100
3.78E-15
4.00
0.00
0.0100
10
174
13.2
0.00990
0.270
15.0
0.00
0.460
25
401
20.0
0.0465
0.521
50.0
0.00
0.993
50
1,770
42.1
0.144
1.14
50.0
1.22
1.81
75
6,970
83.5
0.269
2.27
50.0
3.05
2.95
90
28,300
168
0.377
3.51
50.0
4.57
4.24
100
4,860,000
2,200
1.84
22.3
95.0
33.5
18.2
0.20
0.00
0.00224
0.104
1.03
0.00997
0.410
0.305
0.0267
0.00285
1.60
90.0
0.318
0.516
1.18
0.0525
0.410
2.74
0.0803
0.0316
1.60
240
1.08
0.801
1.23
0.0674
0.430
4.27
0.114
0.0552
1.65
360
4.94
1.36
1.31
0.0812
0.430
9.14
0.22
0.100
1 .6700
800
43.8
3.19
1.61
0.0905
0.430
15.2
0.354
0.181
1.67
5,000
301
7.88
1.91
0.0976
0.450
35.4
0.799
0.302
1.67
5,000
2,420
22.3
2.43
0.115
0.450
610
1.00
1.98
1.67
chemical-specific value
1.00
chemical-specific value
0.00
0.000400
0.0500
1.16
0.305
3.15
0.00145
0.108
1.29
4.57
126
0.00546
0.162
1.43
7.62
315
0.0196
0.233
1.56
15.2
2,210
0.0418
0.294
1.63
30.5
9,780
0.0777
0.333
1.70
79.3
24,800
0.211
0.430
1.80
914
7,660,000
1.00
5.00E-07
0.100
0.000508
2.48
0.00200
11.1
0.00670
43.4
0.0141
227
0.0330
814
0.538
10,800
chemical-specific value
0.104
0.0130
0.00500
7.5
3.20
0.0000128
0.802
0.100
0.00501
7.5
5.21
0.000135
2.44
0.305
0.0152
12.5
6.06
0.000235
5.71
0.714
0.0357
17.5
6.81
0.000430
9.01
1.13
0.0563
17.5
7.42
0.000790
15.6
1.95
0.0976
17.5
7.91
0.00137
40.0
5.00
0.250
27.5
9.69
0.0120
150
0.00
0.000126
0.953
2.49
6.04
15.2
39.4
904
chemical-specific va ue
1.00
chemical-specific va ue
0.00
References
USEPA, 2001
Derived
ABB 1995 and USEPA, 1997b
Derived
USEPA, 2001
USEPA, 2001
USEPA, 2001
Assumption
USEPA, 2001
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985;
Carsel and others, 1 988
Carsel and others, 1 988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA'STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among the
three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.3: IWEM Tier 1 Input Parameters for Waste Pile, No Liner Scenario
Input
Type
o
£J
$
Unsatu rated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS15
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
ASH
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Operational Life (Duration of Leaching)
Base Depth Below Land Surface
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsatu rated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm (soil/water distribution coeff)
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Constant
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles 2
0
5.06
2.25
0.00001
0.0003
10
20.2
4.49
0.0508
0.0602
25
20.2
4.49
0.0787
0.128
50
121
11.0
0.145
0.255
75
1,210
34.8
0.282
0.391
90
4,170
64.6
0.417
0.538
100
1,940,000
1,390
1.84
1.82
20.0
0.00
0.00347
0.120
1.02
0.0114
0.410
0.305
0.0267
0.00421
1.60
0.617
0.624
1.20
0.0487
0.410
1.83
0.0603
0.0339
1.60
2.10
0.946
1.26
0.0608
0.430
3.96
0.107
0.0569
1.65
8.32
1.55
1.38
0.0742
0.450
7.01
0.174
0.100
1.65
36.2
2.71
1.53
0.0854
0.450
15.2
0.354
0.175
1.67
165
5.76
1.82
0.0934
0.450
36.6
0.825
0.294
1.67
2,400
20.2
2.52
0.114
0.450
610
1.00
3.56
1.67
chem cal-specific value
1.00
chemical-specific value
0.00
0.000401
0.0501
1.16
0.305
3.15
0.00153
0.105
1.30
3.60
126
0.00549
0.161
1.43
7.38
317
0.0193
0.235
1.56
15.2
1,890
0.0408
0.297
1.63
33.5
11,000
0.0740
0.335
1.69
91.4
31,500
0.212
0.421
1.80
914
6,750,000
1.00
0.000002
0.101
0.0009
2.69
0.00200
10.8
0.00570
46.8
0.0170
272
0.0330
1,260
0.301
10,900
chem cal-specific value
0.101
0.0126
0.00500
7.50
3.21
0.0000128
0.848
0.106
0.00530
7.50
5.20
0.000132
2.50
0.313
0.0156
12.5
6.07
0.000237
5.59
0.699
0.0350
12.5
6.81
0.000437
8.71
1.09
0.0544
17.5
7.41
0.000794
14.7
1.83
0.0916
22.5
7.90
0.00137
40.0
5.00
0.250
22.5
9.69
0.00998
150
0.00
0.000308
0.868
2.44
6.27
16.9
47.7
892
chem cal-specific value
1.00
chemical-specific value
0.00
References
USEPA, 1986 and 1997b
Derived
ABB, 1995 and USEPA, 1997b
ABB, 1995 and USEPA, 1997b
USEPA, 1996
Assumption of waste pile design
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1988
Carsel and others, 1 988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorterand Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among
the three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.4: IWEM Tier 1 Input Parameters for Land Application Unit Scenario
Input
Type
Source
Unsaturated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS15
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Operational Life (Duration of Leaching)
Base Depth Below Grade
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsaturated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Constant
Lognormal
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles 2
0
20.2
4.49
0.00001
0.00001
10
40.5
6.36
0.0104
0.0130
25
4,050
63.6
0.0686
0.0704
50
40,500
201
0.110
0.110
75
182,000
427
0.212
0.201
90
648,000
805
0.326
0.326
100
80,900,000
8,990
0.745
0.745
40.0
0.00
0.00224
0.0926
1.04
0.0126
0.410
0.305
0.0267
0.00418
1.60
0.586
0.605
1.20
0.0498
0.410
2.13
0.0669
0.0346
1.60
2.01
0.929
1.26
0.0613
0.430
4.57
0.121
0.0578
1.65
7.80
1.51
1.37
0.0749
0.450
8.53
0.208
0.102
1.65
33.8
2.59
1.51
0.0862
0.450
18.3
0.423
0.175
1.67
147
5.41
1.78
0.0942
0.450
45.7
1.00
0.291
1.67
2,510
20.8
2.55
0.115
0.450
610
1.00
1.96
1.67
chemical-specific va ue
1.00
chemical-specific va ue
0.00
0.000402
0.0501
1.16
0.305
3.15
0.00143
0.105
1.29
3.96
94.6
0.00545
0.162
1.43
7.62
315
0.0195
0.235
1.56
19.5
2,190
0.0408
0.295
1.63
53.3
11,000
0.0778
0.334
1.70
144
31,500
0.212
0.427
1.80
914
6,310,000
1.00
0.000002
0.100
0.000556
2.34
0.00200
9.93
0.00800
50.2
0.0223
316
0.0430
1,210
0.430
10,900
chemical-specific va ue
0.108
0.0134
0.00500
7.50
3.21
0.0000149
1.02
0.128
0.00639
7.50
5.20
0.000130
2.99
0.374
0.0187
12.5
6.07
0.000229
6.70
0.838
0.0419
12.5
6.82
0.000421
10.7
1.34
0.0669
17.5
7.42
0.000781
16.1
2.02
0.101
17.5
7.89
0.00133
40.0
5.00
0.250
22.5
9.69
0.0120
150
0.00
0.0000963
1.03
2.83
7.95
21.7
60.1
882
chemical-specific va ue
1.00
chemical-specific va ue
0.00
References
USEPA, 1986 and 1997b
Derived
ABB, 1995 and USEPA, 1997b
ABB, 1995 and USEPA, 1997b
US EPA, 1996
Assumption of LAU Design
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1988
Carsel and others, 1988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada, 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI 1985; Gelhar, 1986; Gelhar, 1992
EPRI 1985; Gelhar, 1986; Gelhar, 1992
EPRI 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA's STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among the
three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 6,557 iterations.
-------
Table C.5: IWEM Tier 1 Input Parameters for Landfill, Single Liner Scenario
Input
Type
Source
Unsatu rated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS11
SS12
SS13
FS1
SS15
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Duration of Leaching
Fraction of Landfill Occupied by Waste of
Concern
Depth of Waste Disposal Facility
Density of Hazardous Waste
Ratio of Waste Concentration to Leachate
Concentration
Base Depth Below Grade
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsaturated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Derived
Constant
Regional Site-Based
Empirical
Constant
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
unitless
m
g/cm3
L/kg
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles2
0
40.5
6.36
0.00001
0.00001
81,100
10
567
23.8
0.0135
0.00944
228,000
25
2,480
49.8
0.0686
0.0253
376,000
50
12,100
110
0.130
0.0432
728,000
75
54,600
234
0.312
0.0445
1,370,000
90
149,000
386
0.446
0.0486
2,930,000
100
3,120,000
1,770
1.15
0.0526
1.63E+10
1.00
0.510
0.700
0.883
0.737
1.32
0.794
2.58
0.889
4.09
1.33
6.14
1.45
10.1
2.10
10000
0.00
0.00377
0.129
1.04
0.0106
0.410
0.305
0.0267
0.00358
1.60
0.598
0.595
1.20
0.0489
0.410
1.68
0.0570
0.0340
1.60
2.06
0.935
1.27
0.0611
0.430
3.96
0.107
0.0568
1.65
7.79
1.52
1.37
0.0746
0.450
6.10
0.154
0.101
1.65
35.0
2.72
1.53
0.0857
0.450
15.2
0.354
0.177
1.67
169
5.92
1.82
0.0937
0.450
36.6
0.825
0.288
1.67
2,450
21.8
2.50
0.115
0.450
610
1.00
1.69
1.67
chemical-specific value
1.00
chemical-specific value
0.00
0.000400
0.0501
1.16
0.305
3.15
0.00151
0.107
1.30
4.03
141
0.00558
0.164
1.43
7.62
631
0.0192
0.236
1.56
12.2
1,890
0.0411
0.295
1.63
32.0
11,000
0.0765
0.334
1.70
91.4
31,500
0.211
0.426
1.80
914
4,290,000
1.00
0.000002
0.100
0.0009
2.97
0.002
14.5
0.00570
52.2
0.0153
297
0.0310
1,280
0.491
11,000
chemical-specific value
0.109
0.0136
0.005
7.50
3.21
0.0000164
0.916
0.114
0.00572
7.50
5.18
0.000131
2.71
0.338
0.0169
12.5
6.05
0.000234
6.15
0.769
0.0385
12.5
6.82
0.000434
9.72
1.22
0.0608
17.5
7.41
0.000810
14.4
1.80
0.0899
22.5
7.93
0.00139
40.0
4.99
0.250
22.5
9.70
0.00984
150
0.00
0.00321
0.944
2.49
6.27
16.1
46.3
897
chemical-specific va ue
1.00
chemical-specific va ue
0.00
References
USEPA, 1986 and 1997b
Derived
ABB, 1995 and USEPA, 1997b
USEPA, 1999
USEPA, 2001
Dolicy for Tier 1
USEPA, 1986 and 1997b
Schanz and Salhotra, 1992
Dolicy for Tier 1
Mo data available
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1 988
Carsel and others, 1 988
Derived
Assumption
Derived
Dolicy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA STORET database
USEPA STORET database
Dolicy for Tier 1
Dolicy for Tier 1
API, 1989
Derived
Assumption
Derived
Dolicy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among the
three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.6: IWEM Tier 1 Input Parameters for Surface Impoundment, Single Liner Scenario
Input
Type
a
(8
Unsatu rated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS15
SS7
SS16
SS22
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Operational Life (Duration of Leaching)
Base Depth Below Grade
Waste Water Ponding Depth
Total Impoundment Operating Depth
Sediment Thickness (Thickness of Sludge)
Distance to Nearest Surface Water Body
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsaturated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Constant
DBGS
HZERO
DEPTH
DSLUDGE
DISSW
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
m
m
m
m
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles2
0
9.30
3.05
1.00E-05
3.78E-15
4.00
0.00
0.0100
10
192
13.8
0.00990
0.042
15.0
0.00
0.460
25
581
24.1
0.0465
0.0629
50.0
0.00
1.06
50
1,860
43.1
0.147
0.108
50.0
1.52
1.83
75
7,810
88.4
0.269
0.163
50.0
3.05
3.09
90
29,800
173
0.377
0.217
50.0
4.57
4.27
100
4,860,000
2,200
1.84
0.798
95.0
33.5
18.2
4.63
0.20
0.00
0.00224
0.0983
1.02
0.00997
0.410
0.305
0.0267
0.00254
1.60
90.0
0.347
0.524
1.18
0.0522
0.410
2.44
0.0737
0.0314
1.60
240
1.20
0.815
1.23
0.0669
0.430
3.70
0.101
0.0550
1.65
chem
360
5.56
1.39
1.31
0.0809
0.430
7.62
0.188
0.0994
1.67
850
49.6
3.31
1.63
0.0904
0.430
15.2
0.354
0.180
1.67
1,800
308
7.97
1.92
0.0976
0.450
30.5
0.691
0.299
1.67
5,000
2,420
22.3
2.43
0.115
0.450
610
1.00
1.98
1.67
cal-specific value
1.00
chem cal-specific value
0.00
0.000400
0.0500
1.16
0.305
3.15
0.00145
0.107
1.29
3.66
108
0.00540
0.162
1.43
7.32
315
0.0195
0.232
1.56
13.7
2,210
0.0415
0.294
1.63
30.0
6,940
0.0780
0.334
1.70
76.2
22,100
0.211
0.430
1.80
914
7,660,000
1.00
5.00E-07
0.100
0.000700
2.11
0.00200
9.36
chem
0.107
0.0134
0.00500
7.5
3.20
0.0000128
0.808
0.101
0.00505
7.5
5.20
0.000136
2.49
0.311
0.0156
12.5
6.07
0.000236
0.00700
34.1
0.0150
193
0.0330
723
0.538
10,800
cal-specific va ue
5.78
0.723
0.0361
17.5
6.82
0.000433
9.06
1.13
0.0566
17.5
7.43
0.000794
15.5
1.94
0.0969
17.5
7.91
0.00137
40.0
5.00
0.250
27.5
9.68
0.0103
150
0.00
0.000126
0.884
2.37
5.70
14.0
35.8
794
chem cal-specific va ue
1.00
chem cal-specific va ue
0.00
References
USEPA, 2001
Derived
ABB 1995 and USEPA, 1997b
Derived
USEPA, 2001
USEPA, 2001
USEPA, 2001
Derived
Assumption
USEPA, 2001
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1 988
Carsel and others, 1 988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA's STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among the
three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.7: IWEM Tier 1 Input Parameters for Waste Pile, Single Liner Scenario
Input
Type
o
e
$
Unsatu rated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS15
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
ASH
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Duration of Leaching
Base Depth Below Grade
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsatu rated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Constant
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles 2
0
5.06
2.25
0.00001
0.00001
10
20.2
4.49
0.0508
0.0264
25
20.2
4.49
0.0787
0.0950
50
121
11.0
0.145
0.127
75
1,210
34.8
0.282
0.133
90
4,170
64.6
0.417
0.135
100
1,940,000
1,390
1.84
0.136
20.0
0.00
0.00347
0.120
1.02
0.0114
0.410
0.305
0.0267
0.00421
1.60
0.617
0.620
1.20
0.0487
0.410
1.83
0.0603
0.0339
1.60
2.09
0.942
1.26
0.0608
0.430
3.96
0.107
0.0566
1.65
8.26
1.54
1.38
0.0743
0.450
7.01
0.174
0.100
1.65
35.8
2.70
1.53
0.0855
0.450
15.2
0.354
0.175
1.67
163
5.76
1.82
0.0935
0.450
36.6
0.825
0.294
1.67
2,400
20.2
2.52
0.114
0.450
610
1.00
3.56
1.67
chemical-specific value
1.00
chemical-specific value
0.00
0.000401
0.0501
1.16
0.305
3.15
0.00153
0.105
1.30
3.60
126
0.00547
0.161
1.43
7.32
315
0.0192
0.235
1.56
15.2
1,890
0.0408
0.298
1.63
33.2
11,000
0.0738
0.336
1.69
91.4
31,500
0.212
0.421
1.80
914
6,750,000
1.00
0.000002
0.101
0.0009
2.64
0.002
10.5
0.00570
45.7
0.0170
263
0.0330
1,240
0.301
10,900
chemical-specific value
0.101
0.0126
0.00500
7.50
3.21
0.0000128
0.845
0.106
0.00528
7.50
5.19
0.000132
2.50
0.312
0.0156
12.5
6.06
0.000237
5.60
0.700
0.0350
12.5
6.80
0.000437
8.73
1.09
0.0546
17.5
7.41
0.000793
14.8
1.85
0.0925
22.5
7.90
0.00137
40.0
5.00
0.250
22.5
9.69
0.00998
150
0.00
0.000308
0.868
2.43
6.24
16.9
47.4
892
chemical-specific value
1.00
chem cal-specific value
0.00
References
USEPA, 1986 and 1997b
Derived
ABB, 1995 and USEPA, 1997b
USEPA, 1999
USEPA, 1996
Assumption of waste pile design
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1988
Carsel and others, 1 988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorterand Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied amor
the three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.8: IWEM Tier 1 Input Parameters for Landfill, Composite Liner Scenario
Input
Type
Source
Unsaturated Zone
1 Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS11
SS12
SS13
FS1
SS15
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Duration of Leaching
Fraction of Landfill Occupied by Waste of
Concern
Depth of Waste Disposal Facility
Density of Hazardous Waste
Ratio of Waste Concentration to Leachate
Concentration
Base Depth Below Grade
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsaturated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Derived
Constant
Regional Site-Based
Empirical
Constant
Lognormal
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
unitless
m
g/cm3
L/kg
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard un
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles 2
0
40.5
6.36
0.00001
0.00
0.00
10
445
21.1
0.0226
0.00
0.00
25
2,480
49.8
0.0780
0.00
0.00
50
12,100
110
0.143
0.00
0.00
75
54,600
234
0.326
0.0000730
301,000,000
90
134,000
365
0.450
0.000169
1.09E+10
100
3,120,000
1,770
1.15
0.000401
8.33E+12
1.00
0.510
0.700
0.879
0.738
1.31
0.794
2.51
0.888
4.09
1.33
6.41
1.46
10.1
2.10
10000
0.00
0.00463
0.130
1.01
0.0118
0.410
0.305
0.0267
0.00347
1.60
0.608
0.614
1.20
0.0490
0.410
1.68
0.0570
0.0337
1.60
2.06
0.930
1.27
0.0613
0.430
3.96
0.107
0.0566
1.65
8.35
1.54
1.38
0.0747
0.450
6.10
0.154
0.102
1.65
36.7
2.73
1.54
0.0857
0.450
15.2
0.354
0.179
1.67
180
6.15
1.83
0.0937
0.450
36.6
0.825
0.294
1.67
2,390
20.3
2.47
0.115
0.450
610
1.00
1.60
1.67
chemical-specific value
1.00
chemical-specific value
0.00
0.000401
0.0502
1.16
0.305
3.15
0.00151
0.105
1.30
3.96
94.6
0.00538
0.163
1.43
7.62
315
0.0188
0.236
1.55
12.2
1,890
0.0413
0.296
1.63
30.5
11,000
0.0762
0.335
1.70
91.4
31,500
0.211
0.424
1.80
914
8,480,000
1.00
0.000002
0.100
0.001
2.51
0.002
10.5
0.00570
45.6
0.0180
250
0.0330
1,200
0.483
10,800
chemical-specific value
0.111
0.0139
0.00500
7.50
3.20
0.00000858
0.958
0.120
0.00599
7.50
5.20
0.000135
2.91
0.364
0.0182
12.5
6.06
0.000238
6.38
0.797
0.0399
12.5
6.79
0.000443
9.87
1.23
0.0617
17.5
7.39
0.000814
14.7
1.84
0.0921
22.5
7.89
0.00140
40.0
4.99
0.250
22.5
9.70
0.0159
150
0.00
0.000936
0.974
2.48
6.07
15.6
44.4
867
chemical-specific value
1.00
chemical-specific value
0.00
References
USEPA, 1986 and 1997b
Derived
ABB, 1995 and USEPA, 1997b
TetraTech, 2001
USEPA, 2001
Policy for Tier 1
USEPA, 1986 and 1997b
Schanz and Salhotra, 1992
Policy for Tier 1
No data available
Carseland Parrish, 1988
Carseland Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carseland Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1988
Carsel and others, 1988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied
among the three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.9: IWEM Tier 1 Input Parameters for Surface Impoundment, Composite Liner Scenario
Input
Type
Source
Unsatu rated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS15
SS7
SS16
SS22
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Duration of Leaching
Base Depth Below Grade
Waste Water Ponding Depth
Total Impoundment Operating Depth
Sediment Thickness
Distance to Nearest Surface Water Body
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsatu rated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Constant
DBGS
HZERO
DEPTH
DSLUDGE
DISSW
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
m
m
m
m
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percentiles 2
0
9.30
3.05
1.00E-05
0.00
4.00
0.00
0.0100
10
206
14.4
0.00990
0.00
15.0
0.00
0.460
25
609
24.7
0.0465
0.00
50.0
0.00
1.07
50
2,020
45.0
0.168
0.0000488
50.0
1.52
1.83
75
8,760
93.6
0.271
0.000202
50.0
3.38
3.15
90
35,200
188
0.450
0.000498
50.0
4.57
4.27
100
4,860,000
2,200
1.84
0.00369
95.0
33.5
18.2
4.63
0.20
0.00
0.00437
0.109
1.02
0.00851
0.410
0.305
0.0267
0.00366
1.60
105
0.375
0.534
1.18
0.0521
0.410
1.83
0.0603
0.0319
1.60
240
1.28
0.817
1.23
0.0668
0.410
3.35
0.0937
0.0552
1.60
360
6.19
1.42
1.31
0.0809
0.430
6.10
0.154
0.0993
1.67
chemical-specific va
1,000
52.3
3.31
1.64
0.0902
0.430
15.2
0.354
0.180
1.67
2,000
305
8.06
1.93
0.0973
0.450
30.5
0.691
0.304
1.67
5,000
2,520
19.8
2.49
0.115
0.450
610
1.00
2.75
1.67
ue
1.00
chemical-specific va ue
0.00
0.000401
0.0501
1.16
0.305
3.15
0.00143
0.100
1.29
3.53
63.1
0.00538
0.160
1.43
6.10
284
0.0195
0.235
1.56
12.2
1,890
0.0407
0.296
1.63
24.4
5,990
0.0768
0.334
1.70
61.0
21,300
0.212
0.429
1.80
914
7,740,000
1.00
5.00E-07
0.100
0.000700
1.53
0.00200
7.44
0.00700
28.2
chemical-specific va
0.101
0.0126
0.00500
7.5
3.20
0.0000103
0.873
0.109
0.00546
7.5
5.22
0.000136
2.54
0.317
0.0159
12.5
6.08
0.000237
5.84
0.731
0.0365
17.5
6.80
0.000429
0.0151
183
0.0330
680
0.650
11,000
ue
9.11
1.14
0.0569
17.5
7.40
0.000796
13.7
1.72
0.0859
22.5
7.89
0.00135
40.0
5.00
0.250
27.5
9.69
0.00823
150
0.00
0.000118
0.803
2.18
5.38
13.1
31.9
908
chemical-specific va ue
1.00
chemical-specific va ue
0.00
References
USEPA, 2001
Derived
ABB 1995 and USEPA, 1997b
Derived
USEPA, 2001
USEPA, 2001
USEPA, 2001
Derived
Assumption
USEPA, 2001
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1 988
Carsel and others, 1 988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA STORET database
USEPA STORET database
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among th<
three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
Table C.10: IWEM Tier 1 Input Parameters for Waste Pile, Composite Liner Scenario
Input
Type
8
!
Unsatu rated Zone
Saturated Zone
Input
No.
SS1
SS2/3
SS5
SS6
SS10
SS15
US1
US2
US3
US4
US5
use
US7
US8
US9
US10
US11
US12
US13
AS1
AS2
ASS
AS4
ASS
AS6
AS7
ASS
AS9
AS10
AS11
AS12
AS13
AS14
AS15
AS16
AS17
AS20
AS21
AS22
AS23
AS24
Parameter
Area
Length/Width
Recharge Rate
Infiltration Rate
Duration of Leaching
Base Depth Below Grade
Saturated Hydraulic Conductivity
Moisture Retention Parameter (alpha)
Moisture Retention Parameter (beta)
Residual Water Content
Saturated Water Content
Thickness of Unsatu rated Zone
Dispersivity
Percent Organic Matter
Bulk Density
Soil/Water Distribution Coefficient
Freundlich Adsorption Isotherm Exponent
Chemical Degradation Rate Coefficient
Biodegradation Rate Coefficient
Average Particle Diameter
Aquifer Effective Porosity
Aquifer Bulk Density
Aquifer Saturated Thickness
Longitudinal Hydraulic Conductivity
Anisotropy Ratio
Hydraulic Gradient
Seepage Velocity
Retardation Factor
Longitudinal Dispersivity
Transverse Dispersivity
Vertical Dispersivity
Temperature of Ambient Aquifer Water
Ambient Groundwater pH
Fraction of Organic Carbon
Radial Distance of Observation Well from
Downgradient Edge of Waste Unit
Angle Off-Center of Observation Well
Depth of Well Below Water Table
Leading Coefficient of Freundlich Adsorption
Isotherm
Freundlich Adsorption Isotherm Exponent
Hydrolysis Degradation Rate Coefficient
Biodegradation Rate Coefficient
Input
Distribution Type
Regional Site-Based
Derived
Regional Site-Based
Regional Site-Based
Constant
Lognormal 1
Johnson SB 1
Johnson SB 1
Johnson SB 1
Constant
Regional Site-Based
Derived
Johnson SB 1
Constant
Derived
Constant
Derived
Constant
Empirical
Derived
Derived
Regional Site-Based
Regional Site-Based
Constant
Regional Site-Based
Derived
Derived
Gelhar Empirical
Gelhar Empirical
Gelhar Empirical
Regional Site-Based
Empirical
Johnson SB
Constant
Constant
Uniform
Derived
Constant
Derived
Derived
Units
(output)
m
m
m/yr
m/yr
yr
m
m/yr
1/m
unitless
unitless
unitless
m
m
unitless
g/cm3
cm3/g
unitless
1/yr
1/yr
cm
unitless
g/cm3
m
m/yr
unitless
unitless
m/yr
unitless
m
m
m
degrees C
standard units
unitless
m
degrees
m
cm3/g
unitless
1/yr
1/yr
Percent! les 2
0
5.06
2.25
0.00001
0.00
10
20.2
4.49
0.0495
0.00
25
20.2
4.49
0.0787
0.00
50
121
11.0
0.147
0.00
75
1,210
34.8
0.286
0.0000730
90
4,170
64.6
0.419
0.000167
100
2,020,000
1,420
1.68
0.000401
20.0
0.00
0.00684
0.100
1.02
0.0156
0.410
0.305
0.0267
0.00250
1.60
0.611
0.616
1.20
0.0492
0.410
1.68
0.0570
0.0336
1.60
2.04
0.939
1.26
0.0610
0.430
3.96
0.107
0.0570
1.65
8.26
1.53
1.37
0.0745
0.450
6.10
0.154
0.101
1.65
35.5
2.74
1.53
0.0857
0.450
15.2
0.354
0.176
1.67
159
6.00
1.82
0.0937
0.450
34.1
0.770
0.291
1.67
2,520
20.2
2.45
0.115
0.450
610
1.00
2.11
1.67
chemical-specific value
1.00
chemical-specific value
0.00
0.000402
0.0501
1.16
0.305
3.15
0.00149
0.106
1.29
3.73
94.6
0.00563
0.168
1.43
7.32
315
0.0200
0.238
1.56
15.2
1,890
0.0422
0.298
1.64
32.0
11,000
0.0781
0.335
1.70
91.4
31,500
0.211
0.423
1.80
914
4,440,000
1.00
0.000002
0.100
0.000903
2.08
0.00200
8.68
0.00570
42.2
0.0180
245
0.0330
1,210
0.390
10,900
chemical-specific va ue
0.101
0.0126
0.00500
7.50
3.21
0.0000116
0.864
0.108
0.00540
7.50
5.23
0.000133
2.58
0.322
0.0161
12.5
6.08
0.000236
5.60
0.701
0.0350
12.5
6.82
0.000435
8.72
1.09
0.0545
17.5
7.42
0.000809
15.2
1.90
0.0948
22.5
7.93
0.00142
40.0
5.00
.250
22.5
9.68
0.0116
150
0.00
0.00270
0.947
2.45
6.08
16.2
46.0
914
chemical-specific va ue
1.00
chemical-specific va ue
0.00
References
USEPA, 1986 and 1997b
Derived
ABB, 1995 and USEPA, 1997b
Tetra Tech, 2001
USEPA, 1996
Assumption of waste pile design
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
Carsel and Parrish, 1988
API, 1989
Gelhar, 1986; EPRI, 1985; USEPA, 1997a
Carsel and others, 1988
Carsel and others, 1 988
Derived
Assumption
Derived
Policy for Tier 1
Shae, 1974
Davis, 1969; McWorter and Sunada 1977
Freeze and Cherry, 1979
API, 1989
API, 1989
Assumption
API, 1989
Derived
Derived
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
EPRI, 1985; Gelhar, 1986; Gelhar, 1992
Collins, 1925
USEPA STORET
USEPA STORET
Policy for Tier 1
Policy for Tier 1
API, 1989
Derived
Assumption
Derived
Policy for Tier 1
1 The actual distribution type depends upon the soil type; the distribution types given here corespond to the silty loam soil (the most common type). In the Tier 1 modeling runs, soil type is automatically varied among the
three soil types; each soil type has it's own values/distributions of values for the soil parameters. The values presented in this table include all three soil types.
2 Values were generated using a Monte Carlo simulation with 10,000 iterations.
-------
APPENDIX D
INFILTRATION RATE DATA
-------
Table D-l. LF HELP-derived Infiltration Rates (m/yr)
ID
19
98
82
95
62
44
99
7
2
67
75
35
43
41
18
86
93
10
42
74
52
55
51
38
36
3
53
29
32
54
88
23
16
100
28
1
6
27
4
25
77
59
City
Albuquerque
Annette
Astoria
Atlanta
Augusta
Bangor
Bethel
Bismarck
Boise
Boston
Bridgeport
Brownsville
Burlington
Caribou
Cedar City
Central Park
Charleston
Cheyenne
Chicago
Cincinnati
Cleveland
Columbia
Columbus
Concord
Dallas
Denver
Des Moines
Dodge City
E. Lansing
E. St. Louis
Edison
El Paso
Ely
Fairbanks
Flagstaff
Fresno
Glasgow
Grand Island
Grand Junction
Great Falls
Greensboro
Hartford
State
NM
AK
OR
GA
ME
ME
AK
ND
ID
MA
CT
TX
VT
ME
UT
NY
SC
WY
IL
OH
OH
MO
OH
NH
TX
CO
IA
KS
MI
IL
NJ
TX
NV
AK
AZ
CA
KY
NE
CO
MT
NC
CT
No Liner
SLT
0.0000
1.6833
1.0762
0.3416
0.2116
0.1471
0.0564
0.0239
0.0008
0.2332
0.1953
0.0549
0.1359
0.1082
0.0000
0.3363
0.2609
0.0005
0.0798
0.1554
0.0780
0.1529
0.0765
0.1585
0.0599
0.0008
0.1143
0.0135
0.1090
0.1435
0.3122
0.0076
0.0000
0.0104
0.0239
0.0307
0.0099
0.0442
0.0000
0.0036
0.3256
0.1709
SNL
0.0000
1.8354
1.1494
0.3993
0.2700
0.2045
0.0721
0.0300
0.0094
0.2383
0.2464
0.1049
0.1781
0.1491
0.0008
0.4171
0.3287
0.0013
0.1138
0.2210
0.1212
0.1989
0.1158
0.2057
0.1067
0.0008
0.1641
0.0345
0.1452
0.1676
0.3914
0.0130
0.0000
0.0234
0.0630
0.0368
0.0074
0.0627
0.0000
0.0069
0.3896
0.2228
SCL
0.0003
1.4610
0.9647
0.2822
0.1674
0.1227
0.0554
0.0196
0.0038
0.1542
0.1615
0.0384
0.1166
0.0886
0.0000
0.2738
0.2123
0.0086
0.0620
0.1539
0.0823
0.1224
0.0663
0.1372
0.0531
0.0036
0.1156
0.0226
0.1102
0.0704
0.2492
0.0081
0.0003
0.0117
0.0226
0.0381
0.0099
0.0323
0.0003
0.0074
0.2705
0.1405
Clay Liner
0.0000
0.0338
0.0526
0.0477
0.0445
0.0432
0.0295
0.0188
0.0046
0.0445
0.0444
0.0241
0.0432
0.0432
0.0013
0.0486
0.0477
0.0188
0.0432
0.0444
0.0409
0.0409
0.0409
0.0432
0.0241
0.0188
0.0409
0.0094
0.0374
0.0409
0.0486
0.0000
0.0013
0.0094
0.0241
0.0046
0.0188
0.0196
0.0188
0.0432
0.0362
0.0445
D.l-1
-------
Table D-l. LF HELP-derived Infiltration Rates (m/yr)
ID
101
73
66
78
85
96
11
20
87
90
12
69
50
24
97
30
47
65
89
83
92
70
80
33
37
76
71
21
39
84
5
40
64
63
8
49
17
45
13
26
58
14
City
Honolulu
Indianapolis
Ithaca
Jacksonville
Knoxville
Lake Charles
Lander
Las Vegas
Lexington
Little Rock
Los Angeles
Lynchburg
Madison
Medford
Miami
Midland
Montpelier
Nashua
Nashville
New Haven
New Orleans
New York City
Norfolk
North Omaha
Oklahoma City
Orlando
Philadelphia
Phoenix
Pittsburg
Plainfield
Pocatello
Portland
Portland
Providence
Pullman
Put-in-Bay
Rapid City
Rutland
Sacramento
Salt Lake City
San Antonio
San Diego
State
HI
IN
NY
FL
TN
LA
WY
NV
KY
AK
CA
VA
WI
OR
FL
TX
VT
NH
TN
CT
LA
NY
VA
NE
OK
FL
PA
AZ
PA
MA
ID
OR
ME
RI
WA
OH
SD
VT
CA
UT
TX
CA
No Liner
SLT
0.0523
0.1300
0.1684
0.1511
0.4107
0.3647
0.0033
0.0000
0.3294
0.3531
0.0787
0.3081
0.0912
0.2073
0.1450
0.0180
0.1062
0.2268
0.4674
0.3520
0.5893
0.2436
0.3122
0.0671
0.0612
0.1016
0.2007
0.0000
0.0894
0.1900
0.0000
0.4171
0.2294
0.2131
0.0069
0.0508
0.0005
0.1212
0.1024
0.0130
0.1095
0.0221
SNL
0.0945
0.1862
0.2136
0.2106
0.4460
0.4641
0.0053
0.0000
0.3970
0.4336
0.0950
0.3612
0.1400
0.2309
0.2201
0.0254
0.1483
0.2812
0.5395
0.4628
0.7445
0.2944
0.0000
0.0795
0.0942
0.1697
0.2609
0.0003
0.1313
0.2540
0.0000
0.4387
0.2840
0.2863
0.0132
0.1003
0.0071
0.1598
0.0876
0.0269
0.1646
0.0340
SCL
0.0366
0.1064
0.1392
0.1102
0.3543
0.2817
0.0094
0.0018
0.2700
0.2824
0.0699
0.2570
0.0686
0.2096
0.1019
0.0135
0.0879
0.1943
0.3769
0.2855
0.4503
0.1969
0.2685
0.0536
0.0389
0.0805
0.1641
0.0003
0.0792
0.1521
0.0000
0.3927
0.1872
0.1753
0.0084
0.0495
0.0033
0.1008
0.0945
0.0185
0.0820
0.0241
Clay Liner
0.0048
0.0444
0.0445
0.0362
0.0486
0.0492
0.0188
0.0000
0.0486
0.0477
0.0013
0.0444
0.0409
0.0432
0.0492
0.0094
0.0432
0.0445
0.0486
0.0526
0.0477
0.0444
0.0362
0.0291
0.0246
0.0362
0.0444
0.0000
0.0432
0.0526
0.0188
0.0432
0.0445
0.0445
0.0188
0.0409
0.0013
0.0432
0.0013
0.0432
0.0253
0.0013
D.l-2
-------
Table D-l. LF HELP-derived Infiltration Rates (m/yr)
ID
102
15
48
68
72
46
81
31
60
91
57
56
22
34
94
79
61
9
Notes:
SLT =
SNL =
SCL =
City
San Juan
Santa maria
Sault St. Marie
Schenectady
Seabrook
Seattle
Shreveport
St. Cloud
Syracuse
Tallahassee
Tampa
Topeka
Tucson
Tulsa
W. Palm Beach
Watkinsville
Worchester
Yakima
Silt Loam cover
State
PR
CA
MI
NY
NJ
WA
LA
MN
NY
FL
FL
KS
AZ
OK
FL
GA
MA
WA
Sandy Loam cover
Silty Clay Loam cover
No Liner
SLT
0.1267
0.0947
0.1651
0.1473
0.1814
0.4384
0.2296
0.0602
0.2545
0.5913
0.0658
0.1049
0.0000
0.0686
0.2611
0.2891
0.2022
0.0000
SNL
0.1923
0.1151
0.2101
0.1928
0.2428
0.4582
0.2939
0.0831
0.3251
0.7308
0.1031
0.1483
0.0003
0.1006
0.3490
0.3556
0.2591
0.0023
SCL
0.0945
0.0841
0.1435
0.1224
0.1427
0.4077
0.1842
0.0554
0.2118
0.4564
0.0475
0.0762
0.0005
0.0465
0.1783
0.2332
0.1697
0.0003
Clay Liner
0.0193
0.0013
0.0432
0.0445
0.0444
0.0432
0.0362
0.0342
0.0445
0.0477
0.0253
0.0350
0.0000
0.0241
0.0477
0.0362
0.0445
0.0188
D.l-3
-------
Table D-2. WP HELP-derived Infiltration Rates (m/yr)
ID
19
98
82
95
62
44
99
7
2
67
75
35
43
41
18
86
93
10
42
74
52
55
51
38
36
3
53
29
32
54
88
23
16
100
28
1
6
27
4
25
77
59
City
Albuquerque
Annette
Astoria
Atlanta
Augusta
Bangor
Bethel
Bismarck
Boise
Boston
Bridgeport
Brownsville
Burlington
Caribou
Cedar City
Central Park
Charleston
Cheyenne
Chicago
Cincinnati
Cleveland
Columbia
Columbus
Concord
Dallas
Denver
Des Moines
Dodge City
E. Lansing
E. St. Louis
Edison
El Paso
Ely
Fairbanks
Flagstaff
Fresno
Glasgow
Grand Island
Grand Junction
Great Falls
Greensboro
Hartford
State
NM
AK
OR
GA
ME
ME
AK
ND
ID
MA
CT
TX
VT
ME
UT
NY
SC
WY
IL
OH
OH
MO
OH
NH
TX
CO
IA
KS
MI
IL
NJ
TX
NV
AK
AZ
CA
KY
NE
CO
MT
NC
CT
No Liner/ Waste Type
Low
0.0003
1.5373
1.2100
0.5160
0.3140
0.2570
0.0502
0.0259
0.0003
0.3220
0.3690
0.2270
0.2130
0.1880
0.0003
0.5230
0.4830
0.0043
0.1680
0.3100
0.1820
0.3100
0.1720
0.2350
0.2580
0.0008
0.2510
0.1010
0.1360
0.2630
0.4900
0.0231
0.0003
0.0077
0.0404
0.0422
0.0366
0.0963
0.0003
0.0259
0.4840
0.2790
Medium
0.0003
1.8146
1.2100
0.5160
0.3140
0.2570
0.0725
0.0259
0.0003
0.3220
0.3690
0.2270
0.2130
0.1880
0.0003
0.5230
0.4830
0.0043
0.1680
0.3100
0.1820
0.3100
0.1720
0.2350
0.2580
0.0008
0.2510
0.1010
0.1360
0.2630
0.4900
0.0231
0.0003
0.0167
0.0404
0.0422
0.0366
0.0963
0.0003
0.0259
0.4840
0.2790
High
0.0003
1.8789
1.2100
0.5160
0.3140
0.2570
0.1225
0.0259
0.0003
0.3220
0.3690
0.2270
0.2130
0.1880
0.0003
0.5230
0.4830
0.0043
0.1680
0.3100
0.1820
0.3100
0.1720
0.2350
0.2580
0.0008
0.2510
0.1010
0.1360
0.2630
0.4900
0.0231
0.0003
0.0777
0.0404
0.0422
0.0366
0.0963
0.0003
0.0259
0.4840
0.2790
Clay Liner/Waste Type
Low
0.0016
0.1352
0.1316
0.1184
0.1193
0.1125
0.0352
0.0124
0.0136
0.1193
0.1062
0.0050
0.1125
0.1125
0.0000
0.1255
0.1184
0.0124
0.1125
0.1062
0.0688
0.0688
0.0688
0.1125
0.0050
0.0124
0.0688
0.0033
0.0481
0.0688
0.1255
0.0968
0.0000
0.0098
0.0105
0.0136
0.0124
0.0422
0.0124
0.1262
0.0804
0.1193
Medium
0.0151
0.1357
0.1355
0.1351
0.1286
0.1273
0.0364
0.0689
0.0434
0.1286
0.1336
0.1329
0.1273
0.1273
0.0556
0.1352
0.1351
0.0689
0.1273
0.1336
0.1325
0.1325
0.1325
0.1273
0.1329
0.0689
0.1325
0.1063
0.1153
0.1325
0.1352
0.1350
0.0556
0.0118
0.1228
0.0434
0.0689
0.1347
0.0689
0.1328
0.1273
0.1286
High
0.0074
0.1354
0.1350
0.1347
0.1279
0.1266
0.0660
0.0950
0.0606
0.1279
0.1332
0.1318
0.1266
0.1266
0.0718
0.1349
0.1347
0.0950
0.1266
0.1332
0.1321
0.1321
0.1321
0.1266
0.1318
0.0950
0.1321
0.1193
0.1114
0.1321
0.1349
0.1344
0.0718
0.0407
0.1234
0.0606
0.0950
0.1342
0.0950
0.1313
0.1266
0.1279
D.2-1
-------
Table D-2. WP HELP-derived Infiltration Rates (m/yr)
ID
101
73
66
78
85
96
11
20
87
90
12
69
50
24
97
30
47
65
89
83
92
70
80
33
37
76
71
21
39
84
5
40
64
63
8
49
17
45
13
26
58
14
City
Honolulu
Indianapolis
Ithaca
Jacksonville
Knoxville
Lake Charles
Lander
Las Vegas
Lexington
Little Rock
Los Angeles
Lynchburg
Madison
Medford
Miami
Midland
Montpelier
Nashua
Nashville
New Haven
New Orleans
New York City
Norfolk
North Omaha
Oklahoma City
Orlando
Philadelphia
Phoenix
Pittsburg
Plainfield
Pocatello
Portland
Portland
Providence
Pullman
Put-in-Bay
Rapid City
Rutland
Sacramento
Salt Lake City
San Antonio
San Diego
State
HI
IN
NY
FL
TN
LA
WY
NV
KY
AK
CA
VA
WI
OR
FL
TX
VT
NH
TN
CT
LA
NY
VA
NE
OK
FL
PA
AZ
PA
MA
ID
OR
ME
RI
WA
OH
SD
VT
CA
UT
TX
CA
No Liner/ Waste Type
Low
0.0501
0.2690
0.2610
0.4090
0.5420
0.6070
0.0020
0.0003
0.4520
0.5380
0.1330
0.2690
0.2020
0.2500
0.4230
0.0757
0.1760
0.3340
0.6140
0.5420
0.8490
0.3990
0.4540
0.1620
0.2420
0.3840
0.3530
0.0003
0.1720
0.3030
0.0003
0.5060
0.3250
0.3480
0.0003
0.1480
0.0135
0.2130
0.1230
0.0193
0.2950
0.0658
Medium
0.1083
0.2690
0.2610
0.4090
0.5420
0.6070
0.0020
0.0003
0.4520
0.5380
0.1330
0.2690
0.2020
0.2500
0.4230
0.0757
0.1760
0.3340
0.6140
0.5420
0.8490
0.3990
0.4540
0.1620
0.2420
0.3840
0.3530
0.0003
0.1720
0.3030
0.0003
0.5060
0.3250
0.3480
0.0003
0.1480
0.0135
0.2130
0.1230
0.0193
0.2950
0.0658
High
0.1983
0.2690
0.2610
0.4090
0.5420
0.6070
0.0020
0.0003
0.4520
0.5380
0.1330
0.2690
0.2020
0.2500
0.4230
0.0757
0.1760
0.3340
0.6140
0.5420
0.8490
0.3990
0.4540
0.1620
0.2420
0.3840
0.3530
0.0003
0.1720
0.3030
0.0003
0.5060
0.3250
0.3480
0.0003
0.1480
0.0135
0.2130
0.1230
0.0193
0.2950
0.0658
Clay Liner/Waste Type
Low
0.0323
0.1062
0.1193
0.0804
0.1255
0.0038
0.0124
0.0968
0.1255
0.1184
0.0000
0.1062
0.0688
0.1262
0.0038
0.0033
0.1125
0.1193
0.1255
0.1316
0.1184
0.1062
0.0804
0.0202
0.0075
0.0804
0.1062
0.0968
0.1125
0.1316
0.0124
0.1125
0.1193
0.1193
0.0124
0.0688
0.0000
0.1125
0.0000
0.1262
0.0200
0.0000
Medium
0.0494
0.1336
0.1286
0.1273
0.1352
0.0236
0.0689
0.1350
0.1352
0.1351
0.0556
0.1336
0.1325
0.1328
0.0236
0.1063
0.1273
0.1286
0.1352
0.1355
0.1351
0.1336
0.1273
0.1264
0.1310
0.1273
0.1336
0.1350
0.1273
0.1355
0.0689
0.1273
0.1286
0.1286
0.0689
0.1325
0.0556
0.1273
0.0556
0.1328
0.1339
0.0556
High
0.0871
0.1332
0.1279
0.1266
0.1349
0.0297
0.0950
0.1344
0.1349
0.1347
0.0718
0.1332
0.1321
0.1313
0.0297
0.1193
0.1266
0.1279
0.1349
0.1350
0.1347
0.1332
0.1266
0.1265
0.1298
0.1266
0.1332
0.1344
0.1266
0.1350
0.0950
0.1266
0.1279
0.1279
0.0950
0.1321
0.0718
0.1266
0.0718
0.1313
0.1333
0.0718
D.2-2
-------
Table D-2. WP HELP-derived Infiltration Rates (m/yr)
ID
102
15
48
68
72
46
81
31
60
91
57
56
22
34
94
79
61
9
Notes:
City
San Juan
Santa maria
Sault St. Marie
Schenectady
Seabrook
Seattle
Shreveport
St. Cloud
Syracuse
Tallahassee
Tampa
Topeka
Tucson
Tulsa
W. Palm Beach
Watkinsville
Worchester
Yakima
State
PR
CA
MI
NY
NJ
WA
LA
MN
NY
FL
FL
KS
AZ
OK
FL
GA
MA
WA
No Liner/ Waste Type
Low
0.1498
0.1510
0.2370
0.2750
0.3410
0.5310
0.4460
0.1520
0.4100
0.8220
0.2720
0.2470
0.0003
0.2490
0.5640
0.4670
0.3310
0.0003
Medium
0.2883
0.1510
0.2370
0.2750
0.3410
0.5310
0.4460
0.1520
0.4100
0.8220
0.2720
0.2470
0.0003
0.2490
0.5640
0.4670
0.3310
0.0003
High
0.4442
0.1510
0.2370
0.2750
0.3410
0.5310
0.4460
0.1520
0.4100
0.8220
0.2720
0.2470
0.0003
0.2490
0.5640
0.4670
0.3310
0.0003
Clay Liner/Waste Type
Low
0.0637
0.0000
0.1125
0.1193
0.1062
0.1125
0.0804
0.0264
0.1193
0.1184
0.0200
0.0174
0.0968
0.0050
0.1184
0.0804
0.1193
0.0124
Medium
0.0793
0.0556
0.1273
0.1286
0.1336
0.1273
0.1273
0.1262
0.1286
0.1351
0.1339
0.1305
0.1350
0.1329
0.1351
0.1273
0.1286
0.0689
Low, Medium, and High denote representative waste types with different hydraulic conductivities:
Low = Fine-grained waste (e.g., fly ash), Hydraulic conductivity is 5xlO~5 cm/sec
Medium = Medium-grained waste (e.g., bottom ash), Hydraulic conductivity is 0.0041 cm/sec
High = Coarse-grained waste (e.g., slag), Hydraulic conductivity is 0.041 cm/sec
High
0.1114
0.0718
0.1266
0.1279
0.1332
0.1266
0.1266
0.1255
0.1279
0.1347
0.1333
0.1302
0.1344
0.1318
0.1347
0.1266
0.1279
0.0950
D.2-3
-------
Table D-3. LAU HELP-Derived Infiltration Rates (m/yr)
ID
19
98
82
95
62
44
99
7
2
67
75
35
43
41
18
86
93
10
42
74
52
55
51
38
36
3
53
29
32
54
88
23
16
100
28
1
6
27
4
25
77
59
101
73
City
Albuquerque
Annette
Astoria
Atlanta
Augusta
Bangor
Bethel
Bismarck
Boise
Boston
Bridgeport
Brownsville
Burlington
Caribou
Cedar City
Central Park
Charleston
Cheyenne
Chicago
Cincinnati
Cleveland
Columbia
Columbus
Concord
Dallas
Denver
Des Moines
Dodge City
E. Lansing
E. St. Louis
Edison
El Paso
Ely
Fairbanks
Flagstaff
Fresno
Glasgow
Grand Island
Grand Junction
Great Falls
Greensboro
Hartford
Honolulu
Indianapolis
State
NM
AK
OR
GA
ME
ME
AK
ND
ID
MA
CT
TX
VT
ME
UT
NY
SC
WY
IL
OH
OH
MO
OH
NH
TX
CO
IA
KS
MI
IL
NJ
TX
NV
AK
AZ
CA
KY
NE
CO
MT
NC
CT
HI
IN
No Liner
SLT
0.0000
1.8049
1.0762
0.3416
0.2116
0.1471
0.1849
0.0239
0.0008
0.2332
0.1953
0.0549
0.1359
0.1082
0.0000
0.3363
0.2609
0.0005
0.0798
0.1554
0.0780
0.1529
0.0765
0.1585
0.0599
0.0008
0.1143
0.0135
0.1090
0.1435
0.3122
0.0076
0.0000
0.1463
0.0239
0.0307
0.0099
0.0442
0.0000
0.0036
0.3256
0.1709
0.0541
0.1300
SNL
0.0000
1.9771
1.1494
0.3993
0.2700
0.2045
0.1981
0.0300
0.0094
0.2383
0.2464
0.1049
0.1781
0.1491
0.0008
0.4171
0.3287
0.0013
0.1138
0.2210
0.1212
0.1989
0.1158
0.2057
0.1067
0.0008
0.1641
0.0345
0.1452
0.1676
0.3914
0.0130
0.0000
0.1483
0.0630
0.0368
0.0074
0.0627
0.0000
0.0069
0.3896
0.2228
0.0983
0.1862
SCL
0.0003
1.5159
0.9647
0.2822
0.1674
0.1227
0.1781
0.0196
0.0038
0.1542
0.1615
0.0384
0.1166
0.0886
0.0000
0.2738
0.2123
0.0086
0.0620
0.1539
0.0823
0.1224
0.0663
0.1372
0.0531
0.0036
0.1156
0.0226
0.1102
0.0704
0.2492
0.0081
0.0003
0.1445
0.0226
0.0381
0.0099
0.0323
0.0003
0.0074
0.2705
0.1405
0.0363
0.1064
D.3-1
-------
Table D-3. LAU HELP-Derived Infiltration Rates (m/yr)
ID
66
78
85
96
11
20
87
90
12
69
50
24
97
30
47
65
89
83
92
70
80
33
37
76
71
21
39
84
5
40
64
63
8
49
17
45
13
26
58
14
102
15
48
68
City
Ithaca
Jacksonville
Knoxville
Lake Charles
Lander
Las Vegas
Lexington
Little Rock
Los Angeles
Lynchburg
Madison
Medford
Miami
Midland
Montpelier
Nashua
Nashville
New Haven
New Orleans
New York City
Norfolk
North Omaha
Oklahoma City
Orlando
Philadelphia
Phoenix
Pittsburg
Plainfield
Pocatello
Portland
Portland
Providence
Pullman
Put-in-Bay
Rapid City
Rutland
Sacramento
Salt Lake City
San Antonio
San Diego
San Juan
Santa maria
Sault St. Marie
Schenectady
State
NY
FL
TN
LA
WY
NV
KY
AK
CA
VA
WI
OR
FL
TX
VT
NH
TN
CT
LA
NY
VA
NE
OK
FL
PA
AZ
PA
MA
ID
OR
ME
RI
WA
OH
SD
VT
CA
UT
TX
CA
PR
CA
MI
NY
No Liner
SLT
0.1684
0.1511
0.4107
0.3647
0.0033
0.0000
0.3294
0.3531
0.0787
0.3081
0.0912
0.2073
0.1450
0.0180
0.1062
0.2268
0.4674
0.3520
0.5893
0.2436
0.3122
0.0671
0.0612
0.1016
0.2007
0.0000
0.0894
0.1900
0.0000
0.4171
0.2294
0.2131
0.0069
0.0508
0.0005
0.1212
0.1024
0.0130
0.1095
0.0221
0.1491
0.0947
0.1651
0.1473
SNL
0.2136
0.2106
0.4460
0.4641
0.0053
0.0000
0.3970
0.4336
0.0950
0.3612
0.1400
0.2309
0.2201
0.0254
0.1483
0.2812
0.5395
0.4628
0.7445
0.2944
0.0000
0.0795
0.0942
0.1697
0.2609
0.0003
0.1313
0.2540
0.0000
0.4387
0.2840
0.2863
0.0132
0.1003
0.0071
0.1598
0.0876
0.0269
0.1646
0.0340
0.2164
0.1151
0.2101
0.1928
SCL
0.1392
0.1102
0.3543
0.2817
0.0094
0.0018
0.2700
0.2824
0.0699
0.2570
0.0686
0.2096
0.1019
0.0135
0.0879
0.1943
0.3769
0.2855
0.4503
0.1969
0.2685
0.0536
0.0389
0.0805
0.1641
0.0003
0.0792
0.1521
0.0000
0.3927
0.1872
0.1753
0.0084
0.0495
0.0033
0.1008
0.0945
0.0185
0.0820
0.0241
0.1049
0.0841
0.1435
0.1224
D.3-2
-------
Table D-3. LAU HELP-Derived Infiltration Rates (m/yr)
ID
72
46
81
31
60
91
57
56
22
34
94
79
61
9
Notes:
SLT =
SNL =
SCL =
City
Seabrook
Seattle
Shreveport
St. Cloud
Syracuse
Tallahassee
Tampa
Topeka
Tucson
Tulsa
W. Palm Beach
Watkinsville
Worchester
Yakima
Silt Loam soil
Sandy Loam soil
State
NJ
WA
LA
MN
NY
FL
FL
KS
AZ
OK
FL
GA
MA
WA
Silty Clay Loam soil
No Liner
SLT
0.1814
0.4384
0.2296
0.0602
0.2545
0.5913
0.0658
0.1049
0.0000
0.0686
0.2611
0.2891
0.2022
0.0000
SNL
0.2428
0.4582
0.2939
0.0831
0.3251
0.7308
0.1031
0.1483
0.0003
0.1006
0.3490
0.3556
0.2591
0.0023
SCL
0.1427
0.4077
0.1842
0.0554
0.2118
0.4564
0.0475
0.0762
0.0005
0.0465
0.1783
0.2332
0.1697
0.0003
D.3-3
-------
Table D.4: Flow rate data used to develop landfill and waste pile composite liner infiltration rates (from TetraTech, 2001)
Landfill
Cell ID1
G228
G232
G233
G234
G235
G236
G237
G238
G239
G240
G241
G242
G243
G244
G245
G246
G247
G248
G249
G250
G251
G252
G232
G233
G234
G235
G236
Cell Type
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
Open
closed
closed
closed
closed
closed
Average M
(L/ha/d)
5.85
11
0
2
4
1
2
0
2
0
0
0
0
0
0
0
0
0
2
6
0
0
2
0
0
1
0
>nthly LDS Flow
Rate
(m/y)
2.14E-04
4.02E-04
O.OOE+00
7.30E-05
1.46E-04
3.65E-05
7.30E-05
O.OOE+00
7.30E-05
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
7.30E-05
2.19E-04
O.OOE+00
O.OOE+00
7.30E-05
O.OOE+00
O.OOE+00
3.65E-05
O.OOE+00
Liner Type
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
GM/GCL
Type of
Waste3
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
MSW
Site Parameters
Location
Mid-Atlantic
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Northeast
Southeast
Southeast
Southeast
Northeast
Northeast
Northeast
Northeast
Northeast
Average
Annual
Rainfall
(mm)
NA
990
1040
1040
1040
1040
1040
1040
1040
1040
1040
1040
1040
1040
1040
1040
1040
1040
760
1090
1090
1090
990
1040
1040
1040
1040
Subsurface Soil
Type
NA
Silty Clay
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand
NA
NA
NA
Silty Clay
Sand & Gravel
Sand & Gravel
Sand & Gravel
Sand & Gravel
Landfill Cell Construction/Operation Information
Cell Area
(ha)
51
4.7
2
2
1.7
1.7
2.8
3.9
2.6
3.8
3.3
3.9
3
4
3
2.8
2.8
4.5
3.8
4
2.4
2.8
4.7
2
2
1.7
1.7
GM Liner
Material4
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
GM Liner
Thickness
(mm)
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1
1
1
1
1
GCL or CCL
Thickness
(mm)
NA
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
250
6
6
6
6
6
6
6
6
Maximum
Height of
Waste
(m)
NA
NA
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
41
28
30
30
NA
24
24
24
24
End
Construction
Date
1988
May-92
Jun-88
Jun-88
Aug-88
Aug-88
Sep-88
Dec-88
Jan-89
Jul-89
Dec-89
Feb-90
Feb-90
Oct-90
Jan-91
Apr-92
May-92
Jan-93
Sep-92
Dec-90
Jan-93
Jan-93
May-92
Jun-88
Jun-88
Aug-88
Aug-88
Waste
Placement
Start Date
1989
May-92
Jul-88
Jul-88
Sep-88
Sep-88
Oct-88
Dec-88
Feb-89
Jul-89
Dec-89
Jul-90
Feb-90
Oct-90
Jan-91
Apr-92
May-92
Jan-93
Dec-92
Feb-91
Jan-93
Jan-93
May-92
Jul-88
Jul-88
Sep-88
Sep-88
Final
Closure
Date
NA
Jul-94
Feb-91
Feb-91
Apr-93
Apr-93
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Jul-94
Feb-91
Feb-91
Apr-93
Apr-93
Source of Data
Eith&Koerner(1997)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
EPA (1998)
Notes:
1. Cell ID as reported by TetraTech (2001)
2. GM = geomembrane; GCL = geosynthetic clay liner
3. MSW = municipal solid waste
4. HOPE = high density polyethylene
NA = not available
- = not applicable
Data Sources:
Eith, A. W., and G.R. Koerner, 1997. Assessment of HOPE geomembrane performance in municipal waste landfill double liner system after eight years of service. Geotextiles and geomembranes, Vol. 15, pp. 277 -
EPA, 1998. Assessment and Recommendations for Optimal Performance of Waste Containment Systems. Office of Research and Development, Cincinatti, Ohio.
-------
Table D.5: Leak Density Data Used to Develop Surface Impound composite liner infiltration rates (from TetraTech, 2001)
Site ID1
L1
L2
L3
L4
L5
L6
L7
L8
L9
L10
L86
L103
L110
L114
L136
L144
L152
L159
L160
L176
L177
L178
L179
L180
L181
L182
Date
1995
1996
1994
1995
1997
1998
1995
1995
1997
1998
Apr-96
Oct-96
Jan-97
Jan-97
Oct-97
May-98
Aug-98
NA
NA
May-98
Sep-96
Apr-97
Sep-98
Sep-98
NA
NA
Area (m2|
18500
14926
13480
11652
8200
9284
67100
66150
11460
18135
9416
4980
11720
7000
13526
5608
3742
15000
10000
13500
15000
7500
5000
13200
48600
8000
Location
France
France
France
France
France
France
Canada
Canada
Canada
France
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
United
Kingdom
NA
NA
Waste Type
domestic
domestic
HW
HW
HW
HW
waste water
treatment
waste water
treatment
black liqueur
domestic
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
waste water
containment
HW
WMU type
landfill
landfill
landfill
landfill
landfill
landfill
pond
pond
pond
landfill
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
pond
landfill
Type of GM
Liner2
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
PBGM
PBGM
PP
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HOPE
HDPE/CCL
Thickness of
GM (mm)
2
2
2
2
2
2
3
3
1.14
2
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1.5
2
Quality of
Material
Beneath GM
high
high
high
high
high
high
high
high
high
high
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Holes
0
4
1
1
0
0
3
1
2
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
NA
NA
Knife
Cuts/Tears
0
0
1
2
0
1
0
1
2
3
0
0
2
3
1
0
0
0
0
0
0
1
0
0
NA
NA
Seam or
Weld
Defects
5
2
1
2
0
0
2
7
2
3
0
0
1
1
0
0
0
0
0
0
0
0
0
0
NA
NA
Total Leaks
5
6
3
5
0
1
5
9
6
6
0
0
3
4
1
0
0
0
0
1
0
1
0
0
21
10
Range of
Hole Size
(mm)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
30x50
NA
NA
NA
Leak Density
(leaks/ha)
2.7
4.02
2.23
4.29
0
1.08
0.75
1.36
5.24
3.31
0
0
2.6
5.7
0.7
0
0
0
0
0.7
0
1.3
0
0
4.3
12.5
Source
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
Rollin etal. (1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
McQuade and
Needham(1999)
Laine(1991)
Laine(1991)
Notes:
1. Cell ID as reported by Tetra Tech (2001)
2. HOPE = high density polyethylene; PBGM = pre-fabricated bituminous geomembrane; PP = polypropylene; CCL = compacted clay liner
NA = not available; - = not applicable
Data Sources:
Rollin, A.L., M. Marcotte, T. Jacqulein, and L. Chaput. 1999. Leak location in exposed geomembrane liners using an electrical leak detection technique. Geosynthetics '99, Vol. 2, pp. 615-626
McQuade, S.J., and A.D. Needham, 1999. Geomembrane liner defects - causes, frequency and avoidance. Geotechnical Engineering, Vol., 137. No. 4, pp. 203-213
Laine, D.L, 1991. Analysis of pinhole seam leaks located in geomembrane liners using the electrical leak location method. Proceedings, Geosynthetics '91, pp.239-253
-------
Table D.6: Comparison of composite liner infiltration rates
Calculated using Bonaparte Equation and Infiltration
Rates for composite-lined landfill cells
Percentile
0
10
20
30
40
50
60
70
80
90
100
Calculated
Infiltration (m/yr)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
1.05E-05
1.37E-05
2.03E-05
3.96E-05
6.01E-05
7.13E-05
1 .87E-04
Observed Infiltration
(m/yr)
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
O.OOE+00
2.19E-05
7.30E-05
7.30E-05
1 .73E-04
4.02E-04
Infiltration Rate Comparison (Head =0.3m, Hole Area = 6mm2)
0.0002
-Calculated Infiltration
-Actual Infiltration value
40 50 60
Percentile
-------
APPENDIX E
BACKGROUND INFORMATION FOR THE
DEVELOPMENT OF REFERENCE GROUNDWATER
CONCENTRATION VALUES
-------
IWEM Technical Background Document Appendix E
E-l Shower Model
E-l.l Shower Model
The shower model calculates the incremental change in the concentration of a
constituent in air that results from the transfer of constituent mass from the water phase
(the shower water) to the vapor phase (the air in the shower stall) over time. The model
then estimates the concentration of the constituent in a bathroom that results from air
exchange within the bathroom and between the bathroom and the rest of the house over
time. After the model calculates the predicted air-phase constituent concentration in the
shower stall and bathroom, we use those concentrations to estimate the average air-phase
constituent concentration to which an individual is exposed over the course of an entire
day. We use this average daily concentration to calculate inhalation HBNs.
The shower model is based on differential equations presented in McKone (1987)
and Little (1992a). We solved the differential equations using a mathematical technique
called "finite difference numerical integration," to produce the equations that we use in
our analysis, Equations E-l to E-l 1 in this Appendix. In reviewing the equations and
reading the following sections, it will help to keep in mind the following two concepts:
We calculate air-phase constituent concentrations for different "compartments"
The shower model is based on the understanding that there are two compartments
in the bathroom: 1) the shower stall and 2) the rest of the bathroom (outside of
the shower stall). We assume that an adult spends time: in the shower stall when
the shower is running; in the shower stall after the shower is turned off; and in the
rest of the bathroom after the shower is turned off (see Equations E-l and E-2).
We calculate air-phase constituent concentrations for different time steps. We
implement the shower model in time steps. That is, we estimate the air-phase
constituent concentration in each of the two compartments in 0.2-minute
increments or time steps. The air-phase constituent concentration at the
beginning of the 0.2-minute time step differs from the concentration at the end of
the 0.2-minute time step because of volatilization of constituent mass from the
shower water (which adds constituent mass) and the exchange of air between the
compartments in the bathroom and the rest of the house (which disperses the
mass). At the beginning of a time step, the air-phase concentration in each
bathroom compartment is equal to the air-phase concentration that was estimated
for the compartment at the end of the previous time step.
E-l
-------
IWEM Technical Background Document Appendix E
The following is our basic procedure for implementing the shower model:
Calculate a mass transfer coefficient for each constituent;
Estimate the air-phase constituent concentration in the shower stall for
sequential 0.2-minute time steps;
Estimate the air-phase constituent concentration in the bathroom (other
than in the shower stall) for sequential 0.2-minute time steps;
Use the air-phase constituent concentrations calculated for the shower
stall, and the air-phase constituent concentrations calculated for the
bathroom, to calculate the average constituent concentration to which an
adult is exposed during the course of a day.
This procedure is explained in greater detail below. Appendix E-3 provides the
values for the constituent-specific properties used in the model. Table E. 1 provides the
values we used for the parameters in the model.
Calculating a Mass Transfer Coefficient
The first step in estimating the concentration of a constituent in air is to quantify
the constituent's "resistance" to movement between the water phase and the air phase.
We quantify this resistance using the mass transfer coefficient presented in Equation E-4,
which incorporates variables calculated in Equations E-3 and E-5. The mass transfer
coefficient depends on properties specific to each constituent evaluated, as well as
physical properties of the water droplet. Specifically, the mass transfer coefficient
depends on:
The constituent's diffusivity in water (the molecular diffusion coefficient
for the constituent in water), which determines how readily the constituent
mass in the center of the water droplet will diffuse to the surface of the
water droplet. If a constituent's diffusivity in water is low, then as the
constituent is emitted from the surface of the water droplet, the rate at
which the surface of the droplet is "supplied" with constituent from the
center of the water droplet will be slow, resulting in less constituent being
emitted from the droplet. Diffusivity influences the concentration gradient
across the droplet.
The Henry's law constant for the constituent, which establishes how the
constituent will partition between the water phase and the air phase to
achieve equilibrium. Henry's law states that, at equilibrium, the amount
-------
IWEM Technical Background Document Appendix E
of a constituent dissolved in water is proportional to the amount of the
constituent in the air phase that is in contact with the water. This
proportion is constituent-specific (each constituent has a different Henry's
law constant). The Henry's law constant influences the magnitude of the
air-phase constituent concentrations more than any other constituent-
specific parameter.
The constituent's diffusivity in air (the molecular diffusion coefficient for
the constituent in air), which determines how readily the constituent will
migrate away from the droplet once it is released into the air surrounding
the droplet. Constituents with lower diffusivities in air will have
comparatively higher concentrations around the water droplet than in the
surrounding air. Therefore, because of Henry's law, less constituent
would need to come out of solution into the air phase in order to achieve
equilibrium.
The amount of time that the droplet is in contact with the air, which we
assume is equivalent to the time it takes for the droplet to fall to the floor
of the shower. We determine the time it takes the droplet to fall by
dividing distance that the droplet has to fall (which we assume is equal to
the height of the shower nozzle) by the velocity at which the water droplet
falls (which we assume is the terminal velocity of the droplet). For this
analysis, we set the nozzle height and the terminal velocity of the droplet
at fixed values, as presented in Table E. 1.
The ratio of the water droplet's surface area to its volume. Because we
assume that the droplet is a sphere, its surface area to volume ratio is equal
to a value of 6 divided by the diameter of the droplet. For this analysis,
the diameter of the droplet, therefore its surface area to volume ratio, is a
fixed value (see Table E.I).
Appendix E-2 presents the constituent-specific diffusivities and Henry's law
constants that we used in our analysis.
E-2
-------
laoie tL.L. anower ivioaei input rarameters
Input Parameter
Description
Value
Units
Reference
Comment
Bathroom Properties
Vb
Volume of the bathroom
10
m3
McKone, 1987
Exchange Rate
Qbh
Qsb
Volumetric exchange rate between the bathroom
and the house
Volumetric exchange rate between the shower
and the bathroom
300
100
L/min
L/min
derived value
derived value
Estimated from the volume and flow rate
in McKone (1987) such that the exchange
rate equals the volume divided by the
residence time (e.g., 10,OOOL/30 min).
Estimated from the volume and flow rate
in McKone (1987) such that the exchange
rate equals the volume divided by the
residence time (e.g., 2000L/20 min).
Exposure Time
ShowerStallTime
r_bathroom
ShowerTime
Time in shower stall after showering
Time spent in bathroom, not in shower
Shower time, 50th percentile
5
5
15
min
min
min
USEPA, 1997c
USEPA, 1997c
USEPA, 1997c
Table 15-23. 50th percentile overall
Table 15-32. 50th percentile overall
Table 15-21. 50th percentile overall
Shower Properties
Vs
NozHeight
ShowerRate
DropVel
DropDiam
Volume of shower
Height of shower head
Rate of water flow from shower head
Terminal velocity of water drop
Diameter of shower water drop
2
1.8
10
400
0.098
m3
m
L/min
cm/s
cm
McKone, 1987
Little, 1992a
derived value
derived value
derived value
Selected based on the maximum height
reported in Table 1 of Little (1992a), a
summary of five studies.
Value obtained by averaging the flow rates
reported in five studies in Table 1 of
Little (1992a) (QL) = 10.08 L/min.
Selected value by correlating to existing
data.
Estimated as a function of terminal
velocity<=600cm/sec (Coburn, 1996).
Groundwater
Cin
Constituent concentration in incoming water
0.001
mg/L
NA
Unit concentration selected.
IWEM Technical Background Document Appendix E
-------
IWEM Technical Background Document Appendix E
Calculating the Air-Phase Constituent Concentration in the Shower
Calculating the air-phase constituent concentration in the shower at the end of
each time step involves:
1. Calculating the fraction of constituent that can be emitted into the air from each
water droplet (Equation E-7);
2. Translating the fraction of constituent that can be emitted from each water droplet
(from step 1) into the mass of constituent that is emitted from the entire volume of
water that is coming into the shower during each time step (Equation E-6); and
3. Determining the constituent concentration at the end of the time step by:
calculating the concentration added to the shower air during the time step
(dividing the constituent mass emitted from the water in step 2 by the volume of
the shower), adding this concentration to the concentration of the constituent that
was already in the shower air at the beginning of the time step, and subtracting the
concentration lost from the shower air due to the exchange of air with the rest of
the bathroom (Equation E-9).
An important element of this analysis is the difference between the time in the
shower stall that is spent showering (15 minutes, Table E.I) and the time in the shower
stall that occurs after showering (5 minutes, Table E.I). The difference in these two time
periods involves how we handle the value for mass of constituent emitted from the
shower water (step 2, above). When we switch the model over from the time period
where the shower nozzle is turned on (the time spent showering), to the time period
where the shower nozzle is turned off (the time spent in the shower stall after showering),
we set the mass emitted from the water to zero. This means that during the 5-minute
period when the individual is in the shower after the shower is turned off, the air-phase
concentration of the constituent is only a function of the concentration of the constituent
in the air at the beginning of the time step and the air exchange between the shower stall
and the rest of the bathroom. The following paragraphs describe steps 1 and 2 in more
detail.
The fraction of the constituent mass that potentially can be emitted from a droplet
at any given time during the droplet's fall through the air (Equation E-7) is a function of
the mass transfer coefficient (the constituent's resistance to movement from the water
phase to the air phase, described previously) and the "fraction of gas phase saturation" in
the shower (calculated using Equation E-8). Inherent in this calculation is an assumption
that the concentration of the constituent in the air is constant over the time it takes the
droplet to fall. The fraction of gas phase saturation is an expression of how close the air-
phase constituent concentration is to the maximum possible (equilibrium) air-phase
-------
IWEM Technical Background Document Appendix E
concentration. Stated another way, Henry's law dictates that for a certain constituent
concentration in water, we can predict the maximum concentration of constituent in the
air that is in contact with the water (assuming the air and water are in equilibrium).
Consequently, if there is already constituent in the air, then, to maintain equilibrium,
there is a limit to how much additional constituent can be emitted from the water to the
air (the less constituent already present in the air, the more constituent that theoretically
may be emitted). The fraction of gas phase saturation is an expression of how close the
air concentration is to that limit at the beginning of each time step. However, as
suggested at the beginning of this paragraph, even though Henry's law influences the
maximum fraction of mass that could be emitted from the droplet, the mass transfer
coefficient also influences how much of the constituent will "free itself from the water.
Factors such as the constituent's dispersivity (in water and air) and the surface area of the
droplet also influence the fraction of constituent mass that can be emitted from the
droplet.
In most cases, for each 0.2-minute time step we evaluate, the mass of a
constituent emitted from the shower water to the air is the product of: the concentration
of the constituent in the shower water, the volume of water emitted from the shower
during the time step, and the fraction of the constituent mass in the water that potentially
could be emitted from the water (discussed above). However, in certain cases (typically
rare), the mass transfer coefficient is of a magnitude that the concentration calculated in
this way exceeds the mass that possibly could be emitted when the water and the air
phases are at equilibrium. In this case, we "cap" the constituent mass that can be emitted
from the shower water during the time step. The cap is the maximum constituent mass
that could be emitted from the water at equilibrium (based on Henry's law) minus the
constituent mass already in the shower stall at the beginning of the time step
Calculating the Air-Phase Constituent Concentration in the Bathroom (other than in
the Shower Stall)
The air-phase constituent concentration in the bathroom (Equation E-10) is a
function of the air-phase constituent concentration calculated for the shower, and the
exchange of air 1) between the shower and the bathroom and 2) between the bathroom
and the rest of the house. Specifically, for each time step, the air-phase constituent
concentration in the bathroom is equal to: the air-phase constituent concentration in the
bathroom at the beginning of the time step, plus the constituent concentration added as a
result of the exchange of air with the shower, minus the constituent concentration lost as
a result of the exchange of air with the rest of the house. Table E. 1 presents the values
we used for the volumetric exchange rate between the shower and the bathroom; the
volumetric exchange rate between the bathroom and the house; and the volume of the
bathroom.
E-6
-------
IWEM Technical Background Document Appendix E
Calculating the Average Daily Constituent Concentration to Which an Individual is
Exposed
To calculate the average concentration of a constituent to which an individual is
exposed on a daily basis (24 hours per day) (Equation E-l 1), we:
1. Calculate the average constituent concentration in the shower air across all time
steps and multiply this concentration by the amount of time an individual spends
in the shower stall (Equation E-2);
2. Calculate the average constituent concentration in the bathroom air (not including
the shower air) across all time steps and multiply this concentration by the
amount of time an individual spends in the bathroom (not including the time spent
in the shower stall);
3. Sum the values calculated in steps 1 and 2, and divide the sum by the length of a
day. This calculation carries with it an assumption that an individual only is
exposed to the constituent in the shower, and in the bathroom after showering
(that is, that the concentration of the constituent in the rest of the house is zero).
E-1.2 Shower Model Uncertainties and Limitations
The primary limitations and uncertainties of the shower model are as follows:
The model is constructed such that air-phase concentration of a constituent
in household air results solely from showering activity. Individuals are
exposed to emissions via inhalation for time spent in the shower while
showering, in the shower stall after showering, and in the bathroom after
showering. Other models calculate indoor air concentrations resulting
from emissions from household use of tap water and/or calculate
inhalation exposures for time spent in the remainder of the house.
However, McKone (1987) found that the risk from inhalation exposures in
the remainder of the house was considerably lower than the risk from
inhalation exposures in the bathroom and during showering. In addition,
there are few data available to estimate the input parameters needed to
calculate exposure concentrations from other household activities,
including variables such as house volume, air exchange rate between the
house and outside air, and exposure time in the house. Given expected the
lower risk due to exposure in the remainder of the house, and the lack of
available data to estimate house constituent concentrations, we focused on
showering as the greatest source of inhalation exposure and risk due to use
of contaminated water.
-------
IWEM Technical Background Document Appendix E
The model currently only considers exposures to adults who shower, and
does not consider exposures to children who bathe in bathtubs. This
limitation of the model may be significant. A recent report by EPA's
National Center for Environmental Assessment states that: "Because of
the longer exposure times, chemical emissions during the use of bathtubs
may be as, or more, significant than during showers, in terms of human
inhalation. This is particularly important given that small children are
typically washed in bathtubs rather than showers and are generally more
sensitive to chemical exposure than are healthy adults" (USEPA, 2000).
Our analysis does not consider either an individual's dermal exposure to
water, or an individual's incidental ingestion of water, while showering.
The model only considers emissions that result from falling droplets of
water in the shower. The model does not include algorithms that account
for emissions from water films on shower walls or puddles on the floor of
the shower. Use of the model also assumes that a droplet falls directly
from the shower nozzle to the shower stall floor, and is not intercepted by
the body of the individual who is showering.
The input parameter values are a source of uncertainty for the shower
model. To select values for the shower properties (shower and bathroom
volume, nozzle height, and flow rate), we generally used central tendency
values that were reported in the literature. Although fixing shower model
input parameters as constant does not capture variability in the results, the
results still compare favorably to experimental data for numerous organic
compounds of varying volatility (Coburn, 1996). The values for droplet
properties (diameter and velocity) are also constants, and are based on
correlation to existing data. The largest uncertainty is likely in the
volumetric exchange rates used between the shower and bathroom and the
bathroom and the rest of house. We derived these values, 300 L/min for
the exchange rate between the bathroom and house, and 100 L/min for the
exchange rate between the shower and bathroom, from McKone (1987).
However, values reported in a five-study summary by Little (1992a)
ranged from 35 to 460 L/min for the exchange between the shower and
bathroom, and 38 to 480 L/min for the exchange between the bathroom
and the rest of the house. Such a large range of volumetric exchange rates
imparts uncertainty to the shower model's estimation of constituent
concentrations.
A constituent's solubility in water depends on a number of factors
including the temperature of the water and the other chemicals (for
-------
IWEM Technical Background Document Appendix E
example, other solvents) that are in the water. When the concentration of
a constituent in water exceeds the constituent's solubility in that water, we
expect that at least some of the constituent will exist in the water as a non-
aqueous (free) phase. Henry's law, a basic principle of the shower model,
only applies to constituents dissolved in water, it does not apply to non-
aqueous phase constituents (USEPA, 1996). As a result, it would not be
appropriate to use the HBNs we developed for the inhalation pathway if
the shower water (which we assume is from a groundwater well)
contained non-aqueous phase constituent. More importantly, however,
EPACMTP, the groundwater fate and transport model that we use to
estimate constituent concentrations in the modeled groundwater, cannot be
used to model non-aqueous phase liquids. Consequently, the IWEM tool
should not be used in cases where non-aqueous phase constituents are
present in leachate. In these situations, another tool must be used that is
capable of evaluating non-aqueous phase liquids.
E-9
-------
IWEM Technical Background Document
Appendix E
Equation E-l. Total time spent in shower and bathroom
BSResTime = ShowerTime + ShowerStall Time + T bathroom
Name
BSResTime
ShowerTime
ShowerStallTime
T_bathroom
Description
Total time spent in shower and bathroom (min)
Duration of shower (min)
Time in shower stall after showering (min)
Time spent in bathroom, not in shower (min)
Value
Calculated above
Provided in Equation E-l 2
Provided in Equation E-l 2
Provided in Equation E-l 2
This equation calculates the total time that a receptor is exposed to vapors.
Equation E-2. Total time spent in shower stall
Shower Res Time = ShowerStallTime + ShowerTime
Name
ShowerResTime
ShowerStallTime
ShowerTime
Description
Total time spent in shower stall (min)
Time in shower stall after showering (min)
Duration of shower (min)
Value
Calculated above
Provided in Equation E-l 2
Provided in Equation E-l 2
This equation calculates the total time that a receptor is exposed to vapors in the shower stall.
E-10
-------
IWEM Technical Background Document
Appendix E
Equation E-3. Dimensionless Henry's law constant
Name
Hprime
HLCcoef
HLC
R
Temp
Hprime = HLCcoef x HLC
TTT C*~-\~f
7/LCcOe/ -
R x lemp
Description
Dimensionless Henry's law constant (dimensionless)
Coefficient to Henry's law constant (dimensionless)
Henry's law constant (atm-mVmol)
Ideal Gas constant (atm-m3/K-Mol)
Temperature (K)
Value
Calculated above
Calculated above
Chemical-specific
0.00008206
298
This equation calculates the dimensionless form of Henry's law constant.
Equation E-4. Dimensionless overall mass transfer coefficient
Name
N
AVRatio
Kol
DropResTime
DropDiam
NozHeight
DropVel
100
N = Kol x AVRatio x DropResTime
6
A. v latino
DropDiam
NozHeight x 100
Di^R^Tim. - ^^^
Description
Dimensionless overall mass transfer coefficient (dimensionless)
Area-to-volume ratio for a sphere (cmVcm3)
Overall mass transfer coefficient (cm/s)
Residence time for falling drops (s)
Drop diameter (cm)
Nozzle height (m)
Drop terminal velocity (cm/s)
Conversion factor (cm/m)
Value
Calculated above
Calculated above
Calculated in Equation E-5
Calculated above
Provided in Equation E-12
Provided in Equation E-12
Provided in Equation E-12
Conversion factor
This equation calculates the dimensionless overall mass transfer coefficient. The above equation is based
on Little (1992a; Equation 5), which provides the equation as N = Kol x A/Q1 where A is the total surface
area for mass transfer and Ql is water flow in volume per time.
E-ll
-------
IWEM Technical Background Document
Appendix E
Equation E-5. Overall mass transfer coefficient
Name
Kol
beta
Dw
Da
Hprime
TS~, j n . . ' ,
KOL - p A t + t
\Dw Da x Hprime)
Description
Overall mass transfer coefficient (cm/s)
Proportionality constant (cm-sA-l/3)
Diffusion coefficient in water (cnf/s)
Diffusion coefficient in air (cmVs)
Dimensionless Henry's law constant (dimensionless)
Value
Calculated above
216
Chemical-specific
Chemical-specific
Calculated in Equation E-3
This equation calculates the overall mass transfer coefficient. The above equation corresponds to Equation
17 in McKone (1987) and was modified to use the dimensionless Henry's law constant. McKone (1987)
noted that the proportionality constant, beta, was a dimensionless value. Little (1992b) indicated that beta
is not dimensionless. The correct units are noted above. The value for beta was derived using data for
benzene and verified for chemicals of varying volatility (Coburn, 1996).
E-12
-------
IWEM Technical Background Document
Appendix E
Equation E-6. Constituent mass emitted in the shower for a given time step
For Et > Emax,
Es = Emax
ForEt < Emax,
Es= Et
Where,
Et = Cin x ShowerRate x ts x fern
Emax = \yeq - ys, tj x Vs x 1 000
Name
Es
Emax
Et
yeq
ys, t
Vs
Cin
ShowerRate
ts
fern
Hprime
1000
Description
Constituent mass emitted in the shower for a given time step
(mg)
Maximum possible mass of constituent emitted from shower
during time step (mg)
Potential mass of constituent emitted from shower during
time step (mg)
Gas-phase constituent concentration in equilibrium between
water and air (mg/L)
Gas-phase constituent concentration in the shower at the
beginning of time step (mg/L)
Volume of shower (m3)
Liquid-phase constituent concentration in the incoming water
(mg/L)
Rate of flow from showerhead (L/min)
Time step (min)
Fraction of constituent emitted from a droplet
(dimensionless)
Dimensionless Henry's law constant (dimensionless)
Conversion factor (L/m3)
Value
Calculated above
Calculated above
Calculated above
Hprime x Cin
Calculated from last time step
Provided in Equation E-12
Provided in Equation E-12
Provided in Equation E-12
0.2
Calculated in Equation E-7
Calculated in Equation E-3
Conversion factor
The above equations are used to determine the mass of constituent emitted for a given time step. The
equilibrium concentration in air (y_eq) is calculated from Equation 1 in Little (1992a). If the mass emitted
based on the mass transfer coefficient (Et) is greater than the amount emitted to reach equilibrium (Emax),
the mass is set to the amount that results in the air concentration at equilibrium.
E-13
-------
IWEM Technical Background Document
Appendix E
Equation E-7. Fraction of constituent emitted from a droplet
fern = (l- Fsat] x (;- e~N\
Name
fern
Fsat
N
Description
Fraction of constituent emitted from a droplet
(dimensionless)
Fraction of gas-phase saturation (dimensionless)
Dimensionless overall mass transfer coefficient
(dimensionless)
Value
Calculated above
Calculated in Equation A-8
Calculated in Equation A-4
This equation is used to calculate the fraction of a given chemical emitted from a droplet of water in the
shower. The equation is based on Equation 5 in Little (1992a). The above equation is obtained by
rearranging the equation in Little given that ys_max/m = Cin and f_sat = ys/ys_max = ys/(m * Cin).
Equation E-8. Fraction of gas-phase saturation in shower
Name
Fsat
yeq
ys, t
Hprime
Cin
Vs,t
77V -K/
1'Sdt
yeq
Description
Fraction of gas-phase saturation in shower (dimensionless)
Gas-phase constituent concentration in equilibrium between
water and air (mg/L)
Current gas-phase constituent concentration in air (mg/L)
Dimensionless Henry's law constant (dimensionless)
Constituent concentration in incoming water (mg/L)
Value
Calculated above
Hprime x Cin
Calculated in Equation E-9 (as
ys, t+ts for previous time step)
Calculated in Equation E-3
Provided in Equation E-12
This equation is used to calculate the fraction of gas phase saturation in shower for each time step. The
equilibrium concentration in air (y_eq) is calculated from Equation 1 in Little (1992a).
E-14
-------
IWEM Technical Background Document
Appendix E
Equation E-9. Gas-phase constituent concentration
Name
ys, t+ts
ys, t
yb, t
Es
Qsb
Vs
ts
1000
[& - (Qsb
in the shower at end of time step
x (ys, t - yb, t\ x ts\
Vs x 1000
Description
Gas-phase constituent concentration in the shower at end of
time step (mg/L)
Gas-phase constituent concentration in the shower at the
beginning of time step (mg/L)
Gas-phase constituent concentration in the bathroom at the
beginning of time step (mg/L)
Mass emitted in the shower for a given time step (mg)
Volumetric exchange rate between the
bathroom (L/min)
shower and the
Volume of shower (m3)
Time step (min)
Conversion factor (L/m3)
Value
Calculated above
Calculated from last time step
Calculated from last time step
Calculated in Equation E-6
Provided in Equation E-12
Provided in Equation E-12
0.2
Conversion factor
This equation is used to calculate the gas-phase constituent concentration in the shower at end of time step.
The equation is derived from Equation 9 in Little (1992a). Es is set to 0 when the shower is turned off (i.e.,
at the end of showering) to estimate the reduction in shower stall air concentrations after emissions cease.
E-15
-------
IWEM Technical Background Document
Appendix E
Equation E-10. Gas-phase constituent concentration in the bathroom at end of time step
yb,n
Name
yb, t+ts
yb, t
ys, t+ts
yh, t
Qsb
Qbh
Vb
ts
1000
\\Qsb X (ys,t + ts- yb,t\ - Qbh X \Vb,t- yh, t\\\
1 V/, / 1 ^' t?
Vb x 1000
Description
Gas-phase constituent concentration in the bathroom at end
of time step (mg/L)
Gas-phase constituent concentration in the bathroom at the
beginning of time step (mg/L)
Gas-phase constituent concentration in the shower at the end
of time step (mg/L)
Gas-phase constituent concentration in the house at the
beginning of time step (mg/L)
Volumetric exchange rate between the shower and the
bathroom (L/min)
Volumetric exchange rate between the bathroom and the
house (L/min)
Volume of bathroom (m3)
Time step (min)
Conversion factor (L/m3)
Value
Calculated above
Calculated from last time step
Calculated in Equation E-9
Assumed deminimus, zero
Provided in Equation E-12
Provided in Equation E-12
Provided in Equation E-12
0.2
Conversion factor
This equation is used to calculate the gas-phase constituent concentration in the bathroom at end of time
step. The equation is derived from Equation 10 in Little (1992a).
E-16
-------
IWEM Technical Background Document
Appendix E
Equation E-ll. Average daily concentration in indoor air
C air indot
Name
Cair_indoor
Cair_shower
Cair_bathroom
ShowerResTime
T_bathroom
ys, t
ys, t+ts
yb, t
yb, t+ts
ns
nb
1440
1000
\Cair shower x ShowerResTime} + \Catr bathroom x T bathroom]
1440
J] [(ys, /+ ts + ys, t ) 1 2J x 1000
C^air shower
ns
^ [(yb, t+ts + >*,/)/ 2J x 1000
Ca/r bathroom
nb
Description
Average daily concentration in indoor air (mg/m3)
Average concentration in shower (mg/m3)
Average concentration in bathroom (mg/m3)
Total time spent in shower stall (min)
Time spent in bathroom, not in shower (min)
Gas-phase constituent concentration in the shower at the
beginning of time step (mg/L)
Gas-phase constituent concentration in the shower at the end
of time step (mg/L)
Gas-phase constituent concentration in the bathroom at the
beginning of time step (mg/L)
Gas-phase constituent concentration in the bathroom at the
end of time step (mg/L)
Number of time steps corresponding to time spent in the
shower (dimensionless)
Number of time steps corresponding to time spent in the
bathroom (dimensionless)
Minutes per day (min)
Conversion factor (L/m3)
Value
Calculated above
Calculated above
Calculated above
Calculated in Equation E-2
Provided in Equation E-12
Calculated from last time step
Calculated in Equation E-9
Calculated from last time step
Calculated in Equation E-10
Summed in model code
Summed in model code
Conversion factor
The above equations are used to calculate the time-weighted average daily indoor air concentration to
which a receptor is exposed. The equation assumes that receptors are only exposed to constituents in the
shower and bathroom.
E-17
-------
IWEM Technical Background Document Appendix E
E-2 Constituent-specific Chemical and Physical Properties for
the Shower Model
To calculate inhalation HBNs, the shower model requires input of several
chemical-specific properties, including Henry's law constant (HLC), solubility (Sol), and
diffusion coefficients in air (DJ and water (DJ. This attachment describes the data
sources and methodologies used to collect and develop these properties. Table E. 12 (at
the end of this appendix lists by constituent the chemical-specific properties used to
calculate inhalation HBNs, along with the data source for each value.
E-2.1 Data Collection Procedure
To select data values available from multiple sources, we created a hierarchy of
references based on the reliability and availability of data in such sources. Our first
choice for data collection and calculations was EPA reports and software. When we
could not find data or equations from EPA publications, we consulted highly recognized
sources, including chemical information databases on the Internet. These on-line sources
are compilations of data that provide the primary references for data values. The specific
hierarchy varied among properties as described in subsequent sections.
For dioxins, the preferred data source in all cases was the Exposure and Human
Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related
Compounds, Part 1, Vol. 3 (Dioxin Reassessment) (USEPA, 2000). We used the
Mercury Study Report to Congress (USEPA, 1997a) as the preferred source for mercury
properties. If values were unavailable from these sources, we followed the same
reference hierarchy that was used for other constituents.
All data entry for chemical and physical properties was checked by comparing
each entry against the original online or hardcopy reference. All property calculation
programs were checked using hand calculations to ensure that they were functioning
correctly.
E-2.2 Solubility (Sol)
For solubility (Sol) values, we looked for data by searching the following sources
in the following order:
1. Superfund Chemical Data Matrix (SCDM) (USEPA, 1997b);
2. CHEMFATE Chemical Search (SRC, 1999);
E-18
-------
IWEM Technical Background Document _ Appendix E
3. Hazardous Substances Data Bank (HSDB) (USNLM, 2001);
4. ChemFinder (CambridgeSoft Corporation, 2001).
For mercury, we obtained a solubility for elemental mercury from The Merck Index: An
Encyclopedia of Chemicals, Drugs, and Biologicals (Budavari, 1996).
E-2.3 Henry's Law Constant (HLC)
Collection of Henry's law constant (HLC) data proceeded by searching sources in
the following order:
1. SCDM;
2. CHEMFATE;
3. HSDB.
When we could not find data from these sources, we calculated HLC using equation 15-8
from Lyman, Reehl, and Rosenblatt (1990):
Sol
where
HLC = Henry's law constant (atm-mVmolej
Pvp = vapor pressure (atm)
Sol = solubility (mol/m3).
E-2.4 Diffusion Coefficient in Water (Dw)
For all chemicals, we calculated the diffusion coefficient in water (Dw) by hand
because few empirical data are available. The preferred calculation was equation 17-6
from the WATER9 model (USEPA, 2001):
T + 273.1 6^ ( MW\ ~°'6
Dw =0.0001518
1 298.16 A p
where
Dw = diffusion coefficient in water (cm2/s)
T = temperature (degrees C)
MW = molecular weight (g/g-mol)
p = density (g/cc).
E-19
-------
IWEM Technical Background Document Appendix E
When we did not know chemical density, we used equation 3.16 from Process
Coefficients and Models for Simulating Toxic Organics and Heavy Metals in Surface
(Process Coefficients) (USEPA, 1987), which only requires molecular weight:
Dw= 0.00022 xMf~2/3
where
Dw = diffusion coefficient in water (cm2/s)
MW = molecular weight (g/mol).
E-2.5 Diffusion Coefficient in Air (DJ
All diffusion coefficients in air (Da) were calculated values because few empirical
data are available. Similar to Dw, we first consulted WATER9 and then used USEPA
(1987). Equation 17-5 in WATER9 calculates diffusivity in air as follows:
0.0029(r+273.16)L5,|
D= V
0.034 + (l- 0.000015MT2)
^
.5/
where
Da = diffusion coefficient in air (cm2/s)
T = temperature (degrees C)
MW = molecular weight (g/g-mol)
p = density (g/cc).
When density was not available, we used equation 3.17 from Process Coefficients
(U.S. EPA, 1987):
-2/3
where
E-20
-------
IWEM Technical Background Document _ Appendix E
Da = diffusion coefficient in air (cm2/s)
MW = molecular weight (g/mol).
For dioxins and furans, we used an equation from the Dioxin Reassessment (USEPA,
2000) to estimate diffusion coefficients from diphenyl's diffusivity:
Da ( MWb\ '
Db
where
Da = diffusion coefficient of constituent in air (cm2/s)
Db = diffusion coefficient of diphenyl at 25 degrees C (0.068
cm2/s)
MWa = molecular weight of constituent (g/mol e)
MWb = molecular weight of diphenyl (154 g/mole).
E-21
-------
IWEM Technical Background Document
Appendix E
Table E.12. Constituent-specific Chemical and Physical Properties
Constituent
Acetaldehyde (ethanal)
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acrolein
Acrylamide
Acrylic acid (propenoic acid)
Acrylonitrile
Aldrin
Aniline (benzeneamine)
3enz(a)anthracene
Benzene
3enzidine
3enzo(a)pyrene
3enzo(b)fluoranthene
Benzyl chloride
3is(2-ethylhexyl)phthalate
3is(2-chloroethyl)ether
3is(2-chloroisopropyl)ether
3romodichloromethane
3romomethane (methyl bromide)
3utadiene, 1,3-
Carbon tetrachloride
Carbon disulfide
Chlordane
Chloro- 1,3 -butadiene, 2- (Chloroprene)
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane (ethyl chloride)
Chloroform
Chloromethane (methyl chloride)
Chlorophenol, 2-
Chloropropene, 3- (allyl chloride)
CASRN
75-07-0
67-64-1
75-05-8
107-02-8
79-06-1
79-10-7
107-13-1
309-00-2
62-53-3
56-55-3
71-43-2
92-87-5
50-32-8
205-99-2
100-44-7
117-81-7
111-44-4
39638-32-9
75-27-4
74-83-9
106-99-0
56-23-5
75-15-0
57-74-9
126-99-8
108-90-7
510-15-6
124-48-1
75-00-3
67-66-3
74-87-3
95-57-8
107-05-1
Da (cm2/s)
1.28E-01 e
1.06E-01 e
1.34E-01 e
1.12E-01 e
1.07E-01 e
1.03E-01 e
1.14E-01 e
2.28E-02 e
8.30E-02 e
5.09E-02 b
8.95E-02 e
3.55E-02 e
2.55E-02 e
4.76E-02 b
6.34E-02 e
1.73E-02 e
5.67E-02 e
4.01E-02 e
5.63E-02 e
l.OOE-01 e
l.OOE-01 e
5.71E-02 e
1.06E-01 e
2.15E-02 e
8.41E-02 e
7.21E-02 e
2.18E-02 e
3.66E-02 e
1.04E-01 e
7.70E-02 e
1.24E-01 e
6.61E-02 e
9.36E-02 e
Dw (cm2/s)
1.35E-05 e
1.15E-05 e
1.41E-05 e
1.22E-05 e
1.26E-05 e
1.20E-05 e
1.23E-05 e
5.84E-06 e
1.01E-05 e
5.89E-06 b
1.03E-05 e
7.59E-06 e
6.58E-06 e
5.51E-06 b
8.81E-06 e
4.18E-06 e
8.71E-06 e
7.40E-06 e
1.07E-05 e
1.35E-05 e
1.03E-05 e
9.78E-06 e
1.30E-05 e
0 e
l.OOE-05 e
9.48E-06 e
5.48E-06 e
1.06E-05 e
1.16E-05 e
1.09E-05 e
1.36E-05 e
9.48E-06 e
1.08E-05 e
HLC
(atm-m3/mol)
7.89e-05 a
3.88e-05 a
3.46e-05 a
1.22e-04 a
l.OOe-09 a
1.17e-07 a
1.03e-04 a
1.70e-04 a
1.90e-06 a
3.35e-06 a
5.55e-03 a
3.88e-ll a
1.13e-06 a
l.lle-04 a
4.15e-04 a
1.02e-07 a
1.80e-05 a
1.34e-04 d
1.60e-03 a
6.24e-03 a
7.36e-02 a
3.04e-02 a
3.03e-02 a
4.86e-05 a
1.19e-02 f
3.70e-03 a
7.24e-08 f
7.83e-04 a
8.82e-03 a
3.67e-03 a
8.82e-03 a
3.91e-04 a
1.10e-02 a
Sol (mg/L)
l.OOe+06 a
l.OOe+06 a
l.OOe+06 a
2.13e+05 a
6.40e+05 a
l.OOe+06 a
7.40e+04 a
1. 80e-01 a
3.60e+04 a
9.40e-03 a
1.75e+03 a
5.00e+02 a
1.62e-03 a
1.50e-03 a
5.25e+02 a
3.40e-01 a
1.72e+04 a
1.31e+03 a
6.74e+03 a
1.52e+04 a
7.35e+02 a
7.93e+02 a
1.19e+03 a
5.60e-02 a
1.74e+03 a
4.72e+02 a
l.lle+01 a
2.60e+03 a
5.68e+03 a
7.92e+03 a
5.33e+03 a
2.20e+04 a
3.37e+03 a
E-22
-------
IWEM Technical Background Document
Appendix E
Table E.12. Constituent-specific Chemical and Physical Properties (continued)
Constituent
Chrysene
Cresol, o-
Cresol,
Cresol, p-
Cresols (total)
Cumene
Cyclohexanol
DDT, p,p'-
3ibenz(a,h)anthracene
3ibromo-3-chloropropane, 1,2-
Dichlorobenzene, 1,2-
Dichlorobenzene, 1,4-
Dichlorobenzidine, 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane, 1,1-
Dichloroethane, 1,2-
Dichloroethylene, 1,1-
Dichloropropane, 1,2-
Dichloropropene, trans- 1,3-
Dichloropropene, 1,3- (isomer mixture)
Dichloropropene, cis-1,3-
Dieldrin
Dimethyl formamide, N,N- (DMF)
3imethylbenz(a)anthracene, 7,12-
Dinitrotoluene, 2,4-
Dioxane, 1,4-
Diphenylhydrazine, 1,2-
3pichlorohydrin
Spoxybutane, 1,2-
ithoxyethanol acetate, 2-
ithoxyethanol , 2-
ithylbenzene
ithylene dibromide
( 1 ,2-dibromoethane)
CASRN
218-01-9
95-48-7
108-39-4
106-44-5
1319-77-3
98-82-8
108-93-0
50-29-3
53-70-3
96-12-8
95-50-1
106-46-7
91-94-1
75-71-8
75-34-3
107-06-2
75-35-4
78-87-5
10061-02-6
542-75-6
10061-01-5
60-57-1
68-12-2
57-97-6
121-14-2
123-91-1
122-66-7
106-89-8
106-88-7
111-15-9
110-80-5
100-41-4
106-93-4
Da (cm2/s)
2.61E-02 e
7.59E-02 e
0.0729 e
7.24E-02 e
7.37E-02 e
6.02E-02 e
7.59E-02 e
1.83E-02 e
2.36E-02 e
3.21E-02 e
5.62E-02 e
5.50E-02 e
4.75E-02 b
7.60E-02 e
8.36E-02 e
8.54E-02 e
8.63E-02 e
7.33E-02 e
7.63E-02 e
7.63E-02 e
7.65E-02 e
2.33E-02 e
9.72E-02 e
4.71E-02 b
3.75E-02 e
8.74E-02 e
0.0343 e
0.0888 e
9.32E-02 e
5.70E-02 e
8.19E-02 e
6.86E-02 e
4.31E-02 e
Dw (cm2/s)
6.75E-06 e
9.86E-06 e
0 e
9.24E-06 e
9.48E-06 e
7.85E-06 e
9.35E-06 e
4.44E-06 e
6.02E-06 e
8.90E-06 e
8.92E-06 e
8.68E-06 e
5.50E-06 b
1.08E-05 e
1.06E-05 e
1.09E-05 e
1.10E-05 e
9.73E-06 e
1.01E-05 e
1.01E-05 e
1.02E-05 e
6.01E-06 e
1.12E-05 e
5.45E-06 b
7.90E-06 e
1.05E-05 e
7.25E-06 e
1.11E-05 e
1.05E-05 e
7.98E-06 e
9.76E-06 e
8.48E-06 e
1.05E-05 e
HLC
(atm-m3/mol)
9.46e-05 a
1.20e-06 a
8.65e-07 a
7.92e-07 a
9.52e-07 a
1.16e+00 a
1.02e-04 f
8.10e-06 a
1.47e-08 a
1.47e-04 a
1.90e-03 a
2.40e-03 a
4.00e-09 a
3.43e-01 a
5.62e-03 a
9.79e-04 a
2.61e-02 a
2.80e-03 a
1.80e-03 i
1.77e-02 a
2.40e-03 i
1.51e-05 a
7.39e-08 i
3.11e-08 a
9.26e-08 a
4.80e-06 a
1.53e-06 a
3.04e-05 a
1.80e-04 f
1.80e-06 i
1.23e-07 a
7.88e-03 a
7.43e-04 a
Sol (mg/L)
1.60e-03 a
2.60e+04 a
2.27e+04 a
2.15e+04 a
2.34e+04 a
6.13e+01 a
4.30e+04 f
2.50e-02 a
2.49e-03 a
1.23e+03 a
1.56e+02 a
7.38e+01 a
3.11e+00 a
2.80e+02 a
5.06e+03 a
8.52e+03 a
2.25e+03 a
2.80e+03 a
2.72e+03 a
2.80e+03 a
2.72e+03 a
1.956-01 a
l.OOe+06 f
2.50e-02 a
2.70e+02 a
l.OOe+06 a
6.80e+01 a
6.59e+04 a
9.50e+04 f
2.29e+05 i
l.OOe+06 a
1.69e+02 a
4.18e+03 a
E-23
-------
IWEM Technical Background Document
Appendix E
Table E.12. Constituent-specific Chemical and Physical Properties (continued)
Constituent
ithylene glycol
ithylene thiourea
ithylene oxide
"ormaldehyde
inirfural
3CH, gamma- (Lindane)
3CH, beta-
3CH, alpha-
rleptachlor epoxide
rleptachlor
Sexachloro- 1 , 3 -butadiene
Sexachlorobenzene
Sexachlorocyclopentadiene
rlexachlorodibenzo-p-dioxins
(HxCDDs)
rlexachlorodibenzofurans (HxCDFs)
rlexachloroethane
rlexane, -
[ndeno( 1 ,2,3 -cd)pyrene
[sophorone
Vlercury
Vlethacrylonitrile
Vlethanol
Vlethoxyethanol acetate, 2-
Vlethoxyethanol, 2-
Vlethyl methacrylate
VIethyl tert-butyl ether (MTBE)
VIethyl isobutyl ketone
VIethyl ethyl ketone
VIethylcholanthrene, 3-
Vlethylene chloride (dichloromethane)
N-Nitrosomethylethylamine
N-Nitrosodimethylamine
N-Nitrosopiperidine
CASRN
107-21-1
96-45-7
75-21-8
50-00-0
98-01-1
58-89-9
319-85-7
319-84-6
1024-57-3
76-44-8
87-68-3
118-74-1
77-47-4
34465-46-8
55684-94-1
67-72-1
110-54-3
193-39-5
78-59-1
7439.97-6
126-98-7
67-56-1
110-49-6
109-86-4
80-62-6
1634-04-4
108-10-1
78-93-3
56-49-5
75-09-2
10595-95-6
62-75-9
100-75-4
Da (cm2/s)
1.17E-01 e
8.69E-02 b
1.34E-01 e
1.67E-01 e
8.53E-02 e
2.74E-02 e
0.0277 e
2.75E-02 e
2.19E-02 e
2.23E-02 e
2.67E-02 e
2.90E-02 e
2.72E-02 e
4.27E-02 j
4.36E-02 j
3.21E-02 e
7.28E-02 e
4.48E-02 b
5.25E-02 e
7.15E-02 e
9.64E-02 e
1.58E-01 e
6.59E-02 e
0.0952 e
7.53E-02 e
7.55E-02 e
6.98E-02 e
9.17E-02 e
2.41E-02 e
9.99E-02 e
8.41E-02 e
9.88E-02 e
6.99E-02 e
Dw (cm2/s)
1.36E-05 e
1.01E-05 b
1.46E-05 e
1.74E-05 e
1.07E-05 e
7.30E-06 e
7.40E-06 e
7.35E-06 e
5.58E-06 e
5.70E-06 e
7.03E-06 e
7.85E-06 e
7.22E-06 e
4.12E-06 b
4.23E-06 b
8.89E-06 e
8.12E-06 e
5.19E-06 b
7.53E-06 e
3.01E-05 e
1.06E-05 e
1.65E-05 e
8.71E-06 e
1.10E-05 e
9.25E-06 e
8.63E-06 e
8.36E-06 e
1.02E-05 e
6.14E-06 e
1.25E-05 e
9.99E-06 e
1.15E-05 e
9.18E-06 e
HLC
(atm-m3/mol)
6.00e-08 a
3.08e-10 a
1.48e-04 f
3.36e-07 a
4.00e-06 a
1.40e-05 a
7.43e-07 a
1.06e-05 a
9.50e-06 a
1.10e-03 a
8.15e-03 a
1.32e-03 a
2.70e-02 a
1.10e-05 c
1.10e-05 c
3.89e-03 a
1.43e-02 a
1.60e-06 a
6.64e-06 a
7.10e-03 k
2.47e-04 a
4.55e-06 a
3.11e-07 d
8.10e-08 f
3.37e-04 a
5.87e-04 f
1.38e-04 a
5.59e-05 a
9.40e-07 a
2.19e-03 a
1.40e-06 i
1.20e-06 a
2.80e-07 a
Sol (mg/L)
l.OOe+06 a
6.20e+04 a
l.OOe+06 g
5.50e+05 a
1.10e+05 a
6.80e+00 a
2.40e-01 a
2.00e+00 a
2.00e-01 a
1. 80e-01 a
3.23e+00 a
5.00e-03 a
1. 80e+00 a
4.40e-06 c
1.30e-05 c
5.00e+01 a
1.246+01 a
2.20e-05 a
1.20e+04 a
5.62e-02 h
2.54e+04 a
l.OOe+06 a
l.OOe+06 i
l.OOe+06 g
1.50e+04 a
5.13e+04 f
1.90e+04 a
2.23e+05 a
3.23e-03 a
1.30e+04 a
1.97e+04 a
l.OOe+06 a
7.65e+04 a
E-24
-------
IWEM Technical Background Document
Appendix E
Table E.12. Constituent-specific Chemical and Physical Properties (continued)
Constituent
N-Nitrosodiphenylamine
N-Nitrosodiethylamine
N-Nitroso-di-n-butylamine
N-Nitrosopyrrolidine
N-Nitroso-di-n-propylamine
Naphthalene
Nitrobenzene
Nitropropane, 2-
3entachlorodibenzo-p-dioxins
(PeCDDs)
3entachlorodibenzofurans (PeCDFs)
3entachlorophenol
r'henol
3hthalic anhydride
3olychlorinated biphenyls (Aroclors)
3ropylene oxide (1,2-epoxypropane)
^yridine
styrene
retrachlorodibenzo-p-dioxin, 2,3,7,8-
(2,3,7,8-TCDD)
Tetrachlorodibenzofurans (TCDFs)*
Tetrachloroethane, 1,1,2,2-
retrachloroethane, 1,1,1,2-
retrachloroethylene
Toluene
Toluenediamine 2,4-
roluidine, o-
Toxaphene (chlorinated camphenes)
rribromomethane (bromoform)
rrichloro-l,2,2-trifluoro-ethane, 1,1,2-
rrichlorobenzene, 1,2,4-
rrichloroethane, 1,1,2-
rrichloroethane, 1,1,1-
rrichloroethylene (TCE)
CASRN
86-30-6
55-18-5
924-16-3
930-55-2
621-64-7
91-20-3
98-95-3
79-46-9
36088-22-9
30402-15-4
87-86-5
108-95-2
85-44-9
1336-36-3
75-56-9
110-86-1
100-42-5
1746-01-6
55722-27-5
79-34-5
630-20-6
127-18-4
108-88-3
95-80-7
95-53-4
8001-35-2
75-25-2
76-13-1
120-82-1
79-00-5
71-55-6
79-01-6
Da (cm2/s)
2.84E-02 e
7.38E-02 e
4.22E-02 e
8.00E-02 e
5.64E-02 e
6.05E-02 e
6.81E-02 e
8.47E-02 e
0.0447 j
4.57E-02 j
2.95E-02 e
8.34E-02 e
5.95E-02 e
2.33E-02 e
1.10E-01 e
9.31E-02 e
7.13E-02 e
4.70E-02 j
4.82E-02 j
4.89E-02 e
4.82E-02 e
5.05E-02 e
7.80E-02 e
7.72E-02 b
7.24E-02 e
2.16E-02 e
3.58E-02 e
3.76E-02 e
3.96E-02 e
6.69E-02 e
6.48E-02 e
6.87E-02 e
Dw (cm2/s)
7.19E-06 e
9.13E-06 e
6.83E-06 e
1.01E-05 e
7.76E-06 e
8.38E-06 e
9.45E-06 e
1.02E-05 e
4.38E-06 b
4.51E-06 b
8.01E-06 e
1.03E-05 e
9.75E-06 e
5.98E-06 e
1.21E-05 e
1.09E-05 e
8.81E-06 e
4.68E-06 b
4.84E-06 b
9.29E-06 e
9.10E-06 e
9.45E-06 e
9.23E-06 e
8.94E-06 b
9.18E-06 e
5.48E-06 e
1.04E-05 e
8.59E-06 e
8.40E-06 e
l.OOE-05 e
9.60E-06 e
1.02E-05 e
HLC
(atm-m3/mol)
5.00e-06 a
3.63e-06 a
3.16e-04 a
1.20e-08 a
2.25e-06 a
4.83e-04 a
2.40e-05 a
1.23e-04 a
2.60e-06 c
5.00e-06 c
2.44e-08 a
3.97e-07 a
1.63e-08 a
2.60e-03 a
1.23e-04 f
8.88e-06 a
2.75e-03 a
3.29e-05 c
1.40e-05 c
3.45e-04 a
2.42e-03 a
1.84e-02 a
6.64e-03 a
7.92e-10 a
2.72e-06 a
6.00e-06 a
5.35e-04 a
4.81e-01 a
1.42e-03 a
9.13e-04 a
1.72e-02 a
1.03e-02 a
Sol (mg/L)
3.51e+01 a
9.30e+04 a
1.27e+03 a
l.OOe+06 a
9.89e+03 a
3.106+01 a
2.09e+03 a
1.70e+04 a
1.18e-04 c
2.40e-04 c
1.95e+03 a
8.28e+04 a
6.20e+03 a
7.00e-02 a
4.05e+05 f
l.OOe+06 a
3.10e+02 a
1.93e-05 c
4.20e-04 c
2.97e+03 a
l.lOe+03 a
2.00e+02 a
5.26e+02 a
3.37e+04 a
1.66e+04 a
7.40e-01 a
3.10e+03 a
1.70e+02 a
3.46e+01 a
4.42e+03 a
1.33e+03 a
1.10e+03 a
E-25
-------
IWEM Technical Background Document
Appendix E
Table E.12. Constituent-specific Chemical and Physical Properties (continued)
Constituent
rrichlorofluoromethane (Freon 1 1)
Trichlorophenol, 2,4,6-
rrichloropropane, 1,2,3-
rriethylamine
Vinyl acetate
Vinyl chloride
Xylene, p-
Xylene, o-
Xylene, m-
Xylenes (total)
CASRN
75-69-4
88-06-2
96-18-4
121-44-8
108-05-4
75-01-4
106-42-3
95-47-6
108-38-3
1330-20-7
Da (cm2/s)
6.55E-02 e
3.14E-02 e
5.75E-02 e
6.63E-02 e
8.51E-02 e
1.07E-01 e
6.84E-02 e
6.91E-02 e
6.85E-02 e
6.87E-02 e
Dw (cm2/s)
1.01E-05 e
8.09E-06 e
9.24E-06 e
7.84E-06 e
l.OOE-05 e
1.20E-05 e
8.45E-06 e
8.56E-06 e
8.47E-06 e
8.49E-06 e
HLC
(atm-m3/mol)
9.70e-02 a
7.79e-06 a
4.09e-04 a
1.38e-04 f
5.11e-04 a
2.70e-02 a
7.66e-03 a
5.19e-03 a
7.34e-03 a
6.73e-03 a
Sol (mg/L)
l.lOe+03 a
8.00e+02 a
1.75e+03 a
5.50e+04 f
2.00e+04 a
2.76e+03 a
1.85e+02 a
1.78e+02 a
1.61e+02 a
1.75e+02 a
Da = air diffusivity; Dw = water diffusivity; HLC = Henry's law constant; Sol = aqueous solubility
CASRN = Chemical Abstract Service Registry Number
* Values used for 2,3,7,8-tetrachlorodibenzofuran (CAS #51207-31-9).
Data Sources:
a SCDM (USEPA, 1997b).
b Calculated based on USEPA, 1987.
c USEPA, 2000.
d Calculated based onLyman, Reehl, and Rosenblatt, 1990.
e Calculated based on WATER9 (USEPA, 2001).
f CHEMFATE (SRC, 1999).
g ChemFinder.com (CambridgeSoft Corporation, 2001).
h The Merck Index (Budavari, 1996).
i HSDB (NLM, 2001).
j Calculated based on USEPA, 2000.
k USEPA, 1997a.
E-26
-------
IWEM Technical Background Document Appendix E
E-2.6 References for Appendix E-2
Budavari, S. (ed). 1996. The Merck Index: An Encyclopedia of Chemicals, Drugs, and
Biologicals. 12th edition. Whitehouse Station, NJ: Merck and Co.
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching.
http://chemfmder.cambridgesoft.com. Accessed July 2001.
Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt. 1990. Handbook of Chemical Property
Estimation Methods: Environmental Behavior of Organic Compounds.
Washington, DC: American Chemical Society.
Syracuse Research Corporation (SRC). 1999. CHEMFATE Chemical Search,
Environmental Science Center, Syracuse, NY.
http://esc.syrres.com/efdb/Chemfate.htm. Accessed July 2001.
USEPA. 1987. Process Coefficients and Models for Simulating Toxic Organics and
Heavy Metals in Surface Waters. Office of Research and Development.
Washington, DC: U.S. Government Printing Office (GPO).
USEPA. 1997a. Mercury Study Report to Congress. Volume IV: An Assessment of
Exposure to Mercury in the United States. EPA-452/R-97-006. Office of Air
Quality Planning and Standards and Office of Research and Development.
Washington, DC: GPO.
USEPA. 1997b. Superfund Chemical Data Matrix (SCDM). SCDMWIN 1.0 (SCDM
Windows User's Version), Version 1. Office of Solid Waste and Emergency
Response, Washington DC: GPO.
http://www.epa.gov/superfund/resources/scdm/index.htm. Accessed July 2001.
USEPA. 2000. Exposure and Human Health Reassessment of 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds, Part 1, Vol. 3.
Office of Research and Development, Washington, DC: GPO.
USEPA. 2001. WATER9. Office of Air Quality Planning and Standards, Research
Triangle Park, NC. http://www.epa.gov/ttn/chief/software/water/index.html.
Accessed July 2001.
USNLM (U.S. National Library of Medicine). 2001. Hazardous Substances Data Bank
(HSDB). http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen7HSDB. Accessed
July 2001.
E-27
-------
IWEM Technical Background Document Appendix E
E-3 Human Health Benchmarks used in the IWEM Tool
Human health benchmarks for chronic oral and inhalation exposures are an
important component of the IWEM 1 tool. The U.S. Environmental Protection Agency
(EPA) uses reference doses (RfDs) and reference concentrations (RfCs) to evaluate
noncancer risk from oral and inhalation exposures, respectively. Oral cancer slope
factors (CSFs), inhalation unit risk factors (URFs), and inhalation CSFs are used to
evaluate risk for carcinogens.
This memorandum provides the toxicity benchmarks we used to develop the
HBNs that we will use in developing Reference Groundwater Concentrations used in the
IWEM tool. Section E-3.1 describes the data sources and general hierarchy used to
collect these benchmarks. Section E-3.2 provides the benchmarks along with discussions
of individual human health benchmarks extracted from a variety of sources.
E-3.1 Methodology and Data Sources
Several sources of health benchmarks are available. Human health benchmarks
were obtained from these sources in the following order of preference:
Integrated Risk Information System (IRIS)
Superfund Technical Support Center Provisional Benchmarks
Health Effects Assessment Summary Tables (HEAST)
Agency for Toxic Substances and Disease Registry (ATSDR) minimal risk
levels (MRLs)
California Environmental Protection Agency (CalEPA) chronic inhalation
reference exposure levels (RELs) and cancer potency factors.
EPA health assessment documents
Various other EPA health benchmark sources.
For dioxins and dibenzofurans, World Health Organization (WHO) toxicity equivalency
factors (TEFs) from Van den Berg et al. (1998) were applied to the HEAST CSF for
2,3,7,8-TCDD to obtain CSFs for all other dioxins and furans (see Section E-3.2.4).
E-3.1.1 Integrated Risk Information System (IRIS)
Benchmarks in IRIS are prepared and maintained by EPA, and values from IRIS
were used to develop HBNs for the IWEM tool whenever IRIS benchmarks were
available. IRIS is EPA's electronic database containing information on human health
effects (USEPA, 200la). Each chemical file contains descriptive and quantitative
information on potential health effects. Health benchmarks for chronic noncarcinogenic
health effects include RfDs and RfCs. Cancer classification, oral CSFs, and inhalation
-------
IWEM Technical Background Document Appendix E
URFs are included for carcinogenic effects. IRIS is the official repository of Agency-
wide consensus of human health risk information.
Inhalation CSFs are not available from IRIS, so they were calculated from
inhalation URFs (which are available from IRIS) using the following equation:
inh CSF = inh URF x 70 kg - 20 m3/d x 1000 ng/mg
In this equation, 70 kg represents average body weight; 20 m3/d represents average
inhalation rate; and 1000 |ig/mg is a units conversion factor (USEPA, 1997). These
standard estimates of body weight and inhalation rate are used by EPA in the calculation
of the URF, and, therefore, the values were used to calculate inhalation CSFs.
E-3.1.2 Superfund Provisional Benchmarks
The Superfund Technical Support Center (EPA's National Center for
Environmental Assessment [NCEA]) derives provisional RfCs, RfDs, and CSFs for
certain chemicals. These provisional health benchmarks can be found in Risk
Assessment Issue Papers. Some of the provisional values have been externally peer
reviewed, and some (e.g., trichloroethylene, tetrachloroethylene) come from previously
published EPA Health Assessment Documents. These provisional values have not
undergone EPA's formal review process for finalizing benchmarks and do not represent
Agency-wide consensus information. Specific provisional values used in the IWEM tool
are described in Section E-3.2.5.
E-3.1.3 Health Effects Summary Tables (HEAST)
HEAST is a listing of provisional noncarcinogenic and carcinogenic health
toxicity values (RfDs, RfCs, URFs, and CSFs) derived by EPA (USEPA, 1997).
Although the health toxicity values in HEAST have undergone review and have the
concurrence of individual EPA program offices, either they have not been reviewed as
extensively as those in IRIS or their data set is not complete enough to be listed in IRIS.
HEAST benchmarks have not been updated in several years and do not represent
Agency-wide consensus information.
E-3.1.4 ATSDR Minimal Risk Levels
The ATSDR MRLs are substance-specific health guidance levels for
noncarcinogenic endpoints (ATSDR, 2001). An MRL is an estimate of the daily human
exposure to a hazardous substance that is likely to be without appreciable risk of adverse
noncancer health effects over a specified duration of exposure. MRLs are based on
noncancer health effects only and are not based on a consideration of cancer effects.
-------
IWEM Technical Background Document Appendix E
MRLs are derived for acute, intermediate, and chronic exposure durations for oral and
inhalation routes of exposure. Inhalation and oral MRLs are derived in a manner similar
to EPA's RfCs and RfDs, respectively (i.e., ATSDR uses the no-observed-adverse-effect-
level/uncertainty factor (NOAEL/UF) approach); however, MRLs are intended to serve
as screening levels and are exposure duration-specific. Also, ATSDR uses EPA's 1994
inhalation dosimetry methodology in the derivation of inhalation MRLs. A chronic
inhalation MRL for mixed xylenes was used as a surrogate for each of the xylene
isomers.
E-3.1.5 CalEPA Cancer Potency Factors and Reference Exposure Levels
CalEPA has developed cancer potency factors for chemicals regulated under
California's Hot Spots Air Toxics Program (CalEPA, 1999a). The cancer potency factors
are analogous to EPA's oral and inhalation CSFs. CalEPA has also developed chronic
inhalation RELs, analogous to EPA's RfC, for 120 substances (CalEPA, 1999b, 2000).
CalEPA used EPA's 1994 inhalation dosimetry methodology in the derivation of
inhalation RELs. The cancer potency factors and inhalation RELs have undergone
internal peer review by various California agencies and have been the subject of public
comment. A chronic inhalation REL for mixed cresols was used as a surrogate for each
of the cresol isomers.
E-3.1.6 Other EPA Health Benchmarks
EPA has also derived health benchmark values in other risk assessment
documents, such as Health Assessment Documents (HADs), Health Effect Assessments
(HEAs), Health and Environmental Effects Profiles (HEEPs), Health and Environmental
Effects Documents (HEEDs), Drinking Water Criteria Documents, and Ambient Water
Quality Criteria Documents. Evaluations of potential carcinogenicity of chemicals in
support of reportable quantity adjustments were published by EPA's Carcinogen
Assessment Group (CAG) and may include cancer potency factor estimates. Health
toxicity values identified in these EPA documents are usually dated and are not
recognized as Agency-wide consensus information or verified benchmarks, however, and
as a result they are used in the hierarchy only when values are not available from IRIS,
HEAST, Superfund provisional values, ATSDR, or CalEPA. Section E-3.2.6 describes
the specific values from these alternative EPA sources that were used in the IWEM tool.
E-3.2 Human Health Benchmark Values
The chronic human health benchmarks used to calculate the health-based numbers
(HBNs) in the IWEM tool are summarized in Table E-3.1, which provides the Chemical
Abstract Service Registry Number (CASRN), constituent name, RfD (mg/kg-d), RfC
(mg/m3), oral CSF (mg/kg-d'1), inhalation URF [(jig/m3)'1], inhalation CSF (mg/kg-d'1),
-------
IWEM Technical Background Document Appendix E
and reference for each benchmark. A key to the references cited and abbreviations used
is provided at the end of the table.
For a majority of the IWEM constituents, human health benchmarks were
available from IRIS (USEPA, 200la), Superfund Provisional Benchmarks, or HEAST
(USEPA, 1997). Benchmarks also were obtained from ATSDR (2001) or CalEPA
(1999a, 1999b, 2000). This section describes benchmarks obtained from other sources,
along with the Superfund Provisional values and special uses (e.g., benzene, vinyl
chloride) of IRIS benchmarks.
E-31
-------
Table E-3.1. Human Health Benchmark Values
Oj
Constituent Name
Acenaphthene
Acetaldehyde (ethanal)
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid (propenoic acid)
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b }fluoranthene
Benzyl chloride
CASRN
83-32-9
75-07-0
67-64-1
75-05-8
98-86-2
107-02-8
79-06-1
79-10-7
107-13-1
309-00-2
107-18-6
62-53-3
120-12-7
7440-36-0
7440-38-2
7440-39-3
56-55-3
71-43-2
92-87-5
50-32-8
205-99-2
100-44-7
RfD
(mg/kg-d)
6.0E-02
l.OE-01
l.OE-01
2.0E-02
2.0E-04
5.0E-01
l.OE-03
3.0E-05
5.0E-03
3.0E-01
4.0E-04
3.0E-04
7.0E-02
3.0E-03
RfDRef
I
I
I
H
I
I
H
I
I
I
I
I
I
I
CSFo
(per
mg/kg-d)
4.5E+0
5.4E-1
1.7E+01
5.7E-3
1.5E+00
1.2E+00
5.5E-02
2.3E+02
7.3E+00
1.2E+00
1.7E-01
CSFo
Ref
I
I
I
I
I
C99a
I
I
I
C99a
I
RfC
(mg/m3)
9.0E-03
3.1E+01
6.0E-02
2.0E-05
l.OE-03
2.0E-03
l.OE-03
6.0E-02
RfC Ref
I
A
I
I
I
I
I
COO
URF
(per
ug/m3)
2.2E-06
1.3E-03
6.8E-05
4.9E-03
1.6E-06
1.1E-04
7.8E-06
6.7E-02
1.1E-03
1.1E-04
4.9E-05
URF Ref
I
I
I
I
C99a
C99a
I
I
C99a
C99a
C99a
CSFi (per
mg/kg-d)
7.7E-03
4.6E+00
2.4E-01
1.7E+01
5.6E-03
3.9E-01
2.7E-02
2.3E+02
3.9E+00
3.9E-01
1.7E-01
CSFi Ref
calc
calc
calc
calc
calc
calc
calc
I
calc
calc
calc
r
"M.
8
I
I
I
-------
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Benzyl alcohol
Beryllium
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane (methyl
bromide)
Butadiene, 1,3-
Butanol
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-
(Dinoseb)
Cadmium
Carbon tetrachloride
Carbon disulfide
Chlordane
Chloro-l,3-butadiene, 2-
(Chloroprene)
Chloroaniline, p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
CASRN
100-51-6
7440-41-7
111-44-4
39638-32-9
117-81-7
75-27-4
74-83-9
106-99-0
71-36-3
85-68-7
88-85-7
7440-43-9
56-23-5
75-15-0
57-74-9
126-99-8
106-47-8
108-90-7
510-15-6
124-48-1
RfD
(mg/kg-d)
3.0E-01
2.0E-03
4.0E-02
2.0E-02
2.0E-02
1.4E-03
l.OE-01
2.0E-01
l.OE-03
5.0E-04
7.0E-04
l.OE-01
5.0E-04
2.0E-02
4.0E-03
2.0E-02
2.0E-02
2.0E-02
RfDRef
H
I
I
I
I
I
I
I
I
I
I
I
I
H
I
I
I
I
CSFo
(per
mg/kg-d)
1.1E+00
7.0E-02
1.4E-02
6.2E-02
1.3E-01
3.5E-01
2.7E-01
8.4E-02
CSFo
Ref
I
H
I
I
I
I
H
I
RfC
(mg/m3)
l.OE-02
5.0E-03
2.0E-02
7.0E-03
7.0E-01
7.0E-04
7.0E-03
6.0E-02
RfC Ref
C99b
I
COO
SF
I
I
H
SF
URF
(per
ug/m3)
3.3E-04
l.OE-05
2.4E-06
1.8E-05
2.8E-04
1.5E-05
l.OE-04
7.8E-05
2.4E-05
URF Ref
I
H
C99a
AC
I
I
I
H
AC
CSFi (per
mg/kg-d)
1.2E+00
3.5E-02
8.4E-03
6.2E-02
9.8E-01
5.3E-02
3.5E-01
2.7E-01
8.4E-02
CSFi Ref
calc
calc
calc
AC
calc
calc
calc
calc
AC
r
"M.
8
I
I
I
Oj
Oj
-------
Oj
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Chloroethane (ethyl chloride)
Chloroform
Chloromethane (methyl
chloride)
Chlorophenol, 2-
Chloropropene, 3- (allyl
chloride)
Chromium (III)
Chromium (VI)
Chrysene
Cobalt
Copper
Cresol, p-
Cresol, o-
Cresol, m-
Cresols (total)
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
CASRN
75-00-3
67-66-3
74-87-3
95-57-8
107-05-1
16065-83-1
18540-29-9
218-01-9
7440-48-4
7440-50-8
106-44-5
95-48-7
108-39-4
1319-77-3
98-82-8
108-93-0
108-94-1
72-54-8
72-55-9
RfD
(mg/kg-d)
l.OE-02
5.0E-03
1.5E+00
3.0E-03
2.0E-02
RfDRef
I
I
I
I
SF
CSFo
(per
mg/kg-d)
1.3E-02
1.2E-01
CSFo
Ref
H
C99a
RfC
(mg/m3)
l.OE+01
l.OE-01
9.0E-02
1.4E-03
l.OE-03
RfC Ref
I
A
I
AC
I
URF
(per
ug/m3)
1.8E-06
6.0E-06
1.1E-05
URF Ref
H
C99a
C99a
CSFi (per
mg/kg-d)
6.3E-03
2.1E-02
3.9E-02
CSFi Ref
calc
calc
calc
(only a drinking water action level is available for this metal)
5.0E-03
5.0E-02
5.0E-02
5.0E-02
l.OE-01
1.7E-05
5.0E+00
H
I
I
sun: (I)
I
solv
I
2.4E-01
3.4E-01
I
I
6.0E-01
6.0E-01
6.0E-01
6.0E-01
4.0E-01
2.0E-05
surr
(COO)
surr
(COO)
surr
(COO)
coo
I
solv
r
"M.
8
I
I
I
-------
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
DDT, p,p'-
Di-n-butyl phthalate
Di-n-octyl phthalate
Diallate
Dibenz{a,h}anthracene
Dibromo-3 -chloropropane,
1,2-
Dichlorobenzene, 1,2-
Dichlorobenzene, 1,4-
Dichlorobenzidine, 3,3'-
Dichlorodifluoromethane
(Freon 12)
Dichloroethane, 1,2-
Dichloroethane, 1,1-
Dichloroethylene, 1,1-
Dichloroethylene, trans-1,2-
Dichloroethylene, cis-1,2-
Dichlorophenol, 2,4-
Dichlorophenoxyacetic acid,
2,4- (2,4-D)
Dichloropropane, 1,2-
Dichloropropene, trans-1,3-
Dichloropropene, cis-1,3-
CASRN
50-29-3
84-74-2
117-84-0
2303-16-4
53-70-3
96-12-8
95-50-1
106-46-7
91-94-1
75-71-8
107-06-2
75-34-3
75-35-4
156-60-5
156-59-2
120-83-2
94-75-7
78-87-5
10061-02-6
10061-01-5
RfD
(mg/kg-d)
5.0E-04
l.OE-01
2.0E-02
9.0E-02
2.0E-01
l.OE-01
9.0E-03
2.0E-02
l.OE-02
3.0E-03
l.OE-02
9.0E-02
3.0E-02
3.0E-02
RfDRef
I
I
H
I
I
H
I
I
H
I
I
A
I
I
CSFo
(per
mg/kg-d)
3.4E-01
6.1E-02
7.3E+00
1.4E+0
2.4E-2
4.5E-01
9.1E-2
6.0E-1
6.8E-2
l.OE-1
l.OE-1
CSFo
Ref
I
H
TEF
H
H
I
I
I
H
I
I
RfC
(mg/m3)
2.0E-04
2.0E-01
8.0E-01
2.0E-01
2.4E+00
5.0E-01
7.0E-02
4.0E-03
2.0E-02
2.0E-02
RfC Ref
I
H
I
H
A
H
COO
I
surr (I)
surr (I)
URF
(per
ug/m3)
9.7E-05
1.2E-03
6.9E-07
1.1E-05
3.4E-04
2.6E-05
1.6E-06
5.0E-05
4.0E-06
4.0E-06
URF Ref
I
C99a
H
C99a
C99a
I
C99a
I
surr (I)
surr (I)
CSFi (per
mg/kg-d)
3.4E-01
4.2E+00
2.4E-03
3.9E-02
1.2E+00
9.1E-02
5.6E-03
1.8E-01
1.4E-02
1.4E-02
CSFi Ref
calc
calc
calc
calc
calc
calc
calc
calc
calc
calc
r
"M.
8
I
I
I
Oj
o,
-------
Oj
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Dichloropropene, 1,3- (mixture
of isomers)
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine, 3,3'-
Dimethyl phthalate
Dimethyl formamide, N,N-
(DMF)
Dimethylbenz{a}anthracene,
7,12-
Dimethylbenzidine, 3,3'-
Dimethylphenol, 2,4-
Dimethylphenol, 3,4-
Dinitrobenzene, 1,3-
Dinitrophenol, 2,4-
Dinitrotoluene, 2,6-
Dinitrotoluene, 2,4-
Dioxane, 1,4-
Diphenylamine
Diphenylhydrazine, 1,2-
Disutfoton
Endosutfan (Endosutfan I and
II,mixture)
CASRN
542-75-6
60-57-1
84-66-2
56-53-1
60-51-5
119-90-4
131-11-3
68-12-2
57-97-6
119-93-7
105-67-9
95-65-8
99-65-0
51-28-5
606-20-2
121-14-2
123-91-1
122-39-4
122-66-7
298-04-4
115-29-7
RfD
(mg/kg-d)
3.0E-02
5.0E-05
8.0E-01
2.0E-04
l.OE-01
2.0E-02
l.OE-03
l.OE-04
2.0E-03
l.OE-03
2.0E-03
2.5E-02
4.0E-05
6.0E-03
RfDRef
I
I
I
I
H
I
I
I
I
H
I
I
I
I
CSFo
(per
mg/kg-d)
l.OE-01
1.6E+01
4.7E+03
1.4E-02
9.2E+00
6.8E-01
6.8E-01
1.1E-2
8.0E-1
CSFo
Ref
I
I
H
H
H
surr(I)
surr(I)
I
I
RfC
(mg/m3)
2.0E-02
3.0E-02
3.0E+00
RfC Ref
I
I
COO
URF
(per
ug/m3)
4.0E-06
4.6E-03
7.1E-02
8.9E-05
7.7E-06
2.2E-04
URF Ref
I
I
C99a
C99a
C99a
I
CSFi (per
mg/kg-d)
1.4E-02
1.6E+01
2.5E+02
3.1E-01
2.7E-02
7.7E-01
CSFi Ref
calc
calc
calc
calc
calc
calc
Oj
r
"M.
8
I
I
I
-------
Oj
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Endrin
Epichlorohydrin
Epoxybutane, 1,2-
Ethoxyethanol acetate, 2-
Ethoxyethanol, 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene oxide
Ethylene dibromide (1,2-
dibromoethane)
Ethylene glycol
Ethylene thiourea
Fluoranthene
Fluorene
Fluoride
Formaldehyde
Formic acid
Furan
Furfural
HCH, beta-
HCH, gamma- (Lindane)
CASRN
72-20-8
106-89-8
106-88-7
111-15-9
110-80-5
141-78-6
60-29-7
97-63-2
62-50-0
100-41-4
75-21-8
106-93-4
107-21-1
96-45-7
206-44-0
86-73-7
16984-48-8
50-00-0
64-18-6
110-00-9
98-01-1
319-85-7
58-89-9
RfD
(mg/kg-d)
3.0E-04
2.0E-03
3.0E-01
4.0E-01
9.0E-01
2.0E-01
9.0E-02
l.OE-01
2.0E+00
8.0E-05
4.0E-02
4.0E-02
6.0E-02
2.0E-01
2.0E+00
l.OE-03
3.0E-03
3.0E-04
RfDRef
I
H
H
H
I
I
H
I
I
I
I
I
smr(T)
I
H
I
I
I
CSFo
(per
mg/kg-d)
9.9E-3
2.9E+02
l.OE+0
8.5E+1
1.1E-01
1.8E+00
1.3E+00
CSFo
Ref
I
RQ
H
I
H
I
H
RfC
(mg/m3)
l.OE-03
2.0E-02
3.0E-01
2.0E-01
l.OE+00
3.0E-02
2.0E-04
4.0E-01
9.8E-03
5.0E-02
RfC Ref
I
I
COO
I
I
coo
H
COO
A
H
URF
(per
ug/m3)
1.2E-06
1.1E-06
l.OE-04
2.2E-04
1.3E-05
1.3E-05
5.3E-04
3.1E-04
URF Ref
I
SF
H
I
C99a
I
I
C99a
CSFi (per
mg/kg-d)
4.2E-03
3.9E-03
3.5E-01
7.7E-01
4.6E-02
4.6E-02
1.9E+00
1.1E+00
CSFi Ref
calc
calc
calc
calc
calc
calc
calc
calc
r
"M.
8
I
I
I
-------
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
HCH, alpha-
Heptachlor
Heptachlor epoxide
Hexachloro- 1 , 3 -butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzo-p-dioxins
(HxCDDs)
Hexachlorodibenzofurans
(HxCDFs)
Hexachloroethane
Hexachlorophene
Hexane, n-
Indeno{ l,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol, 2-
CASRN
319-84-6
76-44-8
1024-57-3
87-68-3
118-74-1
77-47-4
34465-46-8
55684-94-1
67-72-1
70-30-4
110-54-3
193-39-5
78-83-1
78-59-1
143-50-0
7439-92-1
7439.96-5
7439.97-6
126-98-7
67-56-1
72-43-5
109-86-4
RfD
(mg/kg-d)
8.0E-03
5.0E-04
1.3E-05
3.0E-04
8.0E-04
6.0E-03
l.OE-03
3.0E-04
1.1E+01
3.0E-01
2.0E-01
5.0E-04
RfDRef
A
I
I
SF
I
I
I
I
SF
I
I
A
CSFo
(per
mg/kg-d)
6.3E+00
4.5E+00
9.1E+00
7.8E-2
1.6E+0
1.5E+04
1.5E+04
1.4E-02
1.2E+00
9.5E-04
CSFo
Ref
I
I
I
I
I
WHO98
WHO98
I
C99a
I
RfC
(mg/m3)
2.0E-04
2.0E-01
2.0E+00
RfC Ref
I
I
C99b
URF
(per
ug/m3)
1.8E-03
1.3E-03
2.6E-03
2.2E-05
4.6E-04
3.3E+00
3.3E+00
4.0E-06
1.1E-04
URF Ref
I
I
I
I
I
WHO98
WHO98
I
C99a
CSFi (per
mg/kg-d)
6.3E+00
4.6E+00
9.1E+00
7.7E-02
1.6E+00
1.5E+04
1.5E+04
1.4E-02
3.9E-01
CSFi Ref
calc
calc
calc
calc
calc
WHO98
WHO98
calc
calc
(only a drinking water action level is available for this metal)
4.7E-02
l.OE-04
l.OE-04
5.0E-01
5.0E-03
l.OE-03
I
surr (I)
I
I
I
H
3.0E-04
7.0E-04
4.0E+00
2.0E-02
I
H
COO
I
Oj
Oo
r
"M.
8
I
I
I
-------
Oj
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Methoxyethanol acetate, 2-
Methyl parathion
Methyl methacrylate
Methyl isobutyl ketone
Methyl ethyl ketone
Methyl tert-butyl ether
(MTBE)
Methylcholanthrene, 3-
Methylene bromide
(dibromomethane)
Methylene Chloride
(dichloromethane)
Molybdenum
N-Nitroso-di-n-butylamine
N-Nitroso-di-n-propylamine
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Nitrosodiphenylamine
N-Nitrosomethylethylamine
N-Nitrosopiperidine
N-Nitrosopyrrolidine
Naphthalene
Nickel
Nitrobenzene
CASRN
110-49-6
298-00-0
80-62-6
108-10-1
78-93-3
1634-04-4
56-49-5
74-95-3
75-09-2
7439-98-7
924-16-3
621-64-7
55-18-5
62-75-9
86-30-6
10595-95-6
100-75-4
930-55-2
91-20-3
7440-02-0
98-95-3
RfD
(mg/kg-d)
2.0E-03
2.5E-04
1.4E+00
8.0E-02
6.0E-01
l.OE-02
6.0E-02
5.0E-03
8.00E-06
2.00E-02
2.0E-02
2.0E-02
5.0E-04
RfDRef
H
I
I
H
I
H
I
I
SF
SF
I
I
I
CSFo
(per
mg/kg-d)
7.5E-03
5.4E+00
7.0E+00
1.5E+02
5.1E+01
4.9E-03
2.2E+01
2.1E+00
CSFo
Ref
I
I
I
I
I
I
I
I
RfC
(mg/m3)
9.0E-02
7.0E-01
8.0E-02
l.OE+00
3.0E+00
3.0E+00
3.0E-03
2.0E-03
RfC Ref
COO
I
H
I
I
H
I
H
URF
(per
ug/m3)
6.3E-03
4.7E-07
1.6E-03
2.0E-03
4.3E-02
1.4E-02
2.6E-06
6.3E-03
2.7E-03
6.1E-04
URF Ref
C99a
I
I
C99a
I
I
C99a
C99a
C99a
I
CSFi (per
mg/kg-d)
2.2E+01
1.6E-03
5.6E+00
7.0E+00
1.5E+02
4.9E+01
9.1E-03
3.7E+00
9.5E+00
2.1E+00
CSFi Ref
calc
calc
calc
calc
calc
calc
calc
C99a
calc
calc
r
"M.
8
I
I
I
-------
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Nitropropane, 2-
Octamethyl
pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzo-p-dioxins
(PeCDDs)
Pentachlorodibenzofurans
(PeCDFs)
Pentachloronitrobenzene
(PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine, 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls
(Aroclors)
Pronamide
Propylene oxide (1,2-
epoxypropane)
Pyrene
Pyridine
Safrole
CASRN
79-46-9
152-16-9
56-38-2
608-93-5
36088-22-9
30402-15-4
82-68-8
87-86-5
108-95-2
62-38-4
108-45-2
298-02-2
85-44-9
1336-36-3
23950-58-5
75-56-9
129-00-0
110-86-1
94-59-7
RfD
(mg/kg-d)
2.0E-03
6.0E-03
8.0E-04
3.0E-03
3.0E-02
6.0E-01
8.0E-05
6.0E-03
2.0E-04
2.0E+00
2.0E-05
7.5E-02
3.0E-02
l.OE-03
RfDRef
H
H
I
I
I
I
I
I
H
I
surr (I)
I
I
I
CSFo
(per
mg/kg-d)
1.5E+05
7.5E+04
2.6E-01
1.2E-01
4.0E-01
2.4E-01
1.8E-01
CSFo
Ref
WHO98
WHO98
H
I
I
I
RQ
RfC
(mg/m3)
2.0E-02
2.0E-01
1.2E-01
3.0E-02
7.0E-03
RfC Ref
I
COO
H
I
EPA86
URF
(per
ug/m3)
2.7E-03
3.3E+01
1.7E+01
5.1E-06
l.OE-04
3.7E-06
URF Ref
H
WHO98
WHO98
C99a
I
I
CSFi (per
mg/kg-d)
9.5E+00
1.5E+05
7.5E+04
1.8E-02
4.0E-01
1.3E-02
CSFi Ref
calc
WHO98
WHO98
calc
I
calc
r
"M.
8
I
I
I
-------
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene, 1,2,4,5-
Tetrachlorodibenzo-p-dioxin,
2,3,7,8-(2,3,7,8-TCDD)
Tetrachlorodibenzofuran,
2,3,7,8- (2,3,7,8-TCDF)
Tetrachloroethane, 1,1,2,2-
Tetrachloroethane, 1,1,1,2-
Tetrachloroethylene
Tetrachlorophenol, 2,3,4,6-
Tetraethyl dithiopyrophosphate
(Sulfotep)
Thallium
Thiram (Thiuram)
Toluene
Toluenediamine, 2,4-
Toluidine, o-
Toluidine, p-
Toxaphene (chlorinated
camphenes)
Tribromomethane
(bromoform)
CASRN
7782-49-2
7440-22-4
57-24-9
100-42-5
95-94-3
1746-01-6
51207-31-9
79-34-5
630-20-6
127-18-4
58-90-2
3689-24-5
7440-28-0
137-26-8
108-88-3
95-80-7
95-53-4
106-49-0
8001-35-2
75-25-2
RfD
(mg/kg-d)
5.0E-03
5.0E-03
3.0E-04
2.0E-01
3.0E-04
l.OE-09
6.0E-02
3.0E-02
l.OE-02
3.0E-02
5.0E-04
8.0E-05
5.0E-03
2.0E-01
2.0E-02
RfDRef
I
I
I
I
I
A
SF
I
I
I
I
surr (I)
I
I
I
CSFo
(per
mg/kg-d)
1.5E+05
1.5E+04
2.0E-01
2.6E-02
5.2E-02
3.2E+00
2.4E-01
1.9E-01
1.1E+00
7.9E-03
CSFo
Ref
H
WHO98
I
I
HAD
H
H
H
I
I
RfC
(mg/m3)
l.OE+00
3.0E-01
4.0E-01
RfC Ref
I
A
I
URF
(per
ug/m3)
3.3E+01
3.3E+00
5.8E-05
7.4E-06
5.8E-07
1.1E-03
6.9E-05
3.2E-04
1.1E-06
URF Ref
H
WHO98
I
I
HAD
C99a
AC
I
I
CSFi (per
mg/kg-d)
1.5E+05
1.5E+04
2.0E-01
2.6E-02
2.0E-03
3.9E+00
2.4E-01
1.1E+00
3.9E-03
CSFi Ref
H
WHO98
calc
calc
HAD
calc
AC
calc
calc
r
"M.
8
I
I
I
-------
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Trichloro- 1,2,2-
trifluoroethane, 1,1,2-
Trichlorobenzene, 1,2,4-
Trichloroethane, 1,1,1-
Trichloroethane, 1,1,2-
Trichloroethylene (1,1,2-
trichloroethylene)
Trichlorofluoromethane (Freon
11)
Trichlorophenol, 2,4,5-
Trichlorophenol, 2,4,6-
Trichlorophenoxy)propionic
acid, 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid,
2,4,5-
Trichloropropane, 1,2,3-
Triethylamine
Trinitrobenzene, sym-
( 1 ,3 ,5-Trinitrobenzene)
Tris(2,3-
dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene, p-
CASRN
76-13-1
120-82-1
71-55-6
79-00-5
79-01-6
75-69-4
95-95-4
88-06-2
93-72-1
93-76-5
96-18-4
121-44-8
99-35-4
126-72-7
7440-62-2
108-05-4
75-01-4
106-42-3
RfD
(mg/kg-d)
3.0E+01
l.OE-02
2.8E-01
4.0E-03
3.0E-01
l.OE-01
8.0E-03
l.OE-02
6.0E-03
3.0E-02
7.0E-03
l.OE+00
3.0E-03
2.0E+00
RfDRef
I
I
SF
I
I
I
I
I
I
I
H
H
I
surr (H)
CSFo
(per
mg/kg-d)
5.7E-02
1.1E-02
1.1E-02
7.0E+00
9.8E+00
7.2E-01
CSFo
Ref
I
HAD
I
H
RQ
I
RfC
(mg/m3)
3.0E+01
2.0E-01
2.2E+00
6.0E-01
7.0E-01
5.0E-03
7.0E-03
2.0E-01
l.OE-01
4.0E-01
RfC Ref
H
H
SF
COO
H
SF
I
I
I
surr (A)
URF
(per
ug/m3)
1.6E-05
1.7E-06
3.1E-06
4.4E-06
URF Ref
I
HAD
I
I
CSFi (per
mg/kg-d)
5.6E-02
6.0E-03
1.1E-02
1.5E-02
CSFi Ref
calc
HAD
calc
calc
r
"M.
8
I
I
I
-------
Table E-3.1. Human Health Benchmark Values (continued)
Constituent Name
Xylene, m-
Xylene, o-
Xylenes (total)
Zinc
CASRN
108-38-3
95-47-6
1330-20-7
7440-66-6
RfD
(mg/kg-d)
2.0E+00
2.0E+00
2.0E+00
3.0E-01
RfDRef
H
H
I
I
CSFo
(per
mg/kg-d)
CSFo
Ref
RfC
(mg/m3)
4.0E-01
4.0E-01
4.0E-01
RfC Ref
surr (A)
surr (A)
A
URF
(per
ug/m3)
URF Ref
CSFi (per
mg/kg-d)
CSFi Ref
Key:
CASRN
RfD
RfC
Chemical Abstract Service registry number.
reference dose.
reference concentration.
CSFo = oral cancer slope factor.
CSFi = inhalation cancer slope factor.
URF = unit risk factor.
Sources:
A = ATSDRMRLs(ATSDR, 2001) I
AC = developed for the Air Characteristic Study (USEPA, 1999g) RQ
calc = calculated SF
C99a = CalEPA cancer potency factor (CalEPA, 1999a)
C99b = CalEPA chronic REL (CalEPA, 1999b) solv
COO = CalEPA chronic REL (CalEPA, 2000) surr
HAD = Health Assessment Document (USEPA, 1986a, 1987) TEF
H = HEAST (USEPA, 1997) WHO98
IRIS (USEPA, 2001a)
reportable quantity adjustments (USEPA, 1998d,e,f)
Superfund Risk Issue Paper (USEPA, 1998a,b;
1999a,b,c,d,e,f;
2000, 2001b,c,d)
63 FR 64371-0402 (USEPA, 1998c)
surrogate (source in parentheses; see section C.2.8)
toxicity equivalency factor (USEPA, 1993)
World Health Organization (WHO) 1998 toxicity
equivalency factor scheme (Van den Berg et al., 1998)
-------
IWEM Technical Background Document Appendix E
E-3.2.1 Benzene
The cancer risk estimates for benzene are provided as ranges in IRIS. The oral
CSF for benzene is 1.5E-02 to 5.5E-02 (mg/kg/d)'1 and the inhalation URF is 2.2E-06 to
7.8E-06 (jig/m3)"1 (USEPA, 200la). For the Tier 1 tool, the upper range estimates were
used (i.e., 5.5E-02 (mg/kg/d)4 and 7.8E-06 (jig/m3)'1 for the oral CSF and inhalation
URF, respectively).
E-3.2.2 Vinyl Chloride
Based on use of the linearized multistage model, IRIS recommends an oral CSF
of 7.2E-1 per mg/kg-d for vinyl chloride to account for continuous lifetime exposure
during adulthood; this value was used for the Tier 1 Tool.1 Based on use of the linearized
multistage model, an inhalation URF of 4.4E-6 per jig/m3 to account for continuous,
lifetime exposure during adulthood was recommended for vinyl chloride and was used
for the IWEM 1 tool; an inhalation CSF of 1.5E-2 per mg/kg-d was calculated from the
URF.2
E-3.2.3 Polychlorinated Biphenyls
There are two inhalation CSFs available from IRIS for polychlorinated biphenyls
(PCBs): 0.4 per mg/kg-d for evaporated congeners and 2.0 per mg/kg-d for dust or
aerosol (high risk and persistence). The inhalation CSF for evaporated congeners was
used for the IWEM 1 tool.
E-3.2.4 Dioxin-like Compounds
Certain polychlorinated dibenzodioxin, polychlorinated dibenzofuran, and
polychlorinated biphenyl (PCB) congeners are said to have "dioxin-like" toxicity,
meaning that they are understood to have toxicity similar to that of 2,3,7,8-
tetrachlorodibenzo(p)dioxin (2,3,7,8-TCDD). Although EPA has not developed health
benchmarks for each specific compound with dioxin-like toxicity, these compounds have
been assigned individual "toxicity equivalency factors" (TEFs; Van den Berg et al.,
JA twofold increase of the oral CSF to 1.4 per mg/kg-d to account for continuous
lifetime exposure from birth was also recommended but was not used for the IWEM 1
Tool.
2A twofold increase to 8.8E-6 per |ig/m3 for the inhalation URF, to account for
continuous lifetime exposure from birth, was also recommended but was not used for the
IWEM 1 tool.
-------
IWEM Technical Background Document
Appendix E
1998). TEFs are estimates of the toxicity of dioxin-like compounds relative to the
toxicity of 2,3,7,8-TCDD, which is assigned a TEF of 1.0. TEF estimates are based on a
knowledge of a constituent's mechanism of action, available experimental data, and other
structure-activity information. We used the TEFs to calculate cancer slope factors for the
dioxin and furan congeners (and congener groups) in the IWEM tool.
The dioxin-like congeners (and groups of congeners) included in the TIWEM 1
tool are as follows:
2,3,7,8-TCDD,
2,3,7,8-Tetrachlorodibenzofuran (2,3,7,8-TCDF)
Pentachlorodibenzodioxins (PeCDDs)
Pentachlorodibenzofurans (PeCDFs)
Hexachlorodibenzodioxins (HxCDDs)
Hexachlorodibenzofurans (HxCDFs).
2,3,7,8-TCDF has a TEF of 0.1. The dioxin-like PeCDD congener is 1,2,3,7,8-PeCDD,
which has a TEF of 1.0. The dioxin-like PeCDF congeners include 1,2,3,7,8-PeCDF and
2,3,4,7,8-PeCDF which have TEFs of 0.05 and 0.5, respectively. The dioxin-like
HxCDD congeners include 1,2,3,7,8,9-HxCDD, 1,2,3,4,7,8-HxCDD, and 1,2,3,6,7,8-
HxCDD, which have TEFs of 0.1. The dioxin-like HxCDF congeners include
1,2,3,7,8,9-HxCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, and 2,3,4,6,7,8-HxCDF,
which also have TEFs of 0.1. Table C-2 shows the TEFs that we used to calculate CSFs
for the dioxin and furan congeners (and congener groups) for the purpose of developing
HBNs for the Tier 1 tool.
Table E-3.2. TEFs Used for Dioxin and Furan Congeners
Constituent Name
TEF
CSFo
(mkd)1
CSFo
Source
URF
(Hg/m3)1
URF
Source
CSFi
(mkd)1
CSFi Source
Dioxins
Pentachlorodibenzodioxins
2,3,7,8-TCDD
Hexachlorodibenzodioxins
1
1
0.1
1.5E+05
1.5E+5
1.5E+4
WHO 1998
EPA, 1997
WHO 1998
3.3E+01
3.3E+01
3.3E+00
WHO 1998
EPA, 1997
WHO 1998
1.5E+05
1.5E+5
1.5E+4
WHO 1998
EPA, 1997
WHO 1998
Furans
Hexachlorodibenzofurans
Pentachlorodibenzofurans
2,3,7,8-TCDF
0.1
0.5
0.1
1.5E+4
7.5E+4
1.5E+4
WHO 1998
WHO 1998
WHO 1998
3.3E+00
1.7E+01
3.3E+00
WHO 1998
WHO 1998
WHO 1998
1.5E+4
7.5E+4
1.5E+4
WHO 1998
WHO 1998
WHO 1998
WHO 98 = TEFs presented in Van den Berg et al. (1998)
EPA, 1997 = HEAST (USEPA, 1997).
E-45
-------
IWEM Technical Background Document Appendix E
The human health benchmarks calculated using the TEFs for 1,2,3,4,7,8-
hexachlorodibenzo-p-dioxin and 1,2,3,4,7,8-hexachlorodibenzofuran were surrogates for
hexachlorodibenzo-p-dioxins (HxCDDs) and hexachlorodibenzofurans (HxCDFs),
respectively. The human health benchmarks for 1,2,3,7,8-pentachlorodibenzo-p-dioxin
and 2,3,4,7,8-pentachlorodibenzofuran were used to represent pentachlorodibenzodioxins
(PeCDDs) and pentachlorodibenzofurans (PeCDFs), respectively. The human health
benchmarks for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and
2,3,7,8-tetrachlorodibenzofuran were used to represent tetrachlorodibenzo-p-dioxins
(TCDDs) and tetrachlorodibenzofurans (TCDFs), respectively. When TEFs varied
within a class of dioxin-like compounds (i.e., pentachlorodibenzofurans), the TEF most
protective of human health was used.
E-3.2.5 Superfund Technical Support Center Provisional Benchmarks
Table E-3.3 lists the provisional human health benchmarks from the Superfund
Technical Support Center that were used for some of the IWEM constituents. A
provisional subchronic RfC of 2.0E-2 mg/m3 was developed by the Superfund Technical
Support Center (USEPA, 1999a) for carbon tetrachloride; a provisional chronic RfC of
7.0E-3 mg/m3 was derived from this value by applying an uncertainty factor of 3 to
account for the use of a subchronic study.
E-46
-------
IWEM Technical Background Document
Appendix E
Table E-3.3. Provisional Human Health Benchmarks Developed by the Superfund
Technical Support Center
CASRN
108-90-7
7440-48-4
100-41-4
87-68-3
110-54-3
62-75-9
86-30-6
79-34-5
71-55-6
71-55-6
96-18-4
Chemical Name
Chlorobenzene
Cobalt (and compounds)
Ethylbenzene
Hexachlorobutadiene
Hexane, -
N-Nitrosodimethylamine
(N-methyl-N-nitroso-
methanamine)
N-Nitrosodiphenylamine
Tetrachloroethane, 1,1,2,2-
Trichloroethane, 1,1,1-
Trichloroethane, 1,1,1-
Trichloropropane, 1,2,3-
Benchmark
Type
RfC
RfD
URF
RfD
RfD
RfD
RfD
RfD
RfD
RfC
RfC
Benchmark
Value
6.0E-02
2.0E-02
1.1E-06
3.0E-04
1.1E+01
8.0E-06
2.0E-02
6.0E-02
2.8E-01
2.2E+00
5.0E-03
Units
mg/m3
mg/kg-d
(ng/mS)-1
mg/kg-d
mg/kg-d
mg/kg-d
mg/kg-d
mg/kg-d
mg/kg-d
mg/m3
mg/m3
Reference
USEPA, 1998a
USEPA, 200 Ib
USEPA, 1999b
USEPA, 1998b
USEPA, 1999c
USEPA, 200 Ic
USEPA, 200 Id
USEPA, 2000
USEPA, 1999d
USEPA, 1999e
USEPA, 1999f
E-3.2.6 Benchmarks From Other EPA Sources
For some IWEM constituents, human health benchmarks were not available from
IRIS, the Superfund Technical Support Center, HEAST, ATSDR, or CalEPA, but were
available from other EPA sources:
The provisional oral CSF of 5.2E-2 per mg/kg-d, provisional inhalation
URF of 5.8E-7 per i-ig/m3, and the provisional inhalation CSF of 2.0E-3
per mg/kg-d developed for tetrachloroethylene by EPA in a Health
Assessment Document (HAD) (USEPA, 1986a) were used.
For trichloroethylene, provisional cancer benchmarks developed by EPA
in a HAD (USEPA, 1987) were used and include the oral CSF of 1.1E-2
per mg/kg-d, inhalation URF of 1.7E-6 per i-ig/m3, and inhalation CSF of
6.0E-3 per mg/kg-d.
A provisional RfD of 1.7E-5 mg/kg-d and a provisional RfC of 2.0E-5
mg/m3 were derived for cyclohexanol in the final listing rule for solvents
(63 FR 64371) and were used (USEPA, 1998c).
E-47
-------
IWEM Technical Background Document Appendix E
An acceptable daily intake (ADI) of 2.0E-03 mg/kg-d from inhalation
(7.0E-3 mg/m3) was identified for pyridine (USEPA, 1986b).
EPA calculated an oral cancer potency factor of 293 per mg/kg-d for ethyl
methanesulfonate in a reportable quantity adjustment evaluation (USEPA,
1998d).
EPA calculated an oral cancer potency factor of 0.18 per mg/kg-d for
safrole in a reportable quantity adjustment evaluation (USEPA, 1998e).
EPA calculated an oral cancer potency factor of 9.8 per mg/kg-d for
tris(2,3-dibromopropyl)phosphate in a reportable quantity adjustment
evaluation (USEPA, 1998f).
The cancer slope factor for dibenzo(a,h)anthracene was calculated using a
TEF approach developed for polycyclic aromatic hydrocarbons (USEPA,
1993). The TEF approach assigns dibenzo(a,h)anthracene a TEF of 1
relative to the toxicity of benzo(a)pyrene. The oral CSF for
dibenzo(a,h)anthracene is therefore the same as the IRIS (USEPA, 200la)
value for benzo(a)pyrene: 7.3.E+00 (mg/kg-d)"1.
E-3.2.7 Air Characteristic Study Provisional Benchmarks
Provisional inhalation health benchmarks were developed in the Air
Characteristic Study (USEPA, 1999g) for several constituents lacking IRIS, HEAST,
alternative EPA, or ATSDR values. For 2-chlorophenol, a provisional RfC was
developed using route-to-route extrapolation of the oral RfD. Using route-to-route
extrapolations based on oral CSFs from IRIS and HEAST, the Air Characteristic Study
developed provisional inhalation URFs and inhalation CSFs for
bromodichloromethane, chlorodibromomethane, and o-Toluidine.
These provisional inhalation benchmark values are summarized in Table C-4
below. Additional details on the derivation of these inhalation benchmarks can be found
in the Revised Risk Assessment for the Air Characteristic Study (USEPA, 1999g).
E-48
-------
IWEM Technical Background Document
Appendix E
Table E-3.4. Provisional Inhalation Benchmarks Developed in the Air
Characteristic Study
CASRN
75-27-4
124-48-1
95-57-8
95-53-4
Chemical Name
Bromodichloromethane
(dichlorobromomethane)
Chlorodibromomethane
(dibromochloromethane)
2-Chlorophenol (o-)
o-Toluidine (2-methylaniline)
RfC
(mg/m3)
1.4E-03
RfC Target
Effect
Reproductive
development
al
URF (ng/m3) '
1.8E-05
2.4E-05
6.9E-05
CSFi
(mg/kg-d)1
6.2E-02
8.4E-02
2.4E-01
E-3.2.8 Surrogate Health Benchmarks
For several IWEM constituents, IRIS benchmarks for similar chemicals were used
as surrogate data. The rationale for these recommendations is as follows:
cis-l,3-Dichloropropylene and trans-l,3-dichloropropylene were based on
1,3-dichloropropene. The studies cited in the IRIS file for 1,3-
dichloropropene used a technical-grade chemical that contained about a
50/50 mixture of the cis- and trans-isomers. The RfD is 3E-02 mg/kg-d
and the RfC is 2E-02 mg/m3. The oral CSF for 1,3-dichloropropene is 0.1
(mg/kg-d)-1 and the inhalation URF is 4E-06 dig/m3)'1.
The IRIS oral CSF for the 2,4-/2,6-dinitrotoluene mixture (6.8E-01 per
mg/kg-d) was used as the oral CSFs for 2,4-dinitrotoluene and 2,6-
dinitrotoluene.
The RfDs for o- and m-cresol (both 5E-02 mg/kg/d) are cited on IRIS. The
provisional RfD for p-cresol (5E-03 mg/kg/d) is from HEAST. Cresol
mixtures contain all three cresol isomers. Based on the hierarchy
described above (i.e., IRIS is preferred over HEAST because IRIS is
EPA's official repository of Agency-wide consensus human health risk
information), the RfD for m-cresol (5E-02 mg/kg-d) was used as a
surrogate for cresol mixtures.
E-49
-------
IWEM Technical Background Document Appendix E
Fluoride was based on fluorine. The IRIS RfD for fluorine (6E-02 mg/kg-
d) is based on soluble fluoride.
The RfD for methyl mercury (1E-04 mg/kg-d) was used as a surrogate for
elemental mercury.
The RfD for Arochlor 1254 (2E-05 mg/kg-d) was used as a surrogate for
PCBs.
Thallium was based on thallium chloride. There are several thallium salts
that have RfDs in IRIS. The lowest value among the thallium salts (8E-05
mg/kg-d) is routinely used to represent thallium in risk assessments.
p-Xylene was based on total xylenes. An RfD of 2 mg/kg-d is listed for
total xylenes, m-xylene, and o-xylene in IRIS. Total xylenes contain a
mixture of all three isomers; therefore, the RfD likely is appropriate for p-
xylene.
E-3.2.9 Chloroform
EPA has classified chloroform as a Group B2, Probable Human Carcinogen,
based on an increased incidence of several tumor types in rats and mice (USEPA, 200la).
However, based on an evaluation initiated by EPA's Office of Water (OW), the Office of
Solid Waste (OSW) now believes the weight of evidence for the carcinogenic mode of
action for chloroform does not support a mutagenic mode of action; therefore, a nonlinear
low-dose extrapolation is more appropriate for assessing risk from exposure to
chloroform. EPA's Science Advisory Board (SAB), the World Health Organization
(WHO), the Society of Toxicology, and EPA all strongly endorse the nonlinear approach
for assessing risks from chloroform.
Although OW conducted its evaluation of chloroform carcinogenicity for oral
exposure, a nonlinear approach for low-dose extrapolation would apply to inhalation
exposure to chloroform as well, because chloroform's mode of action is understood to be
the same for both ingestion and inhalation exposures. Specifically, tumorigenesis for
both ingestion and inhalation exposures is induced through cytotoxicity (cell death)
produced by the oxidative generation of highly reactive metabolites (phosgene and
hydrochloric acid), followed by regenerative cell proliferation (USEPA, 1998g).
Chloroform-induced liver tumors in mice have only been seen after bolus corn oil dosing
and have not been observed following administration by other routes (i.e., drinking water
and inhalation). As explained in EPA OW's March 31, 1998, and December 16, 1998,
Federal Register notices pertaining to chloroform (USEPA, 1998g and 1998h,
respectively), EPA now believes that "based on the current evidence for the mode of
-------
IWEM Technical Background Document Appendix E
action by which chloroform may cause tumorigenesis, ...a nonlinear approach is more
appropriate for extrapolating low-dose cancer risk rather than the low-dose linear
approach..."(USEPA, 1998g). OW determined that, given chloroform's mode of
carcinogenic action, liver toxicity (a noncancer health effect) actually "is a more sensitive
effect of chloroform than the induction of tumors" and that protecting against liver
toxicity "should be protective against carcinogenicity given that the putative mode of
action understanding for chloroform involves cytotoxicity as a key event preceding tumor
development" (USEPA, 1998g).
The recent evaluations conducted by OW concluded that protecting against
chloroform's noncancer health effects protects against excess cancer risk. EPA now
believes that the noncancer health effects resulting from inhalation of chloroform would
precede the development of cancer and would occur at lower doses than would tumor
development. Although EPA has not finalized a noncancer health benchmark for
inhalation exposure (i.e., an RfC), ATSDR has developed an inhalation MRL for
chloroform. Therefore, ATSDR's chronic inhalation MRL for chloroform (0.1 mg/m3)
was used in Tier 1.
E-3.3 References
ATSDR. 2001. Minimal Risk Levels (MRLs) for Hazardous Substances.
http://atsdrl.atsdr.cdc.gov:8080/mrls.html
CalEP A. 1999a. Air Toxics Hot Spots Program Risk Assessment Guidelines: Part II.
Technical Support Document for Describing Available Cancer Potency Factors.
Office of Environmental Health Hazard Assessment, Berkeley, CA. Available
online at http://www.oehha.org/scientific/hsca2.htm.
CalEP A. 1999b. Air Toxics Hot Spots Program Risk Assessment Guidelines: Part III.
Technical Support Document for the Determination of Noncancer Chronic
Reference Exposure Levels. SRP Draft. Office of Environmental Health Hazard
Assessment, Berkeley, CA. Available online at
http ://www. oehha. org/hotspots/RAGSII.html.
E-51
-------
IWEM Technical Background Document Appendix E
CalEPA. 2000. Air Toxics Hot Spots Program Risk Assessment Guidelines: Part III.
Technical Support Document for the Determination ofNoncancer Chronic
Reference Exposure Levels. Office of Environmental Health Hazard Assessment,
Berkeley, CA. Available online (in 3 sections) at
http://www.oehha.org/air/chroni c_rels/22RELS2k.html,
http://www.oehha.org/air/chroni c_rels/42kChREL.html,
http ://www. oehha. org/air/chronic_rels/Jan2001 ChREL.html.
USEPA. 1986a. Addendum to the Health Assessment Document for Tetrachloroethylene
(Perchloroethylene). Updated Carcinogenicity Assessment for
Tetrachloroethylene (Perchloroethylene, PERC, PCE). External Review Draft.
EPA/600/8-82-005FA. Office of Health and Environmental Assessment, Office
of Research and Development, Washington DC.
USEPA. 1986b. Health andEnvironmental Effects Profile for Pyridine. EPA/600/X-86-
168. Environmental Criteria and Assessment Office, Office of Research and
Development, Cincinnati, OH.
USEPA. 1987. Addendum to the Health Assessment Document for Trichloroethylene.
Updated Carcinogenicity Assessment for Trichloroethylene. External Review
Draft. EPA/600/8-82-006FA. Office of Health and Environmental Assessment,
Office of Research and Development, Washington DC.
USEPA. 1993. Provisional Guidance for Quantitative Risk Assessment ofPolycyclic
Aromatic Hydrocarbons. Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, Cincinnati, OH. EPA/600/R-93-
089.
USEPA. 1994. Methods for Derivation of Inhalation Reference Concentrations and
Application of Inhalation Dosimetry. EPA/600/8-90-066F. Environmental
Criteria and Assessment Office, Office of Health and Environmental Assessment,
Office of Research and Development, Research Triangle Park, NC.
USEPA. 1997. Health Effects Assessment Summary Tables (HEAST). EPA-540-R-97-
036. FY 1997 Update. Office of Solid Waste and Emergency Response,
Washington, DC.
USEPA. 1998a. Risk Assessment Issue Paper for: Derivation of a Provisional Chronic
RfCfor Chlorobemene (CASRN108-90-7). 98-020/09-18-98. National Center
for Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
E-52
-------
IWEM Technical Background Document Appendix E
USEPA. 1998b. Risk Assessment Paper for: Evaluation of the Systemic Toxicity of
Hexachlorobutadiene (CASRN 87-68-3) Resulting from Oral Exposure. 98-
009/07-17-98. National Center for Environmental Assessment. Superfund
Technical Support Center, Cincinnati, OH.
USEPA. 1998c. Hazardous waste management system; identification and listing of
hazardous waste; solvents; final rule. Federal Register 63 FR 64371-402.
USEPA. 1998d. Evaluation of the Potential Carcinogenicity of Ethyl Methanesulfonate
(62-50-0) in Support of Reportable Quantity Adjustments Pursuant to CERLCA
Section 102. Prepared by Carcinogen Assessment Group, Office of Health and
Environmental Assessment, Washington, D.C.
USEPA. 1998e. Evaluation of the Potential Carcinogenicity of Safrole (94-59-7) in
Support of Reportable Quantity Adjustments Pursuant to CERLCA Section 102.
Prepared by Carcinogen Assessment Group, Office of Health and Environmental
Assessment, Washington, D.C.
USEPA. 1998f. Evaluation of the Potential Carcinogenicity of Tris(2,3-
dibromopropyl)phosphate (126-72-7) in Support of Reportable Quantity
Adjustments Pursuant to CERLCA Section 102. Prepared by Carcinogen
Assessment Group, Office of Health and Environmental Assessment,
Washington, D.C.
USEPA. 1998g. National primary drinking water regulations: disinfectants and
disinfection byproducts notice of data availability; Proposed Rule. Federal
Register 63 (61): 15673-15692. March 31.
USEPA. 1998h. National primary drinking water regulations: disinfectants and
disinfection byproducts; final rule. Federal Register 63 (241): 69390-69476.
December 16.
USEPA. 1999a. Risk Assessment Paper for: The Derivation of a Provisional
Subchronic RfCfor Carbon Tetrachloride (CASRN 56-23-5). 98-026/6-14-99.
National Center for Environmental Assessment. Superfund Technical Support
Center, Cincinnati, OH.
USEPA. 1999b. Risk Assessment Issue Paper for: Evaluating the Carcinogenicity of
Ethylbenzene (CASRN 100-41-4). 99-011/10-12-99. National Center for
Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
E-53
-------
IWEM Technical Background Document Appendix E
USEPA. 1999c. Risk Assessment Paper for: An Updated Systemic Toxicity Evaluation
of'n-Hexane (CASRN110-54-3). 98-019/10-1-99. National Center for
Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
USEPA. 1999d. Risk Assessment Issue Paper for: Derivation of Provisional Oral
Chronic RfD and Subchronic RfDsfor 1,1,1-Trichloroethane (CASRN 71-55-6).
98-025/8-4-99. National Center for Environmental Assessment. Superfund
Technical Support Center, Cincinnati, OH.
USEPA. 1999e. Risk Assessment Issue Paper for: Derivation of Provisional Chronic
and Subchronic RfCsfor 1,1,1-Trichloroethane (CASRN 71-55-6). 98-025/8-4-
99. National Center for Environmental Assessment. Superfund Technical
Support Center, Cincinnati, OH.
USEPA. 1999f Risk Assessment Paper for: Derivation of the Systemic Toxicity of 1,2,3-
Trichloropropane (CASRN96-18-4). 98-014/8-13-99. National Center for
Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
USEPA. 1999g. Revised Risk Assessment for the Air Characteristic Study. EPA-530-R-
99-019a. Volume 2. Office of Solid Waste, Washington, DC.
USEPA. 2000. Risk Assessment Paper for: Derivation of a Provisional RfD for 1,1,2,2-
Tetrachloroethane (CASRN 79-34-5). 00-122/12-20-00. National Center for
Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
USEPA. 200la. Integrated Risk Information System (IRIS). National Center for
Environmental Assessment, Office of Research and Development, Washington,
DC. Available online at http://www.epa.gov/iris/
USEPA. 2001b. Risk Assessment Paper for: Derivation of a Provisional RfD for Cobalt
and Compounds (CASRN 7440-48-4). 00-122/3-16-01. National Center for
Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
USEPA. 200 Ic. Risk Assessment Paper for: Derivation of a Provisional RfD for N-
Nitrosodimethylamine (CASRN 62-75-9). 00-122/3-16-01. National Center for
Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
E-54
-------
IWEM Technical Background Document Appendix E
USEPA. 200 Id. Risk Assessment Paper for: Derivation of a Provisional RfD for N-
Nitrosodiphenylamine (CASRN 86-30-6). 00-122/3-16-01. National Center for
Environmental Assessment. Superfund Technical Support Center, Cincinnati,
OH.
Van den Berg, M., L. Birnbaum, A.T.C. Bosveld, et al. 1998. Toxic equivalency factors
(TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife. Environmental Health
Perspectives 106:775-792.
E-55
-------
APPENDIX F
TIER 1 LCTV TABLES
-------
Table F. 1 Landfill LCTVs for No Liner/In-Situ Soil
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-ch loroisopropyljether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
218019
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
1.00E-01
1.00E-01
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
0.0171
0.0122
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
3.67E+01
7.34E-02
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
8.05E-04
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
0.021
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
3.00E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
1.90E-03
7.30E-03
No Liner/In-Situ Soil
Peak
DAF
2.2
2.2
2.2
2.2
2.2
1.0E+30
2.6
2.2
2.3
1.3E+05
2.2
2.2
2.3
5.3
2.2
2.2
58
59
2.2
1.0E+30
6.8
2.2
1.0E+30
2.5
2.1E+07
2.2
2.2
2.7
2.2
2.4
2.8
160
2.2
2.2
2.2
5.8
2.4
2.2
2.3
2.2
2.2
1.0E+30
5.3
LCTV
based on
MCL
(mg/L)
0.014
0.11
4.3
0.011
0.012 c
0.026
1.0E+03b'c
0.20
0.015
0.011
0.014
0.030 a'
0.22
0.19
0.18
0.31
0.25
Non-Carcinogenic Effect
7-yr Avg
DAF
2.2
2.2
2.2
2.2
2.2
1.0E+30
2.6
2.2
2.3
1.3E+05
2.2
2.2
2.3
5.4
2.2
2.2
59
59
2.2
1.0E+30
6.8
2.2
1.0E+30
2.5
2.1E+07
2.2
2.2
2.7
2.2
2.4
2.8
160
2.2
2.2
2.2
5.8
2.4
2.2
2.3
2.2
2.2
1.0E+30
5.4
LCTV based
on Ingestion
3.3
5.4
5.4
1.0E+03b'
0.013
27
9.4E-03"
97 c
0.27
17C
0.023
0.016
3.8
0.2
16
19"
0.14
2.2
1.0E+03b'c
1.2
80 M
5.4
13C
0.054
0.027
5.9
0.048
0.030a'
1.1
0.22
1.1
2.8
1.2
0.55
0.27
81
0.19
LCTV based
on Inhalation
0.49
1.0E+03b'
6.9
1.0E+03"'
33
0.088
2.1
0.42
1.0E+03"
1.0E+03b'c
1.0E+03"'
0.13
4.6
0.059
0.030 a'
0.049
0.44
66
0.74
0.57
0.022
1.0E+03b'
Carcinogenic Effect
30-yr Avg
DAF
2.2
2.2
2.2
2.2
2.2
1.0E+30
2.6
2.2
2.3
1.4E+05
2.2
2.2
2.3
5.4
2.2
2.2
59
59
2.2
1.0E+30
6.8
2.2
1.0E+30
2.5
2.1E+07
2.2
2.2
2.7
2.2
2.4
2.8
160
2.2
2.2
2.2
5.8
2.4
2.2
2.3
2.2
2.2
1.0E+30
5.4
LCTV based
on Ingestion
5.5E-05
4.1E-05"
0.77 c
0.037
1.9E-04
4.3E-04
3.9E-03
9.3E-07
7.8E-04
4.8E-03C
1.0E+03b'c
6.0E-04
3.1E-03
1.0E+03b'c
3.9E-03
2.1E-03
0.030a'
2.1E-03
2.7E-03
0.016
4.3E-03C
LCTV based
on Inhalation
0.091
13
2.3E-03
1.4C
4.9
0.097 c
3.6E-03
5.7
0.32 c
0.037 c
1.0E+03b'c
7.5E-03
0.013
1.0E+03b'c
2.0E-03
8.9E-05
2.2E-03
0.030 a'
6.9
1.8E-03
0.013
1.0E+03b'
0.039 c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.I -1
-------
Table F. 1 Landfill LCTVs for No Liner/In-Situ Soil
Common Name
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylenetrans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropenetrans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
Disulfoton
CAS#
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
606202
117840
123911
122394
122667
298044
MCL
(mg/L)
Ingestion
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
2.45E-02
4.90E-01
6.12E-01
9.79E-04
C
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
1.42E-04
8.78E-03
1.21E-04
Inhalation
NC
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.6
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
1.09E+03
C
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
1.80E-01
2.00E-02
No Liner/In-Situ Soil
Peak
DAF
2.2
2.2
2.2
2.2
2.2
2.2
2.2
1.0E+30
1.8E+13
1.0E+30
8.0E+03
1.2E+10
2.8
2.2
2.2
2.2
2.2
2.5
2.5
2.2
2.2
2.2
2.2
2.2
2.2
2.2
1.0E+30
1.0E+30
1.5E+15
2.9
2.3
550
2.2
2.2
6.5E+12
2.2
2.2
4.8
2.2
2.2
2.2
2.2
1.0E+30
2.2
2.2
2.2
2.1E+06
LCTV
based on
MCL
(mg/L)
3.0
5.5E-04
1.3
0.17
9.9E-03 "
7.0E-03 d
0.15
0.22
0.016
0.15
0.011
Non-Carcinogenic Effect
7-yr Avg
DAF
2.2
2.2
2.2
2.2
2.2
2.2
2.2
1.0E+30
1.8E+13
1.0E+30
8.0E+03
1.2E+10
2.8
2.2
2.2
2.2
2.2
2.5
2.5
2.2
2.2
2.2
2.2
2.2
2.2
2.2
1.0E+30
1.0E+30
1.5E+15
2.9
2.3
550
2.2
2.2
6.6E+12
2.2
2.2
4.8
2.2
2.2
2.2
2.2
1.0E+30
2.2
2.2
2.2
2.2E+06
LCTV based
on Ingestion
1.1
2.7
2.7
0.27
2.7
5.5
9.2E-04
270
1.0E+03b'c
4.9
11
0.36"
0.26 "
0.54
1.1
0.49
0.16
0.54
4.9
1.6
1.0E+03"'
1.0E+03"'
1.0E+03b'c
58
0.55"
5.4
1.1
12C
5.4E-03
0.11
0.11
0.054
1.0E+03b'c
1.4
1.0E+03b'c
LCTV based
on Inhalation
200"'
200s'
200s-
1.0E+03"'
2.9
8.6E-04
8.0E-03
1.7
6.7
1.3
0.45"
0.32 "'"
0.47
0.031
0.13
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
2.2
2.2
2.2
2.2
2.2
2.2
2.2
1.0E+30
1.8E+13
1.0E+30
8.0E+03
1.2E+10
2.8
2.2
2.2
2.2
2.2
2.5
2.5
2.2
2.2
2.2
2.2
2.2
2.2
2.2
1.0E+30
1.0E+30
1.5E+15
2.9
2.3
550
2.2
2.2
6.6E+12
2.2
2.2
4.8
2.2
2.2
2.2
2.2
1.0E+30
2.2
2.2
2.2
2.2E+06
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
13
1.0E+03b'c
1.9E-04
8.9E-03
4.8E-04
6.7E-04"
4.7E-04"
3.6E-04
3.1E-03
2.1E-03
1.0E+03"'
1.0E+03"'
1.0E+03b'c
4.7E-08
0.015
2.3E-05
3. 1 E-04
3.1E-04
0.019
2.7E-04
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'c
0.22
2.9E-03
11C
0.012"
1.5E-03
4.9E-04
6.4E-03
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13 ''
0.40
0.044
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.I -2
-------
Table F. 1 Landfill LCTVs for No Liner/In-Situ Soil
Common Name
Endosulfan (Endosulfan 1 and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1 ,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol 2-
Methoxyethanol acetate 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
CAS#
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
109864
110496
78933
108101
80626
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
2.00E-03
4.00E-02
HBN (mg/L)
Ingestion
NC
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.9
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
0.196
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
2.45E-02
4.90E-02
1.47E+01
1.96E+00
3.43E+01
C
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
7.00E-04
6.50E-03
1.54E+03
4.40E+02
5.10E+02
3.30E+01
1.20E+00
5.30E+00
C
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.5
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
No Liner/In-Situ Soil
Peak
DAF
2.2
7.7E+04
1.0E+30
2.2
2.2
2.2
7.4
2.2
3.9
1.0E+30
2.2
25
2.2
1.0E+30
2.2
2.5
2.2
2.2
2.2
2.2
4.2E+06
2.2
1.0E+30
3.9E+08
2.4
6.3
1.0E+30
1.0E+30
4.6E+07
2.2
3.1
2.2
2.2
1.3E+06
2.2
2.2
2.3
2.3
2.2
1.0E+30
2.2
2.2
2.2
2.2
2.2
LCTV
based on
MCL
(mg/L)
0.02 "'
1.6
1.3E-03
8.7
0.26 c'd
0.26 "
8.0E-03 *'
1.0E+03b'c
6.3E-03 c
1.0E+03b'c
0.037
5.8E-03
10a'c
Non-Carcinogenic Effect
7-yr Avg
DAF
2.2
7.7E+04
1.0E+30
2.2
2.2
2.2
7.4
2.2
3.9
1.0E+30
2.2
25
2.2
1.0E+30
2.2
2.5
2.2
2.2
2.2
2.2
4.3E+06
2.2
1.0E+30
3.9E+08
2.4
6.3
1.0E+30
1.0E+30
4.6E+07
2.2
3.1
2.2
2.2
1.3E+06
2.2
2.2
2.3
2.3
2.2
1.0E+30
2.2
2.2
2.2
2.2
2.2
LCTV based
on Ingestion
0.33
0.020 *'
1.0E+03"'
22
16
160
11
8.5
5.4
110
4.3E-03
2.5 c
6.3
11
110
0.16
0.89b'c'd
0.44
8.0E-03a'
1.0E+03b'c
0.018
0.12C
1.0E+03b'c
0.055
0.023
600 c
0.16
16
11
0.028
2.5
7.2E-03
5.7E-03
27
10"
0.054
0.11
32
4.3
76
LCTV based
on Inhalation
1.0E+03"'
0.53
1.0E+03"'
660
7.3
0.025
1.0E+03"'
1.0E+03"'
110
49
3.0 e
3.0 e
1.0E+03b'c
1.5
1.0E+03"'
2.1E-03
0.015
1.0E+03"'
970
1.0E+03"'
73
2.7
12
Carcinogenic Effect
30-yr Avg
DAF
2.2
7.7E+04
1.0E+30
2.2
2.2
2.2
7.4
2.2
3.9
1.0E+30
2.2
25
2.2
1.0E+30
2.2
2.5
2.2
2.2
2.2
2.2
4.3E+06
2.2
1.0E+30
3.9E+08
2.4
6.3
1.0E+30
1.0E+30
4.8E+07
2.2
3.1
2.2
2.2
1.3E+06
2.2
2.2
2.3
2.3
2.2
1.0E+30
2.2
2.2
2.2
2.2
2.2
LCTV based
on Ingestion
1.0E+03b'
1.0E+03b'
2.9E-05
1.0E+03b'
1.9E-03
1.2E-04
320 c
3.4E-05
8.0E-03a'
1.0E+03b'c
3.0E-03
3.8E-04
1.0E+03b'c
0.30C
0.015
110C
0.23
LCTV based
on Inhalation
1.0E+03"'
0.024
2.1E-03
1.0E+03"'
1.0E+03b'
3.3
0.038
1.0E+03b'c
8.0E-04
8.0E-03 "'
1.0E+03b'c
1.5E-03
2.3E-04
1.0E+03b'c
6.9 c
7.4E-03
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.I -3
-------
Table F. 1 Landfill LCTVs for No Liner/In-Situ Soil
Common Name
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran, 2,3,7,8-
Tetrachlorodibenzo-p-dioxin, 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram]
CAS#
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
7440280
137268
MCL
(mg/L)
Ingestion
5.00E-03
1.00E-03
5.00E-04
5.00E-02
1.00E-01
3.00E-08
5.00E-03
2.00E-03
HBN (mg/L)
Ingestion
NC
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
0.147
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
0.734
1.47E+00
2.45E-01
0.734
1.22E-02
1.96E-03
1.22E-01
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
6.19E-09
6.44E-10
Inhalation
NC
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
3.60E+00
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
1.00E-07
2.20E-09
3.71 E-03 1.90E-03
4.83E-04
1.86E-03
9.40E-01
5.00E-04
2.10E-02
No Liner/In-Situ Soil
Peak
DAF
8.1E+04
2.2
1.0E+30
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.3
1.1E+09
6.1
3.0
4.4E+06
2.5
2.2
2.2
2.2
2.2
1.0E+30
1.0E+30
1.7E+05
2.3
2.2
2.9
2.2
2.2
2.2
2.2
2.3
2.2E+12
1.4E+04
3.0
17
2.2
2.2
1.0E+30
2.2
LCTV
based on
MCL
(mg/L)
0.011
2.2E-03
83 c
0.12
0.22
4.1 E-04 c
0.014 "
0.014 "
0.011
5.8E-03
Non-Carcinogenic Effect
7-yr Avg
DAF
8.1E+04
2.2
1.0E+30
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.3
1.2E+09
6.1
3.0
4.5E+06
2.5
2.2
2.2
2.2
2.2
1.0E+30
1.0E+30
1.7E+05
2.3
2.2
2.9
2.2
2.2
2.2
2.2
2.3
2.2E+12
1.4E+04
3.0
17
2.2
2.2
1.0E+30
2.2
LCTV based
on Ingestion
1.3c'd
0.54
3.3
0.28
1.1
1.1
0.027
4.3E-04
1.1
0.11
1.0E+03b'c
0.12
0.18
1.6
32
4.3E-03
0.32
1.0E+03b'c
1.0E+03b'
82 c
4.2
2.2 c
0.054
0.30
0.37
0.016
11
0.017
3.4E-04C
2.2
24
0.54
1.6
1.0E+03b'c
5.8E-03
0.27
LCTV based
on Inhalation
1.0E+03"
38
22
0.042
0.33
0.73
1.0E+03"'
1.0E+03"'
1.1
3.1
8.0
0.64 "
0.70 *'
Carcinogenic Effect
30-yr Avg
DAF
8.1E+04
2.2
1.0E+30
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.2
2.3
1.2E+09
6.1
3.0
4.5E+06
2.5
2.2
2.2
2.2
2.2
1.0E+30
1.0E+30
1.7E+05
2.3
2.2
2.9
2.2
2.2
2.2
2.2
2.3
2.2E+12
1.4E+04
3.0
17
2.2
2.2
1.0E+30
2.2
LCTV based
on Ingestion
0.029
1.4E-06
4.2E-06
4.0E-05
3.0E-05
0.044
9.7E-06
1.0E-04
3.7E-09
2.8E-03C
9.2E-04
1.8E-03
40 c
8.9E-04
1.2 E-03
1.0E+03b'c
9.0E-06C
0.011
8.0E-03
4.1 E-03
LCTV based
on Inhalation
1.0E+03b'c
0.063
5.1E-05
9.5E-05
8.8E-04
4.4E-05
3.3E-03
1.2
9.9E-03
0.019
2.0
1.9E-07
0.27 c
100a'
23 c
0.038
1.0E+03b'c
3.1E-05C
5.7E-03
8.3E-03
0.047
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.I -4
-------
Table F. 1 Landfill LCTVs for No Liner/In-Situ Soil
Common Name
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1 ,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxyjpropionic acid 2-(2,4,5- (Silv
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
0.0979
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
No Liner/In-Situ Soil
Peak
DAF
2.2
2.2
2.2
2.2
6.3E+03
2.3
2.2
2.3
98
2.5
2.2
2.2
2.2
2.2
2.2
2.2
2.7
2.2
2.2
21
2.2
2.2
2.2
2.2
2.2
2.2
LCTV
based on
MCL
(mg/L)
2.2
0.50 "'
0.18
0.16
0.021 d
0.012
0.011
0.11
4.4E-03
22
Non-Carcinogenic Effect
7-yr Avg
DAF
2.2
2.2
2.2
2.2
6.3E+03
2.3
2.2
2.3
98
2.5
2.2
2.2
2.2
2.2
2.2
2.2
2.7
2.2
2.2
21
2.2
2.2
2.2
2.2
2.2
2.2
LCTV based
on Ingestion
11
1.1
1.0E+03b'c
0.56
0.67"
0.24
16
5.4
0.43
0.54
0.39
1.6
0.50
54
0.16
110
110
110
110
16
LCTV based
on Inhalation
2.9
210C
1.9
0.64 M
0.64 "
0.50 *'
4.7
0.090
0.24
2.7
0.20 *'
2.9
3.1
2.9
3.1
Carcinogenic Effect
30-yr Avg
DAF
2.2
2.2
2.2
2.2
6.3E+03
2.3
2.2
2.3
98
2.5
2.2
2.2
2.2
2.2
2.2
2.2
2.7
2.2
2.2
21
2.2
2.2
2.2
2.2
2.2
2.2
LCTV based
on Ingestion
6.7E-05
8.9E-04
1.1E-03
0.50 *'
0.028
4.9E-04"
4.9E-04"
0.019
0.019
3.7E-05
2.0E-04
3.0E-04
LCTV based
on Inhalation
17
0.080
0.50 "'
0.044
6.72E-04 "
6.7E-04 d
0.015
0.62
5.5E-03
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.I -5
-------
Table F.2 Landfill LCTVs for Compacted Clay Liner
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-ch loroisopropyljether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
218019
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
1.00E-01
1.00E-01
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
0.0171
0.0122
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
3.67E+01
7.34E-02
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
8.05E-04
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
0.021
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
3.00E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
1.90E-03
7.30E-03
Compacted Clay Liner
Peak
DAF
6.4
6.1
6.1
6.1
6.1
1.0E+30
8.8
6.1
6.6
1.6E+15
6.1
6.1
7.2
280
6.1
6.1
5.1E+06
6.2E+06
6.1
1.0E+30
79
6.1
1.0E+30
7.5
1.0E+30
6.1
6.1
11
6.1
7.1
11.0
8.2E+07
6.1
6.1
6.1
36
6.9
6.1
6.3
6.1
6.1
1.0E+30
280
LCTV
based on
MCL
(mg/L)
0.040
0.33
13
0.030
1.0E+03b'c
0.13
1.0E+03b'c
0.60
0.043
0.033
0.055
0.030a'
0.61
0.55
0.50
1.3
1.0
Non-Carcinogenic Effect
7-yr Avg
DAF
6.4
6.1
6.1
6.1
6.1
1.0E+30
8.8
6.1
6.6
1.6E+15
6.1
6.1
7.2
280
6.1
6.1
5.1E+06
6.2E+06
6.1
1.0E+30
79
6.1
1.0E+30
7.5
1.0E+30
6.1
6.1
11
6.1
7.1
11
8.4E+07
6.1
6.1
6.1
36
6.9
6.1
6.3
6.1
6.1
1.0E+30
280
LCTV based
on Ingestion
9.4 c
15
15
1.0E+03b'
0.043
74
0.032 d
1.0E+03b'c
0.74
53 c
0.068
0.050
12
0.45
45
52 e
0.45
6.0
1.0E+03b'c
3.7
220 M
15
52 c
0.15
0.083
17
0.2
0.030 *'
3.0
0.6
3.0
17C
3.4
1.5
0.74
260
0.75
LCTV based
on Inhalation
1.3
1.0E+03"'
19
1.0E+03"'
91
0.25
5.7
0.50 "'
1.0E+03"
1.0E+03b'c
1.0E+03"'
0.37
13
0.23
0.030a'
0.13
1.2
180
2.1
1.6
0.059
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
6.4
6.1
6.1
6.1
6.1
1.0E+30
8.8
6.1
6.6
1.6E+15
6.1
6.1
7.2
280
6.1
6.1
5.2E+06
6.4E+06
6.1
1.0E+30
79
6.1
1.0E+30
7.5
1.0E+30
6.1
6.1
11
6.1
7.1
11
8.5E+07
6.1
6.1
6.1
36
6.9
6.1
6.3
6.1
6.1
1.0E+30
280
LCTV based
on Ingestion
1.9E-04
1.4E-04"
1.0E+03b'c
0.10
1.3E-03
0.023 c
0.011
2.6E-06
69 c
520 c
1.0E+03b'c
7.0E-03
8.4E-03
1.0E+03b'c
0.012
8.2E-03
0.030 *'
0.013
7.9E-03
0.045
0.23 c
LCTV based
on Inhalation
0.25
45
6.6E-03
1.0E+03b'c
13
5.1 c
0.010
16
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.087
0.036
1.0E+03b'c
6.0E-03
2.4E-04
8.4E-03
0.030a'
43 c
5.2E-03
0.036
1.0E+03b'
2.0 c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.2-1
-------
Table F.2 Landfill LCTVs for Compacted Clay Liner
Common Name
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylenetrans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropenetrans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
Disulfoton
CAS#
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
606202
117840
123911
122394
122667
298044
MCL
(mg/L)
Ingestion
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
2.45E-02
4.90E-01
6.12E-01
9.79E-04
C
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
1.42E-04
8.78E-03
1.21E-04
Inhalation
NC
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.6
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
1.09E+03
C
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
1.80E-01
2.00E-02
Compacted Clay Liner
Peak
DAF
6.1
6.1
6.1
6.1
6.2
6.1
6.1
1.0E+30
1.0E+30
1.0E+30
4.9E+08
1.0E+30
9.8
6.1
6.1
6.1
6.1
7.8
7.6
6.1
6.1
6.1
6.1
6.1
6.1
6.1
1.0E+30
1.0E+30
1.0E+30
11
6.8
1.1E+06
6.1
6.1
1.0E+30
6.1
6.1
31
6.1
6.1
6.1
6.1
1.0E+30
6.1
6.1
6.1
1.0E+30
LCTV
based on
MCL
(mg/L)
9.4
2.0E-03
3.7
0.46
0.027 "
0.019"
0.43
0.61
0.043
0.43
0.030
Non-Carcinogenic Effect
7-yr Avg
DAF
6.1
6.1
6.1
6.1
6.2
6.1
6.1
1.0E+30
1.0E+30
1.0E+30
4.9E+08
1.0E+30
9.8
6.1
6.1
6.1
6.1
7.8
7.6
6.1
6.1
6.1
6.1
6.1
6.1
6.1
1.0E+30
1.0E+30
1.0E+30
11
6.8
1.2E+06
6.1
6.1
1.0E+30
6.1
6.1
31
6.1
6.1
6.1
6.1
1.0E+30
6.1
6.1
6.1
1.0E+30
LCTV based
on Ingestion
3.1
7.4
7.4
0.74
7.4
15
2.5E-03
740
1.0E+03b'c
13
30
0.45"
0.32 "
1.5
3.0
0.70 a'
0.45
1.5
13
4.5
1.0E+03"'
1.0E+03"'
1.0E+03b'c
220
1.5"
15
3.0
77 c
0.015
0.30
0.13 *'
0.15
1.0E+03b'c
3.8
1.0E+03b'c
LCTV based
on Inhalation
200 "'
200 *'
200 *'
1.0E+03"'
8.0
2.4E-03
0.028
4.7
7.5s'
3.5
0.45"
0.32 a'd
0.70 '
0.085
0.37
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
6.1
6.1
6.1
6.1
6.2
6.1
6.1
1.0E+30
1.0E+30
1.0E+30
4.9E+08
1.0E+30
9.8
6.1
6.1
6.1
6.1
7.8
7.6
6.1
6.1
6.1
6.1
6.1
6.1
6.1
1.0E+30
1.0E+30
1.0E+30
11
6.8
1.2E+06
6.1
6.1
1.0E+30
6.1
6.1
31
6.1
6.1
6.1
6.1
1.0E+30
6.1
6.1
6.1
1.0E+30
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
6.7E-04
0.025
1.3E-03
1.8E-03"
1.3E-03"
9.8E-04
8.6E-03
5.9E-03
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.4E-07
0.042
6.4E-05
8.6E-04
8.6E-04
0.053
7.4E-04
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'c
0.77
7.9E-03
0.30C
0.034"
4.8E-03
1.3E-03
0.018
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13a'
1.1
0.12
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.2-2
-------
Table F.2 Landfill LCTVs for Compacted Clay Liner
Common Name
Endosulfan (Endosulfan 1 and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1 ,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol 2-
Methoxyethanol acetate 2-
Methyl ethyl ketone
Methyl isobutyl ketone
CAS#
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
109864
110496
78933
108101
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
2.00E-03
4.00E-02
HBN (mg/L)
Ingestion
NC
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.9
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
0.196
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
2.45E-02
4.90E-02
1.47E+01
1.96E+00
C
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
7.00E-04
6.50E-03
1.54E+03
4.40E+02
5.10E+02
3.30E+01
1.20E+00
C
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.5
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
Compacted Clay Liner
Peak
DAF
6.3
1.1E+22
1.0E+30
6.1
6.1
6.1
55
6.1
17
1.0E+30
6.1
1.3E+03
6.1
1.0E+30
6.1
11
6.1
6.1
6.1
6.2
1.0E+30
6.2
1.0E+30
1.0E+30
8.8
570
1.0E+30
1.0E+30
1.0E+30
6.3
31
6.1
6.1
1.0E+30
6.1
6.1
7.0
6.6
6.1
1.0E+30
6.1
6.1
6.1
6.1
LCTV
based on
MCL
(mg/L)
0.020"'
4.3
0.063
27
074b,c,d
0.74 "
8.0E-03"'
1.0E+03b'c
0.13a'c
1.0E+03b'c
0.15
0.019
10"
Non-Carcinogenic Effect
7-yr Avg
DAF
6.3
1.1E+22
1.0E+30
6.1
6.1
6.1
55
6.1
17
1.0E+30
6.1
1.3E+03
6.1
1.0E+30
6.1
11
6.1
6.1
6.1
6.2
1.0E+30
6.2
1.0E+30
1.0E+30
8.8
580
1.0E+30
1.0E+30
1.0E+30
6.3
31
6.1
6.1
1.0E+30
6.1
6.1
7.0
6.6
6.1
1.0E+30
6.1
6.1
6.1
6.1
LCTV based
on Ingestion
0.92 c
0.020 a'
1.0E+03"'
60
45
1.0E+03"'
30
37
15
300
0.012
11C
20
30
300
0.45
2gb,c,d
1.2
8.0E-03 a'
1.0E+03b'c
0.065
0.13"
1.0E+03b'c
0.15
0.22
1.0E+03b'c
0.45
45
30
0.086
8.0
0.20 a'c
0.016
74
10"
0.15
0.30
90
12
LCTV based
on Inhalation
1.0E+03b'
1.5
1.0E+03b'
1.0E+03"'
20
1.2
1.0E+03b'
1.0E+03"'
310
130
8.8 "
8.8 "
1.0E+03b'c
4.0
1.0E+03"'
9.4E-03
0.043
1.0E+03"'
1.0E+03"'
1.0E+03"'
200 a'
7.3
Carcinogenic Effect
30-yr Avg
DAF
6.3
1.1E+22
1.0E+30
6.1
6.1
6.1
55
6.1
17
1.0E+30
6.1
1.3E+03
6.1
1.0E+30
6.1
11
6.1
6.1
6.1
6.2
1.0E+30
6.2
1.0E+30
1.0E+30
8.8
580
1.0E+30
1.0E+30
1.0E+30
6.3
31
6.1
6.1
1.0E+30
6.1
6.1
7.0
6.6
6.1
1.0E+30
6.1
6.1
6.1
6.1
LCTV based
on Ingestion
1.0E+03"'
1.0E+03b'
1.4E-03
1.0E+03b'
5.3E-03
3.3E-04
1.0E+03b'c
9.4E-05
8.0E-03 a'
1.0E+03b'c
0.011
0.035 c
1.0E+03b'c
1.0E+03b'c
0.043
1.0E+03b'c
0.62
LCTV based
on Inhalation
1.0E+03b'
0.067
0.11
1.0E+03"'
1.0E+03b'
9.1
0.10
1.0E+03b'c
2.2E-03
8.0E-03a'
1.0E+03b'c
5.4E-03
0.021 c
1.0E+03b'c
1.0E+03b'c
0.021
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.2-3
-------
Table F.2 Landfill LCTVs for Compacted Clay Liner
Common Name
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran, 2,3,7,8-
Tetrachlorodibenzo-p-dioxin, 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
CAS#
80626
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
MCL
(mg/L)
Ingestion
5.00E-03
1.00E-03
5.00E-04
5.00E-02
1.00E-01
3.00E-08
5.00E-03
HBN (mg/L)
Ingestion
NC
3.43E+01
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
0.147
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
0.734
1.47E+00
2.45E-01
0.734
1.22E-02
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
6.19E-09
6.44E-10
Inhalation
NC
5.30E+00
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
3.60E+00
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
1.00E-07
2.20E-09
Compacted Clay Liner
Peak
DAF
6.1
1.0E+30
6.1
1.0E+30
6.1
6.2
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.6
1.0E+30
660
22
1.0E+30
10
6.1
6.1
6.1
6.1
1.0E+30
1.0E+30
3.1E+15
6.5
6.1
22
6.1
6.1
6.1
6.1
7.5
1.0E+30
1.2E+13
3.71E-03 1.90E-03 13
4.83E-04
1.86E-03
9.40E-01
5.00E-04
2.10E-02
200
6.1
6.1
1.0E+30
LCTV
based on
MCL
(mg/L)
0.031
6.E-03
1.0E+03b'c
0.50
0.61
1.0E+03b'c
0.039"
0.039"
0.030
Non-Carcinogenic Effect
7-yr Avg
DAF
6.1
1.0E+30
6.1
1.0E+30
6.1
6.2
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.6
1.0E+30
670
22
1.0E+30
10
6.1
6.1
6.1
6.1
1.0E+30
1.0E+30
3.1E+15
6.5
6.1
22
6.1
6.1
6.1
6.1
7.5
1.0E+30
1.2E+13
13
200
6.1
6.1
1.0E+30
LCTV based
on Ingestion
210
3.5 b'c'd
1.5
9.2
0.90
3.0
3.3
0.074
1.2E-03
3.0
0.32
1.0E+03b'c
13C
0.73 c
4.5
90
0.012
0.90
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
12
16C
0.15
1.0'
5.0s
0.045
30
0.055
1.0E+03b'c
9.4
300
0.70 s'
4.5
1.0E+03b'c
LCTV based
on Inhalation
32
1.0E+03"
100
62
0.12
0.91
2.0
1.0E+03b'
1.0E+03b'
3.0
5.0 '
22
0.64"
0.70 *'
Carcinogenic Effect
30-yr Avg
DAF
6.1
1.0E+30
6.1
1.0E+30
6.1
6.2
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.1
6.6
1.0E+30
670
22
1.0E+30
10
6.1
6.1
6.1
6.1
1.0E+30
1.0E+30
3.4E+15
6.5
6.1
22
6.1
6.1
6.1
6.1
7.5
1.0E+30
1.2E+13
13
200
6.1
6.1
1.0E+30
LCTV based
on Ingestion
0.080
3.9E-06
1.2E-05
1.1 E-04
8.4E-05
0.12
2.7E-05
2.8E-04
2.78E-08
1.0E+03b'c
3.7E-03
4.9E-03
1.0E+03b'c
2.4E-03
3.3E-03
1.0E+03b'c
1.0E+03b'c
0.047
0.068 d
0.011
LCTV based
on Inhalation
1.0E+03b'c
0.17
1.4E-04
2.6E-04
2.4E-03
1.2 E-04
9. 1 E-03
3.2
0.027
0.053
5.6
1.4E-06
1.0E+03b'c
100a'
1.0E+03b'c
0.10
1.0E+03b'c
1.0E+03b'c
0.024
0.053d
0.13
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.2-4
-------
Table F.2 Landfill LCTVs for Compacted Clay Liner
Common Name
Thallium
Thiram [Thiuram]
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1 ,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxyjpropionic acid 2-(2,4,5- (Silv
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
2.00E-03
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
1.96E-03
1.22E-01
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
0.0979
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
Compacted Clay Liner
Peak
DAF
6.1
6.1
6.1
6.1
6.1
1.8E+08
6.5
6.1
6.6
2.0E+04
7.5
6.1
6.1
6.1
6.1
6.1
6.1
9.3
6.1
6.1
610
6.1
6.1
6.1
6.1
6.1
6.1
LCTV
based on
MCL
(mg/L)
0.018
6.1
0.50"'
0.52
0.46
0.059M
0.037
0.030
0.30
0.012
61
Non-Carcinogenic Effect
7-yr Avg
DAF
6.1
6.1
6.1
6.1
6.1
1.8E+08
6.5
6.1
6.6
2.0E+04
7.5
6.1
6.1
6.1
6.1
6.1
6.1
9.3
6.1
6.1
610
6.1
6.1
6.1
6.1
6.1
6.1
LCTV based
on Ingestion
0.019
0.74
30
3.2
1.0E+03b'c
1.6
0.96 M
0.73
45
15
1.0a'
1.5
1.4
4.5
1.8
150
0.20 "'
300 c
300 c
300 c
300 c
51
LCTV based
on Inhalation
7.9
580 c
5.5
0.96M
0.96"
0.50 "'
13
0.32
0.67
7.3
0.20 "'
7.9
8.5
7.9
8.6
Carcinogenic Effect
30-yr Avg
DAF
6.1
6.1
6.1
6.1
6.1
1.8E+08
6.5
6.1
6.6
2.0E+04
7.5
6.1
6.1
6.1
6.1
6.1
6.1
9.3
6.1
6.1
610
6.1
6.1
6.1
6.1
6.1
6.1
LCTV based
on Ingestion
1.8E-04
2.4E-03
3.1E-03
0.50 "'
0.080
1.4E-03"
1.4E-03"
0.053
0.053
1.3E-04
6.1E-03
8.2E-04
LCTV based
on Inhalation
46
0.22
0.50"'
0.12
1.8E-03"
1.8E-03"
0.041
1.7
0.015
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.2-5
-------
Table F.3 Landfill LCTVs for Composite Liner
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-ch loroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
0.0171
0.0122
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
0.021
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
Composite Liner
Peak
DAF
1.0E+30
1.5E+04
1.5E+04
1.6E+04
2.1E+05
1.0E+30
1.0E+30
1.5E+04
9.3E+05
1.0E+30
2.7E+05
1.6E+04
1.0E+30
1.0E+30
1.9E+04
1.8E+04
1.0E+30
1.0E+30
1.6E+05
1.0E+30
1.0E+30
3.1E+04
1.0E+30
1.2E+07
1.0E+30
2.2E+04
1.6E+05
1.0E+30
1.3E+06
2.4E+06
1.0E+30
1.0E+30
1.8E+04
3.4E+05
3.3E+04
1.0E+30
1.4E+06
1.5E+04
9.7E+04
1.5E+04
1.9E+04
LCTV
based on MCL
(mg/L)
1.0E+03"
5.0s
100s
0.50 a'
1.0E+03b'c
1.0E+03"
1.0E+03b'c
1.0E+03b'
1.0E+03b'c
1.0a
0.50 a'
0.030 "'
100a'
1.0E+03"'
6.0 a'
Non-Carcinogenic Effect
7-yr Avg
DAF
1.0E+30
1.5E+04
1.6E+04
1.6E+04
2.1E+05
1.0E+30
1.0E+30
1.5E+04
9.3E+05
1.0E+30
2.7E+05
1.6E+04
1.0E+30
1.0E+30
1.9E+04
1.9E+04
1.0E+30
1.0E+30
1.6E+05
1.0E+30
1.0E+30
3.1E+04
1.0E+30
1.2E+07
1.0E+30
2.2E+04
1.6E+05
1.0E+30
1.4E+06
2.4E+06
1.0E+30
1.0E+30
1.9E+04
3.4E+05
3.4E+04
1.0E+30
1.4E+06
1.6E+04
9.7E+04
1.5E+04
1.9E+04
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
740 M
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
5.0s
100s
1.0E+03b'c
1.0E+03"'
1.0E+03"
1.0E+03"
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0a
1.0E+03"'
0.50 "'
0.030s'
1.0E+03"'
1.0E+03"'
100a'
1.0E+03b'c
1.0E+03"'
6.0 a'
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
740 M
1.0E+03"'
0.50 a'
1.0E+03"
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
0.50 "'
0.030 "'
410
100a'
1.0E+03"'
6.0 "'
1.0E+03"'
190
Carcinogenic Effect
30-yr Avg
DAF
1.0E+30
1.5E+04
1.6E+04
1.6E+04
2.1E+05
1.0E+30
1.0E+30
1.5E+04
9.3E+05
1.0E+30
2.7E+05
1.6E+04
1.0E+30
1.0E+30
1.9E+04
1.9E+04
1.0E+30
1.0E+30
1.6E+05
1.0E+30
1.0E+30
3.1E+04
1.0E+30
1.2E+07
1.0E+30
2.2E+04
1.6E+05
1.0E+30
1.4E+06
2.4E+06
1.0E+30
1.0E+30
1.9E+04
3.4E+05
3.4E+04
1.0E+30
1.4E+06
1.6E+04
9.7E+04
1.5E+04
2.0E+04
LCTV based
on Ingestion
1.0E+03b'
170
1.0E+03b'c
270
5.0 a
1.0E+03b'c
0.50 "'
7.8E-03
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'
43
1.0E+03b'c
1.0E+03b'
0.50 a'
0.030a'
1.0E+03b'c
1.0E+03b'
110
LCTV based
on Inhalation
620
1.0E+03b'
750"
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
0.50 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'
190
1.0E+03b'c
1.0E+03"'
0.88
0.50 '
0.030 "'
1.0E+03b'c
1.0E+03"'
90
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.3-1
-------
Table F.3 Landfill LCTVs for Composite Liner
Common Name
Chloropropene 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylenetrans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropenetrans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
CAS#
107051
16065831
18540299
218019
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
MCL
(mg/L)
Ingestion
1.00E-01
1.00E-01
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
3.67E+01
7.34E-02
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
C
8.05E-04
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
Inhalation
NC
3.00E-03
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.6
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
C
1.90E-03
7.30E-03
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
Composite Liner
Peak
DAF
1.0E+30
1.0E+30
1.9E+04
1.9E+04
1.9E+04
2.3E+04
2.9E+05
1.7E+04
6.1E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
9.4E+04
9.0E+04
3.7E+05
2.3E+04
1.0E+30
1.0E+30
4.0E+05
3.5E+05
1.8E+04
4.5E+07
1.6E+05
1.9E+04
1.7E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.7E+05
1.6E+04
1.0E+30
8.8E+07
8.7E+06
1.0E+30
2.2E+05
1.5E+05
2.0E+04
LCTV
based on MCL
(mg/L)
1.0E+03"
5.0s
1.0E+03"
1.0E+03"'
1.0E+03b'c
7.5 '
0.45 "
0.32 '"
1.0E+03"'
1.0E+03"'
0.70 '
W'
93
Non-Carcinogenic Effect
7-yr Avg
DAF
1.0E+30
1.0E+30
1.9E+04
1.9E+04
1.9E+04
2.4E+04
3.0E+05
1.7E+04
6.2E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
9.5E+04
9.1E+04
3.7E+05
2.3E+04
1.0E+30
1.0E+30
4.1E+05
3.5E+05
1.8E+04
4.6E+07
1.6E+05
1.9E+04
1.7E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.7E+05
1.6E+04
1.0E+30
9.1E+07
9.0E+06
1.0E+30
2.2E+05
1.5E+05
2.0E+04
LCTV based
on Ingestion
1.0E+03"
5.0s
1.0E+03"
200''
200s-
200s-
1.0E+03"'
1.0E+03b'c
7.0
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.45M
0.32 "
1.0E+03"'
1.0E+03"'
0.70 "'
1.0E+03"'
10 "
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
540
1.0E+03"'
0.13a'
LCTV based
on Inhalation
1.0E+03"'
200 '
200s-
200s-
1.0E+03"'
1.00E+03b'c
6.6
1.0E+03"'
1.0E+03b'c
7.5 s-
1.0E+03b'c
0.45 ""
0.32 "'"
0.70 '-
260
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.00E+038
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
1.0E+30
1.0E+30
1.9E+04
1.9E+04
1.9E+04
2.4E+04
3.0E+05
1.7E+04
6.2E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
9.5E+04
9.1E+04
3.8E+05
2.3E+04
1.0E+30
1.0E+30
4.1E+05
3.5E+05
1.9E+04
5.0E+07
1.6E+05
1.9E+04
1.7E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.7E+05
1.6E+04
1.0E+30
9.5E+07
9.4E+06
1.0E+30
2.2E+05
1.5E+05
2.0E+04
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
7.5 *'
82 c
0.45"
0.32 "'"
0.70s-
26
17
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03
0.13a'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
7.5'-
1.0E+03b'c
0.45 b'd
0.32 '"
070s-
50
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13 '
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.3-2
-------
Table F.3 Landfill LCTVs for Composite Liner
Common Name
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
Disulfoton
Endosulfan (Endosulfan I and 1 1, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1 ,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
CAS#
606202
117840
123911
122394
122667
298044
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
HBN (mg/L)
Ingestion
NC
2.45E-02
4.90E-01
6.12E-01
9.79E-04
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.9
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
0.196
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
C
1.42E-04
8.78E-03
1.21E-04
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
1.09E+03
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
C
1.80E-01
2.00E-02
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.5
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
Composite Liner
Peak
DAF
2.4E+05
1.0E+30
1.6E+04
1.0E+30
6.1E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.6E+04
1.6E+04
1.7E+04
1.0E+30
1.6E+05
1.0E+30
1.0E+30
8.0E+04
1.0E+30
1.5E+04
1.0E+30
1.6E+04
1.0E+30
1.4E+04
1.4E+05
1.6E+04
3.5E+05
1.0E+30
3.5E+05
1.0E+30
1.0E+30
2.5E+11
1.0E+30
1.0E+30
1.0E+30
1.0E+30
6.0E+05
1.0E+30
7.2E+04
1.4E+05
1.0E+30
1.5E+05
2.1E+04
1.0E+30
LCTV
based on MCL
(mg/L)
0.020 a'
1.0E+03b'c
1.0E+03"'
1.0E+03"
1.0E+03b'c
1.0E+03"
8.0E-03 a'
1.0E+03b'c
0.13 a'c
1.00E+03b'c
5.0 "
Non-Carcinogenic Effect
7-yr Avg
DAF
2.4E+05
1.0E+30
1.6E+04
1.0E+30
6.1E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.6E+04
1.6E+04
1.7E+04
1.0E+30
1.6E+05
1.0E+30
1.0E+30
8.1E+04
1.0E+30
1.5E+04
1.0E+30
1.6E+04
1.0E+30
1.4E+04
1.5E+05
1.6E+04
3.6E+05
1.0E+30
3.6E+05
1.0E+30
1.0E+30
2.6E+11
1.0E+30
1.0E+30
1.0E+30
1.0E+30
6.0E+05
1.0E+30
7.3E+04
1.5E+05
1.0E+30
1.5E+05
2.2E+04
1.0E+30
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.020s'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
32
1.0E+03b'c
1.0E+03"
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
8.0E-03''
1.0E+03b'c
0.50s-
0.13"
1.0E+03b'c
3.0 *'
1.0E+03b'c
1.0E+03b'c
1.0E+03"
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.00E+03"
1.00E+03"
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
2.4E+05
1.0E+30
1.6E+04
1.0E+30
6.1E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.6E+04
1.6E+04
1.7E+04
1.0E+30
1.6E+05
1.0E+30
1.0E+30
8.1E+04
1.0E+30
1.5E+04
1.0E+30
1.6E+04
1.0E+30
1.4E+04
1.5E+05
1.6E+04
3.6E+05
1.0E+30
3.6E+05
1.0E+30
1.0E+30
2.6E+11
1.0E+30
1.0E+30
1.0E+30
1.0E+30
6.0E+05
1.0E+30
7.3E+04
1.5E+05
1.0E+30
1.5E+05
2.2E+04
1.0E+30
LCTV based
on Ingestion
35
140
7.4
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
14
19C
1.0E+03b'c
5.5 c
8.0E-03a'
1.0E+03b'c
0.50 "'
0.13"
1.0E+03b'c
1.0E+03b'c
3.0 "
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03b'c
1.0E+03"'
890 c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
130 c
8.0E-03 "'
1.0E+03b'c
0.50 "'
0.13"
1.0E+03b'c
1.0E+03b'c
3.0 "'
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.3-3
-------
Table F.3 Landfill LCTVs for Composite Liner
Common Name
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol 2-
Methoxyethanol acetate 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
CAS#
7439976
126987
67561
72435
109864
110496
78933
108101
80626
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
MCL
(mg/L)
Ingestion
2.00E-03
4.00E-02
5.00E-03
1.00E-03
5.00E-04
5.00E-02
HBN (mg/L)
Ingestion
NC
2.45E-03
2.45E-03
1.22E+01
1.22E-01
2.45E-02
4.90E-02
1.47E+01
1.96E+00
3.43E+01
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
0.147
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
Inhalation
NC
7.00E-04
6.50E-03
1.54E+03
4.40E+02
5.10E+02
3.30E+01
1.20E+00
5.30E+00
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
Composite Liner
Peak
DAF
9.8E+05
1.4E+04
1.0E+30
1.6E+04
1.6E+04
1.6E+04
1.7E+04
1.6E+04
1.0E+30
1.7E+04
1.0E+30
2.0E+05
6.2E+05
1.1E+05
1.7E+04
1.6E+04
1.6E+04
1.6E+04
2.6E+04
1.7E+04
6.4E+04
1.6E+04
1.6E+04
1.6E+04
4.0E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
9.7E+04
1.6E+04
1.5E+05
1.5E+05
1.0E+30
1.0E+30
1.0E+30
4.5E+09
1.6E+04
1.0E+30
1.6E+04
1.3E+07
LCTV
based on MCL
(mg/L)
0.20 af
10a'c
1.0E+03"'
97
1.0E+03b'c
1.0'
Non-Carcinogenic Effect
7-yr Avg
DAF
9.8E+05
1.4E+04
1.0E+30
1.6E+04
1.7E+04
1.6E+04
1.7E+04
1.7E+04
1.0E+30
1.7E+04
1.0E+30
2.0E+05
6.3E+05
1.1E+05
1.8E+04
1.6E+04
1.6E+04
1.6E+04
2.6E+04
1.8E+04
6.5E+04
1.6E+04
1.6E+04
1.6E+04
4.0E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
9.8E+04
1.7E+04
1.5E+05
1.5E+05
1.0E+30
1.0E+30
1.0E+30
4.6E+09
1.7E+04
1.0E+30
1.6E+04
1.3E+07
LCTV based
on Ingestion
0.20"
1.0E+03b'
1.0E+03b'
10"
390
810
200 *'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
2.0s-
3.1
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03"'
290
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
5.0s-
1.0"
5.0 s
LCTV based
on Inhalation
0.20 "
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
200 "'
1.0E+03"'
1.0E+03"'
1.00E+03"
1.0E+03"'
1.0E+03"'
1.0E+03b'c
2.0 '-
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
5.0 *'
Carcinogenic Effect
30-yr Avg
DAF
9.8E+05
1.4E+04
1.0E+30
1.6E+04
1.7E+04
1.6E+04
1.7E+04
1.7E+04
1.0E+30
1.7E+04
1.0E+30
2.0E+05
6.3E+05
1.1E+05
1.8E+04
1.6E+04
1.6E+04
1.6E+04
2.6E+04
1.8E+04
6.6E+04
1.6E+04
1.6E+04
1.6E+04
4.0E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
9.9E+04
1.7E+04
1.5E+05
1.5E+05
1.0E+30
1.0E+30
1.0E+30
4.7E+09
1.7E+04
1.0E+30
1.6E+04
1.4E+07
LCTV based
on Ingestion
1.0E+03b'
0.010
0.030
0.47
0.25
1.0E+03b'c
0.072
0.74
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
80
1.0E+03b'c
6.6
1.0E+03b'c
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03"'
0.37
0.70
6.4
0.52
27
1.0E+03b'c
74
140
1.0E+03b'
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03b'c
280
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.3-4
-------
Table F.3 Landfill LCTVs for Composite Liner
Common Name
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran, 2,3,7,8-
Tetrachlorodibenzo-p-dioxin, 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram]
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1 ,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-(2,4,5- (Silv
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
1.00E-01
3.00E-08
5.00E-03
2.00E-03
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
7.34E-03
4.90E+00
7.34E-03
2.45E-08
0.734
1.47E+00
2.45E-01
0.734
1.22E-02
1.96E-03
1.22E-01
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
0.0979
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
6.19E-09
6.44E-10
Inhalation
NC
3.60E+00
C
1.00E-07
2.20E-09
3.71 E-03 1.90E-03
4.83E-04
1.86E-03
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
9.40E-01
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
5.00E-04
2.10E-02
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
Composite Liner
Peak
DAF
7.7E+05
5.4E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.5E+04
1.1E+07
1.0E+30
3.0E+09
2.9E+04
1.6E+04
1.7E+04
2.0E+05
1.0E+30
3.1E+05
7.4E+04
6.8E+06
1.0E+30
1.4E+07
2.3E+04
2.3E+04
3.8E+10
2.7E+04
4.3E+05
2.5E+05
1.0E+30
1.8E+04
1.7E+05
1.0E+30
1.6E+04
1.6E+04
1.0E+05
8.4E+04
1.1E+05
9.7E+04
LCTV
based on MCL
(mg/L)
1.0E+03b'c
1.0E+03b'c
0.64 "
0.64 "
0.70 a'
1.0E+03"
1.0E+03b'c
0.50 "'
1.0E+03"'
1.0E+03b'c
0.96 M
0.96 M
0.50 *'
1.0"'
0.20 "'
1.0E+03b'c
Non-Carcinogenic Effect
7-yr Avg
DAF
7.8E+05
5.5E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.5E+04
1.1E+07
1.0E+30
3.2E+09
2.9E+04
1.6E+04
1.7E+04
2.1E+05
1.0E+30
3.1E+05
7.4E+04
6.8E+06
1.0E+30
1.4E+07
2.3E+04
2.3E+04
4.2E+10
2.7E+04
4.4E+05
2.5E+05
1.0E+30
1.8E+04
1.8E+05
1.0E+30
1.6E+04
1.6E+04
1.0E+05
8.4E+04
1.1E+05
9.8E+04
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03"'
0.70 *'
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.96M
0.96M
1.0E+03"'
400 *'
1.0a'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"
1.0E+03"'
0.20s-
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"
LCTV based
on Inhalation
1.0E+03b'c
0.64 e
0.70 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.96 b'd
0.96 "
0.50 "'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
0.20 s'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
Carcinogenic Effect
30-yr Avg
DAF
7.8E+05
5.5E+04
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.5E+04
1.2E+07
1.0E+30
3.5E+09
2.9E+04
1.6E+04
1.7E+04
2.1E+05
1.0E+30
3.2E+05
7.5E+04
6.9E+06
1.0E+30
1.4E+07
2.3E+04
2.3E+04
4.2E+10
2.7E+04
4.4E+05
2.5E+05
1.0E+30
1.8E+04
1.8E+05
1.0E+30
1.6E+04
1.6E+04
1.1E+05
8.5E+04
1.1E+05
9.9E+04
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
0.64M
0.64M
0.70s'
0.50
6.9
100
0.50 "'
1.0E+03"'
0.96"
0.96M
0.50s'
2.0'-
1.0E+03"'
1.0E+03b'c
0.20 "'
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'c
0.64 M
0.64 b'd
0.70 '
1.0E+03"'
620
0.50 "'
1.0E+03"'
0.96 e
0.96 b'd
0.50 '
2.0s-
0.20 '-
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.3-5
-------
Table F.4 Surface Impoundment LCTVs for No Liner/In-Situ Soil
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
218019
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
1.00E-01
1.00E-01
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
0.0171
0.0122
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
3.67E+01
7.34E-02
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
8.05E-04
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
0.021
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
3.00E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
1.90E-03
7.30E-03
No Liner/In-Situ Soil
Peak
DAF
2.2
1.3
1.3
1.3
1.3
1.0E+30
1.3
1.3
1.3
380
1.3
1.3
3.6
36
1.3
1.3
110
110
1.3
1.0E+30
2.1
1.3
7.4E+10
1.3
190
1.3
1.3
4.0
1.3
1.3
1.5
130
1.3
1.3
1.3
4.4
1.3
1.3
1.3
1.3
1.3
9.7E+05
36
LCTV
based on
MCL
(mg/L)
8.5E-03
0.080
2.7
6.4E-03
0.021 c
0.28
1.0E+03b'c
0.11
8.9E-03
8.3E-03
7.3E-03
0.030 a'
0.13
0.10
0.10
2.6
0.69
Non-Carcinogenic Effect
7-yr Avg
DAF
2.2
1.3
1.3
1.3
1.3
1.0E+30
1.4
1.3
1.4
380
1.3
1.3
3.6
37
1.3
1.3
110
110
1.3
1.0E+30
2.2
1.4
7.5E+10
1.4
230
1.3
1.3
4.1
1.3
1.4
1.5
140
1.3
1.3
1.4
4.4
1.4
1.3
1.3
1.3
1.3
9.8E+05
37
LCTV based
on Ingestion
3.2
3.2
3.2
1.0E+03b'
6.9E-03
16
5.2E-03"
0.28 c
0.16
27 c
0.014
0.013
2.4
0.097
9.7
11"
0.53
1.3
1.0E+03b'c
0.68
7.7
3.2
20 c
0.033
0.021
3.4
0.025
0.030a'
0.65
0.13
0.67
2.2
0.67
0.33
0.16
100
0.55
LCTV based
on Inhalation
0.29
1.0E+03b'
4.1
1.0E+03b'
20
0.051
1.2
0.25
1.0E+03"
1.0E+03b'c
3.4
0.080
2.6
0.031
0.030 a'
0.029
0.27
40
0.44
0.34
0.013
1.0E+03b'
Carcinogenic Effect
30-yr Avg
DAF
2.3
1.5
1.5
1.5
1.5
1.0E+30
1.7
1.5
1.6
380
1.5
1.5
3.8
37
1.6
1.5
110
110
1.5
1.0E+30
2.6
1.6
7.5E+10
1.6
230
1.6
1.5
4.2
1.6
1.6
1.7
140
1.6
1.5
1.6
4.7
1.6
1.5
1.6
1.5
1.6
2.2E+06
37
LCTV based
on Ingestion
3.5E-05
2.7E-05"
2.1E-03
0.026
1.4E-04
2.9E-03
2.7E-03
6.4E-07
1.4E-03
8.6E-03C
1.0E+03b'c
2.2E-04
2.2E-03
1.0E+03b'c
2.6E-03
1.3E-03
0.030a'
1.7E-03
1.8E-03
1 . 1 E-02
0.029 c
LCTV based
on Inhalation
6.2E-02
8.4E+00
1.6E-03
3.8E-03
3.3E+00
0.66 c
2.5E-03
4.0
0.57 c
0.067 c
1.0E+03b'c
2.8E-03
9.3E-03
1.0E+03b'c
1.3E-03
6.2E-05
1.3E-03
0.030 a'
5.6
1.2E-03
9.0E-03
1.0E+03b'
0.27 c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.4-1
-------
Table F.4 Surface Impoundment LCTVs for No Liner/In-Situ Soil
Common Name
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylenetrans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropenetrans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
Disulfoton
CAS#
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
606202
117840
123911
122394
122667
298044
MCL
(mg/L)
Ingestion
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
2.45E-02
4.90E-01
6.12E-01
9.79E-04
C
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
1.42E-04
8.78E-03
1.21E-04
Inhalation
NC
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.6
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
1.09E+03
C
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
1.80E-01
2.00E-02
No Liner/In-Situ Soil
Peak
DAF
1.3
1.3
1.3
1.3
1.7
1.3
1.3
4.4E+08
3.2E+04
1.0E+30
38
4.8E+03
1.4
1.5
1.5
1.6
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
5.3E+06
5.3E+06
3.3E+04
1.5
3.1
10
1.3
1.3
3.1E+04
1.3
1.3
6.6
1.3
1.3
1.3
1.3
1.0E+30
1.3
1.6
1.4
150
LCTV
based on
MCL
(mg/L)
5.5
2.8E-04
0.88
0.11
5.6E-03 "
4.0E-03 d
0.088
0.13
8.9E-03
0.088
6.3E-03
Non-Carcinogenic Effect
7-yr Avg
DAF
1.3
1.3
1.3
1.3
1.7
1.3
1.3
4.4E+08
3.2E+04
1.0E+30
38
4.9E+03
1.5
1.5
1.5
1.6
1.3
1.4
1.4
1.3
1.3
1.3
1.4
1.3
1.3
1.3
5.9E+06
5.9E+06
3.3E+04
1.5
3.1
11
1.3
1.3
3.1E+04
1.4
1.3
6.6
1.3
1.3
1.3
1.3
1.0E+30
1.3
1.6
1.4
160
LCTV based
on Ingestion
1.2
1.6
1.6
0.16
1.6
4.2
5.5E-04
160
1.0E+03b'c
3.3
6.6
0.22"
0.15"
0.33
0.65
0.29
0.10
0.3
2.9
1.0
1.0E+03"'
1.0E+03"'
40 c
30
0.054
3.2
0.66
16C
3.2E-03
0.065
0.065
0.032
1.0E+03b'c
1.0
0.15
LCTV based
on Inhalation
200"'
200s'
200s-
1.0E+03"'
2.2
5.1E-04
4.2E-03
1.1
4.4
0.78
0.45"
0.32 "'"
0.28
0.018
0.081
1.0E+03"'
1.0E+03"'
1.0E+03"
940
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
1.5
1.5
1.5
1.6
1.9
1.5
1.5
4.4E+08
3.2E+04
1.0E+30
42
4.9E+03
1.7
1.7
1.7
1.8
1.6
1.6
1.6
1.5
1.5
1.6
1.6
1.5
1.5
1.5
1.3E+07
1.3E+07
3.3E+04
1.8
3.2
12
1.5
1.5
3.1E+04
1.6
1.6
6.8
1.5
1.5
1.5
1.5
1.0E+30
1.5
1.8
1.6
200
LCTV based
on Ingestion
1.0E+03b'c
9.0 c
1Qb,c,d
0.066
0.064C
1.2E-04
6.7E-03
3.9E-04
4.6E-04"
3.2E-04"
2.5E-04
2.2E-03
1.5E-03
1.0E+03"'
1.0E+03"'
0.20 c
6.6E-08
0.010
1.6E-05
2.2E-04
2.2E-04
0.013
1.9E-04
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'c
0.14
2.2E-03
8.9 c
8.5E-03 d
1.0E-03
3.4E-04
4.4E-03
1.0E+03"'
1.0E+03"'
3.3 c
94 c
0.13 ''
0.27
0.032
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.4-2
-------
Table F.4 Surface Impoundment LCTVs for No Liner/In-Situ Soil
Common Name
Endosulfan (Endosulfan 1 and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate 2-
Methoxyethanol 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
CAS#
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
110496
109864
78933
108101
80626
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
2.00E-03
4.00E-02
HBN (mg/L)
Ingestion
NC
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.9
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
0.196
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
4.90E-02
2.45E-02
1.47E+01
1.96E+00
3.43E+01
C
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
7.00E-04
6.50E-03
1.54E+03
5.10E+02
4.40E+02
3.30E+01
1.20E+00
5.30E+00
C
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.5
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
No Liner/In-Situ Soil
Peak
DAF
1.8
150
7.6E+04
1.3
1.3
1.3
2.1
1.3
1.6
1.0E+30
1.4
3.5
1.3
7.3E+03
1.3
7.7
1.3
1.3
1.3
1.7
220
1.7
1.0E+30
3.3E+03
5.6
43
1.0E+30
4.9E+08
1.8E+03
1.9
17
1.4
1.3
550
1.3
1.3
3.4
1.3
1.3
1.1E+20
1.3
1.3
1.3
1.3
1.3
LCTV
based on
MCL
(mg/L)
0.020 a'
1.0
1.7E-04
4.9
0.044
0.29 "
8.0E-03 a'
0.66 c
0.043 c
1.0E+03b'c
0.078
2.5E-03
10a'c
Non-Carcinogenic Effect
7-yr Avg
DAF
1.9
150
8.3E+04
1.3
1.3
1.3
2.2
1.3
1.7
1.0E+30
1.5
3.8
1.3
8.3E+03
1.3
7.7
1.3
1.3
1.3
1.7
230
1.7
1.0E+30
3.3E+03
5.6
43
1.0E+30
4.9E+08
1.8E+03
1.9
17
1.4
1.3
550
1.3
1.3
3.4
1.4
1.3
1.8E+20
1.3
1.3
1.3
1.3
1.3
LCTV based
on Ingestion
0.27
0.020s'
1.0E+03"'
13
9.7
49
6.5
3.8
3.6
65
2.6E-03
7.5 c
3.8
6.5
65
0.097
1.0"
0.34
8.0E-03''
1.1C
0.041
0.13"
1.0E+03b'c
0.047
0.13
390 c
0.097
9.7
6.5
0.041
1.6
3.3E-03
3.3E-03
16
1.0E+01 "
0.065
0.032
19
2.6
45
LCTV based
on Inhalation
1.0E+03"'
0.32
1.0E+03"'
400
4.82
3.7E-03
1.0E+03"'
1.0E+03"'
67
29
3.5 e
3.5 e
1.0E+03 b'c
0.95
710
9.4E-04
8.8E-03
1.0E+03b'
670
580
44
1.6
7.0
Carcinogenic Effect
30-yr Avg
DAF
2.1
150
8.8E+04
1.5
1.5
1.5
2.6
1.5
2.0
1.0E+30
1.6
4.3
1.5
8.6E+03
1.5
7.8
1.5
1.5
1.5
1.9
290
1.9
1.0E+30
3.4E+03
5.7
43
1.0E+30
5.0E+08
1.8E+03
2.2
17
1.6
1.5
550
1.5
1.6
3.5
1.6
1.5
1.8E+20
1.5
1.5
1.5
1.5
1.5
LCTV based
on Ingestion
860
1.0E+03 "
4.9E-06
0.81
1.3E-03
1.0E-04
0.021
2.9E-05
8.0E-03a'
0.036
7.1E-03
2.6E-03
3.1 c
1.1E-05C
0.015
0.044C
0.16
LCTV based
on Inhalation
1.0E+03b'
0.018
3.6E-04
4.5
1.0E+03b'
2.3
0.0
0.5
6.9E-04
8.0E-03 "'
9.6E-01 c
3.5E-03
1.5E-03
71 c
2.6E-04 c
7.1E-03
2.1E+01 c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.4-3
-------
Table F.4 Surface Impoundment LCTVs for No Liner/In-Situ Soil
Common Name
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran 2,3,7,8-
Tetrachlorodibenzo-p-dioxin 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram]
CAS#
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
7440280
137268
MCL
(mg/L)
Ingestion
5.00E-03
1.00E-03
5.00E-04
5.00E-02
1.00E-01
3.00E-08
5.00E-03
2.00E-03
HBN (mg/L)
Ingestion
NC
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
0.147
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
0.734
1.47E+00
2.45E-01
0.734
1.22E-02
1.96E-03
1.22E-01
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
6.19E-09
6.44E-10
3.71E-03
4.83E-04
1.86E-03
Inhalation
NC
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
3.60E+00
9.40E-01
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
1.00E-07
2.20E-09
1.90E-03
5.00E-04
2.10E-02
No Liner/In-Situ Soil
Peak
DAF
68
1.3
1.0E+30
1.3
1.3
1.5
1.3
1.3
1.3
1.3
1.3
1.3
1.4
1.3
1.3
1.3
1.3
930
41
15
680
6.8
1.5
1.3
1.3
1.3
6.7E+19
1.0E+30
390
1.4
1.3
14
1.3
1.3
1.3
1.4
4.1
2.0E+04
2.7E+02
1.5
3.0
1.3
1.3
1.0E+30
1.4
LCTV
based on
MCL
(mg/L)
6.3E-03
1.5E-03
0.20 c
0.063
0.14
8.1E-06C
8.2E-03 "
8.2E-03 "
6.4E-03
2.5E-03
Non-Carcinogenic Effect
7-yr Avg
DAF
75
1.3
1.0E+30
1.3
1.3
1.5
1.3
1.3
1.3
1.3
1.3
1.3
1.4
1.3
1.3
1.3
1.4
960
41
15
680
6.8
1.5
1.3
1.3
1.3
1.2E+20
1.0E+30
390
1.4
1.3
14
1.3
1.3
1.3
1.4
4.1
2.0E+04
2.7E+02
1.6
3.2
1.3
1.3
1.0E+30
1.4
LCTV based
on Ingestion
0.46
0.32
2.0
0.16
0.74
0.77
0.016
2.6E-04
0.69
0.066
140 c
0.80
0.50
1.1
19
2.6E-03
0.19
1.0E+03b'c
1.0E+03b'
0.19C
2.6
11C
0.032
0.16
0.17
0.010
6.9
0.030
6.6E-06
1.1
4.7
0.33
0.98
1.0E+03b'c
2.6E-03
0.17
LCTV based
on Inhalation
1.0E+03"
22
13
0.029
0.20
0.44
1.0E+03"'
1.0E+03"'
0.65
1.8
5.1
0.64 "
0.70 a'
Carcinogenic Effect
30-yr Avg
DAF
83
1.5
1.0E+30
1.5
1.5
1.7
1.5
1.5
1.5
1.5
1.6
1.5
1.6
1.5
1.5
1.5
1.6
1.2E+03
41
15
680
7.0
1.7
1.5
1.5
1.5
1.6E+20
1.0E+30
390
1.6
1.5
14
1.5
1.6
1.6
1.6
4.3
2.0E+04
2.7E+02
1.8
3.8
1.6
1.6
1.0E+30
1.6
LCTV based
on Ingestion
0.020
9.8E-07
2.9E-06
2.8E-05
2.1E-05
0.032
6.7E-06
7.0E-05
1.8E-08
4.3E-07
2.6E-03
1.3E-03
0.095C
6.1 E-04
8.4E-04
1.3E-04
1.7E-07
6.7E-03
1 .8E-03
2.9E-03
LCTV based
on Inhalation
1.0E+03b'c
0.043
3.5E-05
6.5E-05
6.1 E-04
3.1E-05
2.3E-03
0.84
6.8E-03
0.013
1.4
9.2E-07
4.1E-05
90
0.055
0.026
2.0E-03 c
6.0E-07
3.4E-03
1.9E-03
0.033
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.4-4
-------
Table F.4 Surface Impoundment LCTVs for No Liner/In-Situ Soil
Common Name
Toluene
Toluenediamine2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1 ,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxyjpropionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
0.0979
C
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
Inhalation
NC
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
C
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
7.34E+00 2.10E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
8.78E-03
1.38E-05
9.89E-06
1.34E-04
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
2.80E-01
2.50E-03
No Liner/In-Situ Soil
Peak
DAF
1.3
1.3
1.3
1.3
42
1.3
1.4
2.6
5.9
1.3
1.3
1.3
1.4
1.3
1.3
1.3
1.4
1.3
1.3
3.5
1.3
1.3
1.5
1.4
1.5
1.5
LCTV
based on
MCL
(mg/L)
1.3
0.13
0.10
0.18
0.012"
6.7E-03
6.4E-03
0.063
2.5E-03
15
Non-Carcinogenic Effect
7-yr Avg
DAF
1.4
1.3
1.3
1.3
42
1.4
1.5
2.6
6.4
1.4
1.3
1.3
1.4
1.3
1.3
1.3
1.4
1.3
1.3
3.5
1.3
1.3
1.5
1.5
1.5
1.5
LCTV based
on Ingestion
6.6
0.66
1.0E+03b'c
0.64
0.40"
0.14
9.8
3.5
0.26
0.32
0.21
1.0
2.6
32
0.10
74
72
74
73
13
LCTV based
on Inhalation
1.8
140
2.2
0.38 M
0.38 "
0.50 a'
2.8
0.048
0.15
1.6
0.20 a'
2.0
2.1
2.0
2.1
Carcinogenic Effect
30-yr Avg
DAF
1.6
1.5
1.5
1.5
44
1.6
1.6
2.8
7.4
1.6
1.6
1.6
1.6
1.6
1.5
1.5
1.7
1.5
1.5
4.2
1.5
1.5
1.7
1.7
1.7
1.7
LCTV based
on Ingestion
4.6E-05
6.1E-04
7.7E-04
3.9E-03
0.019
3.4E-04"
3.4E-04"
0.014
0.014
2.3E-05
4. 1 E-05
2.0E-04
LCTV based
on Inhalation
11
0.055
0.16
0.030
4.7E-04 "
4.7E-04 d
0.011
0.44
3.8E-03
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.4-5
-------
Table F.5 Surface Impoundment for Compacted Clay Liner
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
1.00E-01
1.00E-01
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
0.0171
0.0122
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
3.67E+01
7.34E-02
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
0.021
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
3.00E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
1.90E-03
Compacted Clay Liner
Peak
DAF
17
3.9
3.9
4.0
3.9
1.0E+30
4.8
3.9
4.1
3.7E+08
3.9
3.9
42.4
910
4.1
3.9
2.6E+04
2.6E+04
3.9
1.0E+30
17
4.5
1.0E+30
4.6
1.5E+08
4.2
3.9
55
4.2
4.5
6.0
1.1E+05
4.1
3.9
4.8
87
4.4
3.9
4.1
3.9
4.1
1.0E+30
LCTV
based on
MCL
(mg/L)
0.026
0.26
7.3
0.020
5.2 c
4.5
1.0E+03b'c
0.37
0.029
0.029
0.030
0.030a'
0.48
0.35
0.32
57
5.0s
Non-Carcinogenic Effect
7-yr Avg
DAF
17
4.0
4.0
4.0
4.0
1.0E+30
4.8
4.0
4.2
3.7E+08
4.0
4.0
43
910
4.1
4.0
2.7E+04
2.6E+04
4.0
1.0E+30
17
4.5
1.0E+30
4.7
1.5E+08
4.3
4.0
55
4.2
4.5
6.1
1.1E+05
4.1
4.0
4.9
87
4.5
4.0
4.1
4.0
4.1
1.0E+30
LCTV based
on Ingestion
25 c
9.7
9.7
1.0E+03b'
0.024
48
0.018"
1.0E+03b'c
0.48
310 c
0.047
0.048
7.0
0.29
29
34 e
8.7
4.4
1.0E+03b'c
2.3
140M
9.7
270 c
0.10
0.069
11
0.10
0.030 "'
2.0
0.39
2.4
43 c
2.2
1.0
0.50
450
5.0s
LCTV based
on Inhalation
0.87
1.0E+03b'
12
1.0E+03"'
59
0.16
3.7
0.50 '
1.0E+03"
1.0E+03b'c
1.0E+03"'
0.26
8.5
0.13
0.030a'
0.090
1.0
120
1.3
1.0
0.040
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
17
4.5
4.5
4.5
4.5
1.0E+30
5.6
4.5
4.8
3.7E+08
4.5
4.5
43
910
4.7
4.5
2.7E+04
2.6E+04
4.5
1.0E+30
21
5.0
1.0E+30
5.3
2.6E+08
4.8
4.5
55
4.7
5.1
6.8
1.1E+05
4.6
4.5
5.3
87
5.1
4.5
4.7
4.5
4.7
1.0E+30
LCTV based
on Ingestion
1.2E-04
9.0E-05 d
1.0E+03b'c
7.6E-02
1.1E-03
0.073 c
8.2E-03
1.9E-06
0.35 c
2.1 c
1.0E+03b'c
1.9E-03
6.9E-03
1.0E+03b'c
8.2E-03
5.0E-03
0.030 "'
3.1E-02
5.8E-03
3.3E-02
LCTV based
on Inhalation
0.18
29
4.8E-03
1.0E+03b'c
9.9
16C
7.5E-03
12
140 c
17C
1.0E+03b'c
0.023
0.030
1.0E+03b'c
4.2E-03
1.9E-04
5.2E-03
0.030a'
100 c
3.8E-03
0.027
1.0E+03b'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.5-1
-------
Table F.5 Surface Impoundment for Compacted Clay Liner
Common Name
Chrysene
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylenetrans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropenetrans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
CAS#
218019
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
606202
117840
123911
122394
122667
MCL
(mg/L)
Ingestion
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
2.45E-02
4.90E-01
6.12E-01
C
8.05E-04
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
1.42E-04
8.78E-03
1.21E-04
Inhalation
NC
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.6
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
1.09E+03
C
7.30E-03
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
1.80E-01
2.00E-02
Compacted Clay Liner
Peak
DAF
910
4.0
4.1
4.0
4.3
9.8
3.9
4.1
1.0E+30
1.0E+30
1.0E+30
1.9E+05
1.0E+30
5.5
6.7
6.6
8.7
4.3
4.5
4.4
4.0
3.9
4.1
4.6
3.9
3.9
3.9
1.0E+30
1.0E+30
1.0E+30
6.1
33
2.8E+03
3.9
3.9
1.0E+30
4.7
4.4
140
3.9
3.9
3.9
3.9
1.0E+30
3.9
8.4
5.5
LCTV
based on
MCL
(mg/L)
61
1.1E-03
4.0
0.49
0.018 "
0.012"
0.28
0.39
0.028
0.27
0.020
Non-Carcinogenic Effect
7-yr Avg
DAF
910
4.1
4.1
4.1
4.3
9.8
4.0
4.1
1.0E+30
1.0E+30
1.0E+30
1.9E+05
1.0E+30
5.5
6.8
6.6
8.7
4.3
4.6
4.5
4.1
4.0
4.1
4.7
4.0
4.0
4.0
1.0E+30
1.0E+30
1.0E+30
6.2
33
2.9E+03
4.0
4.0
1.0E+30
4.8
4.4
140
4.0
4.0
4.0
4.0
1.0E+30
4.0
8.5
5.5
LCTV based
on Ingestion
8.0
5.0
5.0
0.50
5.2
24
1.6E-03
500
1.0E+03b'c
15
21
0.45"
0.32 "
1.0
1.9
0.70 *'
0.34
1.0
8.7
2.9
1.0E+03"'
1.0E+03"'
1.0E+03b'c
120
0.98"
9.7
2.2
340 c
9.7E-03
0.19
0.13 *'
0.10
1.0E+03b'c
5.2
LCTV based
on Inhalation
200 "'
200 *'
200 *'
1.0E+03"'
13
1.5E-03
0.016
5.2
7.5 *'
2.5
0.45"
0.32 a'd
0.70 "'
0.055
0.24
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
910
4.6
4.6
4.6
4.8
10
4.5
4.6
1.0E+30
1.0E+30
1.0E+30
1.9E+05
1.0E+30
6.4
7.2
7.0
9.1
4.9
5.3
5.2
4.6
4.5
4.7
5.1
4.5
4.5
4.5
1.0E+30
1.0E+30
1.0E+30
7.0
34
3.7E+03
4.5
4.5
1.0E+30
5.2
4.9
140
4.5
4.5
4.5
4.5
1.0E+30
4.5
8.8
5.9
LCTV based
on Ingestion
0.73 c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
310 c
1.0E+03b'c
4.4E-04
2.8E-02
2.0E-03
1.4E-03"
9.6E-04 d
7.5E-04
6.4E-03
4.3E-03
1.0E+03"'
1.0E+03"'
1.0E+03b'c
6.9E-07
3.1E-02
5.5E-05
6.4E-04
6.4E-04
4.0E-02
7.2E-04
LCTV based
on Inhalation
6.6 c
1.0E+03b'c
1.0E+03b'c
0.50
9.1E-03
45 c
0.025"
3.3E-03
1.0E-03
0.013
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13a'
0.81
0.12
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.5-2
-------
Table F.5 Surface Impoundment for Compacted Clay Liner
Common Name
Disulfoton
Endosulfan (Endosulfan 1 and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate 2-
Methoxyethanol 2-
Methyl ethyl ketone
Methyl isobutyl ketone
CAS#
298044
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
110496
109864
78933
108101
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
2.00E-03
4.00E-02
HBN (mg/L)
Ingestion
NC
9.79E-04
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.9
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
0.196
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
4.90E-02
2.45E-02
1.47E+01
1.96E+00
C
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
7.00E-04
6.50E-03
1.54E+03
5.10E+02
4.40E+02
3.30E+01
1.20E+00
C
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.5
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
Compacted Clay Liner
Peak
DAF
4.0E+07
12
6.5E+06
1.0E+30
3.9
3.9
3.9
18
3.9
7.7
1.0E+30
6.3
79
3.9
1.0E+30
3.9
110
3.9
3.9
3.9
10
5.8E+07
10
1.0E+30
4.2E+15
76
1.2E+03
1.0E+30
1.0E+30
5.2E+14
14
270
6.1
3.9
2.3E+10
3.9
4.1
38
4.1
3.9
1.0E+30
3.9
3.9
3.9
3.9
LCTV
based on
MCL
(mg/L)
0.020"'
4.4
4.0E-03
14
2gb,c,d
2.9 e
8.0E-03"'
1.0E+03b'c
0.13a'c
1.0E+03b'c
0.78
6.9E-03
10a'c
Non-Carcinogenic Effect
7-yr Avg
DAF
4.0E+07
12
6.6E+06
1.0E+30
4.0
4.0
4.0
18
4.0
7.9
1.0E+30
6.4
82
4.0
1.0E+30
4.0
110
4.0
4.0
4.0
10
5.8E+07
10
1.0E+30
4.2E+15
76
1.2E+03
1.0E+30
1.0E+30
5.2E+14
14
270
6.1
4.0
2.3E+10
4.0
4.2
38
4.2
4.0
1.0E+30
4.0
4.0
4.0
4.0
LCTV based
on Ingestion
1.0E+03b'c
1.8C
0.020 *'
1.0E+03"'
39
29
400
19
17
16
190
7.8E-03
110C
11
19
190
0.29
10b,c,d
2.0
8.0E-03 *'
1.0E+03b'c
0.50 *'
0.13"
1.0E+03b'c
0.34
2.0
1.0E+03b'c
0.29
29
20
0.46
4.9
9.4E-03
0.010
48
10"
0.19
0.10
58
7.8
LCTV based
on Inhalation
1.0E+03"'
1.0
1.0E+03"'
1.0E+03b'
21
0.080
1.0E+03"'
1.0E+03b'
200
87
35 e
35 e
1.0E+03b'c
4.0
1.0E+03"'
2.7E-03
0.027
1.0E+03"'
1.0E+03"'
1.0E+03b'
130
4.8
Carcinogenic Effect
30-yr Avg
DAF
4.6E+07
12
6.6E+06
1.0E+30
4.5
4.5
4.5
22
4.5
9.1
1.0E+30
6.8
100
4.5
1.0E+30
4.5
110
4.5
4.5
4.5
11
6.4E+07
11
1.0E+30
4.2E+15
76
1.2E+03
1.0E+30
1.0E+30
5.2E+14
14
270
6.5
4.5
2.3E+10
4.5
4.7
38
4.8
4.5
1.0E+30
4.5
4.5
4.5
4.5
LCTV based
on Ingestion
1.0E+03b'
1.0E+03"'
1.1E-04
1.0E+03"'
4.0E-03
5.6E-04
1.0E+03b'c
1.6E-04
8.0E-03 *'
1.0E+03b'c
0.095
0.073 c
1.0E+03b'c
1.0E+03b'c
0.097
1.0E+03b'c
0.477
LCTV based
on Inhalation
1.0E+03"'
0.074
8.4E-03
1.0E+03b'
1.0E+03"'
6.8
0.18
1.0E+03b'c
3.8E-03
8.0E-03a'
1.0E+03b'c
0.047
0.043C
1.0E+03b'c
1.0E+03b'c
0.046
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.5-3
-------
Table F.5 Surface Impoundment for Compacted Clay Liner
Common Name
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran 2,3,7,8-
Tetrachlorodibenzo-p-dioxin 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
CAS#
80626
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
MCL
(mg/L)
Ingestion
5.00E-03
1.00E-03
5.00E-04
5.00E-02
1.00E-01
3.00E-08
5.00E-03
HBN (mg/L)
Ingestion
NC
3.43E+01
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
0.147
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
0.734
1.47E+00
2.45E-01
0.734
1.22E-02
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
6.19E-09
6.44E-10
3.71E-03
4.83E-04
1.86E-03
Inhalation
NC
5.30E+00
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
3.60E+00
9.40E-01
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
1.00E-07
2.20E-09
1.90E-03
5.00E-04
2.10E-02
Compacted Clay Liner
Peak
DAF
3.9
7.7E+06
3.9
1.0E+30
3.9
4.0
7.0
3.9
3.9
3.9
3.9
4.2
3.9
5.6
3.9
3.9
3.9
4.2
1.7E+14
1.1E+03
230
3.9E+11
95
6.6
3.9
3.9
3.9
1.0E+30
1.0E+30
5.5E+08
5.1
3.9
220
3.9
4.4
4.1
5.6
50
1.0E+30
2.9E+07
7.3
46
4.3
4.4
1.0E+30
LCTV
based on
MCL
(mg/L)
0.020
6.6E-03
1.0E+03b'c
0.17
0.56
0.86C
0.027 "
0.027 "
0.022
Non-Carcinogenic Effect
7-yr Avg
DAF
4.0
7.9E+06
4.0
1.0E+30
4.0
4.1
7.0
4.0
4.0
4.0
4.0
4.3
4.0
5.6
4.0
4.0
4.0
4.2
1.7E+14
1.1E+03
230
3.9E+11
96
6.7
4.0
4.0
4.0
1.0E+30
1.0E+30
5.5E+08
5.1
4.0
220
4.0
4.4
4.1
5.6
51
1.0E+30
2.9E+07
7.3
46
4.4
4.4
1.0E+30
LCTV based
on Ingestion
140
2.3 b'c'd
1.0
6.0
0.44
3.4
2.5
0.048
7.8E-04
2.7
0.21
1.0E+03b'c
21 c
7.0 c
4.9
58
7.8E-03
0.58
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
9.4
160 c
0.10
0.43
0.61
0.030
27
0.37
0.71 c
5.4
68
0.70 a'
3.3
1.0E+03b'c
LCTV based
on Inhalation
21
1.0E+03"
67
41
0.13
0.59
1.3
1.0E+03"'
1.0E+03"'
1.9
5.0 '
20
0.64"
0.70 *'
Carcinogenic Effect
30-yr Avg
DAF
4.5
9.0E+06
4.5
1.0E+30
4.5
4.6
7.3
4.5
4.5
4.5
4.5
4.8
4.5
6.0
4.5
4.5
4.5
4.8
1.8E+14
1.1E+03
230
3.9E+11
96
7.0
4.5
4.5
4.5
1.0E+30
1.0E+30
5.6E+08
5.6
4.5
220
4.5
5.0
4.7
6.0
51
1.0E+30
2.9E+07
8.0
54
4.9
4.9
1.0E+30
LCTV based
on Ingestion
0.059
2.9E-06
8.5E-06
8.5E-05
6.2E-05
0.12
2.0E-05
2.1 E-04
2.9E-07
240 c
0.036
5.7E-03
1.0E+03b'c
1.8E-03
2.7E-03
1.0E+03b'c
0.019 c
0.030
0.026
9.1E-03
LCTV based
on Inhalation
1.0E+03b'c
0.13
1.0E-04
1.9E-04
1.8E-03
9.5E-05
6.8E-03
3.1
0.020
0.039
4.1
1.5E-05
1.0E+03b'c
100a'
1.0E+03b'c
0.077
1.0E+03b'c
0.064C
0.015
0.027
0.10
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.5-4
-------
Table F.5 Surface Impoundment for Compacted Clay Liner
Common Name
Thallium
Thiram [Thiuram
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1 ,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxyjpropionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
2.00E-03
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
1.96E-03
1.22E-01
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
0.0979
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
Compacted Clay Liner
Peak
DAF
5.5
4.6
3.9
3.9
3.9
1.7E+05
4.4
6.2
26
390
4.6
4.2
4.3
5.9
4.4
4.0
3.9
5.0
3.9
3.9
83
3.9
3.9
6.8
6.4
7.1
6.7
LCTV
based on
MCL
(mg/L)
6.6E-03
4.6
0.50"'
0.35
1.8
0.039"
0.023
0.021
0.20
7.8E-03
67
Non-Carcinogenic Effect
7-yr Avg
DAF
5.5
4.6
4.0
4.0
4.0
1.7E+05
4.4
6.2
26
400
4.6
4.3
4.3
5.9
4.4
4.1
4.0
5.1
4.0
4.0
84
4.0
4.0
6.8
6.5
7.1
6.8
LCTV based
on Ingestion
7.4E-03
0.67
23
2.1
1.0E+03b'c
6.4
0.96 M
0.45
32
14
0.80
1.0
0.75
2.9
41
97
0.20 "'
340 c
320 c
350 c
330 c
68
LCTV based
on Inhalation
6.0
590 c
22
0.96M
0.96"
0.50s-
9.0
0.17
0.44
4.8
0.20s-
8.9
9.0
9.2
9.5
Carcinogenic Effect
30-yr Avg
DAF
5.9
5.1
4.5
4.5
4.5
1.7E+05
4.9
6.6
26
490
5.3
4.8
4.8
6.3
4.9
4.6
4.5
5.9
4.5
4.5
89
4.5
4.5
7.2
6.9
7.4
7.2
LCTV based
on Ingestion
1.4E-04
1.8E-03
2.3E-03
0.50 "'
0.060
1.0E-03"
1.0E-03"
0.042
0.043
8.1E-05
8.8E-04
6.0E-04
LCTV based
on Inhalation
34
0.16
0.50 '-
0.094
1.4E-03"
1.4E-03"
0.033
1.4
0.011
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.5-5
-------
Table F. 6 Surface Impoundment LCTVs for Composite Liner
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-ch loroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
0.0171
0.0122
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
0.021
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
Composite Liner
Peak
DAF
1.0E+30
2.7E+05
2.7E+05
2.8E+05
2.4E+05
1.0E+30
2.9E+08
2.7E+05
9.2E+05
1.0E+30
2.6E+05
2.7E+05
1.0E+30
1.0E+30
3.4E+05
2.9E+05
1.0E+30
1.0E+30
2.3E+05
1.0E+30
1.0E+30
5.4E+05
1.0E+30
2.5E+06
1.0E+30
3.9E+05
2.2E+05
1.0E+30
3.8E+05
1.7E+06
9.1E+11
1.0E+30
3.4E+05
2.8E+05
6.6E+05
1.0E+30
1.5E+06
2.7E+05
5.5E+05
2.8E+05
3.5E+05
LCTV
based on MCL
(mg/L)
1.0E+03"'
5.0s
100s
0.50 '-
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0a
0.50 '-
0.030 "'
100a'
1.0E+03"'
6.0 a'
Non-Carcinogenic Effect
7-yr Avg
DAF
1.0E+30
2.7E+05
2.7E+05
2.8E+05
2.4E+05
1.0E+30
2.9E+08
2.7E+05
9.3E+05
1.0E+30
2.6E+05
2.8E+05
1.0E+30
1.0E+30
3.5E+05
2.9E+05
1.0E+30
1.0E+30
2.3E+05
1.0E+30
1.0E+30
5.5E+05
1.0E+30
2.6E+06
1.0E+30
3.94E+05
2.2E+05
1.0E+30
3.8E+05
1.7E+06
9.4E+11
1.0E+30
3.5E+05
2.8E+05
6.7E+05
1.0E+30
1.5E+06
2.8E+05
5.5E+05
2.9E+05
3.5E+05
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'
1.0E+03"'
1.0E+03"'
1.0E+03b'
1.0E+03"'
740 M
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
5.0s
100s
1.0E+03b'c
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0a
1.0E+03"'
0.50 "'
0.030s'
1.0E+03"'
1.0E+03"'
100a'
1.0E+03b'c
1.0E+03"'
6.0 '
1.0E+03"'
LCTV based
on Inhalation
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
740 M
1.0E+03"'
0.50 '-
1.0E+03"
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
0.50 "'
0.030 "'
1.0E+03"'
100a'
1.0E+03"'
6.0 "
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
1.0E+30
2.9E+05
2.8E+05
3.0E+05
2.4E+05
1.0E+30
3.2E+08
2.8E+05
9.7E+05
1.0E+30
2.6E+05
2.8E+05
1.0E+30
1.0E+30
3.6E+05
3.0E+05
1.0E+30
1.0E+30
2.3E+05
1.0E+30
1.0E+30
5.6E+05
1.0E+30
2.6E+06
1.0E+30
4.1E+05
2.2E+05
1.0E+30
3.8E+05
1.8E+06
9.4E+11
1.0E+30
3.6E+05
2.8E+05
6.9E+05
1.0E+30
1.5E+06
2.9E+05
5.7E+05
3.0E+05
3.7E+05
LCTV based
on Ingestion
1.0E+03b'
170
1.0E+03b'c
1.0E+03"'
5.0 a
1.0E+03b'c
0.501 "'
0.13
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'
780
1.0E+03b'c
1.0E+03"'
0.50 '
0.030s-
1.0E+03b'c
1.0E+03"'
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03"'
750"
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
0.50 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
16
0.50 '-
0.030 "'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.6-1
-------
Table F. 6 Surface Impoundment LCTVs for Composite Liner
Common Name
Chloropropene 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylenetrans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropenetrans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
CAS#
107051
16065831
18540299
218019
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
MCL
(mg/L)
Ingestion
1.00E-01
1.00E-01
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
3.67E+01
7.34E-02
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
C
8.05E-04
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
Inhalation
NC
3.00E-03
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.6
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
C
1.90E-03
7.30E-03
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
Composite Liner
Peak
DAF
1.0E+30
1.0E+30
3.3E+05
3.4E+05
3.3E+05
4.1E+05
4.0E+06
2.8E+05
3.3E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.2E+08
1.7E+06
1.6E+06
3.6E+06
4.3E+05
6.4E+07
3.8E+07
3.0E+05
2.8E+05
3.4E+05
8.7E+05
2.3E+05
3.2E+05
3.0E+05
1.0E+30
1.0E+30
1.0E+30
4.1E+09
1.0E+30
1.0E+30
2.6E+05
2.7E+05
1.0E+30
1.0E+06
5.6E+05
1.0E+30
2.4E+05
2.2E+05
3.2E+05
LCTV
based on MCL
(mg/L)
1.0E+03"'
5.0s
1.0E+03"'
1.0E+03"'
1.0E+03b'c
7.5s-
0.45 "
0.32 '"
1.0E+03"'
1.0E+03"'
0.70 "'
W'
1.0E+03"'
Non-Carcinogenic Effect
7-yr Avg
DAF
1.0E+30
1.0E+30
3.3E+05
3.4E+05
3.3E+05
4.1E+05
4.0E+06
2.8E+05
3.3E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.2E+08
1.7E+06
1.6E+06
3.7E+06
4.4E+05
6.4E+07
3.9E+07
3.0E+05
2.8E+05
3.4E+05
8.7E+05
2.3E+05
3.2E+05
3.0E+05
1.0E+30
1.0E+30
1.0E+30
4.1E+09
1.0E+30
1.0E+30
2.7E+05
2.7E+05
1.0E+30
1.0E+06
5.7E+05
1.0E+30
2.5E+05
2.2E+05
3.3E+05
LCTV based
on Ingestion
1.0E+03"'
5.0 "
1.0E+03"'
200 a'
200 '
200s-
1.0E+03"'
1.0E+03b'c
120
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.45M
0.32 "
1.0E+03"'
1.0E+03"'
0.70 "'
1.0E+03"'
10 '
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
610
1.0E+03"'
0.13a'
LCTV based
on Inhalation
1.0E+03"'
200'-
200s-
200s-
1.0E+03"'
1.0E+03b'c
110
1.0E+03"'
1.0E+03b'c
7.5 s-
1.0E+03b'c
0.45 ""
0.32 "'"
0.70 '-
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+038
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
1.0E+30
1.0E+30
3.6E+05
3.6E+05
3.6E+05
4.2E+05
4.1E+06
3.0E+05
3.3E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.3E+08
1.7E+06
1.6E+06
3.8E+06
4.4E+05
6.7E+07
4.0E+07
3.0E+05
2.8E+05
3.6E+05
8.7E+05
2.3E+05
3.4E+05
3.1E+05
1.0E+30
1.0E+30
1.0E+30
4.1E+09
1.0E+30
1.0E+30
2.7E+05
2.8E+05
1.0E+30
1.0E+06
5.7E+05
1.0E+30
2.5E+05
2.2E+05
3.4E+05
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
7.5'-
810C
0.45"
0.32 '"
0.70s-
490
300
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
11
0.13a'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
7.5 ''
1.0E+03b'c
0.45 ""
0.32 '"
0.70 '
900
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13 '
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.6-2
-------
Table F. 6 Surface Impoundment LCTVs for Composite Liner
Common Name
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
Disulfoton
Endosulfan (Endosulfan I and 1 1, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1 ,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
CAS#
606202
117840
123911
122394
122667
298044
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
HBN (mg/L)
Ingestion
NC
2.45E-02
4.90E-01
6.12E-01
9.79E-04
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.9
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
0.196
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
C
1.42E-04
8.78E-03
1.21E-04
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
1.09E+03
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
C
1.80E-01
2.00E-02
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.5
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
Composite Liner
Peak
DAF
2.6E+05
1.0E+30
2.7E+05
2.4E+09
1.0E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.8E+05
2.7E+05
2.7E+05
1.0E+30
2.2E+05
1.0E+30
1.0E+30
1.4E+06
1.0E+30
2.7E+05
1.0E+30
2.7E+05
1.0E+30
2.8E+05
2.2E+05
2.7E+05
4.5E+06
1.0E+30
4.5E+06
1.0E+30
1.0E+30
4.7E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
7.4E+06
1.0E+30
1.3E+06
2.2E+05
1.0E+30
2.2E+05
3.5E+05
1.0E+30
LCTV
based on MCL
(mg/L)
0.02 a'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"
8.0E-03 a'
1.0E+03b'c
0.13 a'c
1.0E+03b'c
5.0 "
Non-Carcinogenic Effect
7-yr Avg
DAF
2.6E+05
1.0E+30
2.7E+05
2.5E+09
1.0E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.78E+05
2.7E+05
2.7E+05
1.0E+30
2.2E+05
1.0E+30
1.0E+30
1.4E+06
1.0E+30
2.7E+05
1.0E+30
2.7E+05
1.0E+30
2.8E+05
2.2E+05
2.8E+05
4.7E+06
1.0E+30
4.7E+06
1.0E+30
1.0E+30
4.7E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
7.4E+06
1.0E+30
1.3E+06
2.2E+05
1.0E+30
2.2E+05
3.5E+05
1.0E+30
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.020 a'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
540
1.0E+03b'c
1.0E+03"
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
8.0E-03a'
1.0E+03b'c
0.50 a'
0.13"
1.0E+03b'c
3.0 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03b'
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'c
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03"
1.0E+03"
1.0E+03b'c
1.0E+03b'c
1.0E+03b'
Carcinogenic Effect
30-yr Avg
DAF
2.6E+05
1.0E+30
2.8E+05
2.7E+09
1.1E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.9E+05
2.7E+05
2.8E+05
1.0E+30
2.2E+05
1.0E+30
1.0E+30
1.5E+06
1.0E+30
2.9E+05
1.0E+30
2.8E+05
1.0E+30
3.0E+05
2.2E+05
2.9E+05
4.7E+06
1.0E+30
4.7E+06
1.0E+30
1.0E+30
4.8E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
7.5E+06
1.0E+30
1.4E+06
2.2E+05
1.0E+30
2.2E+05
3.7E+05
1.0E+30
LCTV based
on Ingestion
36
1.0E+03b'
130 c
1.0E+03b'
1.0E+03"'
1.0E+03"'
1.0E+03"'
240
250 c
1.0E+03b'c
72 c
8.0E-03a'
1.0E+03b'c
0.50 a'
0.13"
1.0E+03b'c
1.0E+03b'c
3.0 a'
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
8.0E-03 a'
1.0E+03b'c
0.50 a'
0.13"
1.0E+03b'c
1.0E+03b'c
3.0s'
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.6-3
-------
Table F. 6 Surface Impoundment LCTVs for Composite Liner
Common Name
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate 2-
Methoxyethanol 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
CAS#
7439976
126987
67561
72435
110496
109864
78933
108101
80626
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
MCL
(mg/L)
Ingestion
2.00E-03
4.00E-02
5.00E-03
1.00E-03
5.00E-04
5.00E-02
HBN (mg/L)
Ingestion
NC
2.45E-03
2.45E-03
1.22E+01
1.22E-01
4.90E-02
2.45E-02
1.47E+01
1.96E+00
3.43E+01
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
0.147
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
Inhalation
NC
7.00E-04
6.50E-03
1.54E+03
5.10E+02
4.40E+02
3.30E+01
1.20E+00
5.30E+00
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
Composite Liner
Peak
DAF
9.2E+05
2.8E+05
1.0E+30
2.7E+05
2.8E+05
2.7E+05
2.7E+05
2.7E+05
1.0E+30
2.7E+05
1.0E+30
2.4E+05
6.8E+05
1.8E+06
3.0E+05
2.7E+05
2.7E+05
2.7E+05
4.0E+05
2.7E+05
1.1E+06
2.8E+05
2.7E+05
2.7E+05
7.0E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.6E+06
2.9E+05
2.2E+05
2.2E+05
1.0E+30
1.0E+30
1.0E+30
4.4E+06
3.0E+05
1.0E+30
2.7E+05
6.2E+05
LCTV
based on MCL
(mg/L)
0.20 "
10a'c
1.0E+03"'
100a'
1.0E+03b'c
1.0'
Non-Carcinogenic Effect
7-yr Avg
DAF
9.2E+05
2.8E+05
1.0E+30
2.7E+05
2.9E+05
2.7E+05
2.7E+05
2.7E+05
1.0E+30
2.8E+05
1.0E+30
2.4E+05
6.8E+05
1.8E+06
3.0E+05
2.7E+05
2.7E+05
2.7E+05
4.1E+05
2.7E+05
1.1E+06
2.8E+05
2.7E+05
2.7E+05
7.0E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.6E+06
2.9E+05
2.2E+05
2.2E+05
1.0E+30
1.0E+30
1.0E+30
4.4E+06
3.1E+05
1.0E+30
2.8E+05
6.3E+05
LCTV based
on Ingestion
0.20"
1.0E+03"'
1.0E+03b'
10"
1.0E+03"'
1.0E+03"'
200s'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
2.0 "'
53
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03"'
430
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
5.0 "
1.0"
5.0 "
LCTV based
on Inhalation
0.20 a'c
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
200 "'
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
1.0E+03b'c
2.0 a'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
5.0 a'
Carcinogenic Effect
30-yr Avg
DAF
9.7E+05
2.9E+05
1.0E+30
2.8E+05
2.9E+05
2.8E+05
2.8E+05
2.8E+05
1.0E+30
2.9E+05
1.0E+30
2.4E+05
7.0E+05
1.9E+06
3.2E+05
2.8E+05
2.8E+05
2.9E+05
4.2E+05
2.9E+05
1.1E+06
2.9E+05
2.8E+05
2.8E+05
7.0E+05
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.7E+06
3.0E+05
2.2E+05
2.2E+05
1.0E+30
1.0E+30
1.0E+30
4.4E+06
3.1E+05
1.0E+30
2.9E+05
6.3E+05
LCTV based
on Ingestion
1.0E+03"'
0.18
0.54
7.5
3.9
1.0E+03b'c
1.3
13
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03b'c
120
340
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'
6.5
12
110
8.4
430
1.0E+03b'c
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03b'c
1.0E+03b'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.6-4
-------
Table F. 6 Surface Impoundment LCTVs for Composite Liner
Common Name
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran 2,3,7,8-
Tetrachlorodibenzo-p-dioxin 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram]
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1 ,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
1.00E-01
3.00E-08
5.00E-03
2.00E-03
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
7.34E-03
4.90E+00
7.34E-03
2.45E-08
0.734
1.47E+00
2.45E-01
0.734
1.22E-02
1.96E-03
1.22E-01
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
0.0979
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
6.19E-09
6.44E-10
3.71E-03
4.83E-04
1.86E-03
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
3.60E+00
9.40E-01
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
1.00E-07
2.20E-09
1.90E-03
5.00E-04
2.10E-02
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
Composite Liner
Peak
DAF
3.4E+05
1.0E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.5E+05
5.9E+05
1.0E+30
3.6E+06
5.5E+05
2.6E+05
2.8E+05
2.4E+05
1.0E+30
9.3E+05
1.3E+06
3.2E+07
1.0E+30
3.0E+06
4.0E+05
4.1E+05
7.3E+06
4.6E+05
3.1E+05
2.6E+05
1.3E+09
2.9E+05
2.3E+05
1.0E+30
2.6E+05
2.8E+05
1.7E+06
1.5E+06
1.9E+06
1.6E+06
LCTV
based on MCL
(mg/L)
1.0E+03b'c
1.0E+03b'c
0.64 "
0.64 "
0.70 a'
380
1.0E+03b'c
0.50 a'
1.0E+03"'
1.0E+03b'c
0.96 M
0.96 M
0.50 a'
1.0a'
0.20 a'
1.0E+03b'c
Non-Carcinogenic Effect
7-yr Avg
DAF
3.5E+05
1.0E+06
1.0E+30
1.00E+30
1.0E+30
1.0E+30
1.0E+30
4.5E+05
6.0E+05
1.0E+30
3.6E+06
5.6E+05
2.7E+05
2.9E+05
2.5E+05
1.0E+30
9.5E+05
1.3E+06
3.2E+07
1.0E+30
3.0E+06
4.1E+05
4.1E+05
7.3E+06
4.6E+05
3.1E+05
2.6E+05
1.3E+09
2.9E+05
2.4E+05
1.0E+30
2.7E+05
2.8E+05
1.7E+06
1.5E+06
1.9E+06
1.6E+06
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03b'
0.70 a'
1.0E+03b'c
1.0E+03b'c
570
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.96M
0.96M
1.0E+03"'
400 a'
1.0a'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
0.20s'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b
LCTV based
on Inhalation
1.0E+03b'c
0.64 "
0.70 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.96 b'd
0.96 b'd
0.50 "'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
0.20 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
Carcinogenic Effect
30-yr Avg
DAF
3.5E+05
1.1E+06
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.5E+05
6.0E+05
1.0E+30
3.6E+06
5.7E+05
2.8E+05
3.0E+05
2.5E+05
1.0E+30
9.9E+05
1.4E+06
3.3E+07
1.0E+30
3.1E+06
4.2E+05
4.3E+05
7.3E+06
4.9E+05
3.1E+05
2.6E+05
1.5E+09
3.0E+05
2.4E+05
1.0E+30
2.8E+05
3.0E+05
1.8E+06
1.6E+06
1.9E+06
1.7E+06
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
0.64M
0.64M
0.70 "'
8.4
120
120
0.50 "'
1.0E+03"'
0.96"
0.96M
0.50 "'
2.0"'
1.0E+03"'
1.0E+03b'c
0.20"'
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'c
0.64 M
0.64 b'd
0.70 "'
1.0E+03"'
1.0E+03"'
0.50 a'
1.0E+03"'
0.96 "
0.96 b'd
0.50 "'
2.0 a'
0.20 a'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.6-5
-------
Table F.7 Waste Pile LCTVs for No Liner/In-Situ Soil
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
ChloropropeneS- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
1.00E-01
1.00E-01
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
1.71E-02
1.22E-02
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
3.67E+01
7.34E-02
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
2.10E-02
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
3.00E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
1.90E-03
No Liner/In-Situ Soil
Peak
DAF
65
10
10
10
10
1.0E+30
12
10
11
1.1E+07
10
10
170
3.3E+03
11
10
4.6E+04
4.6E+04
10
1.0E+30
33
12
1.0E+30
12
8.6E+06
11
10
210
11
12
15
1.1E+05
11
10
14
330
12
10
11
10
11
1.0E+30
LCTV
based on
MCL
(mg/L)
0.087
1.0
24
0.055
9.1 c
8.1
1.0E+03b'c
0.95
0.078
0.10
0.077
0.030a'
1.4
0.94
0.86
67
5.0s
Non-Carcinogenic Effect
7-yr Avg
DAF
66
11
11
11
11
1.0E+30
12
11
12
1.1E+07
11
11
170
3.3E+03
12
11
4.6E+04
4.6E+04
11
1.0E+30
35
13
1.0E+30
12
8.9E+06
12
11
210
12
12
16
1.1E+05
11
11
14
330
12
11
11
11
12
1.0E+30
LCTV based
on Ingestion
97 c
27
27
1.0E+03b'
0.061
130
0.045 d
1.0E+03b'c
1.3
1.0E+03b'c
0.16
0.20
24
0.81
81
95 e
16
12
1.0E+03b'c
6.1
400 M
27
1.0E+03b'c
0.29
0.26
30
0.27
0.030 "'
5.6
1.1
6.9
160 c
6.0
2.8
1.4
1.0E+03"
5.0s
LCTV based
on Inhalation
2.4
1.0E+03"'
34
1.0E+03"'
170
0.44
10
0.50s'
1.0E+03"
1.0E+03b'c
1.0E+03"'
0.71
23
0.33
0.030a'
0.25
2.8
330
3.7
2.9
0.11
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
70
15
15
15
15
1.0E+30
17
15
16
1.1E+07
15
15
174
3.3E+03
16
15
4.6E+04
4.6E+04
15
1.0E+30
49
17
1.0E+30
17
2.7E+07
16
15
210
16
17
21
1.1E+05
16
15
19
340
17
15
16
15
16
1.0E+30
LCTV based
on Ingestion
3.7E-04
2.8E-04 d
63 c
0.26
5.5E-04
0.26 c
0.03
6.3E-06
0.61 c
3.7 c
1.0E+03b'c
4.3E-03
0.024
1.0E+03b'c
0.027
0.016
0.030 "'
0.12
0.020
0.11
LCTV based
on Inhalation
0.62
88
0.016
110C
33
59 c
0.025
39
250 c
29 c
1.0E+03b'c
0.054
0.10
1.0E+03b'c
0.014
6.5E-04
0.016
0.030a'
400 c
0.013
0.089
1.0E+03b'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F. 7-1
-------
Table F.7 Waste Pile LCTVs for No Liner/In-Situ Soil
Common Name
Chrysene
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a, hjanthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylene trans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropene trans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene2,4-
Dinitrotoluene2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
CAS#
218019
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
606202
117840
123911
122394
122667
MCL
(mg/L)
Ingestion
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45E+00
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
2.45E-02
4.90E-01
6.12E-01
C
8.05E-04
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
1.42E-04
8.78E-03
1.21E-04
Inhalation
NC
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.60E+00
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
1.09E+03
C
7.30E-03
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
1.80E-01
2.00E-02
No Liner/In-Situ Soil
Peak
DAF
3.3E+03
11
11
11
12
35
10
11
1.0E+30
6.7E+17
1.0E+30
1.5E+05
1.8E+12
13
22
21
30
12
12
11
11
10
11
13
10
10
10
1.0E+30
1.0E+30
6.5E+13
15
130
3.1E+03
10
10
6.0E+16
13
12
550
10
10
10
10
1.0E+30
10
29
16
LCTV
based on
MCL
(mg/L)
150
2.7E-03
13
1.6
0.046"
0.033d
0.76
1.0
0.076
0.72
0.052
Non-Carcinogenic Effect
7-yr Avg
DAF
3.3E+03
11
11
11
12
35
11
12
1.0E+30
6.7E+17
1.0E+30
1.5E+05
1.8E+12
14
22
21
31
12
12
12
11
11
11
13
11
11
11
1.0E+30
1.0E+30
6.5E+13
15
130
3.4E+03
11
11
6.1E+16
14
12
550
11
11
11
11
1.0E+30
11
29
17
LCTV based
on Ingestion
27
14
14
1.4
15
85 c
4.6E-03
1.0E+03"'
1.0E+03b'c
48
59
0.45"
0.32 "
2.8
5.4
0.70 a'
1.0
2.7
24
8.1
1.0E+03"'
1.0E+03"'
1.0E+03b'c
300
2.7"
27
6.1
1.0E+03b'c
0.027
0.54
0.13s-
0.27
1.0E+03b'c
18
LCTV based
on Inhalation
200s-
200s-
200s-
1.0E+03"'
45
4.3E-03
0.040
17
7.5 s-
7.0
0.45"
0.32 "'"
0.70s-
0.15
0.67
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
3.3E+03
16
16
16
17
39
15
16
1.0E+30
6.7E+17
1.0E+30
1.5E+05
1.8E+12
19
27
26
35
17
17
16
16
15
16
18
15
15
15
1.0E+30
1.0E+30
6.5E+13
22
137
4.7E+03
15
15
6.1E+16
18
17
560
15
15
15
15
1.0E+30
15
33
21
LCTV based
on Ingestion
2.6 c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
240 c
1.0E+03b'c
1.3E-03
0.10
7.5E-03
4.6E-03 "
3.2E-03 d
2.5E-03
0.021
0.015
1.0E+03"'
1.0E+03"'
1.0E+03b'c
2.8E-06
0.10
1.9E-04
2.1E-03
2.1E-03
0.13
2.5E-03
LCTV based
on Inhalation
24 c
1.0E+03b'c
1.0E+03b'c
1.5
0.034
170 c
0.085"
0.010
3.5E-03
0.044
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13a'
2.72
0.42
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F. 7-2
-------
Table F.7 Waste Pile LCTVs for No Liner/In-Situ Soil
Common Name
Disulfoton
Endosulfan (Endosulfan 1 and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethyl benzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1 ,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate 2-
Methoxyethanol 2-
Methyl ethyl ketone
CAS#
298044
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
110496
109864
78933
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
2.00E-03
4.00E-02
HBN (mg/L)
Ingestion
NC
9.79E-04
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.90E+00
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
1.96E-01
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
4.90E-02
2.45E-02
1.47E+01
C
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
7.00E-04
6.50E-03
1.54E+03
5.10E+02
4.40E+02
3.30E+01
C
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.50E+00
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
No Liner/In-Situ Soil
Peak
DAF
2.8E+06
45
2.4E+06
1.0E+30
10
10
10
43
10
20
1.0E+30
20
150
10
1.2E+12
10
450
10
10
10
37
5.9E+06
37
1.0E+30
4.2E+09
310
4.3E+03
1.0E+30
1.0E+30
4.6E+09
51
1.1E+03
19
10
9.9E+07
10
11
150
11
10
1.0E+30
10
10
10
LCTV
based on
MCL
(mg/L)
0.020"'
14
7.4E-03
38
11b'c'd
11"
8.0E-03a'
1.0E+03b'c
0.13a'c
1.0E+03b'c
3.9
0.020
10a'c
Non-Carcinogenic Effect
7-yr Avg
DAF
2.8E+06
45
2.4E+06
1.0E+30
11
11
11
45
11
21
1.0E+30
20
150
11
1.4E+12
11
450
11
11
11
37
6.0E+06
37
1.0E+30
4.3E+09
310
4.3E+03
1.0E+30
1.0E+30
4.7E+09
51
1.1E+03
19
11
1.0E+08
11
12
150
12
11
1.0E+30
11
11
11
LCTV based
on Ingestion
1.0E+03b'c
6.6 c
0.020 a'
1.0E+03b'
110
81
990
54
47
49
540
0.022
440 c
32
54
540
0.81
40b,c,d
7.2 c
8.0E-03 a'
1.0E+03b'c
0.50 a'
0.13"
1.0E+03b'c
1.3
8.2
1.0E+03b'c
0.81
81
56
1.8
17
0.027
0.028
130
10"
0.54
0.27
160
LCTV based
on Inhalation
1.0E+03"'
2.6
1.0E+03"'
1.0E+03"'
66
0.15
1.0E+03"'
1.0E+03"'
560
240
140 "
140 "
1.0E+03b'c
13C
1.0E+03"'
8.4E-03
0.075
1.0E+03"'
1.0E+03"'
1.0E+03"'
200s'
Carcinogenic Effect
30-yr Avg
DAF
4.7E+06
49
2.4E+06
1.0E+30
15
15
15
64
15
30
1.0E+30
25
220
15
3.4E+12
15
450
15
15
15
41
8.6E+06
41
1.0E+30
4.3E+09
310
4.3E+03
1.0E+30
1.0E+30
4.7E+09
55
1.1E+03
24
15
1.0E+08
15
16
160
16
15
1.0E+30
15
15
15
LCTV based
on Ingestion
1.0E+03b'
1.0E+03b'
2.5E-04
1.0E+03b'
0.013
2.2E-03
640 c
6.2E-04
8.0E-03 "'
1.0E+03b'c
0.38
0.13"
1.0E+03b'c
29 c
0.38
1.0E+03b'c
1.6
LCTV based
on Inhalation
1.0E+03b'
0.27
0.019
1.0E+03b'
1.0E+03b'
23
0.69C
1.0E+03b'c
0.015
8.0E-03a'
1.0E+03b'c
0.19
0.13"
1.0E+03b'c
670 c
0.18
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F. 7-3
-------
Table F.7 Waste Pile LCTVs for No Liner/In-Situ Soil
Common Name
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran 2,3,7,8-
Tetrachlorodibenzo-p-dioxin 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
CAS#
108101
80626
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
MCL
(mg/L)
Ingestion
5.00E-03
1.00E-03
5.00E-04
5.00E-02
1.00E-01
3.00E-08
5.00E-03
HBN (mg/L)
Ingestion
NC
1.96E+00
3.43E+01
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
1.47E-01
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
7.34E-01
1.47E+00
2.45E-01
7.34E-01
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
6.19E-09
6.19E-10
3.71 E-03
4.83E-04
1.86E-03
Inhalation
NC
1.20E+00
5.30E+00
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
3.60E+00
9.40E-01
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
1.00E-07
2.20E-09
1.90E-03
5.00E-04
2.10E-02
No Liner/In-Situ Soil
Peak
DAF
10
10
2.0E+05
10
1.0E+30
10
10
22
10
10
10
10
11
10
17
10
10
10
11
2.1E+08
3.9E+03
940
3.2E+08
390
21
10
10
10
1.0E+30
1.0E+30
1.4E+07
14
10
910
10
12
11
17
200
2.3E+15
2.0E+06
19
120
12
12
LCTV
based on
MCL
(mg/L)
0.052
0.021
1.0E+03b'c
0.46
1.7
0.059C
0.073 "
0.073 "
0.059
Non-Carcinogenic Effect
7-yr Avg
DAF
11
11
2.1E+05
11
1.0E+30
11
11
23
11
11
11
11
12
11
17
11
11
11
12
2.1E+08
3.9E+03
940
3.3E+08
390
21
11
11
11
1.0E+30
1.0E+30
1.4E+07
15
11
910
11
13
12
17
200
2.3E+15
2.0E+06
20
130
12
13
LCTV based
on Ingestion
22
380
6.2 b'c'd
2.7
16
1.2
11
9.9
0.13
2. 2 E-03
8.3
0.57
1.0E+03b'c
76 c
29 c
16
160
0.022
1.6
1.0E+03b'c
1.0E+03b'
1.0E+03b'c
27
670 c
0.27
1.0'
2.0
0.085
83
1.5C
0.049 c
14
190
0.70 a'
9.2
LCTV based
on Inhalation
13
58
1.0E+03"
190
110
0.43
1.7
3.6
1.0E+03"'
1.0E+03"'
5.4
5.0 a'
61
0.64"
0.70s'
Carcinogenic Effect
30-yr Avg
DAF
15
15
3.1E+05
15
1.0E+30
15
15
27
15
15
15
15
16
15
21
15
15
15
16
3.4E+08
3.9E+03
940
3.3E+08
390
26
15
15
15
1.0E+30
1.0E+30
1.4E+07
19
15
910
15
17
16
21
210
2.3E+15
2.0E+06
26
180
17
17
LCTV based
on Ingestion
0.20
9.7E-06
2.9E-05
2.9E-04
2.1 E-04
0.42
6.6E-05
6.9E-04
1.2E-06
0.21 c
0.14
0.021
1.0E+03b'c
6.1 E-03
9.1 E-03
1.0E+03b'c
1.3E-03C
0.095
0.085
0.031
LCTV based
on Inhalation
1.0E+03b'c
0.43
3.5E-04
6.5E-04
6.0E-03
3.3E-04
0.023
11
0.068
0.13
14
5.9E-05
20 c
100a'
1.0E+03b'c
0.26
1.0E+03b'c
4.4E-03C
0.048
0.088
0.35
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F. 7-4
-------
Table F.7 Waste Pile LCTVs for No Liner/In-Situ Soil
Common Name
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram
Toluene
Toluenediamine 2,4-
Toluidineo-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
3689245
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
2.00E-03
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
1.22E-02
1.96E-03
1.22E-01
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
9.79E-02
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
No Liner/In-Situ Soil
Peak
DAF
1.0E+30
16
13
10
10
10
1.6E+05
12
19
100
610
12
11
12
18
12
11
10
12
10
10
200
10
10
22
20
23
21
LCTV
based on
MCL
(mg/L)
0.019
13
0.50"'
0.94
7.1
0.11 d
0.060
0.057
0.54
0.021
210C
Non-Carcinogenic Effect
7-yr Avg
DAF
1.0E+30
17
13
11
11
11
1.6E+05
12
20
100
640
12
12
12
18
12
11
11
13
11
11
210
11
11
22
21
23
22
LCTV based
on Ingestion
1.0E+03b'c
0.021
2.0
64
5.9
1.0E+03b'c
25.2
0.96 M
0.96"
88
45
1.0a'
2.7
1.9
8.1
57
270
0.20 s'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
180
LCTV based
on Inhalation
17
1.0E+03b'c
86 c
0.96M
0.96"
0.50s'
25
0.44
1.2
13
0.20s-
29
29
30
30
Carcinogenic Effect
30-yr Avg
DAF
1.0E+30
21
18
15
15
15
1.7E+05
17
24
110
920
17
16
16
23
17
16
15
18
15
15
260
15
15
27
25
28
27
LCTV based
on Ingestion
4.6E-04
6.1E-03
7.7E-03
0.50 "'
0.20
3.5E-03 "
3.5E-03 d
0.14
0.15
2.5E-04
2.5E-03
2.0E-03
LCTV based
on Inhalation
110
0.54
0.50 ''
0.32
4.8E-03"
4.8E-03"
0.11
2.0 *'
0.038
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F. 7-5
-------
Table F.8 Waste Pile LCTVs for Compacted Clay Liner
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
ChloropropeneS- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
1.00E-01
1.00E-01
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
1.71E-02
1.22E-02
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
3.67E+01
7.34E-02
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
2.10E-02
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
3.00E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
1.90E-03
Compacted Clay Liner
Peak
DAF
210
24
24
24
24
1.0E+30
29
24
25
2.6E+11
24
24
560
2.2E+04
26
24
1.5E+06
1.5E+06
24
1.0E+30
120
32
1.0E+30
29
7.9E+09
28
24
760
27
29
42
9.2E+06
26
24
37
1.6E+03
29
24
26
24
26
1.0E+30
LCTV
based on
MCL
(mg/L)
0.16
2.0
48
0.13
290 c
21
1.0E+03b'c
2.3
0.19
0.20
0.21
0.030 *'
3.7
2.3
2.0
160
5.0s
Non-Carcinogenic Effect
7-yr Avg
DAF
210
24
24
25
24
1.0E+30
30
24
26
2.6E+11
24
24
560
2.2E+04
27
24
1.5E+06
1.5E+06
24
1.0E+30
130
33
1.0E+30
30
8.0E+09
28
24
760
28
29
43
9.5E+06
26
24
37
1.6E+03
29
24
26
24
27
1.0E+30
LCTV based
on Ingestion
300 c
60
60
1.0E+03b'
0.15
300
0.11 d
1.0E+03b'c
3.0
1.0E+03b'c
0.34
0.38
50
1.8
180
210"
52
32
1.0E+03b'c
15
880 M
60
1.0E+03b'c
0.68
0.67
72
0.50s'
0.030s-
13
2.4
18
760 c
14
6.0 *'
3.3
1.0E+03"
5.0 s
LCTV based
on Inhalation
5.3
1.0E+03"'
76
1.0E+03b'
365
1.0
23
0.50 '-
1.0E+03"
1.0E+03b'c
1.0E+03"'
1.7
56
0.50 "'
0.030 "'
0.58
7.4
730
6.0 "'
6.3
0.26
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
210
33
33
34
33
1.0E+30
41
33
36
2.6E+11
33
33
560
2.2E+04
35
33
1.5E+06
1.5E+06
33
1.0E+30
180
42
1.0E+30
40
1.7E+10
37
33
760
36
40
57
9.5E+06
35
33
47
1.6E+03
40
33
35
33
35
1.0E+30
LCTV based
on Ingestion
8.9E-04
6.6E-04"
1.0E+03b'c
0.56
0.012
1.7C
0.06
1.4E-05
19C
120 c
1.0E+03b'c
0.016
0.058
1.0E+03b'c
0.063
0.043
0.030"'
0.56
0.046
0.25
LCTV based
on Inhalation
1.4
210
0.036
1.0E+03b'c
73
390 c
0.056
87
1.0E+03b'c
950 c
1.0E+03b'c
0.20
0.25
1.0E+03b'c
0.032
1.5E-03
0.044
0.030 "'
1.0E+03b'c
0.030
0.20
1.0E+03"'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.8-1
-------
Table F.8 Waste Pile LCTVs for Compacted Clay Liner
Common Name
Chrysene
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT, p,p'-
Diallate
Dibenz{a, hjanthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylene trans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropene trans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene2,4-
Dinitrotoluene2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
CAS#
218019
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
606202
117840
123911
122394
MCL
(mg/L)
Ingestion
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45E+00
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
2.45E-02
4.90E-01
6.12E-01
C
8.05E-04
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
1.42E-04
8.78E-03
Inhalation
NC
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.60E+00
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
1.09E+03
C
7.30E-03
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
1.80E-01
Compacted Clay Liner
Peak
DAF
2.2E+04
26
26
26
29
110
24
26
1.0E+30
1.0E+30
1.0E+30
1.1E+07
1.0E+30
35
64
61
92
29
28
27
25
24
26
34
24
24
24
1.0E+30
1.0E+30
1.0E+30
40
430
5.0E+04
24
24
1.0E+30
35
31
2.5E+03
24
24
24
24
1.0E+30
24
87
LCTV
based on
MCL
(mg/L)
370
7.1E-03
38
4.6
0.11 "
0.075 d
1.8
2.4
0.18
1.7
0.12
Non-Carcinogenic Effect
7-yr Avg
DAF
2.2E+04
26
26
26
29
110
24
26
1.0E+30
1.0E+30
1.0E+30
1.1E+07
1.0E+30
36
64
61
93
30
29
28
26
24
27
35
24
24
24
1.0E+30
1.0E+30
1.0E+30
41
430
5.3E+04
24
24
1.0E+30
36
31
2.5E+03
24
24
24
24
1.0E+30
24
89
LCTV based
on Ingestion
73
32
32
3.2
36
260 c
0.010
1.0E+03b'
1.0E+03b'c
140
150
0.45"
0.32 "
6.3
12
0.70s-
2.6
6.0
53
18
1.0E+03"'
1.0E+03"'
1.0E+03b'c
800
6.0"
60
15
1.0E+03b'c
0.06
1.2
0.13a'
0.60
1.0E+03b'c
54 c
LCTV based
on Inhalation
200s-
200s-
200s-
1.0E+03"'
140 c
9.5E-03
0.11
49
7.5 s-
17
0.45"
0.32 "'"
0.70 '
0.34
1.5
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
2.2E+04
35
35
35
38
120
33
35
1.0E+30
1.0E+30
1.0E+30
1.1E+07
1.0E+30
50
73
70
100
38
40
38
35
33
35
44
33
33
33
1.0E+30
1.0E+30
1.0E+30
55
430
7.6E+04
33
33
1.0E+30
46
39
2.5E+03
33
33
33
33
1.0E+30
33
95
LCTV based
on Ingestion
17C
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
3.4E-03
0.28
0.022
0.010 "
7.1E-03"
5.7E-03
0.047
0.032
1.0E+03"'
1.0E+03"'
1.0E+03b'c
8.9E-06
0.23
4.8E-04
4.7E-03
4.7E-03
0.29
LCTV based
on Inhalation
160 c
1.0E+03b'c
1.0E+03b'c
3.9
0.091
500 c
0.19"
0.024
7.8E-03
0.10
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13 '-
6.0
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.8-2
-------
Table F.8 Waste Pile LCTVs for Compacted Clay Liner
Common Name
Diphenylhydrazine 1, 2-
Disulfoton
Endosulfan (Endosulfan I and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethyl benzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1 ,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate 2-
Methoxyethanol 2-
CAS#
122667
298044
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
110496
109864
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
2.00E-03
4.00E-02
HBN (mg/L)
Ingestion
NC
9.79E-04
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.90E+00
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
1.96E-01
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
4.90E-02
2.45E-02
C
1.21E-04
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
7.00E-04
6.50E-03
1.54E+03
5.10E+02
4.40E+02
C
2.00E-02
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.50E+00
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
Compacted Clay Liner
Peak
DAF
45
1.6E+09
138
5.5E+08
1.0E+30
24
24
24
150
24
58
1.0E+30
57
900
24
1.0E+30
24
1.5E+03
24
24
24
110
6.0E+09
110
1.0E+30
1.0E+30
1.1E+03
3.4E+04
1.0E+30
1.0E+30
1.0E+30
160
4.6E+03
53
24
1.7E+14
24
27
490
25
24
1.0E+30
24
24
LCTV
based on
MCL
(mg/L)
0.020 a'
39.6
0.045
72
3gb,c,d
38 e
8.0E-03 a'
1.0E+03b'c
0.13 a'c
1.0E+03b'c
5.0 "
0.039
10a'c
Non-Carcinogenic Effect
7-yr Avg
DAF
45
1.6E+09
139
5.6E+08
1.0E+30
24
24
24
150
24
60
1.0E+30
57
930
24
1.0E+30
24
1.5E+03
24
24
24
110
6.1E+09
110
1.0E+30
1.0E+30
1.1E+03
3.4E+04
1.0E+30
1.0E+30
1.0E+30
160
4.6E+03
53
24
1.7E+14
24
27
490
26
24
1.0E+30
24
24
LCTV based
on Ingestion
1.0E+03b'c
20 c
0.020s'
1.0E+03"'
240
180
1.0E+03"'
120
130
140
1.0E+03"'
0.048
1.0E+03b'c
66
120
1.0E+03"'
1.8
13Qb,c,d
22 c
8.0E-03a'
1.0E+03b'c
0.50 "'
0.13"
1.0E+03b'c
3.0 a'
34
1.0E+03b'c
1.8
180
130
6.0
37
0.058
0.063
300
10"
1.2
0.60
LCTV based
on Inhalation
1.0E+03"'
5.8
1.0E+03"'
1.0E+03b'
190 c
0.91
1.0E+03"'
1.0E+03b'
1.0E+03b'
530
450 "
450 "
1.0E+03b'c
35 c
1.0E+03"'
0.019
0.17
1.0E+03"'
1.0E+03"'
1.0E+03b'
Carcinogenic Effect
30-yr Avg
DAF
56
2.4E+09
150
5.6E+08
1.0E+30
33
33
33
214
33
82
1.0E+30
66
1.4E+03
33
1.0E+30
33
1.5E+03
33
33
33
120
8.1E+09
120
1.0E+30
1.0E+30
1.1E+03
3.4E+04
1.0E+30
1.0E+30
1.0E+30
170
4.6E+03
63
33
1.7E+14
33
36
500
36
33
1.0E+30
33
33
LCTV based
on Ingestion
0.007
1.0E+03b'
1.0E+03b'
1.6E-03
1.0E+03b'
0.029
6.5E-03
1.0E+03b'c
1 .9E-03
8.0E-03a'
1.0E+03b'c
0.50 "'
0.13"
1.0E+03b'c
1.0E+03b'c
1.2
1.0E+03b'c
3.6
LCTV based
on Inhalation
1.1
1.0E+03"'
0.72
0.11
1.0E+03b'
1.0E+03"'
50
2.1 c
1.0E+03b'c
0.044
8.0E-03 "'
1.0E+03b'c
0.50 "'
0.13"
1.0E+03b'c
1.0E+03b'c
0.55
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.8-3
-------
Table F.8 Waste Pile LCTVs for Compacted Clay Liner
Common Name
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran 2,3,7,8-
Tetrachlorodibenzo-p-dioxin 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
CAS#
78933
108101
80626
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
MCL
(mg/L)
Ingestion
5.00E-03
1.00E-03
5.00E-04
5.00E-02
1.00E-01
3.00E-08
5.00E-03
HBN (mg/L)
Ingestion
NC
1.47E+01
1.96E+00
3.43E+01
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
1.47E-01
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
7.34E-01
1.47E+00
2.45E-01
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
6.19E-09
6.19E-10
3.71 E-03
4.83E-04
1.86E-03
Inhalation
NC
3.30E+01
1.20E+00
5.30E+00
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
3.60E+00
9.40E-01
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
1.00E-07
2.20E-09
1.90E-03
5.00E-04
2.10E-02
Compacted Clay Liner
Peak
DAF
24
24
24
2.7E+07
24
1.0E+30
24
25
66
24
24
24
24
28
24
46
24
24
24
26
6.6E+17
2.9E+04
3.8E+03
3.6E+17
1.3E+03
61
24
24
24
1.0E+30
1.0E+30
4.3E+11
39
24
3.6E+03
24
31
26
47
670
1.0E+30
8.9E+09
58
510
30
LCTV
based on
MCL
(mg/L)
0.12
0.061
1.0E+03b'c
0.87
4.7
270 c
0.18 "
0.18 "
0.15
Non-Carcinogenic Effect
7-yr Avg
DAF
24
24
24
2.8E+07
24
1.0E+30
24
25
67
24
24
24
24
29
24
47
24
24
24
27
7.0E+17
2.9E+04
3.8E+03
3.6E+17
1.3E+03
62
24
24
24
1.0E+30
1.0E+30
4.3E+11
40
24
3.6E+03
24
32
27
47
670
1.0E+30
9.0E+09
59
520
30
LCTV based
on Ingestion
200s-
48
830
9.2 b'c'd
6.0
37
2.8
33 c
22
0.30
4.8E-03
23
1.3
1.0E+03b'c
560 c
97 c
46
360
0.048
3.6
1.0E+03b'c
1.0E+03b'
1.0E+03b'c
73 c
1.0E+03b'c
0.60
1.0'
3.8
0.20
230
4.9 c
220 c
43
770
0.70s-
LCTV based
on Inhalation
200 "'
29
130
1.0E+03"
410
250
1.3
2.0 '-
8.0
1.0E+03"'
1.0E+03"'
12
5.0 *'
170
0.64 "
0.70 "'
Carcinogenic Effect
30-yr Avg
DAF
33
33
33
4.5E+07
33
1.0E+30
33
34
76
33
33
33
33
37
33
57
33
33
33
37
9.4E+17
2.9E+04
3.8E+03
3.6E+17
1.3E+03
71
33
33
33
1.0E+30
1.0E+30
4.4E+11
51
33
3.6E+03
33
40
36
57
670
1.0E+30
9.0E+09
72
710
39
LCTV based
on Ingestion
0.44
2.2E-05
6.3E-05
6.7E-04
4.6E-04
1.1
1.5E-04
1.5E-03
4.7E-06
1.0E+03b'c
0.49
0.057
1.0E+03b'c
0.013
0.022
1.0E+03b'c
5.8 c
0.27
0.34
0.072
LCTV based
on Inhalation
1.0E+03b'c
1.0
7.7E-04
1.4E-03
0.013
7.4E-04
0.050
30
0.15
0.29
31
2.4E-04 c
1.0E+03b'c
100a'
1.0E+03b'c
0.57
1.0E+03b'c
20 c
0.14
0.32"
0.70 "'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.8-4
-------
Table F.8 Waste Pile LCTVs for Compacted Clay Liner
Common Name
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram
Toluene
Toluenediamine 2,4-
Toluidineo-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
58902
3689245
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
2.00E-03
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
7.34E-01
1.22E-02
1.96E-03
1.22E-01
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
9.79E-02
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
Compacted Clay Liner
Peak
DAF
31
1.0E+30
45
33
24
24
24
9.5E+06
29
54
340
5.8E+03
29
28
29
50
30
26
24
32
24
24
1.2E+03
24
24
65
58
67
64
LCTV
based on
MCL
(mg/L)
0.035
33
0.50 "'
2.3
24
0.25 M
0.14
0.14
1.0"'
0.048
640 c
Non-Carcinogenic Effect
7-yr Avg
DAF
32
1.0E+30
45
34
24
24
24
9.7E+06
29
55
340
6.0E+03
30
29
29
51
31
26
24
32
24
24
1.2E+03
24
24
65
59
68
64
LCTV based
on Ingestion
23
1.0E+03b'c
0.046
5.5
170
14
1.0E+03b'c
83 c
0.96M
0.96"
210
120
1.0"'
6.0
4.8
18
170
600
0.2 *'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
430
LCTV based
on Inhalation
44
1.0E+03b'c
280 c
0.96 M
0.96 "
0.50 *'
61
1.1
2.7
29
0.20 *'
84
83
88
89
Carcinogenic Effect
30-yr Avg
DAF
40
1.0E+30
56
43
33
33
33
9.7E+06
39
64
340
8.7E+03
40
37
38
61
40
35
33
44
33
33
1.4E+03
33
33
74
68
77
73
LCTV based
on Ingestion
1.0E-03
0.013
0.017
0.50 *'
0.47
7.8E-03"
7.8E-03"
0.33
0.35
6. 1 E-04
0.014
4.5E-03
LCTV based
on Inhalation
250
1.2
0.50 "'
0.74
0.11 "
0.011 d
0.25
2.0 "'
0.084
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.8-5
-------
Table F.9 Waste Pile LCTVs for Composite Liner
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
1.71E-02
1.22E-02
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.00E+01
2.10E-02
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
Composite Liner
Peak
DAF
1.0E+30
7.3E+07
6.9E+07
7.4E+07
4.0E+08
1.0E+30
1.0E+30
7.1E+07
5.9E+08
1.0E+30
4.7E+08
7.3E+07
1.0E+30
1.0E+30
9.2E+07
8.3E+07
1.0E+30
1.0E+30
3.2E+08
1.0E+30
1.0E+30
1.7E+08
1.0E+30
2.3E+09
1.0E+30
1.1E+08
3.0E+08
1.0E+30
1.8E+09
1.2E+09
1.0E+30
1.0E+30
9.2E+07
6.0E+08
1.9E+08
1.0E+30
9.5E+08
7.5E+07
2.2E+08
7.2E+07
9.6E+07
LCTV
based on MCL
(mg/L)
1.0E+03"'
5.0s
100s
0.50 '-
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0a
0.50 '-
0.030 "'
100a'
1.0E+03"'
6.0 a'
Non-Carcinogenic Effect
7-yr Avg
DAF
1.0E+30
7.3E+07
7.1E+07
7.7E+07
4.0E+08
1.0E+30
1.0E+30
7.2E+07
6.0E+08
1.0E+30
4.8E+08
7.4E+07
1.0E+30
1.0E+30
9.4E+07
8.3E+07
1.0E+30
1.0E+30
3.2E+08
1.0E+30
1.0E+30
1.7E+08
1.0E+30
2.3E+09
1.0E+30
1.1E+08
3.1E+08
1.0E+30
1.8E+09
1.2E+09
1.0E+30
1.0E+30
9.3E+07
6.0E+08
2.0E+08
1.0E+30
1.0E+09
7.6E+07
2.2E+08
7.3E+07
9.8E+07
LCTV based on
Ingestion
1.0E+03b'c
1.0E+03b'
1.0E+03b'
1.0E+03"'
1.0E+03b'
1.0E+03"'
740 "
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
5.0s
100s
1.0E+03b'c
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0a
1.0E+03"'
0.50 "'
0.030 "'
1.0E+03"'
1.0E+03"'
100a'
1.0E+03b'c
1.0E+03"'
6.0 '
1.0E+03"'
LCTV based
on Inhalation
1.0E+03b'
1.0E+03"'
1.0E+03b'
1.0E+03b'
1.0E+03b'
740 M
1.0E+03"'
0.50s'
1.0E+03"
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
0.50 "'
0.030s-
1.0E+03"'
100a'
1.0E+03"'
6.0 "'
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
1.0E+30
7.9E+07
7.6E+07
8.1E+07
4.0E+08
1.0E+30
1.0E+30
7.4E+07
6.2E+08
1.0E+30
4.8E+08
7.8E+07
1.0E+30
1.0E+30
9.7E+07
8.7E+07
1.0E+30
1.0E+30
3.2E+08
1.0E+30
1.0E+30
1.8E+08
1.0E+30
2.3E+09
1.0E+30
1.2E+08
3.1E+08
1.0E+30
1.8E+09
1.2E+09
1.0E+30
1.0E+30
9.6E+07
6.0E+08
2.0E+08
1.0E+30
1.0E+09
7.8E+07
2.3E+08
7.7E+07
9.9E+07
LCTV based
on Ingestion
1.0E+03b'
750 M
1.0E+03b'c
1.0E+03"'
5.0 a
1.0E+03b'c
0.50 "'
36
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
0.50 '
0.030 "'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03"'
750 b'd
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
0.50 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03b'
1.0E+03b'c
1.0E+03b'
1.0E+03b'c
0.50s'
0.030s-
1.0E+03b'c
1.0E+03"'
1.0E+03"'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.9-1
-------
Table F.9 Waste Pile LCTVs for Composite Liner
Common Name
ChloropropeneS- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a, hjanthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane1,2-
Dichloroethylene cis-1,2-
Dichloroethylene trans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropene trans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
CAS#
107051
16065831
18540299
218019
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
MCL
(mg/L)
Ingestion
1.00E-01
1.00E-01
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
3.67E+01
7.34E-02
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45E+00
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
C
8.05E-04
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
Inhalation
NC
3.00E-03
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.60E+00
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
C
1.90E-03
7.30E-03
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
Composite Liner
Peak
DAF
1.0E+30
1.0E+30
9.1E+07
9.1E+07
9.1E+07
1.2E+08
1.2E+09
7.7E+07
8.7E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.5E+08
4.3E+08
1.3E+09
1.2E+08
3.4E+14
3.0E+21
7.3E+08
5.8E+08
8.5E+07
1.3E+11
3.1E+08
8.5E+07
8.3E+07
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.7E+08
7.2E+07
1.0E+30
8.9E+11
9.2E+09
1.0E+30
4.0E+08
2.9E+08
LCTV
based on MCL
(mg/L)
1.0E+03"'
5.0s
1.0E+03"'
1.0E+03"'
1.0E+03b'c
7.5 s-
0.45 "
0.32 "'"
1.0E+03"'
1.0E+03"'
0.70 "'
Wa'
1.0E+03"'
Non-Carcinogenic Effect
7-yr Avg
DAF
1.0E+30
1.0E+30
9.1E+07
9.2E+07
9.1E+07
1.2E+08
1.2E+09
7.8E+07
8.8E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.6E+08
4.3E+08
1.4E+09
1.2E+08
3.5E+14
3.0E+21
7.4E+08
5.8E+08
8.7E+07
1.3E+11
3.1E+08
8.6E+07
8.5E+07
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.9E+08
7.2E+07
1.0E+30
9.1E+11
9.4E+09
1.0E+30
4.0E+08
2.9E+08
LCTV based on
Ingestion
1.0E+03"'
5.0s
1.0E+03"'
200''
200s-
200s-
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.45 M
0.32 "
1.0E+03"'
1.0E+03"'
0.70 "'
1.0E+03"'
10 "
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
200 '
200s'
200s-
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03b'c
7.5 s-
1.0E+03b'c
0.45 "
0.32 "'"
0.70s-
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
1.0E+30
1.0E+30
9.6E+07
9.6E+07
9.6E+07
1.2E+08
1.3E+09
8.3E+07
8.8E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.7E+08
4.5E+08
1.4E+09
1.3E+08
4.2E+14
3.0E+21
7.4E+08
5.8E+08
9.3E+07
1.3E+11
3.1E+08
9.0E+07
8.8E+07
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.9E+08
7.7E+07
1.0E+30
9.3E+11
9.4E+09
1.0E+30
4.0E+08
2.9E+08
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
7.5 *'
1.0E+03b'c
0.45 "
0.32 "'"
0.70 '
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
7.5 '
1.0E+03b'c
0.45M
0.32 "'"
0.70s-
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.9-2
-------
Table F.9 Waste Pile LCTVs for Composite Liner
Common Name
Dinitrotoluene2,4-
Dinitrotoluene2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
Disulfoton
Endosulfan (Endosulfan I and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethyl benzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1 ,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
CAS#
121142
606202
117840
123911
122394
122667
298044
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
HBN (mg/L)
Ingestion
NC
4.90E-02
2.45E-02
4.90E-01
6.12E-01
9.79E-04
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.90E+00
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
1.96E-01
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
C
1.42E-04
1.42E-04
8.78E-03
1.21E-04
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
1.09E+03
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
1.00E+01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
C
8.12E-01
1.80E-01
2.00E-02
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.50E+00
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
Composite Liner
Peak
DAF
8.9E+07
4.4E+08
1.0E+30
7.2E+07
1.0E+30
3.0E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
7.3E+07
7.3E+07
7.8E+07
1.0E+30
3.0E+08
1.0E+30
1.0E+30
4.0E+08
1.0E+30
7.3E+07
1.0E+30
7.5E+07
1.0E+30
7.4E+07
2.9E+08
7.5E+07
1.4E+09
1.0E+30
1.4E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.1E+09
1.0E+30
3.8E+08
2.9E+08
1.0E+30
3.0E+08
1.0E+08
1.0E+30
LCTV
based on MCL
(mg/L)
0.020 "'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"
8.0E-03 *'
1.0E+03b'c
0.13 a'c
1.0E+03b'c
5.0 '
Non-Carcinogenic Effect
7-yr Avg
DAF
9.1E+07
4.5E+08
1.0E+30
7.2E+07
1.0E+30
3.0E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
7.3E+07
7.4E+07
8.0E+07
1.0E+30
3.0E+08
1.0E+30
1.0E+30
4.0E+08
1.0E+30
7.3E+07
1.0E+30
7.5E+07
1.0E+30
7.4E+07
2.9E+08
7.6E+07
1.4E+09
1.0E+30
1.4E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.1E+09
1.0E+30
3.9E+08
2.9E+08
1.0E+30
3.0E+08
1.1E+08
1.0E+30
LCTV based on
Ingestion
0.13 *'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.020 *'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
8.0E-03 *'
1.0E+03b'c
0.50 *'
0.13"
1.0E+03b'c
3.0 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
LCTV based
on Inhalation
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
9.5E+07
4.5E+08
1.0E+30
7.6E+07
1.0E+30
3.1E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
7.8E+07
7.7E+07
8.2E+07
1.0E+30
3.0E+08
1.0E+30
1.0E+30
4.2E+08
1.0E+30
7.9E+07
1.0E+30
7.8E+07
1.0E+30
7.8E+07
2.9E+08
8.0E+07
1.5E+09
1.0E+30
1.5E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
2.1E+09
1.0E+30
4.0E+08
2.9E+08
1.0E+30
3.0E+08
1.1E+08
1.0E+30
LCTV based
on Ingestion
0.13 *'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
8.0E-03 *'
1.0E+03b'c
0.50 *'
0.13"
1.0E+03b'c
1.0E+03b'c
3.0 *'
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
0.13a'
1.0E+03b'
1.0E+03b'c
1.0E+03b'
1.0E+03b'c
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
8.0E-03a'
1.0E+03b'c
0.50 "'
0.13"
1.0E+03b'c
1.0E+03b'c
3.0s'
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.9-3
-------
Table F.9 Waste Pile LCTVs for Composite Liner
Common Name
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate 2-
Methoxyethanol 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
CAS#
7439965
7439976
126987
67561
72435
110496
109864
78933
108101
80626
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
MCL
(mg/L)
Ingestion
2.00E-03
4.00E-02
5.00E-03
1.00E-03
5.00E-04
HBN (mg/L)
Ingestion
NC
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
4.90E-02
2.45E-02
1.47E+01
1.96E+00
3.43E+01
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
1.47E-01
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
Inhalation
NC
7.00E-04
6.50E-03
1.54E+03
5.10E+02
4.40E+02
3.30E+01
1.20E+00
5.30E+00
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
Composite Liner
Peak
DAF
6.2E+08
7.3E+07
1.0E+30
7.1E+07
7.4E+07
7.1E+07
7.9E+07
7.5E+07
1.0E+30
7.6E+07
1.0E+30
3.8E+08
3.7E+08
5.1E+08
8.1E+07
7.4E+07
7.4E+07
7.3E+07
1.2E+08
8.0E+07
3.2E+08
7.4E+07
7.3E+07
7.1E+07
3.1E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.6E+08
7.9E+07
2.9E+08
2.9E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
8.4E+07
1.0E+30
7.5E+07
1.6E+10
LCTV
based on MCL
(mg/L)
0.20 "
10"
1.0E+03"'
100a'
1.0E+03b'c
Non-Carcinogenic Effect
7-yr Avg
DAF
6.2E+08
7.5E+07
1.0E+30
7.2E+07
7.6E+07
7.2E+07
8.1E+07
7.6E+07
1.0E+30
7.7E+07
1.0E+30
3.8E+08
3.7E+08
5.1E+08
8.4E+07
7.6E+07
7.5E+07
7.5E+07
1.2E+08
8.0E+07
3.2E+08
7.5E+07
7.3E+07
7.2E+07
3.1E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.6E+08
8.0E+07
3.0E+08
2.9E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
8.5E+07
1.0E+30
7.5E+07
1.6E+10
LCTV based on
Ingestion
1.0E+03b'
0.20 "
1.0E+03"'
1.0E+03"'
10"
1.0E+03"'
1.0E+03"'
200 *'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
2.0 *'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
5.0s-
LCTV based
on Inhalation
0.20"
1.0E+03"'
1.0E+03b'
1.0E+03b'
1.0E+03"'
200s-
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
1.0E+03b'c
2.0 '
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
5.0 '
Carcinogenic Effect
30-yr Avg
DAF
6.4E+08
7.8E+07
1.0E+30
7.4E+07
8.0E+07
7.6E+07
8.3E+07
7.9E+07
1.0E+30
8.0E+07
1.0E+30
3.8E+08
3.9E+08
5.2E+08
8.7E+07
8.0E+07
7.8E+07
7.8E+07
1.3E+08
8.2E+07
3.3E+08
7.7E+07
7.7E+07
7.6E+07
3.1E+09
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
4.8E+08
8.4E+07
3.0E+08
2.9E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
8.9E+07
1.0E+30
8.0E+07
1.6E+10
LCTV based
on Ingestion
1.0E+03b'
50
150
1.0E+03b'
1.0E+03"'
1.0E+03b'c
340
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03b'c
1.0E+03b'
1.0E+03b'c
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03"'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'c
1.0E+03b'
1.0E+03b'
1.0E+03b'
1.0E+03b'c
1.0E+03b'c
100a'
1.0E+03b'c
1.0E+03b'
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.9-4
-------
Table F.9 Waste Pile LCTVs for Composite Liner
Common Name
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran 2,3,7,8-
Tetrachlorodibenzo-p-dioxin 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram]
Toluene
Toluenediamine 2,4-
Toluidineo-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
7440280
137268
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
5.00E-02
1.00E-01
3.00E-08
5.00E-03
2.00E-03
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
7.34E-01
1.47E+00
2.45E-01
7.34E-01
1.22E-02
1.96E-03
1.22E-01
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
9.79E-02
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
6.19E-09
6.19E-10
3.71 E-03
4.83E-04
1.86E-03
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
3.60E+00
9.40E-01
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
1.00E-07
2.20E-09
1.90E-03
5.00E-04
2.10E-02
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
Composite Liner
Peak
DAF
1.1E+09
3.0E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.3E+08
1.3E+10
1.0E+30
1.0E+30
1.7E+08
7.1E+07
8.3E+07
3.9E+08
1.0E+30
4.4E+08
3.7E+08
1.6E+10
1.0E+30
3.3E+09
1.1E+08
1.1E+08
1.0E+30
1.4E+08
7.5E+08
4.7E+08
1.0E+30
8.2E+07
3.5E+08
1.0E+30
7.4E+07
7.6E+07
4.6E+08
4.1E+08
5.0E+08
4.8E+08
LCTV
based on MCL
(mg/L)
1.0'
1.0E+03b'c
1.0E+03b'c
0.64 "
0.64 "
0.70 a'
1.0E+03"'
1.0E+03b'c
0.50 "'
1.0E+03"'
1.0E+03b'c
0.96 M
0.96 M
0.50 *'
1.0"'
0.20 "'
1.0E+03b'c
Non-Carcinogenic Effect
7-yr Avg
DAF
1.2E+09
3.0E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.3E+08
1.3E+10
1.0E+30
1.0E+30
1.7E+08
7.3E+07
8.3E+07
3.9E+08
1.0E+30
4.4E+08
3.8E+08
1.6E+10
1.0E+30
3.3E+09
1.1E+08
1.1E+08
1.0E+30
1.4E+08
7.5E+08
4.7E+08
1.0E+30
8.5E+07
3.5E+08
1.0E+30
7.5E+07
7.8E+07
4.7E+08
4.1E+08
5.2E+08
4.8E+08
LCTV based on
Ingestion
1.0'
5.0s
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03"'
0.70 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.96 M
0.96 b'd
1.0E+03"'
400s-
1.0a'
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
1.0E+03"'
1.0E+03"'
0.20 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03"'
LCTV based
on Inhalation
1.0E+03b'c
0.64e
0.70s-
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
0.96M
0.96e
0.50 "'
1.0E+03"'
1.0E+03"'
1.0E+03"'
1.0E+03"'
0.20 "'
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
Carcinogenic Effect
30-yr Avg
DAF
1.2E+09
3.1E+08
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.0E+30
1.3E+08
1.3E+10
1.0E+30
1.0E+30
1.7E+08
7.5E+07
8.6E+07
3.9E+08
1.0E+30
4.7E+08
3.8E+08
1.6E+10
1.0E+30
3.5E+09
1.2E+08
1.2E+08
1.0E+30
1.5E+08
7.5E+08
4.7E+08
1.0E+30
8.8E+07
3.5E+08
1.0E+30
7.8E+07
8.1E+07
4.8E+08
4.2E+08
5.2E+08
4.9E+08
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
0.64 M
0.64 M
0.70 "'
1.0E+03"'
1.0E+03"'
1.0E+03b'c
0.50 "'
1.0E+03"'
0.96 e
0.96 b'd
0.50 "'
2.0s-
1.0E+03"'
1.0E+03b'c
0.20 ''
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'c
0.64M
0.64M
0.70s'
1.0E+03"'
1.0E+03"'
0.50 '
1.0E+03"'
0.96e
0.96M
0.50 "'
2.0s-
0.20s-
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.9-5
-------
Table F. 10 Land Treatment Unit LCTVs for No Liner/In-Situ Soil
Common Name
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
Antimony
Arsenic
Barium
Benz{a}anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzo{b}fluoranthene
Benzyl alcohol
Benzyl chloride
Beryllium
Bis(2-chloroethyl)ether
Bis(2-ch loroisopropyljether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene 1, 3-
Butanol n-
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro-1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene 3- (Allyl Chloride)
Chromium (III) (Chromic Ion)
Chromium (VI)
Chrysene
CAS#
83329
75070
67641
75058
98862
107028
79061
79107
107131
309002
107186
62533
120127
7440360
7440382
7440393
56553
71432
92875
50328
205992
100516
100447
7440417
111444
39638329
117817
75274
74839
106990
71363
85687
88857
7440439
75150
56235
57749
126998
106478
108907
510156
124481
75003
67663
74873
95578
107051
16065831
18540299
218019
MCL
(mg/L)
Ingestion
6.00E-03
5.00E-02
2.00E+00
5.00E-03
2.00E-04
4.00E-03
6.00E-03
8.00E-02
7.00E-03
5.00E-03
5.00E-03
2.00E-03
1.00E-01
8.00E-02
8.00E-02
1.00E-01
1.00E-01
HBN (mg/L)
Ingestion
NC
1.47E+00
2.45E+00
2.45E+00
4.90E-01
4.90E-03
1.22E+01
2.45E-02
7.34E-04
1.22E-01
7.34E+00
9.79E-03
7.34E-03
1.71E+00
7.34E-02
7.34E+00
4.90E-02
9.79E-01
4.90E-01
4.90E-01
3.43E-02
2.45E+00
4.90E+00
2.45E-02
1.22E-02
2.45E+00
1.71E-02
1.22E-02
4.90E-01
9.79E-02
4.90E-01
4.90E-01
4.90E-01
2.45E-01
1.22E-01
3.67E+01
7.34E-02
C
2.15E-05
1.79E-04
5.68E-06
1.69E-02
6.44E-05
8.05E-05
1.76E-03
4.20E-07
1.32E-05
8.05E-05
5.68E-04
8.78E-05
1.38E-03
6.90E-03
1.56E-03
7.43E-04
2.76E-04
3.58E-04
1.15E-03
7.43E-03
8.05E-04
Inhalation
NC
2.20E-01
1.50E+03
3.10E+00
3.30E-04
1.50E+01
3.80E-02
9.30E-01
1.90E-01
1.80E+02
1.50E-02
6.00E-02
1.90E+00
2.10E-02
2.80E-02
2.20E-02
2.00E-01
3.00E+01
3.30E-01
2.60E-01
9.70E-03
3.00E-03
C
4.10E-02
5.10E+00
1.00E-03
1.00E-05
2.20E+00
1.80E-02
1.60E-03
2.60E+00
5.40E-03
6.30E-04
5.20E-04
1.10E-03
5.90E-03
2.80E+01
8.00E-04
4.00E-05
7.60E-04
1.50E-03
1.20E+00
7.50E-04
5.90E-03
1.90E-03
7.30E-03
No Liner/In-Situ Soil
Peak
DAF
8.5
1.9
1.9
1.9
1.9
1.0E+30
2.2
1.9
2.0
7.6E+07
1.9
1.9
21
370
2.0
1.9
9.2E+03
9.5E+03
1.9
1.0E+30
6.8
2.2
1.0E+30
2.2
6.9E+07
2.0
1.9
26
2.0
2.1
2.8
3.5E+04
2.0
1.9
2.4
39
2.1
1.9
2.0
1.9
2.0
1.0E+30
370
LCTV
based on
MCL
(mg/L)
0.013
0.13
3.5
9.9E-03
1.8C
5.0
1.0E+03b'c
0.17
0.014
0.015
0.014
0.030 a'
0.24
0.17
0.16
43
5.0s
Non-Carcinogenic Effect
7-yr Avg
DAF
8.5
1.9
1.9
1.9
1.9
1.0E+30
2.2
1.9
2.0
7.7E+07
1.9
1.9
22
370
2.0
1.9
9.3E+03
9.5E+03
1.9
1.0E+30
7.0
2.2
1.0E+30
2.2
6.9E+07
2.1
1.9
26
2.0
2.2
2.8
3.6E+04
2.0
1.9
2.4
39
2.2
1.9
2.0
1.9
2.0
1.0E+30
370
LCTV based
on Ingestion
13C
4.7
4.7
1.0E+03"'
0.011
23
8.2E-03"
1.0E+03b'c
0.23
160 c
0.024
0.026
3.6
0.14
14
16"
9.8
2.2
1.0E+03b'c
1.1
69 ""
4.7
130 c
0.049
0.038
5.3
0.048
0.030a'
0.98
0.19
1.2
19C
1.1
0.49
0.24
260
5.0s
LCTV based
on Inhalation
0.42
1.0E+03b'
6.0
1.0E+03b'
29
0.076
1.8
0.38
1.0E+03"
1.0E+03b'c
1.0E+03"'
0.12
4.1
0.059
0.030 "'
0.044
0.48
57
0.66
0.50
0.019
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
8.8
2.2
2.2
2.2
2.2
1.0E+30
2.6
2.2
2.3
7.8E+07
2.2
2.2
22
370
2.3
2.2
9.3E+03
9.5E+03
2.2
1.0E+30
8.2
2.5
1.0E+30
2.5
1.2E+08
2.3
2.2
27
2.3
2.5
3.2
3.6E+04
2.3
2.2
2.7
40
2.5
2.2
2.3
2.2
2.3
1.0E+30
370
LCTV based
on Ingestion
5.6E-05
4.2E-05"
440 c
0.037
5.6E-04
0.030C
4.0E-03
9.2E-07
0.12C
0.77 c
1.0E+03b'c
7.2E-04
3.4E-03
1.0E+03b'c
3.9E-03
2.4E-03
0.030a'
0.014
2.8E-03
0.016
0.30C
LCTV based
on Inhalation
0.090
13
2.3E-03
780 c
4.8
6.7 c
3.7E-03
5.7
50 c
6.0 c
1.0E+03b'c
9.0E-03
0.015
1.0E+03b'c
2.0E-03
9.3E-05
2.4E-03
0.030 "'
48 c
1.9E-03
0.013
1.0E+03"'
2.7 c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.10- 1
-------
Table F. 10 Land Treatment Unit LCTVs for No Liner/In-Situ Soil
Common Name
Cobalt
Copper
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
ODD
DDE
DDT p,p'-
Diallate
Dibenz{a,h}anthracene
Dibromo-3-chloropropane 1,2-
Dichlorobenzene 1,2-
Dichlorobenzene 1,4-
Dichlorobenzidine 3,3'-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethane 1,2-
Dichloroethylene cis-1,2-
Dichloroethylenetrans-1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene 1,3-(mixture of isomers)
Dichloropropene cis-1,3-
Dichloropropenetrans-1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3'-
Dimethyl formamide N,N- [DMF]
Dimethylbenz{a}anthracene 7,12-
Dimethylbenzidine 3,3'-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine 1, 2-
Disulfoton
CAS#
7440484
7440508
108394
95487
106445
1319773
98828
108930
108941
72548
72559
50293
2303164
53703
96128
95501
106467
91941
75718
75343
107062
156592
156605
75354
120832
94757
78875
542756
10061015
10061026
60571
84662
56531
60515
119904
68122
57976
119937
105679
84742
99650
51285
121142
606202
117840
123911
122394
122667
298044
MCL
(mg/L)
Ingestion
1.30E+00
2.00E-04
6.00E-01
7.50E-02
5.00E-03
7.00E-02
1.00E-01
7.00E-03
7.00E-02
5.00E-03
HBN (mg/L)
Ingestion
NC
4.90E-01
1.22E+00
1.22E+00
1.22E-01
1.22E+00
2.45E+00
4.16E-04
1.22E+02
1.22E-02
2.20E+00
4.90E+00
2.45E+00
2.45E-01
4.90E-01
2.20E-01
7.34E-02
2.45E-01
2.20E+00
7.34E-01
7.34E-01
7.34E-01
1.22E-03
1.96E+01
4.90E-03
2.45E+00
4.90E-01
2.45E+00
2.45E-03
4.90E-02
4.90E-02
2.45E-02
4.90E-01
6.12E-01
9.79E-04
C
4.02E-04
2.84E-04
2.84E-04
1.58E-03
1.32E-05
6.90E-05
4.02E-03
2.15E-04
1.06E-03
1.61E-04
1.42E-03
9.66E-04
9.66E-04
9.66E-04
6.04E-06
2.05E-08
6.90E-03
1.05E-05
1.42E-04
1.42E-04
8.78E-03
1.21E-04
Inhalation
NC
1.20E+03
8.80E+02
1.30E+03
1.10E+03
1.30E+00
3.90E-04
2.90E-03
7.70E-01
3.00E+00
5.80E-01
1.60E+00
1.00E+01
2.10E-01
1.40E-02
6.10E-02
7.00E-02
7.50E-02
7.10E+02
1.09E+03
C
8.80E-03
3.80E-01
7.90E-02
1.30E-03
4.90E+00
7.40E-03
6.30E-04
2.20E-04
2.90E-03
3.30E-03
3.50E-03
1.00E-04
3.00E-03
8.12E-01
1.80E-01
2.00E-02
No Liner/In-Situ Soil
Peak
DAF
2.0
2.0
2.0
2.1
5.0
1.9
2.0
1.0E+30
1.0E+30
1.0E+30
6.8E+04
1.0E+30
2.5
3.4
3.3
4.4
2.1
2.1
2.1
1.9
1.9
2.0
2.3
1.9
1.9
1.9
1.0E+30
1.0E+30
1.0E+30
2.7
17
1.3E+03
1.9
1.9
1.0E+30
2.3
2.1
65
1.9
1.9
1.9
1.9
1.0E+30
1.9
4.3
2.7
1.3E+07
LCTV
based on
MCL
(mg/L)
61
4.9E-04
2.0
0.25
8.5E-03 "
6.0E-03 d
0.14
0.19
0.014
0.13
9.4E-03
Non-Carcinogenic Effect
7-yr Avg
DAF
2.0
2.0
2.0
2.1
5.0
1.9
2.0
1.0E+30
1.0E+30
1.0E+30
6.9E+04
1.0E+30
2.5
3.4
3.3
4.4
2.1
2.2
2.1
2.0
1.9
2.0
2.3
1.9
1.9
1.9
1.0E+30
1.0E+30
1.0E+30
2.7
17
1.3E+03
1.9
1.9
1.0E+30
2.3
2.1
65
1.9
1.9
1.9
1.9
1.0E+30
1.9
4.3
2.7
1.3E+07
LCTV based
on Ingestion
5.0
2.4
2.4
0.24
2.5
12
8.0E-04
240
1.0E+03b'c
7.4
10
0.32"
0.22 "
0.48
0.94
0.44
0.17
0.47
4.2
1.4
1.0E+03"'
1.0E+03"'
1.0E+03b'c
53
0.47"
4.7
1.1
160 c
4.7E-03
0.094
0.094
0.047
1.0E+03b'c
2.6
1.0E+03b'c
LCTV based
on Inhalation
200"'
200s'
200s-
1.0E+03"'
6.5
7.5E-04
7.2E-03
2.6
7.5 s-
1.2
0.45"
0.32 "'"
0.42
0.027
0.12
1.0E+03"'
1.0E+03"'
1.0E+03"
1.0E+03"'
1.0E+03"'
Carcinogenic Effect
30-yr Avg
DAF
2.3
2.3
2.3
2.4
5.2
2.2
2.3
1.0E+30
1.0E+30
1.0E+30
7.1E+04
1.0E+30
2.8
3.7
3.6
4.7
2.4
2.5
2.4
2.3
2.2
2.3
2.6
2.2
2.2
2.2
1.0E+30
1.0E+30
1.0E+30
3.1
17
1.6E+03
2.2
2.2
1.0E+30
2.6
2.4
66
2.2
2.2
2.2
2.2
1.0E+30
2.2
4.5
3.0
1.5E+07
LCTV based
on Ingestion
1.0E+03b'c
1.0E+03b'c
1.0E+03b'c
110C
1.0E+03b'c
2.0E-04
0.014
1.0E-03
6.6E-04"
4.7E-04"
3.7E-04
3. 1 E-03
2.1E-03
1.0E+03"'
1.0E+03"'
1.0E+03b'c
3.5E-07
0.015
2.7E-05
3.1E-04
3.1E-04
0.019
3.6E-04
LCTV based
on Inhalation
1.0E+03b'c
1.0E+03b'c
0.22
4.6E-03
23 c
0.012"
1.5E-03
5.0E-04
6.4E-03
1.0E+03"'
1.0E+03"'
1.0E+03b'c
1.0E+03b'c
0.13 ''
0.39
0.060
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.10-2
-------
Table F. 10 Land Treatment Unit LCTVs for No Liner/In-Situ Soil
Common Name
Endosulfan (Endosulfan 1 and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane, 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Fluoranthene
Fluoride
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro-1,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
lndeno{1 ,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Lead
Manganese
Mercury
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol acetate 2-
Methoxyethanol 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
CAS#
115297
72208
106898
106887
110805
111159
141786
60297
97632
62500
100414
106934
107211
75218
96457
206440
16984488
50000
64186
98011
319857
58899
319846
76448
1024573
87683
118741
77474
55684941
34465468
67721
70304
110543
7783064
193395
78831
78591
143500
7439921
7439965
7439976
126987
67561
72435
110496
109864
78933
108101
80626
MCL
(mg/L)
Ingestion
2.00E-03
7.00E-01
5.00E-05
4.00E+00
2.00E-04
4.00E-04
2.00E-04
1.00E-03
5.00E-02
1.50E-02
2.00E-03
4.00E-02
HBN (mg/L)
Ingestion
NC
1.47E-01
7.34E-03
4.90E-02
9.79E+00
7.34E+00
2.20E+01
4.90E+00
2.20E+00
2.45E+00
4.90E+01
1.96E-03
9.79E-01
2.90E+00
4.90E+00
4.90E+01
7.34E-02
7.34E-03
1.96E-01
1.22E-02
3.18E-04
7.34E-03
1.96E-02
1.47E-01
2.45E-02
7.34E-03
2.69E+02
7.34E-02
7.34E+00
4.90E+00
1.22E-02
1.15E+00
2.45E-03
2.45E-03
1.22E+01
1.22E-01
4.90E-02
2.45E-02
1.47E+01
1.96E+00
3.43E+01
C
9.75E-03
3.30E-07
1.14E-06
9.47E-05
8.78E-04
5.36E-05
7.43E-05
1.53E-05
2.15E-05
1.06E-05
1.24E-03
6.04E-05
6.19E-09
6.19E-09
6.90E-03
8.05E-05
1.02E-01
Inhalation
NC
6.00E-02
2.40E-01
2.90E+03
3.00E+02
3.30E+00
9.80E-04
1.20E+04
4.10E-01
5.10E+01
2.20E+01
6.90E-04
6.60E-01
5.33E+02
7.00E-04
6.50E-03
1.54E+03
5.10E+02
4.40E+02
3.30E+01
1.20E+00
5.30E+00
C
1.90E-01
1.10E-02
8.40E-05
5.20E-04
1.60E+03
1.50E+00
1.70E-02
1.60E-03
3.60E-04
1.50E-05
2.80E-04
6.10E-04
3.60E-05
1.44E-07
1.43E-07
3.30E-03
3.80E-02
No Liner/In-Situ Soil
Peak
DAF
6.1
2.0E+06
1.0E+30
1.9
1.9
1.9
6.7
1.9
3.4
1.0E+30
3.1
31
1.9
1.0E+30
1.9
55
1.9
1.9
1.9
5.2
2.1E+07
5.2
1.0E+30
2.8E+15
39
500
1.0E+30
1.0E+30
2.0E+14
6.9
130
3.0
1.9
3.0E+09
1.9
2.0
19
2.0
1.9
1.0E+30
1.9
1.9
1.9
1.9
1.9
LCTV
based on
MCL
(mg/L)
0.020 a'
2.2
1.5E-03
6.2
15b,c,d
1.5"
8.0E-03 a'
1.0E+03b'c
0.13 a'c
1.0E+03b'c
0.25
3.3E-03
10a'c
Non-Carcinogenic Effect
7-yr Avg
DAF
6.1
2.0E+06
1.0E+30
1.9
1.9
1.9
6.8
1.9
3.4
1.0E+30
3.2
32
1.9
1.0E+30
1.9
55
1.9
1.9
1.9
5.3
2.1E+07
5.3
1.0E+30
2.8E+15
39
500
1.0E+30
1.0E+30
2.0E+14
6.9
130
3.0
1.9
3.1E+09
1.9
2.0
19
2.0
1.9
1.0E+30
1.9
1.9
1.9
1.9
1.9
LCTV based
on Ingestion
0.90C
0.020 a'
1.0E+03"'
19
14
150
9.4
7.6
7.7
94
3.7E-03
54 c
5.2
9.4
94
0.14
5.3b'c'd
1.0
8.0E-03a'
1.0E+03b'c
0.29
0.13"
1.0E+03b'c
0.17
0.95
820 c
0.14
14
9.8
0.23
2.4
4.4E-03
4.9E-03
23
1.0E+01 a'c
0.094
0.047
28
3.7
66
LCTV based
on Inhalation
1.0E+03"'
0.46
1.0E+03"'
570
10.4
0.0
1.0E+03"'
1.0E+03"'
97.4
42.0
18"
1.8E+01 "
1.0E+03b'c
2.0
1.0E+03"'
1.3E-03
0.0
1.0E+03"'
970
840
63.0
2.3
10.1
Carcinogenic Effect
30-yr Avg
DAF
6.4
2.0E+06
1.0E+30
2.2
2.2
2.2
8.0
2.2
4.0
1.0E+30
3.4
38
2.2
1.0E+30
2.2
55
2.2
2.2
2.2
5.5
2.3E+07
5.5
1.0E+30
2.8E+15
39
500
1.0E+30
1.0E+30
2.0E+14
7.2
130
3.3
2.2
3.1E+09
2.2
2.3
19
2.3
2.2
1.0E+30
2.2
2.2
2.2
2.2
2.2
LCTV based
on Ingestion
1.0E+03b'
1.0E+03"'
4.4E-05
1.0E+03"'
1.9E-03
2.9E-04
1.0E+03b'c
8.4E-05
8.0E-03a'
1.0E+03b'c
0.049
0.030C
1.0E+03b'c
1.0E+03b'c
0.050
1.0E+03b'c
0.23
LCTV based
on Inhalation
1.0E+03b'
0.038
3.2E-03
1.0E+03b'
1.0E+03b'
3.3
0.093
1.0E+03b'c
2.0E-03
8.0E-03 a'
1.0E+03b'c
0.024
0.018 c
1.0E+03b'c
1.0E+03b'c
0.024
1.0E+03b'c
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.10-3
-------
Table F. 10 Land Treatment Unit LCTVs for No Liner/In-Situ Soil
Common Name
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Molybdenum
Naphthalene
Nickel
Nitrobenzene
Nitropropane2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Selenium
Silver
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran 2,3,7,8-
Tetrachlorodibenzo-p-dioxin 2,3,7,8-
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thallium
Thiram [Thiuram]
CAS#
298000
1634044
56495
74953
75092
7439987
91203
7440020
98953
79469
55185
62759
924163
621647
86306
10595956
100754
930552
152169
56382
608935
30402154
36088229
82688
87865
108952
62384
108452
298022
85449
1336363
23950585
75569
129000
110861
94597
7782492
7440224
57249
100425
95943
51207319
1746016
630206
79345
127184
58902
3689245
7440280
137268
MCL
(mg/L)
Ingestion
5.00E-03
1.00E-03
5.00E-04
5.00E-02
1.00E-01
3.00E-08
5.00E-03
2.00E-03
HBN (mg/L)
Ingestion
NC
6.12E-03
2.45E-01
1.47E+00
1.22E-01
4.90E-01
4.90E-01
1.22E-02
1.96E-04
4.90E-01
4.90E-02
1.47E-01
1.96E-02
7.34E-02
7.34E-01
1.47E+01
1.96E-03
1.47E-01
4.90E-03
4.90E+01
4.90E-04
1.84E+00
7.34E-01
2.45E-02
1.22E-01
1.22E-01
7.34E-03
4.90E+00
7.34E-03
2.45E-08
0.734
1.47E+00
2.45E-01
7.34E-01
1.22E-02
1.96E-03
1.22E-01
C
1.29E-02
6.44E-07
1.89E-06
1.79E-05
1.38E-05
1.97E-02
4.39E-06
4.60E-05
1.24E-09
6.19E-10
3.71E-04
8.05E-04
2.41 E-04
4.02E-04
5.36E-04
6.19E-09
6.44E-10
3.71E-03
4.83E-04
1.86E-03
Inhalation
NC
1.70E+01
1.00E+01
1.90E-02
1.50E-01
3.30E-01
9.00E+02
1.30E+04
4.90E-01
1.40E+00
3.60E+00
9.40E-01
C
1.20E-03
2.80E-02
2.30E-05
4.30E-05
4.00E-04
2.00E-05
1.50E-03
5.20E-01
4.50E-03
8.70E-03
9.20E-01
6.29E-08
6.00E-08
5.40E+01
1.40E-04
1.70E-02
1.00E-07
2.20E-09
1.90E-03
5.00E-04
2.10E-02
No Liner/In-Situ Soil
Peak
DAF
3.6E+05
1.9
1.0E+30
1.9
1.9
3.5
1.9
1.9
1.9
1.9
2.0
1.9
2.8
1.9
1.9
1.9
2.0
3.1E+12
440
110
3.0E+10
48
3.3
1.9
1.9
1.9
1.0E+30
1.0E+30
1.1E+08
2.5
1.9
110
1.9
2.2
2.0
2.8
25
1.0E+30
6.6E+06
3.3
18
2.1
2.1
1.0E+30
2.7
LCTV
based on
MCL
(mg/L)
9.7E-03
3.3E-03
1.0E+03b'c
0.078
0.28
0.20 c
0.013 "
0.013 "
0.011
3.2E-03
Non-Carcinogenic Effect
7-yr Avg
DAF
3.7E+05
1.9
1.0E+30
1.9
2.0
3.5
1.9
1.9
1.9
1.9
2.1
1.9
2.8
1.9
1.9
1.9
2.0
3.1E+12
440
110
3.1E+10
48
3.3
1.9
1.9
1.9
1.0E+30
1.0E+30
1.1E+08
2.5
1.9
110
1.9
2.2
2.0
2.8
26
1.0E+30
6.6E+06
3.3
18
2.1
2.2
1.0E+30
2.7
LCTV based
on Ingestion
1.1b'c'd
0.47
2.9
0.22
1.7
1.2
0.023
3.7E-04
1.4
0.098
1.0E+03b'c
8.6 c
3.6 c
2.4
28
3.7E-03
0.28
1.0E+03b'c
1.0E+03"'
1.0E+03b'c
4.6
79 c
0.047
0.21
0.26
0.015
14
0.19
0.16C
2.5
26
0.52
1.6
1.0E+03b'c
3.7E-03
0.33
LCTV based
on Inhalation
1.0E+03"
32.5
20
0.1
0.3
0.6
1.0E+03"'
1.0E+03"'
0.94
2.7
10
0.64 "
0.70 a'
Carcinogenic Effect
30-yr Avg
DAF
3.8E+05
2.2
1.0E+30
2.2
2.2
3.8
2.2
2.2
2.2
2.2
2.3
2.2
3.0
2.2
2.2
2.2
2.3
3.4E+12
440
110
3.1E+10
48
3.6
2.2
2.2
2.2
1.0E+30
1.0E+30
1.1E+08
2.8
2.2
110
2.2
2.4
2.3
3.0
26
1.0E+30
6.7E+06
3.7
21
2.4
2.4
1.0E+30
3.0
LCTV based
on Ingestion
0.029
1.4E-06
4.1E-06
4.2E-05
3.0E-05
0.060
9.6E-06
1.0E-04
1.5E-07
20 c
0.018
2.9E-03
1.0E+03b'c
8.8E-04
1.3E-03
1.0E+03b'c
4.3E-03C
0.014
1 .OE-02
4.5E-03
LCTV based
on Inhalation
1.0E+03b'c
0.063
5.0E-05
9.4E-05
8.8E-04
4.7E-05
3.3E-03
1.6
9.9E-03
0.019
2.0
7.1E-06
1.0E+03b'c
100a'
1.0E+03b'c
0.037
1.0E+03b'c
0.015 c
7.1E-03
0.010
0.050
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.10-4
-------
Table F. 10 Land Treatment Unit LCTVs for No Liner/In-Situ Soil
Common Name
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-1 ,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene (1,1 ,2-Trichloroethylene)
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxyjpropionic acid 2-(2,4,5- (Silvex)
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene (1,3,5-Trinitrobenzene) sym-
Tris(2,3-dibromopropyl)phosphate
Vanadium
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
Zinc
CAS#
108883
95807
95534
106490
8001352
75252
76131
120821
71556
79005
79016
75694
95954
88062
93721
93765
96184
121448
99354
126727
7440622
108054
75014
108383
95476
106423
1330207
7440666
MCL
(mg/L)
Ingestion
1.00E+00
3.00E-03
8.00E-02
7.00E-02
2.00E-01
5.00E-03
5.00E-03
5.00E-02
2.00E-03
1.00E+01
HBN (mg/L)
Ingestion
NC
4.90E+00
4.90E-01
7.34E+02
2.45E-01
6.85E+00
9.79E-02
7.34E+00
2.45E+00
1.96E-01
2.45E-01
1.47E-01
7.34E-01
1.71E-01
2.45E+01
7.34E-02
4.90E+01
4.90E+01
4.90E+01
4.90E+01
7.34E+00
C
3.02E-05
4.02E-04
5.08E-04
8.78E-05
1.22E-02
1.69E-03
8.78E-03
8.78E-03
1.38E-05
9.89E-06
1.34E-04
Inhalation
NC
1.30E+00
9.50E+01
8.30E-01
6.90E+00
1.90E+00
2.10E+00
3.40E-02
1.10E-01
1.20E+00
2.90E-01
1.30E+00
1.40E+00
1.30E+00
1.40E+00
C
7.50E+00
3.60E-02
3.60E-03
1.90E-02
1.10E-03
6.80E-03
2.80E-01
2.50E-03
No Liner/In-Situ Soil
Peak
DAF
2.2
1.9
1.9
1.9
6.7E+04
2.1
3.1
13
150
2.2
2.0
2.0
2.9
2.1
2.0
1.9
2.3
1.9
1.9
29
1.9
1.9
3.4
3.2
3.5
3.4
LCTV
based on
MCL
(mg/L)
2.2
0.50 a'
0.17
0.93
0.019"
0.011
0.010
0.098
3.8E-03
34
Non-Carcinogenic Effect
7-yr Avg
DAF
2.3
1.9
1.9
1.9
6.7E+04
2.1
3.1
13
150
2.2
2.1
2.1
2.9
2.1
2.0
1.9
2.4
1.9
1.9
29
1.9
1.9
3.4
3.2
3.5
3.4
LCTV based
on Ingestion
11
1.0
1.0E+03b'c
3.3
0.61 M
0.21
15
7.2
0.39
0.47
0.35
1.4
34
47
0.14
170 c
160
170
170
45
LCTV based
on Inhalation
2.9
290 c
11
0.58 M
0.58 "
0.50 a'
4.4
0.080
0.21
2.3
0.20 a'
4.4
4.5
4.6
4.7
Carcinogenic Effect
30-yr Avg
DAF
2.5
2.2
2.2
2.2
6.8E+04
2.4
3.3
14
170
2.5
2.3
2.4
3.2
2.4
2.3
2.2
2.7
2.2
2.2
31
2.2
2.2
3.7
3.5
3.8
3.7
LCTV based
on Ingestion
6.6E-05
8.8E-04
1 . 1 E-03
0.50 "'
0.030
5.1E-04"
5.1E-04"
0.021
0.021
3.7E-05
3. 1 E-04
2.9E-04
LCTV based
on Inhalation
16
0.079
0.50 "'
0.046
6.9E-04 "
6.9E-04 d
0.016
0.68
5.5E-03
a - Toxicity cap
b- 1,000 mg/1 (Policy)
c - Solubility (Warning)
F.10-5
-------
United Stales
Environmental Protected
Agency
&EPA Industrial Waste
Management
Evaluation Model
(IWEM) User's Guide
-------
Office of Solid Waste and Emergency Response (5305W)
Washington, DC 20460
EPA530-R-02-013
August 2002
www.epa.gov/osw
-------
EPA530-R-02-013
August 2002
Industrial Waste Management
Evaluation Model (IWEM)
User's Guide
-------
Office of Solid Waste and Emergency Response (5305W)
U.S. Environmental Protection Agency
1200 Pennsylvania Ave., N.W.
Washington, DC 20460
-------
IWEM User's Guide
ACKNOWLEDGMENTS
Numerous individuals have contributed to this work. Ms. Ann Johnson and Mr. David
Cozzie of the U.S. EPA, Office of Solid Waste (EPA/OSW) provided overall project
coordination, review, and guidance. Mr. Timothy Taylor (EPA/OSW) provided technical
guidance for the IWEM software development. Ms. Shen-Yi Yang and Mr. John Sager
(EPA/OSW) reviewed and coordinated the development of this document. This report
and the IWEM software were prepared by the staffs of Resource Management Concepts,
Inc. (RMC) and HydroGeoLogic, Inc. (HGL) under EPA Contract Number 68-W-01-004.
-------
IWEM User's Guide
FORMAT AND NOTATION
The main font for this document is 12-point Times New Roman font. The IWEM
command buttons, icons, menu items and other action-controls are shown in 11-point
Arial Narrow font, with small capitals style and with vertical bars at the beginning and
end; for example, IFlLEl and lEVALUATlONl are two of the menu items contained in the IWEM
menu bar. When referring to a sequential series of menu selections, such as "click on
File, then click on Open," this sequence of keystrokes is presented as IFlLE|dPENl.
IWEM screen and dialog box titles are presented in underlined text; user-entry labels
are using the same format as IWEM menu items and other action-controls; and references
to user-supplied text are shown in 12-point Courier font. For example, the user could
provide Rodney' s Waste Dump as Facility Name in screen Tier 2 Input: WMU
Type (17).
The IWEM software is organized into screens and dialog boxes and, for easy
reference, these components are labeled using a common numbering scheme. Within the
main IWEM program window, there are a number of screens that are displayed one at a
time as you move through an IWEM analysis. Each of these screens has a title that tells
you what part of the IWEM software you are in; if the IWEM screen is stretched to fill
the IWEM program window, then the title bar containing these titles is located directly
beneath the IWEM toolbar. Additionally, within some of these screens there are several
tabbed screens that resemble tabbed file folders. Each of these tabbed screens has a title
(placed on the screen itself) that tells you more specifically what type of information is
being requested or displayed on the screen. We refer to all screens and tabbed screens in
this document simply as screens. Finally, when you use certain options on the Infiltration
(19) and Constituent List (20) screens, dialog boxes are displayed to allow entry of
additional information. Each of these dialog boxes has a title (placed on the title bar at
the top of the dialog box) that identifies the type of information requested.
Although there are other ways to navigate through the IWEM software, it is
anticipated that most users will generally start at the beginning of a Tier 1 or Tier 2
analysis and then move through the screens sequentially using the INEXTl and IBACKl
buttons. In order to facilitate the reporting of user comments and problems, EPA has
organized all IWEM components into one common sequential numbering scheme
according to the order in which they would be displayed in a typical analysis. Hence, a
first-time IWEM Tier 1 user will see the following sequence screens:
Introductory Screens (screens 1 through 5)
Tier 1 Input screen group (tabbed screens 6 through 8)
11
-------
IWEM User's Guide
Tier 1 Results screen group (tabbed screens 9 through 13)
Tier 1 Evaluation Summary Screen (screen 14)
Similarly, a Tier 2 user will typically see the following sequence of screens and
dialog boxes (however, there are some slight differences in this sequence depending upon
the WMU type and infiltration option chosen by the user):
Tier 2 input screen group (tabbed screens 16 through 23, including dialog box 19a
that is associated with tabbed screen 19 and dialog boxes 20a to 20d that are
associated with tabbed screen 20)
EPACMTP Run Manager located on the Tier 2 Evaluation Screen (screen 24)
Tier 2 Output tabs (tabbed screens 25 through 28)
Tier 2 Evaluation Summary Screen (screen 29)
Please note that the screenshots presented in this User's Guide were captured using
the following settings to ensure maximum legibility:
monitor set to 800 x 600 resolution
large system font
IWEM program window (parent window) maximized
IWEM (tabbed) screen (child window) enlarged to its fullest extent
If you use other settings while running IWEM, you may need to use the sliders that appear
as necessary on the right and bottom edge of the IWEM windows in order to see the
entire screen.
in
-------
IWEM User's Guide Table of Contents
TABLE OF CONTENTS
Section Page
1.0 Introduction 1-1
1.1 Guide for Industrial Waste Management 1-1
1.2 The IWEM Software 1-2
1.3 Objectives 1-3
2.0 IWEM Overview 2-1
2.1 What does the software do? 2-1
2.1.1 Tier 1 Evaluation 2-2
2.1.2 Tier 2 Evaluation 2-3
2.1.3 Tier 3 Evaluation vs IWEM 2-4
2.2 IWEM Software Components 2-5
2.2.1 IWEM User Interface 2-5
2.2.2 EPACMTP Fate and Transport Model 2-6
2.2.2.1 IWEM vs. EPACMTP 2-9
2.2.3 IWEM Databases 2-10
2.3 Assumptions and Limitations of Ground-Water Modeling 2-10
3.0 System Requirements 3-1
4.0 IWEM Software Installation 4-1
5.0 Running the IWEM Software 5-1
5.1 How do I start the IWEM software? 5-1
5.2 What are the key features of the IWEM software? 5-1
5.2.1 What is the Constituent Properties Browser? 5-4
5.2.2 How Do I Navigate Through the IWEM Software? 5-8
5.2.2.1 Screens 5-9
5.2.2.2 Controls 5-9
5.2.3 How Do I Use Online Help? 5-16
5.2.4 How Do I Save My Work? 5-17
5.2.5 How Do I Get Help If I Have a Problem or a Question? 5-18
5.2.6 How Do I Begin Using the IWEM Software? 5-19
5.3 Introductory Screens (Screens 1 through 5) 5-19
5.4 Tier 1 Evaluation 5-28
5.4.1 Tier 1 Input Screen Group 5-28
5.4.1.1 Tier I Input: WMU Type (6) 5-28
5.4.1.2 Tier I Input: Constituent List (7) 5-30
5.4.1.3 Tier I Input: Leachate Concentration (8) 5-34
iv
-------
IWEM User's Guide Table of Contents
TABLE OF CONTENTS (continued)
Section Page
5.4.2 Tier I Output (Summary) Screen Group: MCL Summary
and HBN Summary (9 and 10) 5-36
5.4.3 Tier 1 Output (Details) Screen Group: Results - No Liner,
Single Clay Liner, and Composite Liner (11, 12, and 13) .... 5-40
5.4.4 Tier 1 Evaluation Summary Screen (14) 5-46
5.4.5 Exiting the IWEM software 5-49
5.5 Tier 2 Evaluation 5-50
5.5.1 Tier 2 Input Screens 5-51
5.5.1.1 Tier 2 Input: Waste Management Unit Type (16) . 5-51
5.5.1.2 Tier 2 Input: WMU Parameters (17) 5-53
5.5.1.3 Tier 2 Input: Subsurface Parameters (18) 5-59
5.5.1.4 Tier 2 Input: Infiltration (19) 5-63
5.5.1.5 Probabilistic Screening Module 5-73
5.5.1.6 Tier 2 Input: Constituent List (20) 5-75
5.5.1.7 Tier 2 Input: Constituent Properties (21) 5-84
5.5.1.8 Tier 2 Input: Reference Ground-Water
Concentrations (22) 5-87
5.5.1.9 Tier 2 Input: Input Summary (23) 5-89
5.5.2 Tier 2 Evaluation: Run Manager (24) 5-91
5.5.3 Tier 2 Evaluation Summary: Summary Results Screen
(Screen 25) 5-96
5.5.4 Tier 2 Output (Details) (26, 27, and 28) 5-99
5.5.5 Tier 2 Evaluation Summary (29) 5-104
6.0 Understanding Your IWEM Input Values 6-1
6.1 Parameters Common to Both Tier 1 and Tier 2 Evaluations 6-1
6.1.1 WMU Type 6-2
6.1.2 Waste Constituents 6-4
6.1.3 Leachate Concentration 6-4
6.1.4 Reference Ground-water Concentrations 6-4
6.1.4.1 Maximum Contaminant Level (MCL) 6-5
6.1.4.2 Health-Based Number (HBN) 6-5
6.1.4.3 Selection of the RGC within the IWEM Software . . 6-6
6.2 Additional Parameters for Tier 2 Evaluation 6-6
6.2.1 Basis for Using Site-Specific Parameter Values 6-6
6.2.2 Tier 2 Parameters 6-7
6.2.2.1 Tier 2 Parameters that Require User Inputs 6-7
6.2.2.2 Optional Tier 2 Parameters 6-7
-------
IWEM User's Guide Table of Contents
TABLE OF CONTENTS (continued)
Section Page
6.2.2.3 Default Values for Missing Data 6-10
6.2.2.4 How IWEM Handles Infeasible User
Input Parameters 6-10
6.2.3 Tier 2 Parameter Descriptions 6-10
6.2.3.1 WMU Parameters 6-11
6.2.3.2 Subsurface Parameters 6-15
6.2.3.3 Infiltration and Recharge Parameters 6-21
6.2.3.4 Constituent Parameters 6-25
7.0 Understanding Your IWEM Results 7-1
7.1 Leachate Concentration Threshold Values (LCTVs) 7-1
7.2 Limits on the LCTV 7-2
7.2.1 Toxicity Characteristic Rule (TC Rule) Regulatory Levels .... 7-2
7.2.2 1,000 mg/L Cap 7-2
7.2.3 Constituents with Toxic Daughter Products 7-3
7.3 IWEM Liner Recommendations 7-5
8.0 Trouble Shooting 8-1
9.0 References 9-1
Appendix A: List of Waste Constituents
Appendix B: Sample Reports from Tier 1 and Tier 2
VI
-------
IWEM User's Guide
Table of Contents
LIST OF FIGURES
Page
Figure 2.1 Sample IWEM Screen 2-6
Figure 2.2 Conceptual View of Aquifer System Modeled by EPACMTP 2-7
Figure 5.1 General IWEM Screen Features 5-2
Figure 5.2 Constituent Properties Browser 5-5
Figure 5.3 Constituent Properties Browser Full Source Dialog Box 5-7
Figure 5.4 Example IWEM Screen Identifying Several Types of Controls 5-10
Figure 5.5 Example IWEM Screen Identifying Several Types of Controls 5-11
Figure 5.6 Example IWEM Screen Identifying Several Types of Controls 5-14
Figure 5.7 Example IWEM Screen Identifying Several Types of Controls 5-15
Figure 5.8 IWEM Online Help 5-16
Figure 5.9 Introduction: IWEM Overview (1) 5-21
Figure 5.10 Introduction: Use of IWEM (2) 5-22
Figure 5.11 Introduction: Data Requirements (3) 5-23
Figure 5.12 Introduction: Model Limitations (4) 5-24
Figure 5.13 Introduction: Choose Evaluation Type (5) 5-25
Figure 5.14 Tier 1 Input: WMU Type (6) 5-29
Figure 5.15 Tier 1 Input: Constituent List (7) 5-31
Figure 5.16 Tier 1 Input: Leachate Concentration (8) 5-34
Figure 5.17 Tier 1 Output (Summary): MCL Summary (9) 5-37
Figure 5.18 Tier 1 Output (Summary): HBN Summary (10) 5-38
Figure 5.19 Tier 1 Output (Details): Results - No Liner (11) 5-41
Figure 5.20 Tier 1 Output (Details): Results - Single Clay Liner (12) 5-42
Figure 5.21 Tier 1 Output (Details): Results - Composite Liner (13) 5-43
Figure 5.22 Tier 1 Evaluation Summary (14) 5-46
Figure 5.23 Tier 2 Input: WMU Type (16) 5-52
Figure 5.24 Tier 2 Input: WMU Parameters (17) for Land Application Units ... 5-54
Figure 5.25 Tier 2 Input: WMU Parameters (17) for Landfills 5-55
Figure 5.26 Tier 2 Input: WMU Parameters (17) for Surface Impoundments .... 5-56
Figure 5.27 Tier 2 Input: WMU Parameters (17) for Waste Piles 5-57
Figure 5.28 Tier 2 Input: Subsurface Parameters (18) - Selecting Subsurface
Environment 5-60
Figure 5.29 Tier 2 Input: Subsurface Parameters (18) - Entering Values
of Subsurface Parameters 5-61
Figure 5.30 Tier 2 Input: Infiltration (19) - Initial Appearance 5-64
Figure 5.31 Tier 2 Input: Infiltration (19) - Land Application Unit 5-65
Figure 5.32 Tier 2 Input: Infiltration (19) - Landfill 5-66
Figure 5.33 Tier 2 Input: Infiltration (19) - Surface Impoundment 5-67
Figure 5.34 Tier 2 Input: Infiltration (19) - Waste Pile 5-68
vii
-------
IWEM User's Guide
Table of Contents
LIST OF FIGURES (continued)
Page
Figure 5.35 Tier 2 Input: Climate Center List (19a) 5-71
Figure 5.36 Tier 2 Input: Infiltration (19) - Site Specific Infiltration 5-73
Figure 5.37 Tier 2 Input: Constituent List (20) 5-76
Figure 5.38 Tier 2 Input: Enter New Constituent Data (20a) 5-80
Figure 5.39 Tier 2 Input: New Constituent Data (20b) 5-81
Figure 5.40 Tier 2 Input: Add New Data Source (20d) 5-83
Figure 5.41 Tier 2 Input: Constituent Properties (21) 5-85
Figure 5.42 Tier 2 Input: Reference Ground-Water Concentrations (22) 5-88
Figure 5.43 Tier 2 Input: Input Summary (23) 5-90
Figure 5.44 Tier 2 Evaluation: Run Manager (24) - Appearance Before Launching
EPACMTP Runs 5-92
Figure 5.45 Tier 2 Evaluation: Run Manager (24) - EPACMTP Dialog Box
Displayed During Model Execution 5-94
Figure 5.46 Tier 2 Evaluation: Run Manager (24) - Status and Liner
Protectiveness Summary 5-95
Figure 5.47 Tier 2 Output (Summary): Summary Results (25) 5-97
Figure 5.48 Tier 2 Output (Details): Results-No Liner (26) 5-100
Figure 5.49 Tier 2 Output (Details): Results-Single Liner (27) 5-101
Figure 5.50 Tier 2 Output (Details): Results-Composite Liner (28) 5-102
Figure 5.51 Tier 2 Evaluation Summary (29) 5-105
Figure 6.1 WMU Types Modeled in IWEM 6-3
Figure 6.2 WMU with Base Below Ground Surface 6-12
Figure 6.3 Position of the Modeled Well Relative to the Waste
Management Unit 6-14
Figure 6.4 Locations of IWEM Climate Stations 6-24
Vlll
-------
IWEM User's Guide Table of Contents
LIST OF TABLES
Page
Table 2.1 IWEM WMU and Liner Combinations 2-2
Table 6.1 Tier 2 Parameters 6-8
Table 7.1 Toxicity Characteristic Leachate Levels 7-3
IX
-------
IWEM User's Guide
CAS Number
cm/sec
CSF
DAF
EPA
EPACMTP
GUI
Guide
HBN
HELP
HQ
IWEM
kd
Koc
LAU
LCTV
LF
MB
MCL
MCLG
mg/L
MINTEQA2
MS
NPDWR
OSW
ACRONYMS AND ABBREVIATIONS
Chemical Abstract Service Registry Number
centimeters per second
Cancer Slope Factor
Dilution and Attenuation Factor
Environmental Protection Agency
EPA's Composite Model for Leachate Migration with
Transformation Products
Graphical User Interface
Guide for Industrial Waste Management
Health-Based Number
Hydrologic Evaluation of Landfill Performance
Hazard Quotient
Industrial Waste Management Evaluation Model
Soil - Water Partition Coefficient
Organic Carbon Partition Coefficient
Land Application Unit (also called a Land Treatment Unit)
Leachate Concentration Threshold Value
Landfill
megabyte
Maximum Contaminant Level
Maximum Contaminant Level Goal
milligrams per liter
EPA's geochemical equilibrium speciation model for dilute
aqueous systems
Microsoft
National Primary Drinking Water Regulation
EPA's Office of Solid Waste
-------
IWEM User's Guide
ACRONYMS AND ABBREVIATIONS (continued)
RAM Random Access Memory
RCRA Resource Conservation and Recovery Act
RGC Reference Ground-Water Concentration
SI Surface Impoundment
SPLP Synthetic Precipitation Leaching Procedure
STORET EPA's Data Storage and Retrieval System, National Water Quality
Database
TC Rule Toxicity Characteristic Rule
TCLP Toxicity Characteristic Leaching Procedure
U.S. EPA United States Environmental Protection Agency
WMU Waste Management Unit
WP Waste Pile
XI
-------
IWEM User's Guide Section 1.0
1.0 Introduction
This document describes how to use the Industrial Waste Management Evaluation
Model (IWEM). IWEM is the ground-water modeling component of the Guide for
Industrial Waste Management (Guide) (U.S. EPA, 2002d), which has been developed by
the U.S. Environmental Protection Agency's (EPA's) Office of Solid Waste (OSW) for
the management of non-hazardous industrial wastes. A companion document, the
Industrial Waste Management Evaluation Model Technical Background Document (U.S.
EPA, 2002c), provides technical background information. It is strongly recommended
that you take the time to understand the technical background of IWEM in order to make
the best use of this program. This section of the User's Guide provides an overview of
IWEM and its purpose, operation, and application; describes the major components of the
system; and provides an overview of how the remainder of the document is organized.
1.1 Guide for Industrial Waste Management
The EPA and representatives from 12 state environmental agencies have
developed a voluntary Guide (U.S. EPA, 2002d) to recommend a baseline of protective
design and operating practices to manage nonhazardous industrial wastes throughout the
country. The guidance was designed for facility managers, regulatory agency staff, and
the public, and it reflects four underlying objectives:
Adopt a multimedia approach to protect human health and the
environment;
Tailor management practices to risk using the innovative, user-friendly
modeling software provided in the Guide;
Affirm state and tribal leadership in ensuring protective industrial waste
management, and use the Guide to complement state and tribal programs;
and
Foster partnerships among facility managers, the public, and regulatory
agencies.
The Guide recommends best management practices and key factors to consider to
protect ground water, surface water, and ambient air quality in siting, designing and
operating waste management units (WMUs); monitoring WMUs' impact on the
environment; determining necessary corrective action; closing WMUs; and providing
post-closure care. In particular, the guidance recommends risk-based approaches to
choosing liner systems and waste application rates for ground-water protection and to
TT
-------
IWEM User's Guide Section 1.0
evaluate the need for air controls. The CD-ROM version of the Guide includes user-
friendly air and ground-water models to conduct these risk evaluations. The IWEM
software described in this User's Guide is the ground-water model that was developed to
support the Guide.
1.2 The IWEM Software
The IWEM software is designed to assist you in determining the most appropriate
WMU design to minimize or avoid adverse ground-water impacts, by evaluating types of
liners, the hydrogeologic conditions of the site, and the toxicity and expected leachate
concentrations of the anticipated waste constituents. That is, this software helps you
compare the ground-water protection afforded by various liner systems with the
anticipated waste leachate concentrations, so that you can determine what minimum liner
system is needed to be protective of human health and ground-water resources (or in the
case of land application units (LAUs), determine whether or not land application is
recommended).
The anticipated users of the IWEM computer program are managers of proposed
or existing units, state regulators, interested private citizens, and community groups. For
example:
Managers of a proposed unit could use the software to determine what
type of liner would be appropriate for the particular type of waste that is
expected at the WMU and the particular hydrogeologic characteristics of
the site.
Managers of an existing unit could use the software to determine
whether or not to accept a particular waste at that WMU by evaluating the
performance of the existing liner design.
State regulators may wish to use the software in developing permit
conditions for a WMU.
Interested members of the public or community groups may wish to
use the software to evaluate a particular WMU and participate during the
permitting process.
In an effort to meet the needs of various stakeholders, the guidance for the
ground-water pathway uses a tiered approach that is based on modeling the fate and
1-2
-------
IWEM User's Guide Section 1.0
transport of waste constituents through subsurface soils and ground water to a well1 to
produce a liner recommendation (or a recommendation concerning land application) that
protects human health and the environment. The successive tiers in the analysis
incorporate increasing amount of site-specific data to tailor protective management
practices to the particular circumstances at the modeled site:
Tier 1: A screening analysis based upon national distributions of data;
Tier 2: A location-adjusted analysis using a limited set of the most
sensitive waste- and site-specific data; and
Tier 3: A comprehensive and detailed site assessment.
The IWEM software is designed to support the Tier 1 and Tier 2 analyses. The
unique aspect of the IWEM software is that it allows the user to perform Tier 1 and Tier 2
analyses and obtain liner recommendations with minimal data requirements. Users
interested in a Tier 3 analysis should consult the Guide for information regarding the
selection of an appropriate ground-water fate and transport model.
1.3 Objectives
The objective of this User's Guide is to provide the information necessary to
perform Tier 1 and Tier 2 analyses for four types of WMUs:
Landfills (LFs);
Waste Piles (WPs);
Surface Impoundments (Sis); and
Land Application Units (LAUs) (which are also called Land Treatment
Units).
This User's Guide is organized as follows:
Section 2 provides an overview of the IWEM software;
Section 3 summarizes the computer system requirements for the IWEM
software;
Section 4 provides instructions for installing the IWEM software;
Section 5 provides detailed instructions on how to run the IWEM software,
and guides you step-by-step through Tier 1 and Tier 2 evaluations;
In IWEM, the term "well" is used to represent an actual or hypothetical ground-water monitoring
well or drinking water well, downgradient from a WMU.
-------
IWEM User's Guide Section 1.0
Section 6 presents background information to assist in understanding the Tier
1 and Tier 2 input values; how they affect the model evaluation; and how to
obtain input values for a Tier 2 evaluation;
Section 7 presents background information to assist in understanding the Tier
1 and Tier 2 IWEM results;
Section 8 provides troubleshooting information for some commonly
encountered problems;
Section 9 lists all references cited;
Appendix A presents the list of waste constituents included in IWEM; and
Appendix B presents the Tier 1 and Tier 2 reports for the example evaluations
presented in this document.
If you have a copy of the CD, you can open and read this User's Guide on-screen while
the IWEM software is running on your computer. You may, however, find it easier to use
IWEM's online help or to print out a copy of the User's Guide and refer to this hard copy
while you are using the software.
1-4
-------
IWEM User's Guide Section 2.0
2.0 IWEM Overview
The IWEM software developed by the EPA provides a two-tiered analysis that
requires a minimum of data. The analysis produces recommendations for the type of liner
to be used in a WMU and/or whether land application is appropriate. The two-tiered
analysis is presented within a user-friendly, Windows-based program called IWEM.
IWEM will operate on any standard personal computer using Windows 95 or later
operating system (see Section 3.0 for system requirements). A brief overview of IWEM
is provided in the remainder of Section 2.0.
2.1 What does the software do?
The IWEM software is designed to assist you in determining a recommended liner
design for different types of Resource Conservation and Recovery Act (RCRA) Subtitle
D (non-hazardous) WMUs. IWEM compares the expected leachate concentration2
entered by the user for each waste constituent with the leachate concentration threshold
value (LCTVs)3 calculated by a ground-water fate and transport model for three standard
liner types4.
The IWEM software compiles the results for all constituents expected in the
leachate and then reports the minimum liner scenario that is protective for all
constituents. Table 2.1 shows the combinations of WMUs and liners that are represented
in IWEM. For LAUs, only the no-liner scenario is evaluated because liners are not
typically used at this type of facility.
The IWEM software supports file saving and retrieval so that evaluations can be
archived or retrieved later and modified. The software also has report generation
capabilities to document in hard-copy the input values and resulting liner
recommendations.
The expected leachate concentration means the concentration, in milligrams per liter (mg/L), of
each constituent of concern that is expected to be present in the leachate after emplacement of the waste in a
WMU. Typically this concentration is measured using a laboratory leachate test. Chapter 2 (Characterizing
Waste) of the Guide provides more information on selecting a leachate test.
The LCTV represents the maximum allowable leachate concentration that is protective of ground
water; if the expected leachate concentrations of all constituents are less than their LCTVs for a particular
waste management scenario, then we recommend you select that WMU design to manage that particular
waste.
The three liner designs in IWEM are: no liner, single clay liner, and composite liner (see Table
2.1).
24
-------
IWEM User's Guide
Section 2.0
Table 2.1 IWEM WMU and Liner Combinations
WMU Type
Landfill
Surface Impoundment
Waste Pile
Land Application Unit
Liner Type
No Liner (in-situ soil)
Single Clay
Liner
N/A
Composite Liner
N/A
N/A = Not applicable
2.1.1 Tier 1 Evaluation
In a Tier 1 evaluation, the required inputs are the WMU type you wish to evaluate,
constituents of concern, and the expected leachate concentration for each constituent of
concern. After providing these inputs, IWEM determines a minimum recommended liner
design that is protective for all waste constituents. This determination is made by
comparing the expected leachate concentration for each constituent to tabulated values of
liner- and constituent-specific LCTVs, and identifying for which liner designs the LCTV
of each constituent is equal to, or greater than the input value of expected leachate
concentration. IWEM incorporates LCTV values for 206 organic and 20 metal
constituents (see Appendix A) that are part of the software's built-in database. These
LCTVs were generated by
running EPA's Composite
Model for Leachate Migration
with Transformation Products
(EPACMTP, described in
Section 2.2.2 below) for a wide
range of site conditions
expected to occur at waste sites
across the United States.
The process used to
simulate varying site conditions
is known as Monte Carlo
analysis. The Monte Carlo
analysis determines the
statistical probability that the
release of leachate would result
in a ground-water
About Monte Carlo Analysis:
Monte Carlo analysis is a computer-based method of analysis
developed in the 1940's that uses statistical sampling
techniques to obtain a probabilistic approximation to the
solution of a mathematical equation or model. The name
refers to the city on the French Riviera that is known for its
gambling and other games of chance. Monte Carlo analysis
is increasingly used in risk assessments where it allows the
risk manager to make decisions based on a statistical level of
protection that reflects the variability and/or uncertainty in
risk parameters or processes, rather than making decisions
based on a single point estimate of risk. For further
information on Monte Carlo analysis in risk assessment, see
the EPA's Guiding Principles for Monte Carlo Analysis
(U.S. EPA, 1997).
2-2
-------
IWEM User's Guide Section 2.0
concentration exceeding regulatory or risk-based standards. The Tier 1 LCTVs, are
designed to be protective with 90% certainty for possible waste sites in the United States.
The advantages of a Tier 1 evaluation are that it is fast and does not require site-
specific information. Tier 1 is designed to be a screening analysis that is protective for
most sites. This means that a Tier 1 analysis may result in a liner recommendation that is
more stringent - - and costly to implement - - than is needed for a particular site. For
instance, site-specific conditions such as low precipitation and a deep unsaturated zone
may warrant a less stringent liner design.
2.1.2 Tier 2 Evaluation
A Tier 2 evaluation utilizes information on the unit's location and other site-
specific data enabling you to perform a more precise assessment. If appropriate for site
conditions (e.g., an arid climate), it may allow you to avoid constructing an unnecessarily
costly WMU design. It may also provide an additional level of certainty that liner designs
are protective of sites in vulnerable settings, such as areas with high rainfall and shallow
ground water.
To perform Tier 2 evaluations, IWEM runs a complete EPACMTP fate and
transport simulation using site-specific input data, and generates a probability distribution
of expected ground-water well concentrations for each waste constituent and liner
scenario. It then compares the 90th percentile of the modeled ground-water well
concentration to a reference ground-water concentration (RGC5) value (for instance, a
regulatory maximum contaminant level (MCL)) until it has identified the liner design for
which the 90th percentile of the expected ground-water concentration does not exceed the
RGC.
IWEM is designed to allow Tier 2 evaluations with varying levels of available
site-specific information and data. IWEM allows you to provide site-specific values for
the most important modeling parameters, but if you have limited site data available,
IWEM will use default values or distributions for parameters for which you have no data.
IWEM will also assist you in making the most appropriate use of the information you
have available. For instance, if you know that a site has an alluvial aquifer, but you do
not have site-specific values for ground-water parameters such as hydraulic conductivity,
IWEM will assign representative values for alluvial aquifers from its extensive built-in
database of ground-water modeling parameters.
5 See Section 6.1.4 (page 6-4) for a definition of RGC.
2-3
-------
IWEM User's Guide
Section 2.0
Tier 2 users can perform an evaluation for any of the waste constituents that are
included in Tier 1; Tier 2 users also have the option to include additional waste
constituent(s) and/or modify constituent properties in the default database. Specifically,
you can provide constituent-specific soil - water partition coefficient (kd) and degradation
(A) coefficients, and a user-defined RGC and exposure duration.
In many cases, a Tier 2 evaluation will allow a less stringent and less costly liner
design than the Tier 1 screening analysis will allow. If a site is vulnerable to ground-
water contamination, a Tier 2 analysis will allow you to determine appropriate waste
management options and liner designs with greater confidence than a Tier 1 analysis.
Chapter 4 of the Guide discusses siting considerations for WMUs, including how to
recognize a vulnerable hydrogeological setting. The trade-off in performing a Tier 2
evaluation is that the fate and transport simulations are computationally demanding and
can take hours to complete, even with a very fast personal computer. The reason is that
the Tier 2 model simulations incorporate Monte Carlo analysis to handle the uncertainty
associated with default values and other modeling parameters that are not user-specified.
2.1.3 Tier 3 Evaluation vs IWEM
If the IWEM Tier 1 and Tier 2
evaluations do not adequately simulate
conditions at a proposed site because the
hydrogeology of the site is complex, you
may consider a comprehensive site-
specific risk assessment. For example, if
ground-water flow is subject to seasonal
variations, performing a Tier 2
Evaluation in IWEM may not be
appropriate because the model is based
on steady-state flow conditions. A
comprehensive site-specific ground-water
fate and transport analysis may be
required to evaluate risk to ground water
and alternative liner designs or land
application rates. This type of analysis is
beyond the scope of IWEM. If
appropriate, consult with your state
agency and use a qualified professional,
experienced in ground-water modeling.
EPA recommends that you talk to state
officials and/or appropriate trade
associations to solicit recommendations
Why it is important to use a qualified
professional?
Fate and transport modeling can
be very complex; appropriate
training and experience are
required to correctly use and
interpret models.
Incorrect fate and transport
modeling can result in a liner
system that is not sufficiently
protective or an inappropriate
land application rate.
To avoid incorrect analyses,
check to see if the professional
has sufficient training and
experience in analyzing ground-
water flow and contaminant fate
and transport.
2-4
-------
IWEM User's Guide Section 2.0
for a good consultant to perform the analysis. For more details see Chapter 7A of the
Guide.
2.2 IWEM Software Components
The IWEM software consists of three main components (or modules): (z) a
Graphical User Interface (GUI) which guides you through a series of user-friendly screens
to perform Tier 1 and Tier 2 evaluations; (ii) the EPACMTP computational engine and
integrated Monte Carlo processor that perform the ground-water fate and transport
simulations for Tier 2 evaluations; and (Hi) a series of databases of waste constituents,
WMUs, and site-specific parameters. Each of these three components is discussed briefly
in this section.
2.2.1 IWEM User Interface
When you use the IWEM software, you are interacting with the GUI module.
This module consists of a series of data input and display screens, that enable you to
define a Tier 1 and/or a Tier 2 evaluation; view and select parameter input values from
IWEM's built-in database; enter your own site-specific data; and view the results of the
IWEM evaluation. Figure 2.1 shows a sample IWEM user interface screen. A detailed
description of each IWEM user interface screen is provided in Section 5 of this User's
Guide.
If you are performing a Tier 1 evaluation, the software simply performs a table
look-up of the Tier 1 LCTV tables that are built into the software for the WMU and waste
constituent(s) you selected. Once you have specified all the Tier 1 data inputs, the results
of the evaluation are instantaneously available for on-screen display or printing in a hard-
copy report.
If you are performing a Tier 2 evaluation, the GUI will take you through a step-
wise process of assembling the pertinent site-specific data. The GUI module also
includes options to view and modify constituent-specific data, as well as add additional
constituents to IWEM's constituent database. Once IWEM has gathered all your data, it
will then run the EPACMTP model. Upon completion of the site-specific fate and
transport simulations, IWEM will display the liner recommendation and generate a
printed report if desired.
2-5
-------
IWEM User's Guide
Section 2.0
Menu Bar
Toolbar
Title Bar
Name of
Screen Group
Screen Name
Related
Constituents
79-06-1
ConstrtuentName
Acrylamide
Concentration
Constituent Properties
Toxicity
Standard
RGC
(mg/L)
2 20E-OS
Log(Koc)
(Vkg)
-O.S89
Ka
(/mol/yr)
31.5
Kn(/yr)
0018
Kb
(/mol/yr)
OOOE*00
Kd (L/kg)
Overall Decay
Coefficient (/yr)
Depth of base of the LF below ground surface (m)
*VMU depth (m) [requires site specific value]
Depth to water table (m).
Soil type. SILT LOAM
nfittrotion.
No Liner .0864
Single Liner. .0295
Composite Liner: Monte Carlo
Recharge Rate: 0.0561
-* [Aquifer Thickness (m):
0 Regional hydraulic gradient
32 Aquifer hydraulic conductivity (m/yr)
(not specified) Distance to well (rn).
(not specified)
(not specified)
(not specified)
150
J
« Previous
i
Nexl»
Figure 2.1 Sample IWEM Screen.
2.2.2 EPACMTP Fate and Transport Model
EPACMTP is a sophisticated fate and transport model that simulates the
migration of waste constituents in leachate from land disposal units through soil and
ground water. EPACMTP has been developed by EPA's OSW to support risk-based
ground-water assessments under RCRA. EPACMTP has been applied to waste
identification, hazardous waste listing and other regulatory evaluations. This User's
Guide provides only a brief summary of the EPACMTP; a complete description of the
model is provided in the EPACMTP Technical Background Document (U.S. EPA,
2002a). The IWEM Technical Background Document (U.S. EPA, 2002c) describes how
we used EPACMTP to develop the Tier 1 and Tier 2 Evaluations in IWEM.
2-6
-------
IWEM User's Guide
Section 2.0
LEACHATE CONCENTRATION
WASTE MANAGEMENT UNIT
UNSATURATED
ZONE
SATURATED
ZONE
LAND SURFACE
WATER TABLE
LEACHATE PLUMED
Figure 2.2 Conceptual View of Aquifer System Modeled by EPACMTP.
EPACMTP simulates fate and transport of constituents in both the unsaturated
zone and the saturated zone. Figure 2.2 shows a conceptual, cross-sectional view of fate
and transport modeled by EPACMTP. The source of constituents is a WMU located at or
near the ground surface overlying an unconfined aquifer. Waste constituents leach from
the base of the WMU into the underlying soil. They migrate vertically downward until
they reach the water table. As the leachate enters the saturated zone, it will mix with
ambient ground water (which is assumed to be free of pollutants) and a ground-water
plume will develop that extends in the direction of downgradient ground-water flow.
Although it is not shown in Figure 2.2, EPACMTP accounts for the spreading of the
plume in all three dimensions.
Leachate generation is driven by the infiltration of precipitation that has
percolated through the WMU into the soil. The type of liner at the base of the WMU
affects the rate of infiltration that can occur and, hence, the release of leachate into the
soil. EPACMTP models flow in the unsaturated zone and in the saturated zone as steady-
state processes, that is, it models long-term average flow conditions. EPACMTP also
simulates the ground-water mounding that may occur underneath a WMU with a high
infiltration rate and its effect on ground-water flow. This may be significant, particularly
in the case of unlined Sis. In cases of very high infiltration rates in settings with shallow
ground water, EPACMTP may cap the infiltration rate to avoid having the modeled
ground-water mound rise above the bottom of the WMU.
EPACMTP accounts for the dilution of the constituent concentration caused by
the mixing of the leachate with ground water. EPACMTP also accounts for attenuation
due to sorption of waste constituents in the leachate onto soil and aquifer solids, as well
2-7
-------
IWEM User's Guide Section 2.0
as bio-chemical transformation (degradation) processes in the unsaturated and saturated
zone. These processes decrease constituent concentrations in the ground water as the
distance from the WMU increases.
Sorption refers to the process whereby constituents in the leachate attach
themselves to soil particles. For organic constituents, EPACMTP models sorption
between the constituents and the organic matter in the soil or aquifer, based on
constituent-specific organic carbon partition coefficients (Koc) and a site-specific organic
carbon fraction in the soil and aquifer. For metal constituents, EPACMTP accounts for
more complex geochemical reactions by using effective sorption isotherms for a range of
aquifer geochemical conditions, as generated using the MINTEQA26 geochemical
speciation model.
In Tier 1 and as the default in Tier 2, EPACMTP only accounts for constituent
transformations caused by hydrolysis reactions. Hydrolysis refers to constituent
decomposition that results from chemical reactions with water. In Tier 2 analyses,
however, you may also enter site-specific biodegradation rates. Biodegradation refers to
constituent decomposition reactions involving bacteria and other micro-organisms.
EPACMTP simulates all transformation processes as first-order reactions, that is, as
processes that can be characterized with a half-life.
EPACMTP accounts for constituents which hydrolyze into toxic daughter
products. In that case, the final liner recommendations are determined in such a way that
they accommodate both the parent constituent as well as any toxic daughter products. For
instance, if a parent waste constituent rapidly hydrolyzes into a persistent daughter
product, the ground-water exposure caused by the parent itself may be minimal (it has
already degraded before it reaches the well), but the final liner recommendation would be
based on the exposure caused by the daughter product.
In Tier 2, IWEM makes liner recommendations by comparing ground-water
exposure concentration values predicted by EPACMTP against RGCs that are either
regulatory MCLs or cancer and non-cancer Health-Based Numbers (HBNs). For the
IWEM analysis, the ground-water exposure concentration is evaluated at a hypothetical
well that is located downgradient from the WMU. EPACMTP accounts for the finite life-
span of WMUs, which results in a time-dependent ground-water exposure concentration.
The exposure concentration calculated by EPACMTP is the maximum average
concentration during the time period in which the ground-water exposure at the well
occurs. The length of the exposure averaging period is adjusted to match the assumptions
MINTEQA2 (U.S. EPA, 1991) is a geochemical equilibrium speciation model for computing
equilibria among the dissolved, absorbed, solid, and gas phases in dilute aqueous solution.
-------
IWEM User's Guide Section 2.0
incorporated in the RGC. For instance, when the ground-water exposure concentration is
compared to a RGC that is based on cancer risk, the averaging period is set to 30 years;
whereas for non-cancer effects caused by ingestion of water, EPA considered only
childhood exposure, and set the averaging period to 7 years (covering the time period
from birth through the 6th year of life).
In both Tier 1 and Tier 2 analyses, the groundwater modeling results of the
EPACMTP model are summarized by IWEM in terms of Dilution and Attenuation
Factors (DAFs). A DAF is a numerical value that represents the reduction in the
concentration of a constituent arriving at the modeled ground-water well as compared to
the concentration of that constituent in the waste leachate. A DAF value of 10 means that
the concentration at the well is 10 times less than the concentration in the leachate. Using
DAFs is a convenient way to go back-and forth between leachate concentrations and
exposure concentrations, or ground-water reference concentrations.
2.2.2.1 IWEM vs. EPACMTP
As an IWEM user, you should understand the differences between IWEM and
EPACMTP. EPACMTP is a full-featured ground-water flow and transport model with
probabilistic modeling capabilities; it is a sophisticated software program which requires
a significant amount of computer and ground-water modeling expertise to create the
necessary input files, execute the model, and interpret the results.
In contrast, IWEM is a relatively simple and user-friendly program created
specifically to conduct Tier 1 and/or Tier 2 analyses of the ground-water pathway within
the context of the EPA's Guide. Specifically, within Tier 1, IWEM can be used to query
a database of existing EPACMTP modeling results in the form of LCTV values, and to
analyze these tabulated results to produce a Tier 1 WMU design recommendation that is
specific to your waste. Within Tier 2, IWEM converts your input values into the required
EPACMTP input files, executes a series of EPACMTP modeling runs, and then compiles
and analyzes the results to produce a Tier 2 WMU design recommendation that is specific
to your waste and your waste site. In addition, for both tiers of analysis the IWEM
software has the capability to print and save document-ready reports that include the liner
recommendations and the input data on which they are based.
In summary, IWEM can be thought of as an application of EPACMTP that is
tailored specifically for use in non-hazardous industrial waste management decision-
making. In order to make IWEM appropriate and easy to use in performing these Tier 1
and Tier 2 analyses, not all of the EPACMTP functionality is available to the IWEM user;
however, the IWEM provides added capabilities to interpret results and develop reports,
which are not available within EPACMTP.
2-9
-------
IWEM User's Guide Section 2.0
2.2.3 IWEM Databases
The third component of IWEM is an integrated set of databases that include waste
constituent properties and other ground-water modeling parameters. The waste
constituent database includes 206 organics and 20 metals. Appendix A provides a list of
the constituents in the database. The constituent properties include physical and chemical
data needed for ground-water transport modeling, as well as RGCs. These RGC's
include: 1) regulatory MCLs, and 2) cancer and non-cancer HBNs for drinking water
ingestion and inhalation of volatiles during showering. Section 7 of this User's Guide
discusses how IWEM uses these RGC's to calculate LCTVs.
In addition to constituent data, IWEM includes a comprehensive database of
ground-water modeling data, including infiltration rates for different WMU types and
liner designs for a range of locations and climatic conditions throughout the United
States; and soil and hydrogeological data for different soil types and aquifer conditions
across the United States. Details of these databases are provided in the EPACMTP
Parameters/Data Background Document (U.S. EPA, 2002b), and in the IWEM Technical
Background Document (U.S. EPA, 2002c).
EPA used these databases to develop the IWEM Tier 1 LCTVs, and they are
incorporated into the IWEM software to perform Tier 2 evaluations. When site-specific
data are available for a Tier 2 evaluation, they will override default database values.
Conversely, when site-specific data are not available for a Tier 2 evaluation, IWEM will
use default values or random sampling of values from distributions in its databases to
augment the user-provided data.
2.3 Assumptions and Limitations of Ground-Water Modeling
The tiered approach developed to evaluate WMU designs uses sophisticated
probabilistic techniques to account for uncertainty and parameter variability. To perform
the evaluations recommended by the Guide, the mathematical models represent
conditions that may potentially be encountered at waste management sites within the
United States. Efforts have been made to obtain representative, nationwide data and
account for the uncertainty in the data.
However, given the complex nature of the evaluations, a number of limitations
and caveats must be delineated. These limitations are described in this section. Before
using this software, you need to verify that the model assumptions are appropriate for the
site you are evaluating. The IWEM Technical Background Document (U.S. EPA, 2002c)
provides additional information to assist you in this process.
2-10
-------
IWEM User's Guide Section 2.0
EPACMTP represents WMU's in terms of a source area and a defined rate and
duration of leaching. EPACMTP only accounts for the release of leachate through the
base of the WMU and assumes that the only mechanism of constituent release is through
dissolution of waste constituents in the water that percolates through the WMU.
EPACMTP does not account for the presence of non-aqueous free-phase liquids, such as
an oily phase that might provide an additional release mechanism into the subsurface.
EPACMTP does not account for releases from the WMU via other environmental
pathways, such volatilization or surface run-off. EPACMTP assumes that the rate of
infiltration through the WMU is constant, representing long-term average conditions; the
model does not account for fluctuations in rainfall rate, or degradation of liner systems
that may cause the rate of infiltration and release of leachate to vary over time.
EPACMTP does not explicitly account for the presence of macro-pores, fractures,
solution features, faults or other heterogeneities in the soil or aquifer that may provide
pathways for rapid movement of constituents. A certain amount of heterogeneity always
exists at actual sites, and it is not uncommon in ground-water modeling to use average
parameter values. This means that the input values for parameters such as hydraulic
conductivity, dispersivity, etc. represent effective site-wide average values. However,
EPACMTP may not be appropriate for sites overlying fractured or very heterogeneous
aquifers.
EPACMTP is designed for relatively simple ground-water flow systems.
EPACMTP treats flow in the unsaturated zone and saturated zone as steady state and does
not account for fluctuations in the infiltration or recharge rate, either in time or areally.
As a result, the use of EPACMTP may not be appropriate at sites with large seasonal
fluctuations in rainfall conditions, or at sites where the recharge rate varies locally.
Examples of the latter include the presence of surface water bodies such as rivers and
lakes or ponds, and/or man-made recharge sources near the WMU. EPACMTP does not
account for the presence of ground-water sources or sinks such as pumping or injection
wells.
Leachate constituents can be subject to complex biological and geochemical
interactions in soil and ground water. EPACMTP treats these interactions as equilibrium
sorption and first-order degradation processes. In the case of sorption processes, the
equilibrium assumption means that the sorption process occurs instantaneously, or at least
very quickly relative to the time-scale of constituent transport. Although sorption, or the
attachment of leachate constituents to solid soil or aquifer particles, may result from
multiple chemical processes, EPACMTP lumps these processes together into an effective
soil-water partition coefficient. In the case of metals, EPACMTP allows the partition
coefficient to vary as a function of a number of primary geochemical parameters,
including pH, leachate organic matter, soil organic matter, and the fraction of iron-oxide
in the soil or aquifer.
241
-------
IWEM User's Guide Section 2.0
Although EPACMTP is able to account for the most important ways that the
geochemical environment at a site affects the mobility of metals, the model assumes that
the geochemical environment at a site is constant and is not affected by the presence of
the leachate plume. In reality, the presence of a leachate plume may alter the ambient
geochemical environment. EPACMTP does not account for colloidal transport or other
forms of facilitated transport. For metals and other constituents that tend to strongly sorb
to soil particles, and which EPACMTP will simulate as relatively immobile, movement
as colloidal particles can be a significant transport mechanism. However given sufficient
site-specific data, it is possible to approximate the effect of these transport processes by
using a lower value for the kd as a user-input in Tier 2.
EPA's ground-water modeling database includes constituent-specific hydrolysis
rate coefficients for constituents that are subject to hydrolysis transformation reactions;
for these constituents, EPACMTP simulates transformation reactions subject to site-
specific values of pH and soil and ground-water temperature, but other types of
transformation processes are not explicitly simulated in EPACMTP. For many organic
constituents, biodegradation can be an important fate mechanism, but EPACMTP has
only limited ability to account for this process. The user must provide an appropriate
value for the effective first-order degradation rate. In the IWEM application of
EPACMTP, the model uses the same degradation rate coefficient for the unsaturated and
saturated zones if this parameter is provided as a user-input in Tier 2 evaluations. In an
actual leachate plume, biodegradation rates may be different in different regions in the
plume; for instance in portions of the plume that are anaerobic some constituents may
biodegrade more readily, while other constituents will biodegrade only in the aerobic
fringe of the plume. EPACMTP does not account for these or other processes that may
cause a constituent's rate of transformation to vary in space and time.
2-12
-------
IWEM User's Guide
Section 3.0
3.0 System Requirements
The IWEM software is designed to run under the Microsoft (MS) Windows
operating system. Version 1.0 of IWEM has been designed and tested to run on the latest
versions of Windows 95, 98, NT version 4.0, 2000, and XP. In addition, in order to
ensure that all the files required to run IWEM are present on your computer, the latest
version of MS Internet Explorer that is compatible with your operating system needs to be
installed. Details are given in the table below:
Latest versions of MS Windows operating systems
95 (Version 4.00.950B)
98 Second Edition (Version 4.10.2222A)
NT 4.0 (Service Pack 6a)
2000 (Service Pack 2)
XP (Version 2002)
Corresponding version of MS
Internet Explorer
Version 5.5 Service Pack 2
Version 6.0
Version 6.0
Version 6.0
Version 6.0
If you do not have the latest version of your particular operating system, you may
encounter IWEM installation or execution problems (see Section 8.0). To avoid these
problems, make sure that you have the latest version MS Windows and Internet Explorer
installed on your computer before installing the IWEM software. To check the version
number of the operating system installed on your computer, right-click on the I MY
GovPUTERl icon on your desktop. Then choose I PROPERTIES! from the displayed list. The
ISYSTEM PROPERTIES! dialog box is then displayed, and the IGENERAL! screen is displayed by
default. The operating system name and version number are displayed under the ISYSTEM
heading.
If you find that you do not have the latest version of your particular operating
system, consult with your computer system administrator, or you may download the
updated version for free from the following website:
http://www.microsoft.com
From the main menu, click on |DCWNLQADS|WNDCWS UPDATE]. Then click on the link for
PRODUCT UPDATES|. The first time you do this, you will be asked to install the Windows
Update Control Package. Doing so will enable the automatic creation of a list of
available updates that is customized for your computer and operating system. Then
install the recommended updates to ensure that you are running the latest version of your
operating system.
3-1
-------
IWEM User's Guide Section 3.0
To check the version of MS Internet Explorer that is installed on your computer,
double-click on the I INTERNET EXPLORER! icon on your desktop. From the main menu, choose
hELP ABOUT INTERNET EXPLORER). The version number is displayed beneath the MS Internet
Explorer banner; make sure that the version number is at least 5.50.xxxx.xxxx if you are
running Windows 95 or is at least 6.00.xxxx.xxxx if you are running Windows 98 or
later. Only the first few digits of the Internet Explorer version number are important to
ensure correct operation of the IWEM software.
If you find that you do not have the latest version of MS Internet Explorer, you
may download the updated version for free from the following website:
http://www.microsoft.com
From the main menu, click on |DCWNLQADS|WNDOV\S UPDATE|. Then click on the link for
PRODUCT UPDATES! . The first time you do this, you will be asked to install the Windows
Update Control Package. Doing so will enable the automatic creation of a list of
available updates that is customized for your computer and operating system. If you do
not have the latest version of MS Internet Explorer, then this program will be included in
the list of recommended updates. In that case, download and install the recommended
file(s) in order to ensure that IWEM will operate correctly.
Your computer must meet the minimum hardware requirements for the version of
Windows that is installed on your computer. In addition, it is recommended that the
computer have at least 128 megabytes (MB) of RAM and 100 MB or more of available
hard-drive space. A printer is required for printing hard-copy reports.
To check your computer's random access memory (RAM), right-click on the IIW
GoiVPUTERl icon on your desktop. Then choose I PROPERTIES! from the displayed list. The
ISYSTEM PROPERTIES! dialog box is then displayed, and the IGENERAL! screen is displayed by
default. The amount of RAM is displayed as the last item under the IGoiVPUTERl heading.
To check your computer's available hard-drive space, double-click on the I MY GoiVPUTERl
icon on your desktop. Then choose |VIEW]DETAILS] from the main menu. The I MY GoiVPUTERl
dialog box is then displayed where you can check the amount of free space on your hard-
drive.
Running Tier 2 evaluations is computationally demanding. A fast computer
processor (e.g., at least a 500 MHz Pentium IE) is strongly recommended. Even
so, you should expect that Tier 2 analyses for multiple waste constituents may take
several hours to complete. A screen will be displayed during your Tier 2
evaluation to keep you informed about the progress of the computations.
3-2
-------
IWEM User's Guide Section 4.0
4.0 IWEM Software Installation
To use the IWEM software for the first time, you must install the software on your
hard-drive from the Guide CD-ROM, or download it from the EPA's non-hazardous
industrial waste website (http://www.epa.gov/industrialwaste/). Depending on the
security settings of your operating system, if your computer is connected to a network, or
if your computer uses the Windows NT, 2000, or XP operating systems, this software
may need to be installed and uninstalled by someone with administrator privileges.
Instructions for installing and uninstalling the program are provided below. Any updates
to these instructions are located in the Readme.txt file on the Guide CD-ROM and on the
website. If you have difficulty implementing the instructions below, please see your
network administrator for help, or contact the RCRA Information Center as explained in
Section 5.2.5.
Installation from the Guide CD-ROM
1. Close all applications, such as word processing and e-mail programs. Close or
disable virus protection software.
2. If you have previously installed the Guide on your computer, then insert the
Guide CD into your CD-ROM drive. Depending upon your computer settings,
the Guide CD may automatically be launched.
If not, double-click on IMYGoiVPUTERl, double-click on your CD-ROM drive, and
then double-click on ISTART.EXEl
OR
Select |START|RUN| and type "D : \START . EXE," replacing the "D :" in this command
with the correct drive designation for your CD-ROM, as appropriate.
3. After following the prompts to log onto the Guide CD, use the command buttons
within the interactive Guide CD to navigate to the Industrial Waste Management
Main Menu. From there, select the Protecting Ground Water section, and then
select the Assessing Risk to Ground Water subsection.
4. Click the INEXT| button to display the Assessing Risk to Ground Water Topic Menu,
and then click on the following sequence of command buttons:
ITOOLS AND RESOURCES!
ITOOLS!
I INFO! for the IWEM model
I LAUNCH|
44
-------
IWEM User's Guide Section 4.0
llNSTALLNO/Vl
5. The IWEM Welcome screen then appears. If all your other applications are
already closed (Step 1), click INDCTl. If not, press the ITABl key while the lALTl key is
depressed to scroll through your open applications, closing each in turn.
6. The next screen is titled Choose Destination Location. This screen displays the
default installation location for the IWEM files. If you want to change the
location, click the IBROASEl button and specify a different directory. Click the INDCTl
button to proceed with the IWEM installation process.
7. The next screen is titled Select Program Manager Group. The default setting is to
create a new program group named "IWEM;" however, if desired, you can instead
choose one of the existing program groups from the list below or replace "IWEM"
with a name that you type in. Then click the INDCTl button to proceed with the
IWEM installation process.
8. The next screen is titled Start Installation. If you are happy with your selections
up to this point, click the INDCTl button to install the IWEM software to your hard-
drive. Otherwise, click the IBACKl button to change your installation settings.
9. The next screen is titled Installing. The Current File and All Files progress bars
are automatically updated as files are copied to your hard drive, and an estimate of
the time required to finish the installation is displayed on-screen.
10. As the installation process is finishing, a message box will be displayed that says
"Updating System Configuration, please wait..."
11. If you do not encounter any installation problems, the Installation Complete
screen will display the message, "IWEM has been successfully installed." In this
case, all you need to do is click on the IFlNlSHl button to complete the installation.
However, if you do experience installation problems, please see your computer
system administrator for help, or contact the RCRA Information Center as
explained in Section 5.2.5.
Installation from the EPA's non-hazardous industrial waste website
1. Close all applications, such as word processing and e-mail programs. Close or
disable virus protection software.
2. Open your internet browser and type in the following website:
4-2
-------
IWEM User's Guide Section 4.0
http://www.epa.gov/industrialwaste/
3. From the bulleted list, double-click on the link for the Guide.
4. Scroll down to the bottom of the page and click on the link for the IWEM.
5. Scroll down the page and click on the Download Model link.
6. The File Download dialog box will then appear. Choose the option to save the
program to disk and click the ION button to download this IWEM setup file to
your hard-drive.
7. The Save As dialog box will then appear. Navigate to the folder where you would
like the file to be saved and then click the ISAVEl button. The progress bar is
automatically updated as the IWEM setup file (IWEMSetup.exe) is downloaded to
your hard drive.
8. At the bottom of the Save As dialog box is a checkbox to specify if you want the
dialog box to close automatically when the download is complete. If you leave
the checkbox empty, then click on the lOPENl button when the download is
complete. If you have the checkbox selected, the dialog box will close upon
completion of the download. In this case, open IIWCoMPUTERl, browse to the folder
location where you saved the IWEM setup file, and double-click on the icon for
I I\AEMSERJP.EXE!
OR
Select ISfARTlRUNl, and either browse to the folder location where you saved the
IWEM setup file or type this folder location directly into the textbox. Then click
on the I OKI button.
9. The IWEM Welcome screen then appears. If all your other applications are
already closed (Step 1), click I NEXTl. If not, press the ITABl key while the lALTl key is
depressed to scroll through your open applications, closing each in turn.
10. The next screen is titled Choose Destination Location. This screen displays the
default installation location for the IWEM files. If you want to change the
location, click the IBROASEl button and specify a different directory. Click the INDCTl
button to proceed with the IWEM installation process.
11. The next screen is titled Select Program Manager Group. The default setting is to
create a new program group named "IWEM;" however, if desired, you can instead
-------
IWEM User's Guide Section 4.0
choose one of the existing program groups from the list below or replace "IWEM"
with a name that you type in. Then click the INEXTl button to proceed with the
IWEM installation process.
12. The next screen is titled Start Installation. If you are happy with your selections
up to this point, click the INEXTl button to install the IWEM software to your hard-
drive. Otherwise, click the IBACKl button to change your installation settings.
13. The next screen is titled Installing. The Current File and All Files progress bars
are automatically updated as files are copied to your hard drive, and an estimate of
the time required to finish the installation is displayed on-screen.
14. As the installation process is finishing, a message box will be displayed that says
"Updating System Configuration, please wait..."
15. If you do not encounter any installation problems, the Installation Complete
screen will display the message, "IWEM has been successfully installed." In this
case, all you need to do is click on the IFlNlSHl button to complete the installation.
However, if you do experience installation problems, please see your computer
system administrator for help, or contact the RCRA Information Center as
explained in Section 5.2.5.
Uninstalling
1. Click on the Microsoft Windows ISTARTI button in the extreme lower left corner of
your screen.
2. Select ISETTiNGSl, and then IGoNTTOL PANEL!.
3. Double-click on IADD/REMOVE PROGRAMS!.
4. Select I IWEM and then click on the ICHANGE/REMOVEl button.
5. The IWEM Select Uninstall Method screen is now displayed. You can choose
either an automatic or a custom uninstall process. The automatic process removes
only the IWEM files that were copied to your computer during IWEM installation;
that is, files of saved IWEM analyses are not deleted if you choose the automatic
uninstallation process. The custom uninstallation process allows you to specify
exactly which files you want to delete. Clicking on the ISELECTALLl button each
time it appears in the custom process can be used to delete every file that is
associated with the IWEM application, including shared files and saved IWEM
analyses.
-------
IWEM User's Guide Section 4.0
6. The IWEM Perform Uninstall screen then appears. If you are happy with your
selections up to this point, click the IFlNlSHl button to uninstall the IWEM software
from your hard-drive. Otherwise, click the IBACKl button to change your
uninstallation settings.
7. If the IWEM uninstall program finds that any of the files to be deleted is a shared
file that is no longer used by any programs, a message box titled Remove Shared
Component then appears. The filename will be displayed and you will be asked if
you want to delete this file. If any programs are still using this file and it is
removed, then those programs may not function correctly. Leaving the file on
your computer will not harm your system, but it does take up space on your hard-
drive. If you are unsure what to do, then you should select the I No TO ALLl button.
8. If you do not encounter any uninstallation problems, the IWEM program will then
be removed from the list of programs on the Add/Remove Programs dialog box.
However, if you do experience uninstallation problems, please see your computer
system administrator for help, or contact the RCRA Information Center as
explained in Section 5.2.5.
4-5
-------
IWEM User's Guide
Section 5.0
5.0 Running the IWEM Software
This section provides detailed instructions on how to run the IWEM software.
Specifically, this section:
Instructs you how to launch the IWEM software;
Explains the key features of the IWEM software; and
Guides you step-by-step through Tier 1 and Tier 2 evaluations.
5.1 How do I start the IWEM software?
To use the program for the first time, you can install the software from the Guide
CD (or download it from EPA's website: http://www.epa.gov/industrialwaste) to your
hard-drive. Section 4 gives detailed installation instructions.
U.S. Environmental
Protection Agency Office
of Solid Waste
Industrial Waste Management
Evaluation Model
IWEM
Version 1.0
Initializing...
After installation, you can launch the program by choosing | START PROGRAMS | (at
the lower left corner of the screen) and then choosing I\AEM program group and the
program I\AEM . Alternatively, you can create a short-cut to the | I\AEM| program and
move it to your Windows desktop. In this case, the program can be launched by double-
clicking the IWEM | icon
on your desktop.
5.2 What are the key features of the IWEM software?
The IWEM software has a user-friendly interface which is designed to operate in
accordance with MS Windows conventions. The first screen that you see after
5-1
-------
IWEM User's Guide
Section 5.0
launching the program is the Start-Up screen (shown above) which will appear only while
the program is loading.
The first time you run the IWEM software, it displays five Introduction screens.
After reading them once, you can skip these screens in the future by un-checking the box
at the lower left of the introduction screens (see Section 5.3).
Menu Bar
Toolbar
Title Bar
i;HlWEM [Untitledwen
nput Summary (23)
Constituent Properties
Related
Constituents
CAS
Constituent Name
Leachate
Concentration
(mgAJ
Toxiclty
Standard
RGC
(mg/L)
Log(Koc)
(Ukg)
Ka
(/mol/yr)
Kn(/yr)
Kb
(/mol/yr)
Kd (L/kg)
Overall Decay
Coefficient (/yr)
79-06-1
Acrylernide
01
HBN - 2 20E-05
Ingestion
Cancer
-0.989
315
0018
O.OOE«00
Area (m*2):
Depth of base of the LF below ground surface (m):
WMU depth (m) [requires site specific value]
Depth to water table (m).
Soil type. SILTLOAM
nfiltration:
No Liner: .0561
Single Liner. .0295
Composite Liner: Monte Carlo
Recharge Rate 0.0561
- t^quifer thickness (m).
0 Regional hydraulic gradient,
32 Aquifer hydraulic conductivity (m/yr)
(not specified) Distance to well (m)
(not specified)
(not specitiecf)
(not specified)
150
~~
,1
Next»
Figure 5.1 General IWEM Screen Features.
5-2
-------
IWEM User's Guide
Section 5.0
As shown in Figure 5.1, the IWEM software interface follows a common layout
with the following features:
Menu Bar allows you to perform common file operations;
Toolbar also allows you to perform common operations efficiently;
Title Bar at the top displays the software title and the name of the current
IWEM project file;
Name of Screen Group identifies the general topic addressed by the
individual screens that comprise this group (e.g., Tier 2 input screen group);
Screen Name more specifically identifies the type of information being
requested or displayed in the screen;
| PREVIOUS| button takes you to the previous screen; and
Ntxr| button allows you to proceed to the next screen.
From the menu bar, you can select among the following menu items:
File: performs general file operations, such as open and save;
Evaluation: proceeds directly to either the Tier 1 Evaluation or the Tier 2
Evaluation;
Options: enables or suppresses toolbar visibility; and
Help: provides access to the following information: search IWEM online
help; view IWEM introductory screens; browse constituent properties; view
contact information for IWEM technical support; and view the IWEM About
screen.
Using the toolbar is a quick way to perform common operations:
ml
Clicking on this button begins a | NEW EVALUATION |
C3l
Clicking on this button launches the | OPEN RLE dialog box to select the
previously saved evaluation file to be opened;
Clicking on this button launches either the | SAVE As or | SAVE| dialog box
so that you can specify the filename and folder for your analysis;
5-3
-------
IWEM User's Guide Section 5.0
Clicking on this button begins the TIER 1 EVALUATION |;
Clicking on this button begins the TlER 2 EVALUATION |; and
Clicking on this button opens the | CCNSTITIJENT PROPERTIES BROWSER dialog
box.
&
If you are unsure about the function of any of the toolbar buttons, you can display
| TOOL TIPS| (which identifies the button's function) for each button by placing the mouse
cursor on top of the button.
In this section of the User's Guide, we present detailed, step-by-step instructions
for running the IWEM software. These instructions include screenshots for each of the
screens and dialog boxes that you will see when performing a Tier 1 or Tier 2 analysis in
IWEM. The screenshots presented in Section 5 have added annotations (in small boxes
above and below the screenshot) to point out the important features on each screen.
These annotations are each labeled with a letter (A, B, C, etc) and are then listed and
explained sequentially in the text immediately following each screenshot.
5.2.1 What is the Constituent Properties Browser?
The Constituent Properties Browser, accessed from the Main Menu sequence
I-ELP CONSTITUENT PROPERTIES] or by clicking on the flask toolbar button, displays the data in
the constituent properties database that is distributed with IWEM (see Figure 5.2). You
can select a constituent by Chemical Abstract Service Registry number (CAS number) or
by name. The information displayed in the upper portion of the browser includes
chemical and physical properties required for fate and transport modeling. RGC values,
cancer slope factors (CSFs), and non-cancer reference doses and reference concentrations
are given in the lower portion of the screen. For each property value in the database
(except constituent type, carcinogenicity, and molecular weight), the |DATASCURCE| field
provides access to a complete bibliographic citation (see Figure 5.3).
5-4
-------
IWEM User's Guide
Section 5.0
r^rence.nthe.WEM
JH Constituent Properties Brotiser
Select a constituent bv CAS n
CAS Number: 17440-36-0
Physical Properties
urnber
^J Constituent Name: |Antimor y
_|p|x|
il
Parameter
|Value
Data
Source
Carcinogen1? No
Molecular weight (g/mol)
Log KOC (distribution coefficient for organic carbon) N/A
Ka: acid-catalyzed hydrolysis rate constant (1 /yr) N/A
Kn: neutral hydrolysis rate constant (1 /yr) N/A
Kb: base-catalyzed hydrolysis rate constant (1 /yr)
Solubility (mg/L)
Diffusivity in air (cm~2/s)
121 76 N/A
J
1000000 iCanmidgeSoft Cojp£rati£n.^OoT"J
Reference Ground-water Concentration Values
Parameter
Maximum Contaminant Level
HBN - Ingestion. Cancer
Carcinogenic Slope Factor - Oral
HBN - Ingestion. Non-Cancer
Value
0.006
N/A
N/A
01
1098
Data Source
USEPA 2000h
USEPA 3
Olb
3
J
^J
To view a full source, dick in the Data
Source cell, then click the "Full Source"
button.
QK
Full Source
D. Reference ground-water
concentrations and
abbreviated reference
in the IWEM database
F. Click to view full
|[)ATA SOURCE| of
selected property
Figure 5.2 Constituent Properties Browser.
The features identified in Figure 5.2 are explained in more detail in the following
paragraphs.
A. Choose Constituent to View by Selecting CAS Number
To select which constituent to view, use either of the two list boxes at the top of
the screen. You can click on the drop-down list control ~ at the right edge of the CAS
NUMBER listbox to display a drop-down list of all available waste constituents. Then use
5-5
-------
IWEM User's Guide Section 5.0
the mouse or the | ARROW) keys on your keyboard to scroll through the list of constituents
until the desired constituent is highlighted. You can also type in the leading digits of the
CAS number for the constituent you would like to view. IWEM will then skip forward in
the list to the first constituent whose CAS number starts with the entered digits, and you
can then use the mouse or the ARROW keys on your keyboard to move to the desired
constituent. Left click on the mouse or hit the ENTER | key to make your selection.
B. Choose Constituent to View by Selecting Name
You can also select which constituent to view by using the | CONSTITUENT NAIVE)
listbox on the right side of the screen. Click on the drop-down list control _LJ at the right
edge of the | CONSTITUENT NAIVE) listbox to display a drop-down list of all available waste
constituents. Then use the mouse or the ARROW keys on the keyboard to scroll through
the list of constituents until the desired constituent is highlighted. You can also type in
the first letter of the name of the constituent that you would like to view. IWEM will
then skip forward in the list to the first constituent whose name begins with the entered
letter, and you can then use the mouse or the ARROW keys on your keyboard to move to
the desired constituent. Left click on the mouse or hit the ENTER) key to make your
selection.
C. Physical Properties and Abbreviated Reference in the IWEM Database
For the selected waste constituent, the pertinent physical and chemical property
values that are used in the IWEM analysis and their corresponding data sources are listed
in the upper window on this screen.
D. Reference Ground-water Concentrations and Abbreviated Reference in the IWEM
Database
For the selected waste constituent, the RGC input parameter values that are used
in the IWEM analysis and their corresponding data sources are listed in the lower table on
this screen.
E. Close Constituent Properties Browser
Click the OK) button at the bottom of the screen to close this screen.
5-6
-------
IWEM User's Guide
Section 5.0
F. Click to View Full | DATA SOURCE | of Selected Property
You can view the complete bibliographic citation of a constituent property by
selecting the corresponding entry under the | DATA SOURCE heading and clicking on the
| FULL SOURCE button on the lower right-hand side of the screen. Doing so will cause a
message box to appear on-screen, as is shown in Figure 5.3.
Constituent Properties Browser
Select a. constituent by CAS number or name.
CAS Number: 17440-36-0
- Physical Properties
Constituent Name; (Antimony
lvalue
No
j/mol)
3n coefficient for organic carbon) N/A
hydrolysis rate constant (1 /yr) N/A
sis rate constant (1 /yr) N/A
i hydrolysis rate constant (1 /yr) N/A
| Data Source
121.76 N/A
1000000 CambridgeSott Corporation. 2001
A |
J
Full Source
Reference Ground^a
Parameter
CambrldgeSoft Corporation. 2001. ChemFinder .com database and Internet searching.
http://chemfinder.cambridgesoft.com. Accessed July 2001.
Maximum Contaminai
HBN - Ingestion, Cane
Carcinogenic Slope F
HBN-Ingestion, Non-Cancer
To view a full source, click in the Data
Source cell, then click the "Full Source"
button.
0.0098 I
JSEPA2001b
Full Source
B. Click to close the
|FuiL SOURCE]
dialog box
A. Full IDATA SOURCE]
of selected property
Figure 5.3 Constituent Properties Browser Full Source Dialog Box.
5-7
-------
IWEM User's Guide Section 5.0
The features identified in Figure 5.3 are explained in more detail in the following
paragraphs.
A. Full | DATA SOURCE | of Selected Property
The bibliographic citation of the selected property is displayed in the FULL
SOURCE dialog box.
B. Click to Close the | FULL SOURCE Dialog Box
Click the OK| button to close the dialog box.
5.2.2 How Do I Navigate Through the IWEM Software?
The IWEM software is comprised of a series of screens containing controls for
entering data and viewing results. This section describes in detail how to move from
screen to screen and control to control, as well as how the various controls are used
together to facilitate your use of the IWEM software. Although this guide assumes you
will be using a mouse to navigate through the screens and features, you may also navigate
using the keyboard exclusively.
Navigating with the keyboard involves the use of the following keys: the |TAB|
key, the |BACK-TAB| key, the |ARRCW| keys, the |ALT| key, and the |ENTER| key. The |TAB| key
moves the cursor from one control to the next in a predefined order. The term cursor
refers to either a vertical bar "I" that indicates the position of the next typed character, or
the change in a control's appearance from normal to a highlighted appearance, as
presented below.
OK
OK
Normal Highlighted
When a control is highlighted, it is considered actively awaiting input from the
keyboard or mouse. The |BACK-TAB| key (press the |TAB| key while holding down the |SHIFT|
key) moves the cursor in the reverse order. When the cursor is on a command button,
press the |ENTER| key to "click" the button. Radio buttons always appear in a set of two or
more options; when the cursor is on any radio button, press the |ARRCW-UP| or |ARROW-DCWN|
key to select a different radio button. The TAB| key moves you off the radio button group.
The |TAB|, |BACK-TAB|, and |ARRCW| keys are also used to move from cell to cell in a data grid.
A drop-down list displays the current choice of several possible choices; when the drop-
5-8
-------
IWEM User's Guide Section 5.0
down list is active (highlighted), use the |ARROW-UP| or |ARRCW-DOV\M| keys to display the
desired choice.
The |ALT| key is used in combination with other key strokes to access controls or
menu items quickly through pre-defined "hot-keys" that correspond to underlined
characters on a control or menu item. For example, the underlined "O" on the |OK| button
above indicates that pressing and holding down the |Al_l| key and then pressing the |Q key
would have the same result as a mouse click on the button. Similarly, the main menu
system is activated by pressing the |Al_l| key; the first letter of each menu item is
underlined and can be accessed in the manner just described.
5.2.2.1 Screens
Screens in IWEM appear as a single screen or as a group of screens with manila
folder-like "tabs" along the top to differentiate between the individual screens. The
Introductory screens (see Figures 5.9 through 5.13) are examples of individual screens
that have PREVIOUS! and/or |NEXT| command buttons along the bottom for navigating from
screen to screen. The Tier 1 Input screen group (see Figure 5.14) consists of three screens
where you select a WMU type, identify the constituents in your waste, and enter your
leachate data. In addition to the navigational command buttons available on single
screens, you can also move to adjacent screens by clicking on their corresponding "tab".
5.2.2.2 Controls
The following controls make the IWEM software easy-to-use:
Text boxes;
Dialog boxes;
List boxes;
Radio Buttons;
Data grids;
Command buttons; and
Drop-down lists.
Each of these controls is explained in more detail in this section. In general, a
control is activated or selected by clicking on it with the mouse or by using the keyboard
(e.g., using the |TAB| key or the hot-key).
5-9
-------
IWEM User's Guide
Section 5.0
Text Boxes
Text boxes are used to display or accept information. The screen shown in Figure
5.4, text boxes (box B) are used to accept the name or CAS number of a constituent. As
you type characters or numbers into the text box, the list box cursor moves to the
constituent in the list that best matches your input. The screen shown in Figure 5.5 uses
text boxes to display data (box B) and to receive inputs (box E).
Search By -
mstituent Nam;
CAS Numbs r
Infiltraii :n (19)
Constituent List (20)
SortBy-
I Constituent Pit aerties (21)
Constituent Name
CAS Number
Type of Constitut nt
< All constituents
<~ Orgonics
r Metals
All Constituen s
83-32-9 Acer aphthene
75-07-0 Acet
ildehyde [Ethanal]
67-64-1 Acetlne (2-propanone)
75-05-8 Acetinitrile (methyl cyanide)
98-85-2 Aceflphenone
107-02-8 Acrolain
79-06-1 Acrylamide
79-10-7 Acrylic acid fpropenoic acid]
HihflfcifJBBlS
309-00-2 Aldrin
107-18-6 Allyl alcohol
62-53-3 Aniline (benzeneamine)
Selected Constituents
CAS
Number
107-13-1
Constituent Name
Aoylonitrile
Add New ConqMuent
Leach ate
Concentration
(mg/L)
« Previous
Next»
D. Command Button
to move to previous
E. Command Buttons to
move items from list box
to data grid and vice
versa
F. Command Button
to start adding a
new constituent
G. Data Grid for
data display and
entry
H. Command
Button to
move to next
Figure 5.4 Example IWEM Screen Identifying Several Types of Controls.
5-10
-------
IWEM User's Guide
Section 5.0
A. Data Grid for
display and selection
B. Text Boxes for
data display
Cone. (22) ] Input Summery (23) 1
^pply Standards" button to save each selectior
Constituent Properties (21)
[ Reference GV
Si ilect a constituent from the grid, then the desired standard fror i the list Click the "
Related
Constituents
Constituent
Standard
Parent
107-1H Acrylonitnle
HBN-lngestion, C-encer
Daughter
Daughter
79-06-1 Acrylernide
HBN - Ingestion. Cancer
79-10-7 Acrylic acid [propenoic acid]
HBN - Ingestion. NonCancer
Standards for 79-10-7 Acrylin acid ||>rii| enoic acid]
Reference Grqund-weter Ex aosure
Concentration
rng/L)
Du
Select Standard
r
C HI.::
<~ HBN - Inhalation. Non-Cancer
C HP'
( HBN - Ingestion. Nort-Cancer
r User-Defined
» Compare to all available standards
:elect the desired standard by clicking its radio button. Click the "Apply Stan
ation (yr)
12
T
Justification
T
aids" button to save your selection.
« Previous
(Apply Standard(s)
Next»
C. Radio Buttons
for option selection
D. Command Button
for option
confirmation
E. Text Boxes for
data entry
Figure 5.5 Example IWEM Screen Identifying Several Types of Controls.
Dialog and Message Boxes
Dialog boxes appear throughout the IWEM software as additional data entry
screens containing one or more of the controls mentioned above (i.e., see Figure 5.35: the
Climate Center List dialog box), or as a way of informing the user (i.e., see Figure 5.3:
the Full Source message box). Data entry dialog boxes usually appear as a direct result of
clicking on a command button, whereas message boxes appear as the result of a user's
input, or the model's calculation.
5-11
-------
IWEM User's Guide Section 5.0
List Boxes
List boxes are used to display a list from which you can select one or many of the
listed items. In Figure 5.4, the list box (box A) displays all of the constituents in the
IWEM database that can be used in a Tier 2 analysis. This list permits multiple selections
and is described in more detail in Section 5.5.1.6 of this document.
Radio Buttons
Radio buttons always appear in a set of two or more options and have a variety of
uses. In the screen in Figure 5.4, the radio buttons (box C) control the display of
constituents in the list box (box D). In the screen in Figure 5.5, you can use the radio
buttons to select one of the available standards for the current constituent (box C). The
selection is not recorded, however, until the APPLYSTANDARD command button is pressed.
Data Grids
Data grids are used in many different ways throughout the IWEM software: to
display data, to accept data, a combination of data display and entry, or to select a grid
item that affects other controls on a screen. As a user, you will need to manipulate these
grids to view, enter and select information. The grids are very similar to a spreadsheet in
that the column widths and row heights can be manipulated with the mouse by moving
the mouse cursor over the separators along the left side or top of the grid until the cursor
changes to a horizontal or vertical bar. When the cursor changes, click and drag the
mouse until you are happy with the new grid dimension, then release the mouse button.
Moving from cell to cell can be controlled by mouse clicks or by the ITABl or lARRO/Vl keys
as explained in Section 5.2.2.
Selecting a particular row of the grid is accomplished by clicking on the cell in
that row or along the left border of the grid or using the ITABl or lARROM keys to move to a
particular row. In the screen in Figure 5.4, removing a constituent from the list displayed
in the data grid (box G) requires selecting the row of the grid and then clicking the
command button with the left-pointing arrow (box E). Selecting a row in a grid is also
required when you are assigning a standard to a constituent on the screen presented in
Figure 5.5. When moving from row to row in this grid (box A), the radio buttons (box C)
and text boxes (box E) change as a function of the constituent displayed in the selected
grid row. In addition, when a standard has been selected, the last column in the grid is
updated to reflect the selected standard.
5-12
-------
IWEM User's Guide Section 5.0
Command Buttons
Command buttons are used throughout the tool to execute an action, to navigate
from screen to screen, to verify a choice, or to acknowledge a message. Figure 5.4 shows
a screen from IWEM where command buttons are used for various purposes: navigation
(boxes D, H), moving information (box E), and initiating some action (box F). Command
buttons are activated by a mouse click or by pressing the (ENTER key when the button is
highlighted or active. The screen in Figure 5.5 (box D) uses a command button to verify a
selection made with a radio button group and then updates a cell in a data grid with the
selected standard.
Drop-down Lists
Drop-down lists are used to make one selection from a list and then display only
the selected item. In some cases, the list may be modified by the user. In Figure 5.6, you
can select from the list of chosen constituents (box A) to view and/or edit constituent
properties. The data grids are updated based upon the selection in the drop-down list. In
Figure 5.7, a drop-down list is used to choose from a pre-defined list of options (box A),
however, you may enter your own data. This type of control is usually referred to as
"combo" box control: a combination of a text box control and drop-down box control.
5-13
-------
IWEM User's Guide
Section 5.0
A. Drop-down lists
to choose item
1
__J_nJ x |
J Constituent List (20
I Constituent Properties (21) | Reference GWConc. (22)
Select a constituent from the first list below. Properties of IP
properties of a daughter product select it from the second
iected constituent will be displayed in the gr ds. To see the
Waste Constituents: 1107-13-1 Acrylonitrile
Daughter products: |
Default Properties of 107-13-1 Acrylonitrile
3
User Supplied Property Values
Property
Koc(L/kg)
Rate
Acid-catalyzec
hydrolysis - Ka
(/mol/yr)
-------
IWEM User's Guide
Section 5.0
A. Drop-down list
for data entry or
selection
Tier 2 Input
WMU Type (16)
WMU Parameters (17) [ Subsurface Parameters (18)
This screen allows you to enter or change surface impoundment parameters. Justifications for parameters ere r
Distance to Nearest Surface Water Body (m) [Unknown, but less than 2000m (Model uses 360m)
iquired.
Parameter
Value | Data Source
Depth of base of the SI below ground surface (m)
Sludge thickness (m)
Surface impoundment area (m"2) [requires site specific value]
Ponding depth (m) [requires site specific value]
Operational lite (yr)
150
0
.2
1234556
1.6
Default
Default
Default
Topo maps
Initial Estimate
50 Default
« Previous
Apply Defaults
Next»
B. Command Button
to populate
data grid
Figure 5.7 Example IWEM Screen Identifying Several Types of Controls.
5-15
-------
IWEM User's Guide
Section 5.0
5.2.3 How Do I Use Online Help?
IWEM provides online |hELP| that can be accessed from any screen either by
pressing the IF1I key or by selecting hELP CONTENTS from the IWEM menu bar. Selecting
hELP CONTENTS] from the IWEM menu bar will cause the screen shown as Figure 5.8 to be
displayed.
Help Topics: Industrial Waste Management Eval
Contents j |ndex \ Find |
Click a book, and then click Open. Or click another tab, such as Index.
Program Overview
Working With IWEM
^ Program Components
^ Navigating the IWEM Interface
^t Understanding IWEM Inputs
^ Interacting with EPACMTP
^ Interpreting TWEM Results
^ IWEM Reports
) Help for Specific Dialogs
^p Introductory Screens
^ Tier 1 Evaluation Screens
^ Tier 2 Evaluation Screens
^ Windows Available at Any Time
Open
Print...
Cancel
Figure 5.8 IWEM Online Help.
From this main hELP screen (shown in Figure 5.8), you can use the mouse or
keyboard keys to explore the IGcNTENTSl tab which is automatically displayed by default, or
you can navigate to either of the other two tabs: I INDEX! and IFiNDl. On the IGoNTENTSl tab,
you can double-click on the book icon to the left of each topic to expand that topic; some
main topics contain multiple levels of sub-topics, but after navigating down to the most
detailed level, a |hELP| screen will be displayed that contains descriptive text that explains
a particular feature of the IWEM software. Many of these text descriptions contain
5-16
-------
IWEM User's Guide Section 5.0
hyper-text links to related items in the online hELP; these hyper-text links are formatted
with colored and underlined text. Double-click on any hyper-text link to display detailed
information about that topic. On the llNDEXl tab, you can find help for a particular topic by
typing a phrase into the text box at the top or by selecting a topic from the list box at the
bottom and then clicking the IDSPLAYl button. The IFlNDl tab enables you to search for
specific words and phrases in online hELP, instead of searching for information by
category. Just follow the on-screen prompts on the |FiND| tab to create and search a list of
words in online hELP.
Pressing the IF1I key will automatically display an online |hELP| screen that is
appropriate for the current IWEM screen that you are using. This information is similar
to that presented in Sections 5.4 and 5.5 of this document and is also presented in the last
topic listed on the IGoNTHsnBl tab: IhELP FOR SPECIFIC DIALOGS!.
Once you find the information you need in online hELP, you can use the main
menu or the command buttons at the top of the |hELP| screen to skip to other sections of
online hELP or to print out a particular topic.
5.2.4 How Do I Save My Work?
You have several options within the IWEM software to save your analysis. After
performing a new Tier 1 or Tier 2 analysis, you can click on the ISAVEI button on the
Toolbar or choose IFlLElSAVEl or IFlLElSAVE Asl from the Menu Bar to launch the standard
Windows iSave Asl dialog box. If you open a saved analysis, and then make changes to it,
clicking on the ISAVEI button on the Toolbar or choosing IFlLElSAVEl from the Menu Bar
will overwrite the contents of your original file with the current analysis settings; if you
want to save these changes to a new file, you must choose IFlLElSAVE Asl from the Menu
Bar. If you forget to save before trying to exit the IWEM software, a dialog box will
automatically ask if you want to save your data before exiting the software.
For each saved analysis, IWEM creates two project files:
*.wem file
*.mdb file
The combination of these two files completely describes the information you have
entered (*.mdb) and any model-generated results (*.wem). The asterisk (*) is replaced by
the name you assign to the project; the files will be saved in the project folder you
specified.
5-17
-------
IWEM User's Guide Section 5.0
Note that IWEM will not allow you to save both model inputs and results at a
point where the inputs do not correspond to the model-generated results (e.g., when Tier 2
results have been generated, you return to an input screen, change an input and attempt to
save the project). If you do choose to save your work in a situation like this, only the
inputs will be saved; that is, when you later open up this file, you will have to run either
the Tier 1 or Tier 2 analysis to create the corresponding results.
You may open a previously saved IWEM analysis by clicking on any one of the
following options:
lOPENl button on the Toolbar
IFlLE|OPENl selection from the Menu Bar
IOPEN SAVED ANALYSIS (*.WEMFiLE)l radio button from the I IWEM ANALYSIS
OPTIONS! dialog box (see Item B in Section 5.3)
Once the lOPENl dialog box is displayed, highlight the appropriate file and click the
lOPENl button to open the desired file. You will then see a dialog box in which you can
specify what type of analysis you want to perform - Tier 1 or Tier 2 (see Item B in
Section 5.3).
5.2.5 How Do I Get Help If I Have a Problem or a Question?
If you have a copy of the Guide CD, you can open and read this User's Guide on-
screen while the IWEM software is running on your computer. You may find it easier to
use IWEM's online help or to print out a copy of the User's Guide and refer to this hard
copy while you are learning to use the IWEM software or to use the IWEM online |hELP|
(see Section 5.2.3). This section of the User's Guide contains screen-by-screen
instructions for using the software.
A dialog box containing a keyword or parameter definition used in IWEM can be
displayed by clicking on any underlined text in the Data Requirements screen (see Screen
3, in Section 5.3). These definitions can also be displayed at any time by choosing
| DEFINITION WNDCW from the I-ELP| menu.
If you have a technical question about installing or running the IWEM software,
you should contact the RCRA Information Center. This information center is a publicly
accessible clearinghouse that provides up-to-date information on RCRA rulemakings and
responds to requests for regulatory publications and information resources. Please note
that the information center cannot provide regulatory interpretations.
To get your technical questions about the IWEM software answered, please
contact the RCRA Information Center in any of the following ways:
548
-------
IWEM User's Guide Section 5.0
E-mail: rcra-docket@epa.gov
Phone: 703-603-9230
Fax: 703-603-9234
In person: Hours: 9:00 am to 4:00 pm, weekdays, closed on Federal Holidays
Location: U. S. EPA
West Building, Basement
1300 Constitution Avenue, NW
Washington, DC
Mail: RCRA Information Center (5305W)
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0002
When contacting the RCRA Information Center, please cite RCRA Docket
number: F1999-IDWA-FFFFF.
5.2.6 How Do I Begin Using the IWEM Software?
The following subsections provide a screen-by-screen tutorial that describes the
data you are asked to enter at each screen and your data entry options (for instance, some
Tier 2 input data are required and others are optional). The guidance will assist you in
performing a Tier 1 and a Tier 2 analysis for an industrial WMU to determine the
minimum recommended WMU design that will be protective of ground water. You will
not need all the information provided here because this document addresses all WMU
liner designs and several different levels of site-specific data for Tier 2. Follow only
those subsections that are applicable to your particular waste and WMU.
5.3 Introductory Screens (Screens 1 through 5)
The text on Screens 1 through 5 provides a brief introduction to the IWEM
software. Specifically, these screens present an overview of IWEM statement regarding
proper use of the model and coordination with regulatory agencies, a list of data input
requirements, a summary of model limitations, and the option to begin a Tier 1 or Tier 2
evaluation.
The key operational features of the introductory screens are as follows.
5-19
-------
IWEM User's Guide Section 5.0
The features identified in Figures 5.9 through 5.13 are explained in more detail in
the following paragraphs.
A. Explanatory Text about IWEM
The following five screens contain brief introductory information on the following
aspects of the software:
Screen 1: An overview of the IWEM software
Screen 2: How to use IWEM
Screen 3: Data requirements
Screen 4: Model limitations
Screen 5: Evaluation types
5-20
-------
IWEM User's Guide
Section 5.0
i * ^ Introduction
njxj
IWEM Overview (1)
Purpose: This program is designed to give facility managers, regulatory agency staff, and
citizens a simple-to-use tool to evaluate appropriate liner systems for landfills, surface
impoundments, and waste piles, and to evaluate whether wastes are suitable for land application.
How: This program provides the results of fate and transport modeling of constituents from a
waste management unit through subsurface soils to ground water. The model contains two
evaluation tiers. Tier 1 provides recommendations for each type of waste management unit,
based on estimated constituent concentrations in leachate from the unit. Tier 2 provides
location-adjusted recommendations that are more tailored to a specific site, while still less
resource intensive than a detailed site-specific analysis.
Tier 2 allows the user to enter data for a limited
waste characteristics, to get recommendations
i umber of site-specific parameters, along with
or protective unit design and management.
Results: The model provides four types of recot imendations
Next»
Figure 5.9 Introduction: IWEM Overview (1).
5-21
-------
IWEM User's Guide
Section 5.0
Use of IWEM (2)
This model is in final form and can be used to assist in waste management decision-making.
We strongly encourage the user of this model to work with his/her State Agency prior to using this
tool or making decisions regarding design standards for new waste management units.
We also strongly encourage users to review the "Assessing Risk" section of Chapter 7 ("Protecting
Ground-water Quality") in the Guide for Industrial Waste Management for a description of the model
and a discussion of key parameters and critical issues that affect modeling results.
« Previous
Next» ( i
Figure 5.10 Introduction: Use of IWEM (2).
5-22
-------
IWEM User's Guide
Section 5.0
:orl
er 1, the model requires the following information:
WMU type.
Estimated leachate concentration for each constituent.
For Tier 2, the model requires the following location-adjusted information:
WMU type,
WMU area.
WMU depth for landfills or ponding depth for surface impoundments
Estimated leachate concentration for each constituent,
WMU infiltration rate(user-defined or select from database with soil type
and geographic location for all WMUs except surface impoundments)
Regional infiltration rate (select from database with soil type and geographic location)
For Tier 2, the model uses the following optional information (The user may
Show these introductory screens each time IWEM starts.
« Previous
Next»
Figure 5.11 Introduction: Data Requirements (3).
5-23
-------
IWEM User's Guide
Section 5.0
Model Limitations (4)
As is true of any model, this model is based on a number of simplifying assumptions which may
make the use of this model inappropriate in certain situations. This model should not be used in the
following situations:
1) If the soil and aquifer cannot be treated as uniform porous media, each consisting of a single
layer. For instance, if the aquifer is composed of limestone or fractured bedrock, ground-water flow
is likely to be significantly influenced by preferential pathways, such as solution cavities or fractures.
The model does not account for the presence of preferential ground-water flow pathways or layering
in the unsaturated or saturated zones.
2) If there is a mobile oil phase or other Non-Aqueous Phase Liquid (NAPL) present at the facility.
Significant contaminant migration may occur within such a phase (due to the differing densities of
NAPL and ground water), which is not accounted for in the model.
These are the most important limitations of the m odel. The IWEM Background Document discusses
J7 [Show these introductory screens each time IWEM starts.!
«Previous 0
Next»
Figure 5.12 Introduction: Model Limitations (4).
5-24
-------
IWEM User's Guide
Section 5.0
Choose Evaluation Type (5)
Select the Tier 1 evaluation to compare your estimated leachate concentrations against the
thresholds calculated by the EPA using national data. Choose the Tier 2 evaluation to investigate the
impact of using model input parameters that are specific to a particular facility and location. First
time users may want to begin with the Tier 1 evaluation and then proceed to the Tier 2 evaluation, if
desired.
J7 [Show these introductory screens each time IWEM starts]
«Previous A | Tier 1 Evaluation
Tier 2 Evaluation
Figure 5.13 Introduction: Choose Evaluation Type (5).
B, Vncheck to Skip Introductory Screens at Next Start-up
After reading this introductory information, you can uncheck the SHO/VTHESE
IMTRODUCTORYSCREENS EACHTllVE IWEMSfARTS check-box at the bottom of the screen to
prevent these screens from being displayed the next time the program is run. The
introductory information can be viewed at any time by choosing INTRODUCTION) from the
I HELP menu.
If you uncheck this check box, the next time you launch IWEM, you will see the
following dialog box:
5-25
-------
IWEM User's Guide
Section 5.0
IWEM Analysis Options
Start New Tier 1 Analysis!
Start NGWTier 2 Analysis
Open Saved Analysis f .wem File)
Select the ISfART NBA/TIER 1 ANALYSIS! radio button and click the lOPENl button to start
a new Tier 1 analysis; doing so will take you directly to the WMU Type (6) screen - the
first Tier 1 input screen.
Select the ISfARTNEWTiER 2 ANALYSIS! radio button and click the lOPENl button to start
a new Tier 2 analysis; doing so will take you directly to the WMU Type (16) screen - the
first Tier 2 input screen.
Select the IdPEN SAVED ANALYSIS (*.wemRLE)l radio button and click the IdPENl button to
open a previously saved IWEM analysis; doing so will launch the familiar Windows
lOPENl dialog box where you can navigate to the folder and file containing the previously
saved IWEM analysis. This file will have a ".wem" file extension. After you select the
appropriate file, the following dialog box will be displayed:
Open File For...
(* Tier 1 Analysis
P Tier 2 Analysis
I
You can select the ITiER 1 ANALYSIS! radio button and click the lOPENl button to open
your saved analysis in Tier 1; doing so will take you directly to the WMU Type (6) screen
- the first Tier 1 input screen. Or, you can select the ITlER 2 ANALYSIS! radio button and click
the IdPENl button to open your saved analysis in Tier 2; doing so will take you directly to
the WMU Type (16) screen - the first Tier 2 input screen. By default, IWEM will open
the file for a Tier 1 analysis.
5-26
-------
IWEM User's Guide Section 5.0
C. Go to Next IWEM Screen
Click the NEXT button at the bottom right of the screen to proceed to the next
screen.
D. Go to Previous IWEM Screen
Click the PREVIOUS button at the bottom left of the screen to go back to the
previous introductory screen.
E. Click to Display More Information
Clicking on any keyword displayed in blue underlined text will display a text box
containing a definition or other information about the underlined item. After reading the
definition, you can click on the OK button at the bottom of the dialog box to close the
text box and return to the Data Requirements (3) screen.
F. Move Slider Down to View More Text
Depending upon your monitor settings, you may need to use the scroll-bar on the
far right side of these screens to display more text if the complete text does not fit on the
screen all at once.
G. Go to WMU Type (6) screen
Click on the TIER 1 EVALUATION | button to begin a Tier 1 analysis for your waste.
Generally, you should perform the Tier 1 analysis first and then proceed on to the Tier 2
analysis, if appropriate. A Tier 1 evaluation begins at WMU Type (6) screen (Section
5.4).
H. Go to WMU Type (16) screen
Click on the TIER2 EVALUATION) button to begin a Tier 2 analysis for your waste.
Generally, you should perform the Tier 1 analysis first and then proceed on to the Tier 2
analysis, if appropriate. However, if desired, you can proceed directly to Tier 2 by
clicking this button. A Tier 2 evaluation begins at WMU Type (16) screen (Section 5.5).
You can also begin an evaluation by using either of these methods:
Click on the | EVALUATION) menu and choose from | TIER 11 or TIER2 , or
Click on the T1 or T21 toolbar buttons.
5-27
-------
IWEM User's Guide Section 5.0
5.4 Tier 1 Evaluation
The IWEM Tier 1 analysis automates the comparison of your expected leachate
concentration^) with the Tier 1 LCTV lookup table to produce waste management
recommendations for your particular waste. The IWEM Tier 1 analysis consists of four
main screen groups: Tier 1 Input, Tier 1 Output (Summary), Tier 1 Output (Details), and
Tier 1 Evaluation Summary. Each of the first three of these groups contains several
screens.
The Tier 1 Input screen group consists of three screens:
WMU Type (6)
Constituent List (7)
Leachate Concentration (8)
The Tier 1 Output (Summary) screen group consists of two screens:
MCL Summary (9)
HBN Summary (10)
The Tier 1 Output (Details) screen group consists of three screens:
Results for No Liner (11) [based on MCL and HBN1
Results for Single Liner (12) [based on MCL and HBN1
Results for Composite Liner (13) [based on MCL and HBN]
The overall Tier 1 result is then displayed on the Tier 1 Evaluation Summary (14)
screen.
The available options and data displayed on each of these screens are explained in
the following sections.
5.4.1 Tier 1 Input Screen Group
5.4.1.1 Tier I Input: WMU Type (6)
This is the first input screen for a Tier 1 evaluation; you can select the WMU type
and enter facility identification information on this screen, as explained below.
5-28
-------
IWEM User's Guide
Section 5.0
« Tie -1 Input
! WMU Type (6)
SelfdWMU Type
-------
IWEM User's Guide Section 5.0
Landfill
Surface Impoundment
Waste Pile
Land Application Unit
B. Enter Descriptive Facility Identification Information
Then, in the text boxes located in the lower half of the screen, enter the following
information about the WMU being evaluated:
Facility name
Address of the WMU (street, city, state, zip)
Date of waste constituent sample analysis
User name (name of the person performing the liner evaluation)
Any additional identifying information that you would like to include
All facility identification information will be included on the printed Tier 1, and if
performed, Tier 2 Evaluation Reports.
C. Go to Next IWEM screen
After entering your site information, click the | NEXT| button at the bottom right of
the screen to proceed to the next screen.
5.4.1.2 Tier I Input: Constituent List (7)
On this screen you can, select constituents expected in leachate by searching for
the name or CAS number or by scrolling through the displayed list of IWEM constituents,
as explained below.
What waste constituents can I enter in the IWEM software?
On the Constituent List (7) screen, you will find the list of waste constituents that
are included in the IWEM database. This list of constituents includes 206 organics and
20 metals. These constituents are presented in Appendix A.
5-30
-------
IWEM User's Guide
Section 5.0
D. ADD highlighted
constituents to
1 SELECTED CONSTITUENTS]
list
WMUType(6)
Constituent
Se
Constituent Name:|
CASNumberr
All Constituents
83-32-9 Acenaphthene
75-07-0 Acetaldehyde [Ethanel]
67-64-1 Acetone (2-propanone)
75-05-8 Acetomtrile (methyl cyanide)
98-86-2 Acetophenone
1 07-02-8 Acrolem
79-06-1 Acrylemide
79-1 0-7 Acrylic acid [propenoic acid]
107-13-1 Acrvlomtnle
309-00-2 Ald'rm
107-1 8-6 Allyl alcohol
62-53-3 Aniline (benzenearnme)
120-1 2-7 Anthracene
M40-36-0 Antimony
7440-38-2 Arsenic
jst (7)
iortBy
Constituent Name
CAS Number
A. Filter
ALL CONSTITUENTS
ist
Leachate Concentration (8)
Type of Constituent
ff All Constituents
l~ Organics
r Metals
Selected Constituents
71 -43-2 Benzene
75-09-2 Methylene Chloride (Dichloromethane)
7440-36-0 Antimony
« Previous
C. Select constituents
to be included in
Tier 1 analysis
F. REMOVE highlighted
constituents from
SELECTED CONSTITUENTS]
list
Figure 5.15 Tier 1 Input: Constituent List (7).
The features identified in Figure 5.15 are explained in more detail in the following
paragraphs.
A. Filter ALLGOr^nTUENTs| List
You can choose to display only organics, only metals, or all constituents by
clicking one of the radio buttons within the frame titled | TYPEOFGOrxBHTUErxTr|.
5-31
-------
IWEM User's Guide Section 5.0
B. Choose Sorting Order for ALL CCNSTnUENlS\ List
You can determine whether the constituents are sorted by name or by CAS
number by clicking one of the radio buttons within the frame titled | SORT BY .
C. Select Constituents to be Included in Tier 1 Analysis
The following keyboard functions simplify the selection of more than one waste
constituent:
To add a group of constituents that are displayed sequentially in the list (that
is, one after another without any non-selected constituents in the middle),
click on the first desired waste constituent, press down the SHIFT| key, and
then click on the last desired waste constituent. All waste constituents listed
between the first and last chosen constituents should now be highlighted.
To add a number of constituents that not are displayed sequentially, click on
the first waste constituent, and then hold down the | CONTROL | (Ctrl) key while
selecting additional constituents using the mouse.
Once your selection is complete, use the ADD button (described below) to
transfer all the highlighted constituents to your list.
D. Add Highlighted Constituents to \ SELECTED CONSTITUENTS List
Once the appropriate constituents are highlighted in the list (on the left of the
screen), you can click the ADD button ,XJ in the center of the screen to transfer it to your
list of constituents present in the leachate (on the right side of the screen). Note that a
waste constituent can also be added quickly to your list by double-clicking on it in the list
on the left. Likewise, multiple selections can be added using the same technique:
double-clicking on your highlighted list of constituents once you have created it using the
| SHIFT| or CONTROL | keys, as described above.
E. List of Constituents to be Included in Tier 1 Analysis
After adding a constituent to your analysis, that constituent's name and CAS
number will appear in the | SELECTED CONSTITUENT| listbox on the right side of the screen.
5-32
-------
IWEM User's Guide
Section 5.0
F. Remove Highlighted Constituents from SELECTED CONSTITUENTS | List
Similarly, you can click the
REMOVE) button ~3*J to remove highlighted
constituent(s) from your list of selected constituents. You may also use the short-cut
techniques previously described in item D above ( SHIFT and CONTROL keys, double-
clicking) to delete constituents.
G. Search for Constituents by Name or CAS Number
As an alternative to selecting constituents by scrolling through the display list, you
can search for constituents by entering their name or CAS number in the | SEARCH B/| box
at the top-left of the screen. IWEM will match the name or CAS number to its database
while you type and as soon as you have typed in enough information to identify one of the
listed constituents, that waste constituent will be highlighted in the list. You can use the
| ARROW| keys on the keyboard to move up or down the list if the highlighted constituent is
not exactly the one you intended to select.
You can move through the constituent display list to select a particular constituent
by using any of these methods:
To move through the list of waste constituents:
1) Use the scroll bar at the right of the displayed list
2) Use the ARROW keys on the keyboard (once one
constituent in the list is selected)
3) Type in the constituent name or CAS number in the
I SEARCH BY text box
Once your list of waste constituents is complete, you can proceed with the Tier 1
evaluation by clicking on either the screen titled | LEACHATECCNCEMTFiATlCN| or the NEXT|
button at the bottom of the screen.
5-33
-------
IWEM User's Guide
Section 5.0
5.4.1.3 Tier I Input: Leachate Concentration (8)
On this screen, you can enter the expected leachate concentration (in milligrams
per liter [mg/L]) for each selected waste constituent, as explained below. Please see
Chapter 2 - Waste Characterization of the Guide for analytical procedures that can be
used to determine leachate concentrations for waste constituents.
The Tier 1 Evaluation cannot be performed until an expected leachate
concentration is entered for each selected waste constituent.
MTier 1 Input
.JnJxJ
Leachate Concentration (8)
CAS
Constituent Name
Es
mated Leachate Concentration
(mg/L)
71-43-^
75-03-2
7440-36-0
Benzene
0.01
Methylene Chloride (Dichloromethane)
Antimony
0.02
0.03
« Erevious
Mext»
Figure 5.16 Tier 1 Input: Leachate Concentration (8).
5-34
-------
IWEM User's Guide Section 5.0
The features identified in Figure 5.16 are explained in more detail in the following
paragraphs.
A. List of Constituents to be Included in Tier 1 Analysis
The constituent names and CAS numbers for all selected waste constituents will
appear in the table on this screen.
B. Enter Expected Leachate Concentration^)
This table is similar to a spreadsheet. Using the mouse, click on the first empty
cell in the | ESTIMATED LEACHATE CONCENTRATION column, and type in your expected leachate
concentration. The concentration must be entered in units of mg/L, and cannot exceed
1,000 mg/L.1 The IWEM software will display a warning message similar to the one
shown below (after the description of item C) if you enter an expected leachate
concentration that exceeds the solubility of that constituent, as cited in the IWEM
database. If you accidentally entered the wrong value, click the | YES| button and correct
the expected leachate concentration on the Leachate Concentration (8) screen. If you
want to proceed with the evaluation using your entered value, click the No| button. In
this case, a similar warning message about your input leachate concentration will be
included in the printed report.
After entering the expected leachate concentration for the first selected
constituent, then click on the cell below, press the | TAB| key, or press the ARROW-DOWN
key to move to the next cell and enter the next concentration. Repeat this process until
you have entered expected leachate concentrations for all waste constituents. You can
move up and down through the list of leachate concentration values and edit them by
using the ARROW-UP and ARROW-DOWMJ keys on your keyboard or by using the mouse to
click on the value that you want to change and entering a new concentration value.
C. Perform Tier 1 Analysis
Simply click on the | NEXT| button at the bottom right of the screen to perform the
Tier 1 evaluation and view your results. Before allowing you to proceed, IWEM will
check to make sure that you have entered a leachate concentration for all constituents, and
will compare the leachate concentration(s) to the corresponding solubility limits in the
EPA does not expect leachate concentrations from units covered by this guidance to exceed 1,000 mg/L for
a single constituent. Additionally, the fate and transport assumptions in IWEM may not be valid at high
concentrations. Therefore, the EPA has designed IWEM so that the input expected leachate concentrations
are not allowed to exceed 1,000 mg/L.
5^35
-------
IWEM User's Guide
Section 5.0
constituent database. If any leachate concentration^) exceed the solubility limit, the
following warning message will be displayed to alert you and to ask if you want to change
the concentration value. If you select No|, the analysis will proceed.
The leachate concentration specified for Acenaphthene is greater than the cited solubility value in
the database of 4.24 mg/l.
Do you want to change the leachate concentration ?
Ves
No
5.4.2 Tier I Output (Summary) Screen Group: MCL Summary and HBN
Summary (9 and 10)
The IWEM Tier 1 analysis is essentially a query to an existing database of
modeling results. The results of this database query are immediately presented in
summary form on screens 9 and 10, as shown below in Figures 5.17 and 5.18.
5-36
-------
IWEM User's Guide
Section 5.0
IJB Tier 1 Output (Summary)
MCL Summary (9)
HBN Summary (10)
CAS Number Constituent Name
Minimum Liner Recommendation
71-13-2
Benzene
No Liner
75-09-2
Methylene Chloride (Dichloromethane)
Single Liner
7440-36-0
Antimony
SlllL|lK' L III':
Based on consideration of the MCL values of all listed constituents, the Single Liner
minimum liner recommended is:
« Previous
Detailed Results
Next»
C. Go to
Results - No Liner (II)
B. Overall
Tier 1 liner
recommendation
based on MCLs
D. Go to
HBN Summary (10)
screen
Figure 5.17 Tier 1 Output (Summary): MCL Summary (9).
5-37
-------
IWEM User's Guide
Section 5.0
H Tier 1 Output (Summary)
MCL Summary (9)
J HBN Summary (10)
Minimum Liner Recommendation
Composite Liner
No Liner
Single Liner
CAS Number
Constituent Name
71 -43-2
75-09-2
Benzene
Methylene Chloride (Dichloromethane)
7440-36-0
Antimony
Based on consideration of the HBN values of all listed constituents, the
minimum liner recommended is:
Composite Liner
« Previous
Detailed Results
Becommendation >:
i.
C. Go to
Results-No Liner (I I)
E. Go to
Tier 1 Evaluation
Summary (14)
Figure 5.18 Tier 1 Output (Summary): HBN Summary (10).
The features identified in Figures 5.17 and 5.18 are explained in more detail in the
following paragraphs.
A. Tier 1 Liner Recommendations Based on MCLs/HBNs
The results of the Tier 1 Evaluation are first presented on-screen in summary
form. The summary results are divided into two screens: one, for LCTVs calculated
based on MCLs; and one, for LCTVs calculated based on HBNs.
5-38
-------
IWEM User's Guide Section 5.0
Not all waste constituents have both an MCL and an HBN. The MCL summary
screen provides a minimum liner recommendation for each of the selected constituents
that have an MCL. Likewise, the HBN screen presents a minimum liner recommendation
for each of the selected constituents that have an HBN. These recommendations are
based on a comparison of the expected leachate concentration for that constituent to the
calculated LCTV using the constituent-specific MCL or HBN. For those constituents that
have more than one HBN, the LCTV is calculated for each HBN, and the HBN that
produces the lowest LCTV is used to determine the Tier 1 liner recommendation. The
value and type (pathway and effect) of the controlling HBN are shown on the Detailed
Results screens (11 through 13).
For each constituent in an IWEM Tier 1 evaluation, a liner recommendation that
is protective is presented in green text. If the composite liner scenario is not protective,
this message is presented in red text. If a constituent does not have a liner
recommendation on the MCL Summary (9) screen because it does not have an MCL, this
message is presented in black text.
B. Overall Tier 1 Liner Recommendation Based on MCLs/HBNs
This text box displays an overall minimum liner recommendation which is based
on consideration of all waste constituents.
The overall liner recommendation may be different based upon whether HBNs or
MCLs are being used. Depending upon the waste constituents being evaluated and the
appropriate RGC for each, you may have to create for yourself a final list of LCTV values
and minimum liner recommendations, some based on MCLs and some based on HBNs.
You should obtain direction from your state regulatory authority regarding which RGC
should be used for the Tier 1 evaluation of a particular waste.
C. Go to Results - No Liner (11) screen
Clicking on this button will take you to a detailed listing of the Tier 1 results,
including the constituent-specific LCTVs for all evaluated liner scenarios.
D. Go to HBN Summary (10) screen
Clicking on this button will take you to minimum liner recommendations based
on a comparison of expected leachate concentrations to calculated LCTVs.
5-39
-------
IWEM User's Guide Section 5.0
E. Go to Tier 1 Evaluation Summary (14) screen
Clicking on this button will skip over the Tier 1 detailed results and will take you
directly to the Tier 1 Evaluation Summary Screen where you can choose to view the Tier
1 report or proceed on to a Tier 2 Evaluation.
5.4.3 Tier 1 Output (Details) Screen Group: Results - No Liner, Single Clay Liner,
and Composite Liner (11,12, and 13)
Clicking the | DETAILED RESULTS button leads you to the detailed results of the Tier
1 Evaluation. This screen group consists of the following three screens, one for each liner
scenario: no liner; single clay liner; and composite liner. Each screen presents results
based on MCL and HBN reference concentrations for one of the liner scenarios.
The layout of these screens is the same, the only difference is the liner scenario,
which is indicated on the tab showing the screen name.
5-40
-------
IWEM User's Guide
Section 5.0
A. No-liner
LCTV based
on MCL
fTier 1 Output (Details)
Results -No Liner (11)
Results - Single Liner (1 2)
CAS Constituent MCI
71-43-2 Benzene
. 75-09-2 Methylene Chloride
(Dichloromethane)
7440-36-0 Antimony
CAS Constituent HBN
(mg/L) Cc
71-43-2 Benzene 00016
75-09-2 Methylene Chloride 0.013
(Dichloromethane)
7440-36-0 Antimony 00098
Results Based on MCL
-(mg/L) Leactee
Concentration (mg/L)
0005 001
0.005 002
0.006 003
DAF
(
22 i
B. Results of
comparison between
LCTV and expected
leachate concentratioi
Res
CTV Protective
ig/q
| 0011
2,2 0011 Ho
i
-Inlxl
ills - Composite Liner (1 3)
\
N/A 0014 No
Results Based on HBN
Leachate DAF
ncentration (mg/L)
LCTV (mg/L)
Out 22 00036
0.02 2.2 g
0.03 N/A
'Some LCTVs may be capped Details are given m Tier! Report See User's Guide or Help tor mort
« Previous
F. Go ba
Summa
screen
i ) Summary Results
. 0.029
0023
Protective? Controlling Pathway & Effect
No Inhalat
'sst
No
rnformation
ck to C. No-liner
rv Results (9) LCTV based
on HBN
on Cancer
1 Ingestjon Cancer .
Ingestron Non-cancer
Ne>
D. Results of
comparison
between LCTV
and expected
leachate
concentration
1
»
E. HBN
and effect
Figure 5.19 Tier 1 Output (Details): Results - No Liner (11).
5-41
-------
IWEM User's Guide
Section 5.0
1 Output (Detailt)
Results-No Liner (11)
Results - Single Liner (12)
B. Results of
comparison between
LCTV and expected
leachate concentration
ills - Composite Liner (13)
Results Based on MCL
CAS
75-09-2
7440-36-0
Constituent
Methylene Chloride
(Dichloromethane)
Antimony
MCL(mg/L)
0.005
0.006
Leach &IB
Concentration (mg/L)
0.02
0-03
DAF
6.2
N/A
I JTV
( i
0.031
Protective
Results Based on HBN
CAS
Constituent
HBN
uriy.'L)
Leachate
Concentration (mg/L)
DAF
LCTV
(mg/L)
Protective'
Controlling Pathway i Effed
71-43-2
Benzene
75-Q9-Z
Methylene Chloride
(Dichloromethane)
00016
0.01
6,1
0,0097
Inhalation Cancer
0.013
6.2 0.081
Ingestion Cancer
7440-36-0
Antimony
00096
0.03
N/A
O.OE9
Yes
ingestion Non-cancer
* Some LCTVs mey be capped Details are given in Tierl Report See User's Guide or Help for rtiori
Summary Results
F. Go back to
Summary Results (9)
Figure 5.20 Tier 1 Output (Details): Results - Single Clay Liner (12).
5-42
-------
IWEM User's Guide
Section 5.0
A. Composite-
liner LCTV
based on MCL
B. Results of
comparison
between LCTV
and expected
leachate
concentration
Results Based on HBN
CAS
Constituent
HBN
inig/L)
Leachate
Concentration (mg/L)
DAF
LCTV
(mg/L)
Protective?
Controlling Pathway & Etfecl
71-13-2
Benzene
00016
0,01 1.90E*04
0.5
Inhalation Cancer
75-09-2
71-10-36-0
Methylene Chlonde
(Dictiloromethane)
Antimony
0013
00098
0,02
0,03
6.30E»05
N/A
1000
Yes
1000
Yes
Ingestion Cancer
Ingestion Non-cancer
* Some LCTVs may be capped Details are given in Tierl Report, See User's Guide or Help lor more int
« Previous
Summary Results
BfiCGrnffi -ndatron
F. Go back to
Summary Results (9)
Figure 5.21 Tier 1 Output (Details): Results - Composite Liner (13).
5-43
-------
IWEM User's Guide Section 5.0
The features identified in Figures 5.19 through 5.21 are explained in more detail
in the following paragraphs.
A. Liner-Specific LCTV based on MCL
The Tier 1 constituent- and liner-specific LCTV is displayed on this screen. An
LCTV is the maximum concentration of a constituent in the waste leachate that is
protective of ground water. That is, if the concentration in the leachate does not exceed
the LCTV, then the modeled concentration in ground water (at the modeled well) will not
exceed the MCL for that constituent.
B. Results of Comparison between LCTV and Expected Leachate Concentration
The data displayed in the top window of the screen present the result on which the
liner recommendation is based for each selected constituent. The last column in the table
(with the header PROTECTIVE? ) tells you whether or not the specified liner is protective of
ground water for that constituent. This determination is made by comparing the entered
leachate concentration with the LCTV calculated from the MCL. If the expected leachate
concentration is greater than the LCTV, the liner is not recommended as being protective
("No"), whereas, if the expected leachate concentration is less than the LCTV, the liner is
recommended as being protective ("Yes"). If the LCTV is not calculated for that
constituent because the MCL is not available, "NA" (not applicable) is displayed in this
cell.
To properly interpret the results of the Tier 1 Evaluation, you should consult with
the appropriate state regulatory agency to determine which RGC should be used for each
constituent of concern. For wastes with multiple constituents of concern, you may need
to construct your own final list of liner recommendations, some from LCTVs based on
MCLs and some from LCTVs based on HBNs.
For waste streams with multiple constituents, the most protective liner specified
for any one constituent is the overall recommended liner type.
C. Liner-Specific LCTV based on HBN
The Tier 1 constituent- and liner-specific LCTV is displayed on this screen. An
LCTV is the maximum concentration of a constituent in the waste leachate from a
modeled WMU that is protective of ground water. That is, if the concentration in the
leachate does not exceed the LCTV, then the modeled concentration in ground water (at
the modeled well) will not exceed the HBN for that constituent.
5-44
-------
IWEM User's Guide Section 5.0
D. Results of Comparison between LCTVand Expected Leachate Concentration
The data displayed in the bottom window of the screen present the liner
recommendation for each selected constituent. The column with the header PROTECTIVE?
tells you whether or not the specified liner is protective of ground water for that
constituent. This determination is made by comparing the entered leachate concentration
with the LCTV based on the most protective HBN. If the expected leachate concentration
is greater than the LCTV, the liner is not recommended as being protective ("No"),
whereas, if the expected leachate concentration is less than the LCTV, the liner is
recommended as being protective ("Yes").
To properly interpret the results of the Tier 1 evaluation, you should consult with
the appropriate state regulatory agency to determine which RGC should be used for each
constituent of concern. For wastes with multiple constituents of concern, you may need
to construct your own final list of liner recommendations, some from LCTVs based on
MCLs and some from LCTVs based on HBNs.
For waste streams with multiple constituents, the most protective liner specified
for any one constituent is the overall recommended liner type. For constituents that have
more than one HBN, IWEM calculates the LCTV for each HBN and uses the HBN that
produces the lowest LCTV to determine the Tier 1 liner recommendation.
E. HBN Pathway and Effect
The exposure pathway and health effect for the HBN that is used to calculate the
LCTV, that is, the controlling HBN, is displayed in the column labeled | CONTROLLING
PATHWAY & EFFECT . IWEM accounts for direct ingestion and inhalation pathways, and
carcinogenic and non-carcinogenic health effects. The |H3N| column in the table shows
the value, in mg/L, of the controlling HBN.
F. Go Back to the Summary Results (9) screen
Clicking on this button will take you back to the Tier 1 MCL Summary Results
(9) screen.
G. Go to Tier 1 Evaluation Summary (14) screen
Clicking on the RECOMI\/ENDAT1ON| button on screen 13 will take you to the next
screen, the Tier 1 Evaluation Summary screen, where you can choose to view the
printable Tier 1 report, or proceed on to a Tier 2 evaluation.
5-45
-------
IWEM User's Guide
Section 5.0
5.4.4 Tier 1 Evaluation Summary Screen (14)
This screen (Figure 5.22) contains an overall summary of the Tier 1 evaluation
results along with options for further (Tier 2) evaluation. You can also view or print a
report of the Tier 1 evaluation by clicking on the REPORT button at the bottom of the
screen.
111 Tier 1 Evaluation Summary
To refine the
the Tier 2 evi
Tier 1 Evaluation Summary (14)
The results of the Tier 1 analysis recommend the following design:
Composite Liner
liner recommendation, you may continue on with this program. You will be guided through
luation. where you will have the opportunity to input data that are specific to your site.
In addition to gathering site-specific data for a Tier 2 analysis, you may consider pollution prevention,
treatment, and more protective liner designs as well as consultation with regulators, the public, and
industry to ensure that wastes are protectively managed.
You may print the Tier 1 results before continuing or exiting this program.
« Previous
Report
Continue
Figure 5.22 Tier 1 Evaluation Summary (14).
The features identified in Figure 5.22 are explained in more detail in the following
paragraphs.
5-46
-------
IWEM User's Guide Section 5.0
A. Overall Tier 1 Liner Recommendation
The Tier 1 liner recommendation, based on consideration of all available RGC
values for each waste constituent, is displayed at the top of this screen. For landfills,
surface impoundments, and waste piles the available recommendations are: "no liner,"
"single clay liner," "composite liner," or "not protective." For LAUs, the available
recommendations are: "no liner" or "not protective." If your Tier 1 evaluation results in a
recommendation of "not protective," this indicates that either the chosen WMU is not
appropriate for managing your waste or you may need to continue to a Tier 2 or Tier 3
analysis to further evaluate your site.
B. List of IWEM Options
After reviewing your Tier 1 results on-screen, you can choose to continue by,
Going back to the previous screens of the Tier 1 results by clicking on
the PREVIOUS button,
Viewing the Tier 1 report by clicking the REPORT | button, or
Beginning a Tier 2 Evaluation by clicking the CONTINUE button.
Or, you can choose to save your results and exit IWEM as described in Section
5.2.4 of this User's Guide.
C. Display Tier 1 Reports
Clicking on the REPORT button first displays a dialog box with the following
question:
| DO YOU WANTTOSHOWTHE DETAILS?
Choosing | No| will display a summary version of the IWEM Tier 1 Report. This
short version of the report includes the following information and data:
Facility data entered on Screen 6
List of selected constituents and their corresponding leachate
concentrations
Tier 1 summary results for each selected constituent, based on both MCLs
and HBNs
Tier 1 detailed results for each selected constituent, based on both MCLs
and HBNs, and including an explanation of any caps or warnings that
apply to the presented LCTVs
5-47
-------
IWEM User's Guide
Section 5.0
Choosing | YES| will display a complete version of the IWEM Tier 1 Report. This
detailed version of the report includes the following additional information and data:
Constituent properties and RGCs for each selected constituent, including
full references for the data sources.
After making your choice, the selected report will be displayed on-screen. The
following toolbar buttons to print, save, and scroll through the pages of the report are
prov ided along the top of the screen:
Print the report; the PRINT | dialog box allows you to adjust printer
settings or print all or selected pages.
Export the report in order to save it to a file; after specifying the file
type, destination type, and the pages to be included, the | CHOOSE
EXPORT RLE | dialog box then appears; you can specify the file type, and
then select the file name and directory. The file types in this list are
dependent upon what software you have installed on your personal
computer. Most users will find that the option for PDF format will
produce a document-ready report.
View the next page of the report.
View the last page of the report.
View the previous page of the report.
View the first page of the report.
5-48
-------
IWEM User's Guide
Section 5.0
1QO%
Change the display size of the report.
A Tier 1 Report Includes:
1) List of selected waste constituent(s) and constituent
data
2) Minimum liner requirement based on MCLs
3) Minimum liner requirement based on HBNs
4) Data used to calculate the LCTV for each liner
An example Tier 1 report is included in this User's Guide in Appendix B.
D. Go to WMU Type (16) screen
Clicking here will take you to the Tier 2 Input screen. WMU Type, facility
description information, and your list of selected Tier 1 constituents are automatically
transferred to the Tier 2 analysis.
5.4.5 Exiting the IWEM software
You can exit the IWEM software by clicking on the | RLE| menu, and choosing
| EXIT . If you forget to save before trying to exit the IWEM software, a dialog box will
ask if you want to save your data before exiting the software.
5-49
-------
IWEM User's Guide Section 5.0
5.5 Tier 2 Evaluation
In a Tier 2 evaluation, IWEM analyzes available site-specific data to develop liner
recommendations that are more tailored to your site conditions than the national,
screening-level Tier 1 evaluations. This section of the User's Guide describes the Tier 2
input and results screens.
The main Tier 2 Input screen group (Figure 5.23) consists of the following screens
and dialog boxes:
WMUTvpe(16)
WMU Parameters (17)
Subsurface Parameters (18)
Infiltration (19)
Climate Center List (19a)
Constituent List (20)
Enter New Constituent Data (20a)
Add New Constituent (20b)
Add New Data Source (20d)
Constituent Properties (21)
Toxicity Standards (22)
Input Summary (23)
After you complete the Tier 2 data inputs, IWEM will begin the Tier 2 analysis.
The Tier 2 Evaluation Run Manager (24) screen is displayed during the Tier 2
analysis. Depending upon the model inputs and the speed of your PC, a Tier 2 analysis
may take anywhere from several minutes to several hours to complete.
The Tier 2 results are then presented on the Summary Results (25) screen. The
Detailed Results screen for the Tier 2 Evaluation varies according to the option you chose
for the infiltration rate. When using an IWEM-generated location-based estimate of
infiltration, the Detailed Results screen for Tier 2 consists of either three screens (for
landfills, surface impoundments, and waste piles) or one screen (for LAUs):
Results - No Liner (26)
Results - Single Clay Liner (27)
Results - Composite Liner (28)
5-50
-------
IWEM User's Guide Section 5.0
When using a user-specified infiltration rate, the Detailed Results screen for
Tier 2 consists of only a single screen:
User-Defined Liner Results (28)
The overall Tier 2 result is then displayed on the Tier 2 Evaluation Summary (29).
The available options and data displayed on each of these screens and dialog
boxes are explained in the following sections.
5.5.1 Tier 2 Input Screen Group
If you begin with the Tier 1 Evaluation and choose to proceed to the Tier 2
Evaluation with the same selected constituents, then the WMU type, list of waste
constituents, and the expected leachate concentrations specified in Tier 1 are
automatically transferred to Tier 2. These values can also be edited in Tier 2, if desired.
5.5.1.1 Tier 2 Input: Waste Management Unit Type (16)
The first screen of the Tier 2 Input screen group, WMU Type (16), is identical to
the Tier 1 WMU Type screen.
5-51
-------
IWEM User's Guide
Section 5.0
M Tier 2 Input
WMU Typ
> (16) ] WMU Parameters (17) ]
Select WMU T^e
<" Surface Impoundment
<~ Waste Pile
<~ Land Application Unit
Facility Identification Information
Southern Industries Landfill
122 Industrial Ave
Raleigh
27611
October 31,1998
Next»
B. Enter descriptive
facility information
Figure 5.23 Tier 2 Input: WMU Type (16).
The features identified in Figure 5.23 are explained in more detail in the following
paragraphs.
A. Choose WMU Type
First, select one of the following choices from the | SELECT\AMJTYPE) option list by
clicking on the appropriate radio button:
Landfill
Surface Impoundment
Waste Pile
Land Application Unit
5-52
-------
IWEM User's Guide Section 5.0
B. Enter Descriptive Facility Information
In the text boxes located in the lower half of the screen, enter the following
information about the WMU being evaluated:
Facility name
Address of the WMU (street, city, state, zip)
Date of waste constituent analysis
Your name (name of the person performing the liner evaluation)
Any additional identifying information that you would like to include
All information entered in these text boxes will be included on the printed Tier 2
Evaluation Reports (and in the Tier 1 report, if these data were carried over from a
previous Tier 1 analysis).
5.5.1.2 Tier 2 Input: WMU Parameters (17)
The Tier 2 evaluation uses site-specific WMU data to assess potential ground-
water impacts. The WMU parameters are entered on the WMU Parameters (17) screen.
A complete list of all WMU parameters is shown below, however, not all parameters are
applicable for each WMU type. For instance, data on the WMU's operational life is used
only for surface impoundments, waste piles, and LAUs. This parameter is not applicable
to landfills. Some parameters are marked as (required). This means that you must
provide a site-specific value for this parameter. If a parameter is not marked as
(required), IWEM will use a site-specific value if you have it. If you do not have this
data, IWEM gives you the option to select a default value, or distribution of values.
These default values are generally the median values of the distributions of values used in
Tier 1.
WMU Parameters:
Area of the WMU (required)
Distance to well
Depth of WMU (LF only) (required)
Ponding depth (SI only) (required)
Operational life of WMU (WP, SI, and LAU only)
Depth of WMU base below ground surface (LF, WP, and SI only)
Sludge thickness (SI only)
Distance to nearest surface water body (SI only)
Brief explanation for each site-specific value (required)
5-53
-------
IWEM User's Guide
Section 5.0
For each type of WMU, the Tier 2 WMU screen looks slightly different, as shown
below in Figures 5.24 through 5.27.
IJB Tier 2 Input
-JDlxl
WMU Type (16) | WMU Parameters (17) \ Subsurface Parameters (18) |
This screen allows you to enter or change land application unit parameters. Justifications for parameters are required.
A. Enter available
site-specific
values for LAU
Figure 5.24 Tier 2 Input: WMU Parameters (17) for Land Application Units.
5-54
-------
IWEM User's Guide
Section 5.0
WMUType(16)
WMU Parameters (17) Subsurface Parameters (18)
This screen allows you to enter or change landfill parameters. Justifications for parameters are required.
Perameter
Value | Data Source
6.5
Distance to well (m)
150
Landfill area (rrT2) [requires site specific value]
Depth of base of the LF below ground surface (m)
123556
Log Book
Default
Topo Maps
Default
« Previous
Apply Defaults
Ne>
A. Enter available
site-specific
values for LF
Figure 5.25 Tier 2 Input: WMU Parameters (17) for Landfills.
5-55
-------
IWEM User's Guide
Section 5.0
C. Enter or select
the distance to
the nearest surface
water body
t Tier 2 Input
WMUType(16)
Subsurface Parameters (18)
This screen allows you to enter or change surface impoundment parameters Justifications for parameters are n
Distance to Nearest Surface Water Body (m) [Unknown, but less than 2000m (Model uses 360m)
quired.
Parameter
Radial distance to well (m)
Depth of base of the SI below ground surface (m)
Sludge thickness (m)
Surface impoundment area (m"2) [requires site specific value]
Ponding depth (m) [requires site specific value]
erational life (yr)
Value | Data Source
150
Default
Default
.2 Default
1234556 Topo maps
1.6
50
Initial Estimate
Default
« Previous
Apply Defaults
A. Enter available
site-specific
values for SI
Figure 5.26 Tier 2 Input: WMU Parameters (17) for Surface Impoundments.
5-56
-------
IWEM User's Guide
Section 5.0
WMU Type (16) | WMU Pa
This screen allows you to enter or change waste pile parameters. Justifications for parameters are required
A. Enter available
site-specific
values for WP
Figure 5.27 Tier 2 Input: WMU Parameters (17) for Waste Piles.
For all Tier 2 input parameters for which you enter site-specific values,
remember to type in a brief justification or explanation of this value. This
information is required and will be included in the printed report.
The features identified in Figure 5.24 through 5.27 are explained in more detail in
the following paragraphs.
5-57
-------
IWEM User's Guide Section 5.0
A. Enter Available Site-Specific Values
Land Application Unit (Figure 5.24)
For LAUs, site-specific values for the following parameters may be entered:
Area of the LAU (required)
Distance to nearest well (optional; default = 150m)
Operational life of the LAU (optional; default = 40 yrs)
Landfill (Figure 5.25)
For LFs, site-specific values for the following parameters may be entered:
Area of the LF (required)
Distance to nearest well (optional; default = 150m)
Depth of the LF (required)
Depth of the LF base below ground surface (optional; default = Om)
Surface Impoundment (Figure 5.26)
For Sis, site-specific values for the following parameters may be entered:
Area of the SI (required)
Distance to nearest well (optional; default = 150m)
Ponding depth (required)
Operational life of the SI (optional; default = 50 yrs)
Depth of SI base below ground surface (optional; default = Om)
Sludge thickness (optional; default = 0.2 m)
Waste Pile (Figure 5.27)
For WPs, site-specific values for the following parameters may be entered:
Area of the WP (required)
Distance to nearest well (optional; default = 150m)
Operational life of the WP (optional; default = 20 yrs)
Depth of the WP base below ground surface (optional; default = Om)
5-58
-------
IWEM User's Guide Section 5.0
B. Enter Data Source
For all Tier 2 input parameters for which you enter site-specific values, remember
to type in a brief explanation of this value. This information is required and will be
included in the printed report.
C. Enter or Select the Distance to the Nearest Surface Water Body
For a SI, you must also either enter a value for the distance to the nearest
(permanent) surface water body or choose one of the default selections for this input
parameter. This parameter is used in the calculation of ground-water mounding to ensure
the model uses a realistic infiltration rate. If you do not know the exact distance to the
nearest surface water body, select "unknown" from the drop-down list by clicking on the
drop-down list control _LJ to select an approximate distance (i.e., unknown (model uses
360 m); unknown, but less than 2,000 m; unknown, but greater than 2,000 m).
5.5.1.3 Tier 2 Input: Subsurface Parameters (18)
This screen is where you enter site-specific data that describes the subsurface
environment at your site.
The subsurface parameters used in IWEM are listed below. You must select the
type of subsurface environment at your site from the supplied list. Section 6.2.3.2
provides more information on the subsurface environments. If you have no
hydrogeological information for your site, then "unknown" is an available choice. If your
list of waste constituents includes any metals, you must also provide a value for the
ambient ground-water pH. For the other subsurface parameters, you can provide a site-
specific value if you have it, but IWEM will use a default value or distribution of values
if you do not have this data.
Subsurface Parameters:
Subsurface environment (required, although "unknown" is an available
choice)
Depth to water table
Aquifer thickness
Regional hydraulic gradient
Aquifer hydraulic conductivity
Ground-water pH (required only if a metal is included in the waste
constituents)
5-59
-------
IWEM User's Guide
Section 5.0
Subsurface Parameters (IB) [^
Infiltration (19)
This screen allows you to enter or change the subsurface parameters
You MUST select a Subsurface Environment. If you select 'unknown' then the default values will be used for all parameters. In addition, you WAY enter values for one or
more hydrogeologic parameter(s). Data sources are required.
Select the Subsurface Environment: |
Alluvial & Flood Plain with Overtoank Deposits
Alluvial & Flo get P'l^in ''itflin!J-' ''i'1
Depiti to water table (m)
Aquiter hydraulic conductivity (in/v,
Regional hydraulic gradient
kness(m)
Till and Till over Outwash
Unconsoltdated and Semiconsolidated Shallow Aquifers
Coastal Beaches
Solution Limestone
Unknown
« Previous
Next»
A. Select subsurface
environment
Figure 5.28 Tier 2 Input: Subsurface Parameters (18)
Selecting Subsurface Environment.
The features identified in Figure 5.28 are explained in more detail in the following
paragraph.
A. Select Subsurface Environment
IWEM includes twelve different types of subsurface environments that represent
different hydrogeological settings. If you do not know what type of environment is
appropriate for your site, select "unknown." In effect, the "unknown" subsurface
environment is an average of the twelve known environments. You must select one of
the available subsurface environments. Figure 5.29 presents an example of what this
screen will look like if you choose one of the available subsurface environments (the
screen appears only slightly different if you set the subsurface environment to
"unknown").
5-60
-------
IWEM User's Guide
Section 5.0
This screen allows you to enter or change the subsurface parameters
You MUST select a Subsurface Envitonrnent. II you select 'unknown' then the default values will be used for all parameters. In addition, you MAY enter values for one or
more hydrogeologic parameter(s). Data sources are required.
Selectthe Subsurface Environment; (Sand and Gravel _^J
\ Parameter
Ground-water pH value (metals
Depth to water table (m)
. ikauliccGnduclrvityfm/yr)
Regional hydraulic gradient
Aquifer thickness (m)
Default
Value Data Source
I Distribution
Monte Carlo [see IWEM TBD 4.2.3.1]
Distribution
I Distribution
I Distribution
I Distribution
Monte Carlo [see IWEM TBD 4.2.3.1]
Monte Carlo [see IWEM TBD 4.2.3.1]
Monte Carlo [see IWEM TBD 4.2.3.1]
Monte Carlo [see IWEM TBD 4.2.3.1]
« Previous
Next»
A. Enter available
site-specific values
Figure 5.29 Tier 2 Input: Subsurface Parameters (18) -
Entering Values of Subsurface Parameters.
The features identified in Figure 5.29 are explained in more detail in the following
paragraphs.
A. Enter Available Site-Specific Values
If you select one of the twelve subsurface environments, then screen 18's
appearance will be similar to that shown in Figure 5.29. You may enter values for any
subsurface parameters for which you have site-specific data. However, you may enter
data for only some (but not all) of the parameters and continue with the Tier 2 analysis.
In this case, a distribution of parameter values that corresponds to the specified
subsurface environment will be used to generate values for any parameter for which you
do not enter a site-specific value. The word "Distribution" displayed in the default value
column and the phrase "Monte Carlo [see IWEM TBD 4.2.3.1]" in the data source
5-61
-------
IWEM User's Guide Section 5.0
column indicate that IWEM will randomly select values for this parameter from the
appropriate distribution during the Tier 2 analysis process. The distributions reflect the
range of values that each parameter can have.
If you do not know the type of subsurface environment beneath your WMU, then
you can select the "unknown" subsurface environment. For the unknown subsurface
environment, a default value (the one displayed in the default value column) will be used
for any input parameter for which you do not enter a site-specific value; that is, the value
displayed on the screen will be input to the model as a constant value (no distribution of
values is used). Each default value corresponds to the mean value of the available data
for that parameter from all twelve subsurface environments. This value is representative
of a national average. You may enter values for subsurface parameters that you have site-
specific data for. However, if you are lacking data for one or more of the requested
parameters for your site, you can still perform a Tier 2 analysis. In this case, the default
(displayed) value will be used. The displayed value in the data source column and the
phrase "Default [see IWEM TBD 4.2.3.1]" in the data source column indicate that IWEM
will use the displayed default value for this input parameter in the Tier 2 analysis.
The subsurface parameters for which you can enter site-specific values are:
Ground-water pH
Depth to water table
Aquifer hydraulic conductivity
Regional hydraulic gradient
Aquifer thickness
A site-specific value for ground-water pH is only required if the modeled waste
constituents include metals; this parameter is not needed as a user-input for modeling
organic constituents.
B. View or Edit Data Source for Each Value
If you select one of the twelve subsurface environments, then for any Tier 2 input
parameter that you enter as a site-specific value, you must document the data source or
explain the value used. IWEM provides a default data source for all optional data. The
default data source is "Monte Carlo [see IWEM TBD 4.2.3.1]" as a reminder that a
distribution of values (rather than a single, constant value) is being used for this
parameter. All data sources or explanations for default or user-specified data are included
in the printed Tier 2 report.
5-62
-------
IWEM User's Guide Section 5.0
If you select the unknown subsurface environment, then for any Tier 2 input
parameter that you enter as a site-specific value, you must document the data source or
explain the value used. IWEM provides a data source for all default data. For the
"unknown" subsurface environment, the default data source is "Default [see IWEM TBD
4.2.3.1]" as a reminder that a single, constant value (rather than a distribution of values)
The information provided on screens 17 and 18 completely describes the WMU
setting as required by IWEM. When you click NEXT| on screen 18, IWEM will
check your inputs to evaluate whether the setting you have described is physically
possible and consistent with the EPACMTP model.
IWEM verifies that:
the bottom of LFs and WPs are above the water table; and
the elevation of ponded water in a SI is higher than the water table
elevation.
If you do not specify the depth to ground water, IWEM will postpone this evaluation
until screen 19 has been completed. IWEM will notify you if either of the above
conditions is violated with a message box informing you of your options. If none of
the suggested options is consistent with the conditions at your site, IWEM is not
appropriate for your site, and you should consider a Tier 3 analysis. Consult Section
2.3 of this User's Guide, or the IWEM Technical Background Document (U.S. EPA,
2002c) for more information on the assumptions built into the EPACMTP model
which may make it unsuitable for a particular site.
is being used for this parameter. All data sources or explanations for default or
user-specified data are included in the printed Tier 2 report.
5.5.1.4 Tier 2 Input: Infiltration (19)
On screen 19 (Figure 5.30), you enter or select the infiltration rate that IWEM will
use in modeling your site. The first selection is whether you have site-specific infiltration
data, or wish to use IWEM default data if you do not have site-specific data.
In IWEM, infiltration refers to the liquid (leachate) that infiltrates to the
subsurface directly below a WMU; recharge refers to the natural precipitation that
infiltrates to the subsurface outside the footprint of the WMU.
5-63
-------
IWEM User's Guide
Section 5.0
Choose one of the following options for specifying infiltration rate:
YES, I HAVE9iE-spEancIMPLICATION| (i.e., a measured, modeled, or calculated
value);
No, I DO NOT HAVE 9TE-SPEanc INFLATION | (the model will estimate values for
you based on the selected soil type (or waste type permeability, for WPs) and
geographic location of the WMU site).
^^^^~ T v
[ Subsurface Parameters (18) [
3SUI
Do you have site-specific infiltration?
P Yes, I have Site-Specific Infiltration Results will be reported
for your user-defined liner.
Soil Data
Please select a soil type.
Coarse-grained soil (sandy loam)
Medium-grained soil (silt loam)
Fine-grained soil (silty clay loam)
Constiti ant List (20)
Mo. I do not have Site-Specific Infiltration. Re
reported forJhejJefault linertype(sj._
ultswillbej
i
r Local Climate Data -
Nearest Climate Center
View Cities List
Selected city Ptease select a city
Infiltration Rates (m/yr)
No Liner
| Single Liner | Composite Liner
<
uL
1
_^
Recharge Rate (m/yr)
All Scenarios
« Previous
Next»
Figure 5.30 Tier 2 Input: Infiltration (19) - Initial Appearance.
5-64
-------
IWEM User's Guide
Section 5.0
At its initial appearance (with the | No, I DO NOT HAVE 9TE-SPEQFIC INFILTRATION | radio
button selected by default), screen 19 will generally appear like Figure 5.30 (although this
screen can be slightly different depending upon the selected WMU type).
jl Tier 2 Input
VMU Parai; -
| Subsurface Parameters (1 8) |
Do you have site-specific infiltration?
.- Yes, 1 have Site-Specific Infiltration. Results will be reported .- No,
for your user-defined liner. rep
Infiltration (19) [
Id
3rtt
Constituent List (20)
o not have Site-Specific Infiltration. Results will be
sd for the default liner type(s).
Please select a soil tv/oe" [Coarse-qramed soil (sandy loam)
1
/ledium-aramed soil (silt oam)
Fine-grained soil (silty clay loam)
[Unknown soil type
I rw r.
Nearest Climate Center
Selected city
_
No Liner
0.326
View Cities List
Greensboro NC
« Previous
F
_
All Scenarios
0.326
Next»
Figure 5.31 Tier 2 Input: Infiltration (19) - Land Application Unit.
If you do not have a site-specific value for infiltration, once you have selected a
soil type (or waste type permeability, for waste piles) and climate center, screen 19 will
appear like one of the screens presented in Figures 5.31 through 5.34 depending on the
WMU type you have selected.
5-65
-------
IWEM User's Guide
Section 5.0
j| Tier 2 Input
Jn|x|
Subsurface Parameters (18) [ jjnfijtration (19]J
Constituent List (20)
Do you have site-specific infiltration?
,~ Yes. I have Site-Specific Infiltration. Results will be reported ff No. I do not have Site-Specific Infiltration. Results will be
for your user-defined liner. reported for the default liner type(s).
Please select a soil type:
Nearest Climate Center
Selected city
_ .
No Liner | Si
0.326 0.(
±LJ
Coarse-grained soil (sandy loam)
Fine-grained soil (silty clay loam)
Unknown soil type
View Cities List
Greensboro NC
_ _ . , .
ngle Liner Composite Liner All Scenarios
36 Monte Carlo 0.326
t
« Previous
Next»
Figure 5.32 Tier 2 Input: Infiltration (19) - Landfill.
5-66
-------
IWEM User's Guide
Section 5.0
j| Tier 2 Input
Subsurface Parameters (18)
Infiltration (19)
Constituent List (20)
Do you have site-specific infiltration?
-- Yes, I hove Site-Specific Infiltration. Results will be reported ,~ No. I do not have Site-Specific Infiltration. Results will be
for your user-defined liner. reported for the default liner type(s).
Soil Data ===^======^^^^^^^=^^^^^^^^=^^^^^^^^^^^^^^^=
Please select a soil type: |Coars^trainedsoil(sandyloarri)
rvtedium-drained sen ism looml
Fine-grained soil (silty clay loam)
Unknown soil type
Local Climate Data
Nearest Climate Center
View Cities List
Selected city Greensboro
Infiltration Rates (m/yr)
NC
No Liner
I Single Li
iner
Monte Carlo
Monte Carlo
I Composite Liner
Monte Carlo
Recharge Rate (m/yr)
All Scenarios
0.326
« Previous
Next»
Figure 5.33 Tier 2 Input: Infiltration (19) - Surface Impoundment.
5-67
-------
IWEM User's Guide
Section 5.0
|f Tier 2 Input
»M1~:> J Subsurface Parameters (18) J Infiltration (1 9) | Constituent List (20)
Do you have site-specific infiltration?
P Yes, 1 have Site-Specific Infiltration. Results will be reported ^ |No, 1 do not have Site-Specific Infiltration. Results will be j
for your user-defined liner. jreported for the default liner typejs).
Soil Data
PlpnsRSRlfirtnsniltvna- | Coarse-grained soil(sandy loam)
IBratHllnBilr-llitailai
ilrsilt loam)
Fine-grained soil(silty clay loam)
Unknown soil type
Reese select a permeability Low permeability
corresponding to waste type: Medium permeability *f_ , View Cities List
Hiqh permeability Climate Center
_ . ,
No Liner | Single Liner
Monte Carlo Monte Carlo
r-, u r^ . / / \
Compos te Liner All Scenarios |
Monte C< ilo 0.326
|_ J J
« Previous
Next»
F. Select waste
type according
to permeability
Figure 5.34 Tier 2 Input: Infiltration (19) - Waste Pile.
The features identified in Figures 5.30 through 5.34 are explained in more detail
in the following paragraphs.
A. Specify Infiltration Data Option
Displayed at the top of screen 19 is the following question:
"Do you have a site-specific value for infiltration rate?"
Select one of the two available options:
YES, I HAVE A9TE-SPEQFIC INFILTRATION RATE|, or
NO, I DO NOT HAVE A9TE-SPEQFIC INFILTRATION RATE |
5-68
-------
IWEM User's Guide Section 5.0
If you choose | No , the Tier 2 evaluation will be performed for the default liner
type(s). There are three liner types for landfills, surface impoundments, and waste piles
(no liner, single clay liner, and composite liner). IWEM will evaluate only the no-liner
scenario for land application units because engineered liners are not usually used at this
type of facility.
If you choose | YES| , the Infiltration Screen will appear as in Figure 5.36 and the
Tier 2 evaluation will be performed for your specified WMU infiltration rate. This liner
scenario is referred to as a "user-defined liner". This is the appropriate option to choose
if you know the infiltration rate for your particular liner design.
The final result of a Tier 2 analysis is a recommended minimum liner design that
is protective for all the selected constituents in your waste. When you specify a site-
specific infiltration rate, IWEM will evaluate a "user-defined liner" scenario for
protectiveness; otherwise, IWEM will evaluate all appropriate default liner scenarios.
B. Choose Soil Type
Regardless of whether or not you have a site-specific value for infiltration, you
need to specify the soil type and geographic location of the WMU so that the model can
generate a recharge rate for your site. Additionally, if you do not have a site-specific
value for infiltration, the specified soil type and geographic location are used to estimate
the infiltration rate for your site for the standard liner scenarios for landfills, land
application units, and waste piles (infiltration rates for surface impoundments are a
function of the ponding depth).
First, select the appropriate soil type from the choices shown in the SOIL DATA|
dialog box:
Coarse-grained soil (sandy loam)
Medium-grained soil (silt loam)
Fine-grained soil (silty clay loam)
Unknown soil type
If you choose one of the three default soil types, the Tier 2 Monte Carlo process
will randomly assign values for the required soil-related input parameters according to
probability distributions that are appropriate for the specified soil type. If you choose
"unknown soil type" (the default selection), the Tier 2 Monte Carlo process will randomly
select one of the three possible soil types in accordance with their nationwide frequency
of occurrence. For more details, please see Section 4.2.3.2 of the IWEM Technical
Background Document (U.S. EPA, 2002c).
5-69
-------
IWEM User's Guide Section 5.0
C. Choose Climate Center
For unlined units, except Sis, and for single clay-lined LFs and WPs, infiltration
and recharge rates for representative regions and locations, or "climate centers," around
the country have been calculated based on meteorological data and soil type. By
choosing the climate center that is representative of the modeled WMU site, you can use
the infiltration and recharge rate(s) for this climate center as an estimate of the rate(s)
expected at your site.
In many cases, selecting the climate center that is closest to your site will provide
the best estimate of infiltration rate. A map of the IWEM climate centers is presented in
Figure 6.4 of Section 6.2.3.3 of this document. You should, however, verify that the
overall climate conditions at the selected climate station are representative of your site.
Section 4.2.2 of the IWEM Technical Background Document (U.S. EPA, 2002c) provides
a detailed discussion of how the infiltration rates were developed. To choose a climate
center, click on the | VlEWQTlESLJST button. The dialog box shown in Figure 5.35 will
appear.
D. Infiltration Rate(s)
If you do not have a site-specific infiltration rate (see Figures 5.31 through 5.34),
once you have selected a soil type and the nearest climate center, the model will estimate
the infiltration rates for each of three standard liner scenarios (no liner, single clay liner,
and composite liner) for your WMU site (note that only the no-liner scenario is evaluated
for LAUs). The resulting value(s) are listed in the table at the bottom left of the
infiltration screen.
E. Recharge Rate
Once you have selected a soil type and the appropriate climate center, the model
will estimate the recharge rate for your WMU site. The resulting value is listed in the
table at the bottom right of the infiltration screen.
F. Select Waste Type According to Permeability
For a WP, you must also specify the waste type permeability (this value is used in
determining the no-liner and single clay-liner infiltration rate). There are three choices
for waste permeability: high (4.1 x 10~2 centimeters per second [cm/sec]), medium (4.1 x
10~3 cm/sec), and low (5.0 x 10~5 cm/sec). These values are representative of wastes
commonly disposed in WPs.
5-70
-------
IWEM User's Guide
Section 5.0
To choose a climate center to provide default recharge and infiltration data, click
on the VlEWQlESUST button on the Infiltration (19) screen. The dialog box shown below
in Figure 5.35 will then be displayed.
C. Select nearest
climate center
B Climate Center 1 ist (19a)
m^^^^^^^^^^^^^^^^^^^^m
^lease select a cil
Albuquerque
Annette
Astoria
Atlanta
Augusta
Bang or
Bethel
Bismarck
Boise
Boston
iBridqep
^^^^^^w^^^^^^^^^^
f from this list
MM
AK
OR
GA
ME
ME
AK
ND
ID
VIA
ort CT
B. Slide down
to scroll
through list
-In
t
j
X
h
w
'
Brownsville TX
Burlington VT
Caribou ME
Cedar City UT
Central Park NY _^J
You selected Bridgeport CT
Cancel
<* SortbyCily
Sort by State
D. Verify
selected
climate center
A. Select
sort order
E. Enter selected
climate center and
return to
Infiltration (19) screer
Figure 5.35 Tier 2 Input: Climate Center List (19a).
5-71
-------
IWEM User's Guide Section 5.0
The features identified in Figure 5.35 are explained in more detail in the following
paragraphs.
A. Select Sort Order
You can sort the climate centers alphabetically by city or by state by choosing one
of the SORT BY options.
B. Slide Down to Scroll through List
You can view the entire list using the ARROW keys on the keyboard or by
manipulating the scroll bar to the right of the list.
C. Select Nearest Climate Center
Select a climate center by using the | ARRCW| keys to highlight an entry, or by a
single click on the entry with your mouse.
D. Verify Selected Climate Center
You can verify that the correct climate center is selected by looking at the city
name printed at the bottom of this dialog box.
E. Enter Selected Climate Center and Return to Infiltration (19) screen
Clicking on the OK| button or double-clicking on the highlighted entry will enter
your selection and return you to the Infiltration (19) screen.
If you choose the YES, I HAVE STE-SPECIFIC INFILTRATION option at the top of the
Infiltration (19) screen, then this screen will appear as shown in Figure 5.36.
-------
fWEM User's Guide
Section 5.0
[^j Tier 2 Input
Subsurface Parameters (1 8) ] Infiltration (19)
-Inlxj
Constituent List (20)
Do you have site-specific infiltration?
ff Yes, 1 have Site-Specific Infiltration. Results will be reported p No. 1 do not have Site-Specific Infiltration. Results will be
for your user-defined liner. reported for the default liner type(s).
Rnil Datn
Ploaco cplort « enil K,pB- [Coatsp-grained sculisandy loam)
EEs
LFme
Unk
o-, ~ , . .
Parameter
M Site-specific
infiltration (m/vr)
lum-grained somsilt loam)
-grained soil(silty clay loam)
i own soil type
Value
012
(
, , ,_,._ ^_ r,_*_
Nearest Climate Center
Vie
Selected city Greensboro
« Previous
Data Source
Test Value
!
n r-,,._ / I. ...
'Cities List AILScenarios
NC
Next»
A. Enter site-specific
infiltration rate
and data source
Figure 5.36 Tier 2 Input: Infiltration (19) - Site Specific Infiltration.
The features identified in Figure 5.36 are explained in more detail in the following
paragraphs.
A. Enter Site-Specific Infiltration Rate and Data Source
Enter your site-specific infiltration rate and provide a brief explanation of the data
source for your value in the DATASOURCE cell. Both the value and your explanation will
be included in the printed Tier 2 report.
5.5.1.5 Probabilistic Screening Module
The EPACMTP model used in IWEM to simulate ground-water fate and transport
incorporates certain constraints to ensure that the parameter values that are selected in the
5-73
-------
IWEM User's Guide Section 5.0
Tier 2 Monte Carlo process will represent physically realistic WMU settings. These
constraints are:
1. The base of a LF or WP must be above the water table,
or,
The elevation of ponded water in a SI must be higher than the water table
elevation; and
2. Infiltration- and recharge-induced mounding of the water table cannot rise
above the ground surface.
If either one of these constraints is violated, the model will not run. Given the
range of parameter values that may be generated in the Monte Carlo process, in
combination with user-specified site-specific values, it is possible that the simulation
model might encounter a scenario where a constraint is frequently violated, and the model
is unable to complete the Monte Carlo simulation process.
IWEM screens your Tier 2 input values and parameter distributions prior to
performing the EPACMTP Monte Carlo simulation to ensure that an adequate number of
Monte Carlo realizations can be conducted. The Probabilistic Screening module of
IWEM examines your inputs to determine if you have provided complete and valid
information. If you specify a constant value for every parameter on screens 17 through
19, the screener will determine the magnitude of water table mounding (that is, IWEM
will evaluate the constraints on hydraulic connections between the WMU and the water
table). If the screening is successful, IWEM will take you to screen 20, otherwise a
message box will alert you to the most violated constraint and suggest potential remedies.
If all proposed remedies are inconsistent with site conditions, then IWEM is not
appropriate for your site and a Tier 3 analysis should be considered.
If you do not provide site-specific values for all possible Tier 2 inputs, the
screener will generate values for the missing input parameters according to their
appropriate distributions, and then evaluate the constraints. The screening process
usually takes ten or twenty seconds to complete, but can take up to a minute or two. A
progress bar, like the one displayed below, is updated during the screening process.
Now checking the Feasibility of your input values .
Please Wait.
5-74
-------
IWEM User's Guide Section 5.0
As part of the screening process, IWEM will check that the aquifer that will be
modeled has a sufficiently high transmissivity to supply enough water to a domestic
drinking water well. A low transmissivity value corresponds to a combination of a low
hydraulic conductivity in the saturated zone and a small saturated thickness. If this
situation is encountered, IWEM will display a warning message dialog box like the one
shown below which asks if you want to continue. If you click | OK|, IWEM will continue
with the input parameters you provided.
v
X
Transmissivity Check Warning
IWEM has determined that the aquifer system you have described is not likely to support a
drinking water well,
If this is inconsistent with your site conditionsj you may wish to increase the value of aquifer
thickness or aquifer hydraulic conductivity,If either of these changes are inappropriate for your
site, you may still proceed with the analysis.
Do you wish to proceed with this analysis?
Yes |
No
5.5.1.6 Tier 2 Input: Constituent List (20)
This is where you select the constituents that are present in the waste, and enter
their leachate concentration. You can select constituents in several ways. You can:
Search by Constituent Name or CAS Number, or
Scroll through the list of IWEM constituents, using display and sort
options.
If you performed a Tier 2 evaluation immediately after a Tier 1 evaluation, the
waste constituents selected in Tier 1 are automatically transferred to Tier 2 and the Tier 1
leachate concentrations are also imported. If you are starting a Tier 2 evaluation and need
to enter waste constituents, follow the steps described here.
The Constituent List (20) screen for Tier 2 is nearly identical to the Tier 1
Constituent List (7) screen, and the options and controls on this screen work exactly the
same as the ones on the Screen 7. You can choose to include in your Tier 2 analysis any
of the 206 organic constituents and 20 metal constituents included in the IWEM database
5-75
-------
IWEM User's Guide
Section 5.0
(see Appendix A). However, unlike Tier 1, in Tier 2 you can also add constituents to the
IWEM list.
D. Add highlighted
constituent to
[SELECTED CONSTITUENTS!
B. Choose sorting order
for |Au CONSTITUENTS]
list
reme't
Infilfra
Search By i
instituentNamef
CAS Number: T
All Constituents
83-32-9 Acenaphthene
75-07-0 Acetaldehyde [Ethanal]
67-64-1 Acetone (2-propanone)
75-05-8 Acetonitrile (methyl cyanide)
98-86-2 Acetophenone
107-02-8 Acrolein
79-06-1 Acrylemide
79-10-7 Acrylic acid [propenoic acid]
309-00-2 Aldrin
107-18-fa\llyl alcohol
62-53-3, sniline (benzeneamme) w \
on (19)
Constituei
A. Filter
IALL CONSTITUENTSl
list
t List (20) J Constituent Properti
Sort By
" Constituent Name
~ CAS Number
Type of Constituent
< All constituents
(~ Organics
(~ Metals
s(21)
Selected Constituents
CAS
Number
Constituent Name
107-13-1 Actylonitrile
Add New Confluent
Leach ote
Concentration
(mg/L)
01
« Previous
N >xt»
G. Remove highlighted
constituent from
SELECTED CONSTITUENTS]
I. Add new
constituent
E. List of
constituents
to be included
in Tier 2 analysis
F. Enter
expected
leachate
concentration! s)
Figure 5.37 Tier 2 Input: Constituent List (20).
5-76
-------
IWEM User's Guide
Section 5.0
The features identified in Figure 5.37 are explained in more detail in the following
paragraphs.
A. Filter ALL CONSTITUENTS | List
You can choose to display only organic constituents, only metals, or a combined
list of all constituents by clicking one of the radio buttons under TYPE OF CONSTITUENT .
B. Choose Sorting Order for ALL CONSTITUENTS | List
You can determine whether the constituents are sorted by name or by CAS
number by clicking one of the SORT BY radio buttons.
C. Select Constituents to be Included in Tier 2 Analysis
To move through the list of waste constituents:
1) Use the scroll bar at the right of the display window
2) Use the ARROW keys on the keyboard (once one
constituent in the list is selected)
3) Type in the constituent name or CAS number in the
I SEARCH BY! box
You can select constituents by using one of these methods:
To add an individual constituent, select that constituent by clicking on its
name.
To add multiple constituents that are listed in contiguous order (that is, one
after another without any non-selected constituents in the middle), click on the
first waste constituent, press down the SHIFT| key, and then click on the last
waste constituent. All waste constituents listed between the first and last
chosen constituents should now be highlighted.
To add multiple constituents that are not in contiguous order, click on the first
waste constituent, and then hold down the CTRL key while selecting
additional constituents using the mouse.
5-77
-------
IWEM User's Guide Section 5.0
Once your selection is complete, use the ADD button (described below) to
transfer all the highlighted constituents to your list.
D. Add Highlighted Constituent^) to SELECTED CONSTITUENTS List
Once the appropriate constituents are highlighted in the list (on the left of the
screen), you can click the ADD ,2J button in the center of the screen to transfer it to your
list of leachate constituents (on the right side of the screen). Note that a waste constituent
can also be added directly to your list by double-clicking on it in the list on the left.
E. List of Constituents to be Included in Tier 2 Analysis
Once you have successfully added a constituent to your analysis, that constituent's
name and CAS number will appear in the SELECTED CONSTITUENTS window on the right
side of the screen.
If any of the selected waste constituents hydrolyze into toxic daughter products,
the daughter products are automatically added to the Tier 2 evaluation. You can modify
constituent properties and toxicity standards of the daughter product(s) in the upcoming
screens.
F. Enter Expected Leachate Concentrations
For each waste constituent in the | SELECTED CONSTITUENTS list, you must enter your
expected leachate concentration in mg/L. This value cannot exceed 1,000 mg/L. Consult
Chapter 2-Characterizing Waste in the Guide (U.S. EPA, 2002d) for analytical
procedures that can be used to determine expected leachate concentrations for waste
constituents. Because the expected leachate concentrations of daughter products are
controlled by the leachate concentration of the parent constituent, the daughter product
leachate concentrations are not IWEM inputs.
The IWEM software will display a warning message similar to the one shown
below if you enter an expected leachate concentration that exceeds the solubility of that
constituent, as cited in the IWEM database. If you accidentally entered the wrong value,
click the YES button and correct the expected leachate concentration on the Leachate
Concentration (8) screen. If you want to proceed with the evaluation using your entered
value, click the | No| button. In this case, a similar warning message about your input
leachate concentration will be included in the printed report.
5-78
-------
IWEM User's Guide
Section 5.0
The leachate concentration specified For Acenaphthene is greater than the cited solubility value in
the database of 4.24 rng/l.
Do you want to change the leachate concentration ?
Yes
No
The Tier 2 Evaluation cannot be performed until the expected leachate
concentration is entered for each selected waste constituent.
G. Remove Highlighted Constituent from \ SELECTED CONSTITUENTS List
Analogous to the | ADD| button, you can click the REMOVE | _£J button to delete a
highlighted constituent from the your list of selected constituents.
H. Search for Constituents by Name or CAS #
Type the name or the CAS number in the SEARCH BY| window to select a particular
constituent on the IWEM list. As soon as you have typed in enough information to
identify the constituent, it will be highlighted in the constituent window on the left of the
screen. You can then use the | ARROW| keys on the keyboard to move up or down in the
list if the highlighted constituent is not exactly the one you intended to select.
/. Add New Constituent
To add a new waste constituent, click on the ADD NEW CONSTITUENT | button at the
bottom of the Constituent List. The message box shown below in Figure 5.38 will
appear:
5-79
-------
IWEM User's Guide
Section 5.0
A. Enter B. Enter
CAS number constituent name
LJH
[ Infiltration (1 9) |
mstituentName:!
CAS Numberl
Cc nstituent List (!
G Co istituent Name
<~ CA 3 Number
MM Enter New Constituent Data (20a)
83-32-9 Acenophthene
75-07-0 Acetaldehyde [Ethanal] Q^g Number
67-64-1 Acetone (2-propanone)
75-05-3 Acetonitrile (methyl cyanid
98-86-2 Acetophenone ' Constituent Nome
1 07-02-8 Acrolein
79-06-1 Acrylamide
179-1 0-7 Acrylic acid [pro noicac Cancel
<
OK
QTQQOQjg^^QQQ^im^m
1 07-1 8-6 Alryl alcohol
62-53-3 Aniline (benzeneamine) w\
Add New Constituent
« Previous
^JnJ.xJ
1) Constituent Properties (21)
-T tr*
< All constituents
f Organics
C Metals
x]
1 1
s
Leachate
Concentration
(mg/L)
0.1
Next»
C. Click to enter
new constituent data
Figure 5.38 Tier 2 Input: Enter New Constituent Data (20a).
The features identified in Figure 5.38 are explained in more detail in the following
paragraphs.
A. Enter CAS Number
The CAS number of a new constituent must be entered and it must be a number
that is not already in use by one of the IWEM constituents. If a CAS number is not
available or you do not know the number for a new constituent, any number can be used
here, as long as it is a unique number between 50,000 and 999,999,999.
5-80
-------
IWEM User's Guide
Section 5.0
B. Enter Constituent Name
The constituent name must be entered and it must be a name that is not already in
use by one of the constituents in the IWEM database.
C. Click to Enter New Constituent Data
After you click OK , a new entry in the database will be created for your new
constituent, and screen 20b (Figure 5.39) will appear.
-lolxl
Data Source
Molecular weigh!
Solubility value
Log(Koc) (L/kg)
stalyzed hydrolysis rate constant - Ka
Neutral hydrolysis rate constent- Kn (/yr))
Base-catalyjed hydrolysis rote constant - Kb
, -!
Qirtustvity in water (m2/yr)
Henrys law constant (etm-m3/mol)
CambndgeSoft Corpotation 2001 ChemFinder com
New Source
NO REFERENCE AVAILABLE
CambridgeSoft Corporation. 2001. ChemFindef.com database and internets
USEPA 199 3a Environmental Fate Constants lor Orgaimc Chemicals Undet
USEPA 1997a. Heaitli Effects Assessment Summary Tables (HEAST). EP>
t
irching.
-540-R-97-036.
USEPA 1996d Evaluation of the Potential Cardnogeniciy ot Elhyl Melhane! ultonate
USEPA 1986a. Addendum to the Health Assessment Document for Tstrach iroelhylene
I Propertj
MCL (mg/L)
hBN[>:-lnges](mg/L)
CSFo (kg-d/mg)
HBN [NC-lngest] (mg/L)
RID (mg/kg-d)
HBN[O-lnhal](mg/l)
'<"r~\ (kg-d/mg)
J [NC-lnhol.] Cmg/U
(mg/m3)
Value
Data Source
Cancel
C. Add new constituent to the
database and return to
Constituent List (20)
screen
A. Enter available
data for constituent
properties
Figure 5.39 Tier 2 Input: New Constituent Data (20b).
5-81
-------
IWEM User's Guide
Section 5.0
The features identified in Figure 5.39 are explained in more detail in the following
paragraphs.
A. Enter Available Data for Constituent Properties
You can provide the following constituent physical-chemical data as optional
inputs. In addition, you can provide a "User-defined RGC" later on, in screen 22.
Molecular weight
Solubility
Log Koc
Acid-catalyzed hydrolysis rate constant
Neutral hydrolysis rate constant
Base-catalyzed hydrolysis rate constant
Diffusivity in air
Diffusivity in water
Henry's Law constant
MCL (Maximum Contaminant Levels)
HBN (Non-carcinogenic-Ingestion)
HBN (Carcinogenic-Ingestion)
HBN (Non-carcinogenic-Inhalation)
HBN (Carcinogenic-Inhalation)
If you do not enter a value for the physical-chemical parameters, a default value of
zero will be used for each of these parameters. However, for each constituent at least one
non-zero RGC value must be entered (either an MCL, or an HBN). If you enter an HBN
RGC, you must also enter its corresponding toxicity value (listed in the column next to
each HBN). IWEM assumes a 30-year exposure duration for cancer HBNs and 7-year
exposure duration for non-cancer HBNs.
B. Select Type of Data Source for Each Input Value
For each constituent property value that you enter, you must specify the source of
the data. Clicking in the | DATA SOURCE field after entering your data will display the drop-
down list control J. Click on this control to reveal the drop-down list shown in Figure
5.39. You can select from the current list of references in the IWEM database, or you can
choose NEWSOURCE to enter a bibliographic reference that is not included in the IWEM
database (see Figure 5.40).
5-82
-------
IWEM User's Guide
Section 5.0
C. Add New Constituent to the Database and Return to the Constituent List (20)
screen
After entering the available data and selecting or entering a reference for each
value, click the | ADD| button to update the list of IWEM constituents. Once you have
done this, a message box will appear asking if you want to include this newly added
constituent in your Tier 2 analysis. Even if you decide not to use the new constituent in
your current analysis, the new constituent will be permanently added to the IWEM
database.
Add New Data Sourc e (20d)
x]
Source
Data Source
| Data Source (Full Entry)
Author. Year
Enter full bibliographic citation here
Add New Source
Cancel
C. Add data source
and go back to
Add New Constituent (20b)
D. Cancel the creation
of a new data source
and go back to
Add New Constituent (20b)
screen
Figure 5.40 Tier 2 Input: Add New Data Source (20d).
5-83
-------
IWEM User's Guide Section 5.0
The features identified in Figure 5.40 are explained in more detail in the following
paragraphs.
A. Enter Brief Bibliographic Citation
If you choose | NBA/SOURCE on dialog box 20b, the dialog box shown in Figure
5.40 will appear. Enter a brief bibliographic citation in this field, in the form of "Author,
Year." IWEM uses this information to index all citations, and therefore, this entry must
not duplicate an existing reference in the IWEM database.
B. Enter Complete Bibliographic Citation
Enter a complete bibliographic citation in this field. You can use the existing
references in the IWEM database as a guide for formatting your newly added citation.
C. Add Data Source and Go Back to Add New Constituent (20b) screen
Click the ADD NBA/SOURCE | button to enter this citation into the IWEM database
and return to dialog box 20b.
D. Cancel and Go Back to Add New Constituent (20b) screen
Check the | CANCEL button if you do not wish to use the new bibliographic
citation. This will return you to dialog box 20b.
5.5.1.7 Tier 2 Input: Constituent Properties (21)
On this screen, you can modify constituent sorption and degradation parameters.
For each selected waste constituent, IWEM will display default values that are stored in
its database. These values will be used in the Tier 2 analysis, unless you override them
with user-supplied values. For all constituents, you can enter a value for the soil-water
partition coefficient (kd). For organic constituents, you can also enter an overall first-
order degradation rate.
5-84
-------
IWEM User's Guide
Section 5.0
Constituent List (20
Select a constituent from the first list below. Properties oft!
properties of a daughter product select it from the second
Waste Constituents: 1107-13-1 Acrylonitnle
Daughter products: |
Default Properties of 107-13-1 Acrylonitrile
Reference GWConc (22)
lected constituent will be displayed in the grids. To see the
User Supplied Property Values
Property
Koc(L/kg)
Rate
Acid-catalyjec
hydrolysis - Ka
(/mol/yr)
-------
IWEM User's Guide Section 5.0
constituents, click on the drop-down list control -=J at the right edge of the DAUGHTER
PRODUCTS listbox. If the DAUGHTER PRODUCTS box is blank, it means that the currently
displayed waste constituent has no hydrolysis daughter products. Then use the mouse or
the | ARRCW| keys to scroll through the list of constituents until the desired constituent is
highlighted. Left click on the mouse or hit the ENTER key to make your selection.
B. Default Values
The constituent properties and their default values for the selected waste
constituent are listed in the table on the left side of the screen.
C. Data Sources for Default Values
The data source for each default parameter value of the selected waste constituent
is listed in the "Data Source" field.
D. Enter Site-Specific or Updated Values
For each constituent, IWEM assigns default values for Koc (kd for metals) and
hydrolysis rate constants (for organics only) (see constituent list in Appendix A);
however, you can enter and use site-specific values for kd (organics and metals) and
overall decay rate (organics only) if these data are available. To enter site-specific values,
just type them into the table on the right side of the screen.
By default, IWEM accounts for degradation from constituent hydrolysis only.
IWEM calculates the hydrolysis rate from constituent-specific values for the acid-
catalyzed (ka), neutral (kn) and base-catalyzed (kb) hydrolysis rate constants.
Biodegradation can also be an important process. However, biodegradation rates can
vary greatly from site to site. You should only increase the overall decay rate above the
value corresponding to the hydrolysis rate constants if there is clear evidence of
biodegradation occurring at a site. For organics, the calculation of the overall decay rate
from the hydrolysis rate constants and the calculation of kd from Koc is given in Sections
4.2.4.1 and 4.2.4.3 of the IWEM Technical Background Document (U.S. EPA, 2002c).
E. Enter Data Source
For each Tier 2 input parameter for which you enter a site-specific value,
remember to type in a brief explanation of this value. This information is required and
will be included in the printed report.
5-86
-------
IWEM User's Guide Section 5.0
Once your list of waste constituents and expected leachate concentrations is
complete, click on the | NEXT| button to specify RGC values to be used in the Tier 2
evaluation.
5.5.1.8 Tier 2 Input: Reference Ground-Water Concentrations (22)
In screen 22, you select which RGC is to be used to evaluate each waste
constituent in the Tier 2 analysis. You can select RGCs (MCLs and HBNs) that are in the
IWEM database, or you can supply a user-defined RGC. The following options are
available:
Maximum Contaminant Level (MCL)
Health-Based Number (HBN)
User-defined standard (this can be any value and is generally determined by
your state regulatory authority)
Compare to all available standards
The features identified in Figure 5.42 are explained in more detail in the following
paragraphs.
A. Select Constituent
On the row for the desired constituent, click in the cell on the far left of the table
to display a small arrow indicating which constituent is selected. Once a constituent is
selected, the available toxicity standards are displayed on the bottom half of this screen.
B. Select Standard(s) to Apply
Once a constituent listed at the top of the screen is selected, the available ground-
water standards (and RGC values) are displayed at the bottom. Using the radio buttons,
click on the appropriate standard to use in your Tier 2 analysis. If a constituent has more
than one standard, you should consult with the appropriate state regulatory agency to
determine which RGC should be used. If none of the default choices are appropriate for
your analysis, you can enter a new RGC value and associated exposure duration (see
items C and D, below). Additionally, if you choose the last option, | COMPARE TO ALL
AVAILABLE STANDARDS |, then the IWEM model will use the most stringent standard to
determine the Tier 2 liner recommendation.
5-87
-------
IWEM User's Guide
Section 5.0
i ilect a constituent from the grid, then the desired standard from the list. Click the "Apply Standards" button to save each selectior
Constituent Properties (21) [ Reference GW Cone. (22) ] Input Summary (23)
Related
Constituents
Constituent
standard
Parent
107-13-1 Acrylonitrile
HBN - Ingestion. Cancer
Daughter
Daughter
79-06-1 Acrylamide
HBN-Ingestion. Cancer
79-10-7 Acrylic acid [propenoic acid]
HBN - Ingestion. NonCancer
Standards for 79-10-7 Acrylic acid [propenoic acid]
Reference Ground-water
Concentration (mg/L)
Select Standard
r
r ,
f HBN - Inhalation. Non-Cancer
r HI
( HBN - Ingestion. Non-Cancer
r User-Defined
Compare to all available standards
electthe desired standard I.'. .<> tnq its radio button Click the "Apply S
Exposure
Duration (yr)
12
T
Justification
T
andards" button to save yout selection
« Previous
Apply Standard(s)
Next»
E. Apply selected
standard) s) to
selected constituent
C. View default
values or enter
user-defined value
Figure 5.42 Tier 2 Input: Reference Ground-Water Concentrations (22).
C. View Default Values or Enter User-Defined Value
These textboxes display the RGC values in the IWEM database; and in the case of
the user-defined RGC, this is where you enter the appropriate RGC value and its
associated exposure duration. In the IWEM model, the exposure duration corresponds to
the time interval over which the average ground-water concentration is calculated.
Consult with the appropriate state regulatory agency for additional guidance on entering
your own RGC value and exposure duration.
5-88
-------
IWEM User's Guide Section 5.0
D. Enter Data Source for User-Defined Value
If you enter a user-specified RGC for any constituent, be sure to provide a brief
explanation of this value in the JUSTIFICATION textbox.
E. Apply Selected Standard(s) to Selected Constituent
After you have chosen the appropriate standard(s) for the selected constituent,
click on the | APPLY STANDARDS button to input your choice. After you have done so, your
selection will be displayed in the | STANDARD | column in the table at the top of the screen.
5.5.1.9 Tier 2 Input: Input Summary (23)
This screen displays a summary of the input data for your Tier 2 analysis. You
cannot enter or edit data on the Input Summary screen; rather, its purpose is to
consolidate into one place all the data you have already entered for the Tier 2 Evaluation.
If you notice that you have entered any data incorrectly, use the PREVIOUS button or click
on the desired screen tab to go back to the appropriate screen on the Tier 2 Input Screen.
The input summary screen has three sections containing data on: 1) constituent
properties; 2) source and unsaturated zone; and 3) saturated zone. Each section has a
scroll bar which can be used to view information that does not fit on the screen.
The features identified in Figure 5.43 are explained in more detail in the following
paragraphs.
A. Identification of Constituent as Either a Parent or a Toxic Daughter
The first section contains a table of the selected waste constituents, listing their
CAS number, name, expected leachate concentration, the type and value of the selected
RGC, and fate parameters (log Koc, kd, hydrolysis rate constants, and/or overall decay
rate). The entry in the "Related Constituents" column on the left side of the screen
indicates whether the constituent is present in the waste ("parent") or whether it is
included because it is a daughter product of a waste constituent ("daughter"). In the latter
case, the parent constituent is listed immediately above the daughter.
B. Summary of Constituent Properties
For your reference, the constituent-specific properties for each waste constituent
in the Tier 2 analysis are displayed in the table at the top of the screen.
5-89
-------
IWEM User's Guide
Section 5.0
C. Verify Tier 2 Input Values
The bottom section of this screen consists of two tables that present the selected
values for the WMU and subsurface parameters. To the left, the selected values for the
WMU (source) and unsaturated zone parameters are displayed. To the right, the selected
values for the saturated zone parameters are listed. Note that each table has a scroll bar
on the right-hand side which can be used to view information which does not fit on the
screen.
B. Summary of
constituent properties
Re
erenceGWConc (22)
Input Summary (23)
Constituent Properties
Related
Constituents
CAS
Constituent
Name
Leachate
Concentratjon
(mg/L)
Toxiaty
Standard
RGC
(mg/L)
Log(Koc)
(L/kg)
Ka
(/mol/yr)
Kn(/yr)
Kb
(/mo!/yr)
Kd (L/kg)
Overall Decay
Coefficient (/yr)
107-13-1
Acrylonitnle
0 1 HBN -
Ingeslion.
Cancer
1 8DE-04 -0.089
500
O.OOE'OO
5.20E*03
Daughter
79-06-1
Acryamide
0134 HBN-
Ingestion.
Cancer
Daughter
79-10-7
1
Aciylicacid
propenoic acid]
nniii
-0969
31.5
0018
0,OOE»00
HBN-
Ingestion.
NonCancer
12
-1.B4
O.OOE*00
O.OOE+00
UUOE-DO
Depth to
oil type.
ndKrolion
I ''('
»se ol the LF below ground surface (m)
(rr>) [requires site specific value].
r table (m):
SILT LOAM
2345 AJAquifer thickness (m)
0 Regional hydreu ic gradient:
6.5 Aquiter hydraulic conductivity (m/yr)
(not specified) Distance to well (m):
(not specified)
(not specified)
(not specified)
150
No Liner: 3256
Single Liner 0362
Composite Liner Monte Carlo
Recharge Rate 0 3256
« previous
A. Identification of
constituent as either
a parent or a toxic
daughter
Figure 5.43 Tier 2 Input: Input Summary (23).
5-90
-------
IWEM User's Guide Section 5.0
5.5.2 Tier 2 Evaluation: Run Manager (24)
After you have verified that all Tier 2 inputs are correct, click the NEXr| button on
the Input Summary screen (23) to perform the Tier 2 evaluation. The Tier 2 Run
Manager (Screen 24) will be displayed.
In a Tier 2 evaluation, after you click on the START EPACMTP| button, the ground-
water model is automatically executed for each waste constituent for each applicable liner
scenario using the chosen waste constituent-specific and site-specific inputs. Any toxic
daughter products produced by hydrolysis of the selected constituents are also evaluated.
Each combination of constituent and liner scenario requires one probabilistic Monte
Carlo modeling run consisting of 10,000 model realizations. Depending upon model
inputs and the speed of your personal computer, each modeling run may take from several
minutes to several hours. For this reason, we have developed a Run Manager dialog box
which displays the current status of your modeling analysis; this way, you will know that
the model is working and how much progress has been made at any given point in time.
The following sequence of screen images (Figures 5.44 through 5.46) demonstrate
how the Tier 2 Run Manager and the EPACMTP dialog box help you track the progress
of your Tier 2 modeling analysis.
5-91
-------
IWEM User's Guide
Section 5.0
A. EPACMTP run
status and liner
protectiveness
summary
2 Evaluation Run Manager (24)
EPACMTP Run Status
>
Index
1
2
3
Constituent Name
Acrylonitrile
Acrylemide
Acrylic acid [propenoic acid]
Related
Constituents
Parent
Daughter
Daughter
R
<
for Landfills
n Status
1
No Liner
Single Liner
Composite
Liner
«P_revious
Start EPACMTP
C. Go to
Input Summary (23)
screen
B. Launch EPACMTP
runs for selected set
of constituents
Figure 5.44 Tier 2 Evaluation: Run Manager (24) -
Appearance Before Launching EPACMTP Runs.
The features identified in Figure 5.44 are explained in more detail in the following
paragraphs.
Figure 5.44 shows a summary table listing all the constituents and liner scenarios
in a typical Tier 2 analysis prior to launching the first EPACMTP run. During an
EPACMTP run, a dialog box is displayed (Figure 5.45), allowing you to track the
progress of the model's execution. The summary table shown in the background (Figure
5.46) keeps you informed of the overall progress of the Tier 2 analysis. The EPACMTP
runs proceed from the first to the last selected constituent. For each constituent,
5-92
-------
IWEM User's Guide Section 5.0
EPACMTP runs are sequentially launched for the no-liner, single clay-liner, and
composite-liner scenarios until a protective scenario is found. That is, if the single clay-
liner scenario is determined to be protective for a given constituent, the composite-liner
scenario for that constituent is not modeled. For the LAU or user-defined liner/
infiltration scenarios, only one scenario per constituent is evaluated. During EPACMTP
model execution, the message "Running" appears in the table cell corresponding to the
current constituent and liner scenario. After the completion of a run, the results are
analyzed by IWEM to determine whether the liner scenario is protective for the current
constituent. An up-to-date summary of the results is displayed in the summary table as
shown in Figure 5.46.
A. EPACMTP Run Status and Liner Protectiveness Summary
This summary table shows the current status of the analysis. For each waste
constituent, you can see whether the required modeling is in progress or has been
completed. In addition, this table will tell you whether or not each liner scenario is
protective of ground water.
B. Launch EPACMTP Runs for Selected Set of Constituents
Click on the START EPACMTP | button to launch the required EPACMTP runs for
the selected set of waste constituents. During an EPACMTP model run, the dialog box
shown below in Figure 5.45 appears on-screen and displays the status of the current
model run, including estimated time to completion.
C. Go to Input Summary (23) screen
You can click the PREVIOUS button at the bottom left of the screen to go back to
the Tier 2 Input Summary (23)screen.
5-93
-------
IWEM User's Guide
Section 5.0
EPACMTP V2
File View State Help
i Processing
INDUSTRIAL WASTE MANAGEMENT
EVALUATION MODEL
GROUND-WATER PATHWAY
FATE AND TRANSPORT ANALYSIS
BASED ON
EPA'S COMPOSITE MODEL FOR LEACHATE
MIGRATION WITH TRANSFORKATION PRODUCTS
VERSION 2.0
Simulating
Acryloniccile
Leaching From
A Landfill With No Liner
Current Realization: 63 OF 10000
Elapsed Time: 0:00:15 (hh:Rtn:ss)
Estimated Time Remaining
In This Simulation: 0:37:29 (hh:ra»:ss)
m
nnmg
A. Status of
current
EPACMTP run
Figure 5.45 Tier 2 Evaluation: Run Manager (24) - EPACMTP
Dialog Box Displayed During Model Execution.
5-94
-------
IWEM User's Guide
Section 5.0
A. Status of Current EPACMTP Run
A Run Manager dialog box will be displayed during each EPACMTP run to help
you monitor the model's progress in real time. Note that the information displayed on
this screen includes: constituent name, WMU type and liner scenario, current realization
number, time elapsed, and estimated time remaining.
The summary table displayed on the Run Manager (24) screen, presented below in
Figure 5.46, shows you the overall progress of the Tier 2 analysis - the liner
recommendation for each completed EPACMTP model run and which (if any) model
runs have not yet begun.
A. EPACMTP run
status and liner
protectiveness
summary
Tier 2 Evaluation - Run Manager (24)
EPACMTP Run Statu
for Landfills
Index
Constituent Name
Related
Constituents
Run Status
No Liner
Single Liner
Composite
Liner
Acrylonitnle
Parent
Completed
Not Protective
Not Protective
Protective
Acryl amide
Daughter
Completed
Not Protective
Not Protective
Protective
Acrylic acid [propenoic acid]
Daughter ' Completed
Protective
Protective
Protective
«£revious
C. Go to
Input Summary (IB)
screen
B. Go to
Summary Results (251
Figure 5.46 Tier 2 Evaluation: Run Manager (24) -
Status and Liner Protectiveness Summary.
5-95
-------
IWEM User's Guide Section 5.0
The features identified in Figure 5.46 are explained in more detail in the following
paragraphs.
A. EPACMTP Run Status and Liner Protectiveness Summary
This summary table shows the current status of the analysis. For each waste
constituent, you can see whether the required modeling is in progress or has been
completed. In addition, this table will tell you whether or not each liner scenario is
protective of ground water.
B. Go to Summary Results (25) screen
You can click on the | NEXT| button at the bottom right of the screen to proceed to
the brief listing of the Tier 2 results that is presented on the Summary Results (25) screen.
C. Go to Input Summary (23) screen
You can click the PREVIOUS button at the bottom left of the screen to go back to
the Tier 2 Input Summary (23) screen.
5.5.3 Tier 2 Evaluation Summary: Summary Results Screen (Screen 25)
The presentation of the liner recommendation for the Tier 2 evaluation is
determined by which option you chose to specify the infiltration rate (either a location-
based estimate or a user-specified value) and your WMU type. But whichever infiltration
option you choose, the results are divided into two sets: summary results and detailed
results. The first set of results is a summary which reports a liner recommendation for
each individual waste constituent and the overall liner recommendation that is protective
for all constituents. The second set of results, the detailed results, present the data upon
which the liner evaluation is based. For each waste constituent, the expected leachate
concentration, the DAF, the Tier 2 LCTV, specified RGC type and value, and the
resulting 90th percentile ground-water concentration calculated by EPACMTP are listed.
These detailed results allow you to understand how the liner design recommendations
were developed.
The results of the Tier 2 Evaluation are first presented on-screen in a summary
form. The Summary Results screen provides a liner design recommendation for each of
the selected constituents which are listed by name and CAS number. The
recommendation is based on a comparison of the resulting 90th percentile ground-water
concentration and the specified RGC. If the ground-water concentration does not exceed
the specified RGC, then the evaluated liner scenario is protective for that constituent. If
5-96
-------
IWEM User's Guide
Section 5.0
the ground-water concentration exceeds the specified RGC, then the evaluated liner
scenario is not protective for that constituent. Only the no-liner soil scenario is evaluated
for LAUs. In this case, if the no-liner scenario is not protective of ground water, then
land application of the modeled waste is not recommended at the site.
A. Tier 2 liner
recommendation
for each constituent
Tier 2 Output - Output Summary (25)
>
CAS Number
107-13-1
79-06-1
79-10-7
Constituent Name
Actylonitrile
Acryl amide
Acrylic acid [propenoic acid]
Mi
<
innum Liner Recommendation
Composite Liner
> Composite Liner
No Liner
Based on consideration of the toxicity standards of all listed constituents, the Composite Liner
minimum liner recommended is:
« Previous
detailed Results
Recommendation »
D. Go to
Results - No Liner (26)
B. Overall Tier 2
liner recommendation
based on selected
toxicity standard(s)
C. Go to
Tier 2 Evaluation
Summary (29J
Figure 5.47 Tier 2 Output (Summary): Summary Results (25).
5-97
-------
IWEM User's Guide Section 5.0
The features identified in Figure 5.47 are explained in more detail in the following
paragraphs.
A. Tier 2 Liner Recommendation for Each Constituent
If you evaluated a landfill, waste pile, or surface impoundment and used a
location-based estimate of the infiltration rate, the liner recommendation is the minimum
recommended liner of the three types that are evaluated (no liner, single clay liner, and
composite liner). If you evaluated a LAU and used a location-based estimate of the
infiltration rate, the resulting recommendation is whether or not land application of this
waste at this site will be protective of ground-water.
If you entered a site-specific infiltration rate (for any type of WMU), then the liner
recommendation is whether or not the modeled liner type is recommended as being
protective of ground water.
For a Tier 2 evaluation, the no-liner, single clay-liner, and composite-liner
recommendations are displayed in green text. If the composite liner is not protective,
then this message is displayed in red text. If the liner recommendation is "Not
Applicable," then this message is displayed in black text.
B. Overall Tier 2 Liner Recommendation Based on Selected Toxicity Standard(s)
The bottom of the screen displays an overall liner recommendation which is based
on consideration of all waste constituents (and their daughter products).
If EPACMTP predicts that the 90th percentile values of ground-water well
concentration for all constituents under the no-liner scenario are below their respective
RGCs, then IWEM will recommend that no liner is needed to protect groundwater. If the
modeled ground-water concentration of any constituent under the no-liner scenario is
higher than its RGC, then at least a single clay liner is recommended (or in the case of
LAUs, land application is not recommended). If the predicted ground-water
concentration of any constituent exceeds the RGC under the composite liner scenario,
then consider pollution prevention, treatment, and more protective liner designs, as well
as consultation among regulators, the public, and industry to ensure such wastes are
protectively managed. See Chapter 4 of the Guide (U.S. EPA, 2002d) for further
information.
For waste streams with multiple constituents, the least stringent liner design that is
protective for all constituents is the overall recommended liner design.
5-98
-------
IWEM User's Guide Section 5.0
C. Go to Tier 2 Evaluation Summary (29) screen
Clicking on the RECQMI\/ENDAT1ON| button will take you to the Tier 2 Evaluation
Summary screen where you can choose to view the Tier 2 report or save your analysis and
exit the IWEM software.
D. Go to Results - No Liner (26) screen
Clicking on the DETAILED RESULTS) button will take you to a detailed listing of the
Tier 2 results, including the constituent-specific modeling results for all evaluated liner
scenarios.
5.5.4 Tier 2 Output (Details) Screen Group (26, 27, and 28)
The detailed results table for each evaluated liner type presents the data on which
the liner recommendation are based. For each waste constituent, this information
includes the expected leachate concentration, the DAF, the Tier 2 LCTV, the specified
RGC type and value, the resulting 90th percentile ground-water concentration, and text
explaining whether or not the liner is recommended as being protective of ground water.
These detailed results allow you to understand how the liner design recommendations
were developed.
If you directly enter a value for infiltration (for any of the four types of WMUs),
EPACMTP will use this value of the infiltration rate in its fate and transport simulation,
and IWEM will then compare the predicted ground-water well concentration to each
constituent's RGC. In this case, the detailed results will consist of only one screen, rather
than the three that are shown below in Figures 5.48 through 5.50.
Also, for a Tier 2 analysis of a LAU, only the no-liner scenario is evaluated since
engineered liners are not typically used at this type of facility. In this case, the detailed
results will consist of only one screen.
5-99
-------
IWEM User's Guide
Section 5.0
E. Selected
RGC value
2 OutpuKDetaifc)
F. Exposure
level
(ground-water
concentration)
Results - No Liner (26)
Results - Sing "Liner (27)
Results - Composite L
ner (28)
CAS
Constituent Name
107-13-1 Aciytonitnl
79-06-1 Aoylamide
73-1 D-7
Acrylic acid
(propenoic acid]
I eecHate
:entrotion
ng/L)
0131
01358
L'/ h
(mg/l 1
M 11 IE
2.5
2.1
550E-05
288
Toxicitj
Standar
HBN-lngefion,
Cancer
HBN-lngestion,
Cancer
HBN-lngestion.
NonCancer
Referenci
Concent
Groundwater
stton (mg/L)
90tti F srcsntile
Expos ire Level
(n g/U
1 8QE-OT
0,0113
220E-06
12
0.0539
00562
Protectiv
H. Go to
Summary Results (25)
Figure 5.48 Tier 2 Output (Details): Results-No Liner (26).
5-100
-------
IWEM User's Guide
Section 5.0
E. Selected
RGC value
Her 2 Output (Detaik)
F. Exposure
level
(ground-water
concentration)
Results - No Liner (26)
I lesulls - Sing
e Liner (27)
Results - Composite I
ner(28)
CAS
Constituent
Nome
C on
chate
intration
Kig/L)
D/F
LC V
(mg L)
Toxicrty
Standard
Reft 'ence Groundwater
Co centrotion (mg/L)
Oth Percentile
E
-------
IWEM User's Guide
Section 5.0
E. Selected
RGC value
2 Output (I M.| ,,rl,)
F. Exposure
level
(ground-water
concentration)
- nix
Results - No Liner (26)
Resulls-Sing
esults - Composite
.iner (28)
CAS Constituent Name
1.1 n
.eachate
icentration
(mg/L)
DAF
uprv
Toxicrt> Standard
irence Groundwater
ncentration (rng/L)
90lh Percsntile
Ixposure Level
(mg/L)
Protective?
107-13-1
Acrylomtnle
01
40E.04
432 HBN - In^estion.
Cancer
1 80E-04
410E-06
Acrylamide
0131
1.00E*30
1000
HBN - Ingestion.
Cancer
2 20E-05
OOOE-00
79-10-7
Acrylic acid
[propenoic acid]
01358
N/A
N/A
HBN - Ingestion.
NonCancer
12
N/A
See No Liner Results
« Brevious
Summary Results
Becommendation »
H. Goto
Summary Results (25)
1. Goto
Tier 2 Evaluation
Summary (21)) screen
Figure 5.50 Tier 2 Output (Details): Results-Composite Liner (28).
The features identified in Figures 5.48 through 5.50 are explained below.
A. Entered Leachate Concentration
The entered leachate concentration for each constituent is displayed in the third
column. This is the value that was used by IWEM in the EPACMTP ground-water fate
and transport modeling.
5-102
-------
IWEM User's Guide Section 5.0
B. Dilution and Attenuation Factor
This column shows the 90th percentile value of the ground-water DAF calculated
by EPACMTP. DAF values are capped at IxlO30.
C. Estimated LCTV
The constituent- and liner-specific Tier 2 LCTV is also displayed on this screen.
The LCTV for organics is calculated as follows:
LCTV = DAF x RGC
where:
LCTV = leachate concentration threshold value (mg/L)
DAF = dilution-attenuation factor (EPACMTP model output)
(dimensionless)
RGC = reference ground-water concentration (MCL, HBN, or user-
specified value) (mg/L)
In Tier 2, the LCTV for metal constituents is an estimated value due to the non-
linear nature of metals adsorption (that is, for metals the DAF is not constant across all
leachate concentrations, as it is for organics). For this reason, an adjustment factor of
0.85 is used to estimate the LCTVs for metals in order to ensure adequate protection of
the ground water. The Tier 2 LCTV for metals is calculated as follows:
LCTV = DAF x RGC x 0.85
D. Selected RGC Type
The selected RGC type is displayed in this table for your reference. In addition to
regulatory MCLs, four types of HBNs can be evaluated in the IWEM software, covering
the direct ingestion and inhalation pathways, and carcinogenic and non-carcinogenic
health effects. However, if the existing values in the IWEM software are not appropriate
for your analysis, you may enter your own RGC to be used in the Tier 2 analysis. In any
case, the specified RGC type and value are displayed for each waste constituent.
E. Selected RGC Value
The selected RGC value is also displayed in this table for your reference. Note
that is value may be an MCL, an HBN, or a user-defined value.
5-103
-------
IWEM User's Guide Section 5.0
F. Exposure Level (Ground-water Concentration)
In order to determine whether or not this liner scenario is protective for a given
constituent, the resulting 90th percentile ground-water concentration is compared with the
specified RGC. If the ground-water concentration does not exceed the specified RGC,
then the evaluated liner is protective for that constituent. If the ground-water
concentration exceeds the specified RGC, then the evaluated liner is not protective for
that constituent.
G. Is the Exposure Level Less than the RGC?
The result of the comparison between the modeled 90th percentile exposure level
(ground-water concentration) and the specified RGC is displayed at the far right of this
table.
If the 90th percentile exposure level does not exceed the specified RGC, then the
evaluated liner is protective for that constituent and the text in the last column of this
table will read | YES for that constituent.
If the 90th percentile exposure level exceeds the specified RGC, then the evaluated
liner is not protective for that constituent and the text in the last column of this table will
read | NO for that constituent.
H. Go to Summary Results (25) Screen
Clicking on the RESULTS SuiVMARY button will take you back to the Tier 2
Summary Results (25) screen.
/. Go to Tier 2 Evaluation Summary (29) Screen
Clicking on the RECOMI\/ENDAT1ON| button will take you to the next screen, the Tier
2 Evaluation Summary (29) screen where you can choose to view the Tier 2 report or
save your analysis and exit the IWEM software.
5.5.5 Tier 2 Evaluation Summary (29)
The Tier 2 Evaluation Summary screen identifies the overall Tier 2 liner
recommendations and lists the available options within the IWEM software.
5-104
-------
IWEM User's Guide
Section 5.0
B. List of
IWEM options
A. Overall Tier 2
liner recommendation
Tier 2 Evalual ion Summary
You may choc
1 or Tier 2 ev«
Tier 2 Evaluation Summary (29)
The results of the Tier 2 analysis recommend the following design:
Composite Liner
se to print the results and exit this program. You may also return to the beginning of the Tier
Juation, or you may conduct your own site-specific assessment.
Beport
D. Go back to
previously viewed
results screen
Figure 5.51 Tier 2 Evaluation Summary (29).
The features identified in Figure 5.51 are explained in more detail in the following
paragraphs.
A. Overall Tier 2 Liner Recommendation
The Tier 2 liner recommendation is displayed at the top of this screen. For
landfills, surface impoundments, and waste piles that were modeled using a location-
based estimate of the infiltration rate, the available recommendations are: no-liner, single
clay-liner, composite-liner, and not protective. For LAUs that were modeled using a
location-based estimate of the infiltration rate, the available recommendations are: no-
liner and not protective. If you entered a user-specified value for the infiltration rate, the
5-105
-------
IWEM User's Guide Section 5.0
available recommendations are: protective and not protective. If your Tier 2 evaluation
results in a recommendation of "not protective", then the chosen WMU for managing the
waste may not be appropriate at the selected site. In this case, consider pollution
prevention, treatment, and more protective liner designs, as well as consultation among
regulators, the public, and industry to ensure such wastes are protectively managed. See
Chapter 4 of the Guide (U.S. EPA, 2002d) for further information.
B. List of IWEM Options
After reviewing your Tier 2 results on-screen, you have several options to
continue within the IWEM software:
Go back to the previous screens of the Tier 2 results by clicking on the
| PREVIOUS| button.
View the Tier 2 report by clicking the | REPORT) button.
At this point, you can also choose to save your results, exit the IWEM software, or
conduct a Tier 3 Evaluation. For more information about Tier 3 Evaluations, see Chapter
7A (Protecting Ground Water - Assessing Risk) of the Guide.
There are several ways to save the Tier 2 Evaluation:
Click on the | FILE) menu and choose | SAVE) or | SAVE As . A dialog box will
then open which prompts you for the filename and directory location, as
appropriate. Once you have provided a filename, the tool will save two files,
automatically applying the "wem" and "mdb" extensions for you. The
combination of these two files completely describes the data you have entered
and any model-generated results. Please note that you cannot save any files to
the cd-rom, so you must specify a directory on your hard-drive or a floppy disk
to save the file.
Click on the | SAVE| button on the toolbar. If you are editing a previously
saved evaluation, the file will be automatically updated. If you have created a
new evaluation, the SAVE As dialog box will open, as described above.
Note that IWEM will not allow you to save both model inputs and results at a
point where the inputs do not correspond to the model-generated results. If you do
choose to save your work in a situation like this, only the inputs will be saved; that is,
when you later open up this file, you will have to perform either the Tier 1 or Tier 2
evaluation to create the corresponding results. Once you have completed an evaluation
5-106
-------
IWEM User's Guide
Section 5.0
you should save it under an appropriate file name. If you want to start a new evaluation
by editing an existing IWEM file, you should first save the new evaluation under a
different name to avoid losing the results of your original evaluation.
EXIT
You can exit the IWEM software by clicking on the | RLE) menu, and choosing
If you forget to save before trying to exit the IWEM software, a dialog box will
ask if you want to save your data before exiting the software.
You can open a previously saved IWEM analysis by clicking on any one of the
following options:
IdPENl button on the Tool Bar
IFlLE|OPENl selection from the Menu Bar
IOPEN SAVED ANALYSIS (*.WEMFiLE)l radio button from the I IWEM ANALYSIS OpnoNSl
dialog box (see Item B in Section 5.3)
Once the lOPENl dialog box is displayed, highlight the appropriate file and click the
lOPENl button to open the desired file. You will then see a dialog box in which you can
specify what type of analysis you want to perform - Tier 1 or Tier 2.
C. Display Tier 2 Reports
Clicking on the REPORT button displays the IWEM Tier 2 Report.
Once the Tier 2 report is displayed on-screen, you can then use the following
toolbar buttons to print, save, and scroll through the pages of the report:
Print the report; the PRINT | dialog box then appears where you
can adjust printer setting or choose to print selected pages.
Export the report in order to save it to a file; after specifying the
file type, destination type, and the pages to be included, the
| CHOOSE EXPORT FILE | dialog box then appears; you can specify
the file type, and then select the file name and directory. The
file types in this list are dependent upon what software you have
installed on your PC. Most users will find that the option for
PDF format will produce a document-ready report.
View the next page of the report
5-107
-------
IWEM User's Guide
Section 5.0
H
View the last page of the report.
View the previous page of the report
View the first page of the report.
!"IQO% ^1 Change the display size of the report.
Tier 2 Report Includes:
WMU facility data entered on screen 16
List of selected constituents and their corresponding leachable concentrations
entered on screen 20
List of Tier 2 input values and explanations of user-input data, as summarized on
screen 23
Tier 2 summary results for each selected constituent, based on the user-specified
RGC for each constituent
Tier 2 detailed results for each selected constituent, based on the user-specified
RGC for each constituent, and including an explanation of any appropriate caps
or warnings about the presented results
Constituent properties and RGCs for each selected constituent, including full
references for the data sources
5-108
-------
IWEM User's Guide Section 5.0
An example Tier 2 report is included in this User's Guide in Appendix B.
D. Go Back to Previously Viewed Tier 2 Results
Click on the PREVIOUS button to return to the Tier 2 results that were previously
displayed. That is, if you navigated directly to the Tier 2 Evaluation Summary (29)
screen from the Summary Results (25) screen, then screen 25 is the screen you will return
to. However, if you viewed the detailed results before navigating to the Tier 2 Evaluation
Summary (29) screen, then clicking the | PREVIOUS | button will return you to the Results-
Composite Liner (28) screen.
5-109
-------
IWEM User's Guide Section 6.0
6.0 Understanding Your IWEM Input Values
This section of the User's Guide will assist you in understanding the WMU, waste
constituent and other fate and transport data that IWEM uses to evaluate whether a liner
design is protective.
Broadly speaking, there are three main categories of input values:
WMU data,
Waste constituent data, and
Location-specific climate and hydrogeological data.
A Tier 1 analysis requires only a few key inputs. A Tier 2 analysis, which is
designed to provide a more accurate evaluation, requires you to provide additional site-
specific input data. Section 6.1 describes basic inputs that are common to both Tier 1 and
Tier 2 evaluations. Section 6.2 describes the additional inputs for a Tier 2 evaluation.
The IWEM Technical Background Document (TBD) provides additional detail on
the Tier 1 and Tier 2 input values. To assist you in cross-referencing the discussion on
each input parameter to the corresponding section(s) of the TBD, specific references to
the TBD are provided for each IWEM input. The references are indicated pictorially as
follows:
J Section x.y.z
TBD
6.1 Parameters Common to Both Tier 1 and Tier 2 Evaluations
The common parameters are:
1) WMU type.
2) Constituent(s) of concern that are present in the WMU, and
3) Leachate concentration (in mg/L) of each constituent.
6-1
-------
IWEM User's Guide Section 6.0
6.1.1 WMUType UJ Section 3.1; 4.2.1
TBD
IWEM address four different types of WMUs. Each of the four unit types reflects
waste management practices that are likely to occur at industrial Subtitle D facilities. The
WMU can be a landfill, a waste pile, a surface impoundment, or a land application unit.
The latter is also sometimes called a land treatment unit. Figure 6.1 presents schematic
diagrams of the different types of WMU's modeled in IWEM.
Landfill. Landfills are facilities for the final disposal of solid waste on land.
IWEM considers closed landfills with an earthen cover and either no-liner, a single clay
liner, or a composite, clay-geomembrane liner. IWEM assumes there is no leachate
collection system. The release of waste constituents into the soil and ground water
underneath the landfill is caused by dissolution and leaching of the constituents due to
precipitation which percolates through the landfill. The type of liner that is present
controls, to a large extent, the amount of leachate which is released from the unit.
Because the landfill is closed, the concentration of the waste constituents will diminish
with time due to depletion of landfill wastes. The leachate concentration value that is
used as an input is the expected initial leachate concentration when the waste is 'fresh'.
Surface Impoundment. A surface impoundment is a WMU which is designed to
hold liquid waste or wastes containing free liquid. Surface impoundments may be either
ground level or below ground level flow-through units. They may be unlined, or they
may have a single clay liner or a composite clay-geomembrane liner. Release of leachate
is driven by the ponding of water in the impoundment, which creates a hydraulic head
gradient across the barrier underneath the unit. In Tier 1, IWEM uses a national
distribution of values for surface impoundment operational life. In Tier 2, you can enter a
site-specific value. The Tier 2 default is 50 years.
Waste Pile. Waste piles are typically used as temporary storage or treatment units
for solid wastes. Due to their temporary nature, they will not typically be covered.
IWEM does consider liners to be present, similar to landfills. In Tier 1 analyses, IWEM
assumes that waste piles have a fixed operational life of 20 years, after which the waste
pile is removed. In Tier 2, you can provide a site-specific value for the operational life.
The default value is 20 years. After the operational period, IWEM assumes the waste pile
is removed.
Land Application Unit. Land application units (or land treatment units) are areas
of land receiving regular applications of waste which can be either tilled directly into the
soil or sprayed onto the soil and subsequently tilled into the soil. IWEM models the
leaching of wastes after they have been tilled with soil.
6-2
-------
IWEM User's Guide
Section 6.0
Cover
unsaturated zone
V
saturated zone
(A) LANDFILL
unsaturated zone
V
saturated zone
(C) WASTE PILE
unsaturated zone
V
saturated zone
(B) SURFACE IMPOUNDMENT
unsaturated zone
v
saturated zone
(D) LAND APPLICATION UNIT
Figure 6.1 WMU Types Modeled in IWEM.
6-3
-------
IWEM User's Guide Section 6.0
IWEM does not account for the losses due to volatilization during or after waste
application. In Tier 1, land application units have a 40 year active life. In Tier 2, you can
enter a site-specific value. The Tier 2 default value for operational life is 40 years. Land
application units are evaluated for only the no-liner scenarios because liners are not
typically used at this type of facility.
6.1.2 Waste Constituents
The IWEM software includes a built-in database with 206 organic constituents
and 20 metals. Appendix A provides a list of these constituents. In IWEM you select the
waste constituents for each WMU scenario that you wish to evaluate from a drop-down
list, either by constituent name or by Chemical Abstract Service (CAS) identification
number, or from a list of constituents sorted by constituent name or by CAS number.
With each constituent, you also select a set of constituent-specific reference ground-water
concentrations (see Section 6.1.4) and fate and transport characteristics. The fate and
transport characteristics include sorption parameters and hydrolysis rate constants.
In Tier 1, you can only evaluate constituents found in the built-in database, and
you are not able to change the fate and transport characteristic values associated with each
constituent. In Tier 2, you can add constituents to IWEM's database as well as modify
fate and transport characteristic values for constituents already in the database.
6.1.3 Leachate Concentration tsUI Section 4.2.1.3
TBD
You must provide the leachate concentration in mg/L for each selected waste
constituent that you expect in the leachate that will infiltrate into the soil underneath a
WMU. EPA has developed a number of tests to measure the leaching potential of
different wastes and waste constituents in the laboratory. These include the Toxicity
Characteristic Leaching Procedure (TCLP) and the Synthetic Precipitation Leaching
Procedure (SPLP). Consult Chapter 2 of the Guide (Characterizing Waste) for analytical
procedures that can be used to determine expected leachate concentrations for waste
constituents.
6.1.4 Reference Ground-water Concentrations tsUI Section 5.0
TBD
Associated with each waste constituent is a set of RGCs that reflect not-to-exceed
exposure levels for both drinking water ingestion and shower inhalation cancer risks and
non-cancer hazards. These include regulatory MCLs and HBNs. Collectively, HBNs and
MCLs are referred to in IWEM as RGCs. Each type of RGC is briefly described below.
6-4
-------
IWEM User's Guide Section 6.0
6.1.4.1 Maximum Contaminant Level (MCL) IbU Section 5.0
TBD
For a number of constituents, the EPA has set MCLs as part of the National
Primary Drinking Water Regulations (NPDWR). The MCL is the maximum permissible
level of a contaminant in public water systems. For each contaminant to be regulated,
EPA first sets a Maximum Contaminant Level Goal (MCLG) at a level that protects
against health risks. EPA then sets each contaminant's MCL as close to its MCLG as
feasible, taking costs and available analytical and treatment technologies into
consideration.
6.1.4.2 Health-Based Number (HBN) !UJ Section 5.0
TBD
All constituents included in the IWEM software have one or more HBNs. An
HBN is the maximum exposure concentration of a contaminant in a domestic water
supply that will not cause adverse health effects. Health effects and certain exposure
assumptions are considered in the determination of the HBN, while other factors, such as
the cost of treatment, are not considered. The HBNs in IWEM are based on the ingestion
of drinking water and the inhalation of volatiles during showering. HBN values are based
on a target risk of IxlO"6 for carcinogens and a hazard quotient of 1 for non-carcinogens.
HBNs in IWEM were calculated using standard EPA risk assessment assumptions and
equations. An overview of the approach used to develop HBNs is given below. Section
5 of the IWEM Technical Background Document provides a detailed description.
Ingestion of Drinking Water fcsU Section 5.1
TBD
We calculated ingestion HBNs for a residential receptor who ingests contaminated
drinking water for 350 days/year. Consistent with EPA policy, the ingestion HBNs were
calculated to reflect consideration of children's exposure. The calculation of cancer
HBNs assumed an exposure duration of 30 years and used a time-weighted average
drinking water intake rate for individuals aged 0 to 29 years, equal to 0.0252 liters per day
per kilogram body weight. In the case of cancer HBNs, the 30-year exposure period
represents a high-end (95th percentile) value for population mobility. We chose the 30-
year period to cover ages 0-29 to ensure childhood years were included. Non-cancer
ingestion HBNs were developed to be protective of children aged 0 to 6 years; the
calculations used a daily ingestion rate that is representative of children in this age-group,
and is equal to 0.0426 liters per day per kilogram body weight.
6-5
-------
IWEM User's Guide Section 6.0
Inhalation of Volatiles During Showering fcsU Section 5.2
TBD
Inhalation HBNs were calculated for adults because we assumed that children take
baths. We assumed daily 15 minutes showers for 350 days per year over 30 years and
used a shower model to calculate the average constituent concentration in air to which an
individual is exposed during a day as a result of volatilization of a constituent in shower
water. We assumed that the shower water is ground water from the well modeled by
EPACMTP. We also made the important assumption that constituents are released into
household air only a result of showering activity, and that exposure to air-phase
constituents only occur in the shower stall and bathroom. EPA acknowledges that not
considering exposures to children who bathe in bathtubs may be a significant limitation.
However, we have not yet developed a "bath" model for evaluating children.
6.1.4.3 Selection of the RGC within the IWEM Software
Tier 1 LCTVs are provided for both MCLs and HBNs. In the case of HBNs, the
LCTV reflects the most restrictive pathway and effect, i.e., the lowest of the available
HBNs. At Tier 2, you can select the type of RGC (either MCL, ingestion HBN,
inhalation HBN, or all) that you wish to use. You may also enter your own constituent-
specific RGC values. For example, your state regulatory authority may request that you
use HBNs that are calculated using a different target risk level or a different assumption
regarding the weight of an adult. (Instructions regarding the selection of RGCs and
entering user-specified RGCs are provided in Section 5.4.1.6 of this User's Guide.)
6.2 Additional Parameters for a Tier 2 Evaluation
This section describes the additional parameters for which you can provide site-
specific values in a Tier 2 evaluation. There are two categories of Tier 2 input
parameters: required parameters for which you must provide site-specific values; and
optional parameters for which you can provide site-specific values if data are available.
When site-specific data for some of the optional model inputs are not available, the
suggested default values or distributions of values can be used.
6.2.1 Basis for Using Site-Specific Parameter Values
The Tier 1 evaluation provides a quick screening analysis of whether or not a
WMU design is protective for wastes of concern. The IWEM Tier 1 analysis
compensates for the lack of site-specific information by being conservative. Tier 1
LCTVs are based on simulating a wide range of conditions, and then selecting the 90th
percentile of the predicted ground-water concentration as the basis for assigning the
6-6
-------
IWEM User's Guide Section 6.0
LCTV. In other words, the Tier 1 evaluation is expected to be protective in 90% of the
cases.
The Tier 2 evaluation, which is designed to simulate a specific WMU, has less
uncertainty in its liner recommendation than a Tier 1 evaluation of the same site. This
reduction in uncertainty is achieved by using site-specific data which are both easily
measured and important to the model output.
6.2.2 Tier 2 Parameters
Table 6.1 provides a list of the Tier 2 IWEM parameters. The table indicates: (1)
the parameters the user may specify in Tier 2 grouped by the main input groups of the
IWEM software, (2) the units of measurement; (3) whether the parameter is a required
user input; (4) the IWEM default if the parameter is not a required user input; and (5) the
ranges of allowable input values.
Parameters that require user inputs are indicated with YES in the corresponding
column of the table. All other parameters are optional user inputs. The following
sections discuss the Tier 2 parameters in more detail.
6.2.2.1 Tier 2 Parameters that Require User Inputs
Parameters in Table 6.1 that are marked with YES in the 'Required User Input?'
column are those for which you must provide a site-specific value in Tier 2; the software
does not have a default value. In addition to selecting the WMU type and providing
constituent leachate concentrations, there are only four other key parameters for which the
user must provide data. They are:
WMU Area;
WMU Depth for landfills;
Ponding Depth for surface impoundments; and
Climate Center that is nearest to your site.
6.2.2.2 Optional Tier 2 Parameters
Except the required parameters listed above, all other Tier 2 parameters listed in
Table 6.1 are optional user input parameters. Use of site-specific data is strongly
recommended for these parameters, but if you do not have a value, the IWEM software
will allow you to select a default value.
6-7
-------
IWEM User's Guide
Section 6.0
Table 6.1 Tier 2 Parameters
Parameter
Units
Required
User
Input?
Default
Range
Min
Max
WMU Parameters
WMU Area
WMU Depth (LF only)
Ponding Depth (SI Only)
Sediment Layer Thickness (SI Only)
WMU Base Depth below ground surface
Operational Life (SI, WP, LAU)
Surface Water Body within 2,000
(SI Only)
Distance to Ground-Water Well
m2
m
m
m
m
yr
m
m
YES
YES
YES
-
-
-
-
-
0.2
0.0
(1)
360
150
1
>0
0.01
0.2
-100b)
1.0
0
0
l.OE+8
10
100
100a)
100b)
200
5,000
1,609
Subsurface Parameters
Subsurface Environment
Depth to Water Table
Saturated Zone Thickness
Hydraulic Gradient
Hydraulic Conductivity
Subsurface pH
- Solution limestone environment
- All other
-
m
m
m/m
m/yr
~
-
-
-
-
-
~
(2)
(3)
(3)
(3)
(3)
7.5
6.2
NA
0.1
0.3
>0
3.15
7
1
NA
1,000
1,000
1
IxlO8
14
14
Infiltration and Recharge Parameters
Infiltration Rate
Nearest Climate Center
Regional Soil Type
Waste Type Permeability
m/yr
-
-
-
-
YES
-
-
(4)
(5)
(6)
(6)
0
NA
NA
NA
100
NA
NA
NA
Constituent Parameters
Constituent Name
CAS Number
Koc (organics only)
Overall Decay Coefficient (organics only)
Acid Hydrolysis Rate
Neutral Hydrolysis Rate
-
-
L/kg
1/yr
l/(M-yr)
1/yr
-
-
-
-
-
-
(7)
(7)
(7)
(7)
(7)
(7)
NA
50-00-0
0.0
0.0
0.0
0.0
NA
999999-99-9
l.OE+10
100
l.OE+10
100
6-8
-------
IWEM User's Guide
Section 6.0
Table 6.1 Tier 2 Input Parameters (continued)
Parameter
Base Hydrolysis Rate
MCL
Ingestion HBN - Cancer
Ingestion HBN - Non Cancer
Inhalation HBN - Cancer
Inhalation HBN - Non Cancer
User RGC
Exposure Duration
Units
l/(M-yr)
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
vrs
Required
User
Input?
-
-
-
-
-
-
-
-
Default
(7)
(7)
(7)
(7)
(7)
(7)
(8)
(9}
Range
Min
0.0
>0
>0
>0
>0
>0
>0
>0
Max
l.OE+10
NA
NA
NA
NA
NA
NA
70
NA = Not Applicable
a) Value cannot be larger than impoundment ponding depth
b) Negative value indicates base is above ground surface; depth value cannot be larger than depth to water
table.
NOTES:
(1) Default operational life is 50 years for Surface Impoundments, 20 years for Waste Piles, and 40
years for Land Application Units.
(2) Select from the IWEM list; if you select type "unknown," the subsurface parameters will be set to
mean values from the IWEM nationwide database.
(3) Assigned from the IWEM database according to the selected subsurface environment.
(4) Assigned from the IWEM database according to the selected climate station, soil type or waste
type.
(5) You must select a center from the IWEM list, usually the center nearest to your WMU location.
(6) Select from the IWEM list; if you select type "unknown," the soil type or waste type will be chosen
randomly from the three known types during the Tier 2 modeling process.
(7) Applicable only when you wish to add constituents to the IWEM constituent list; you must provide
at least one MCL or HBN value for each new constituent.
(8) Applicable when you want to add an HBN to a constituent already in the IWEM database.
(9) Applicable only when you supply a user-specific RGC.
6-9
-------
IWEM User's Guide Section 6.0
6.2.2.3 Default Values for Missing Data
Default values for Tier 2 parameters are generally obtained from IWEM's internal
ground-water modeling and constituent property databases. The IWEM software is
designed to help you make reasonable choices for default parameter values. For instance,
if you do not know the specific values for ground-water parameters, such as the thickness
of the saturated aquifer zone and the hydraulic ground-water gradient, but you do know
the general hydrogeology of your site (e.g., you have an alluvial aquifer at your site),
IWEM will use this information to select appropriate ground-water values for alluvial
aquifers.
Depending on the parameter involved, IWEM may use either a single default
value for a missing parameter, or it may use a probability distribution of values, to
accommodate a range of possible values.
6.2.2.4 How IWEM Handles Infeasible User Input Parameters
The IWEM software checks all entered data values. It verifies that only numeric
data are entered in data fields and that values are non-negative. In addition, IWEM
checks that values are all within feasible ranges. When a value is outside the feasible
range, IWEM will display a warning and will not allow you to proceed until you change
the entered value. Table 6.1 lists the minimum and maximum allowed values for each
Tier 2 parameter.
In addition to checking individual parameters, IWEM ensures that combinations
of parameters will not lead to physically unrealistic results. This is particularly the case
for parameter combinations which could cause an excessive degree of ground-water
mounding underneath a WMU. The extent of ground-water mounding depends on WMU
characteristics, the permeability of the unsaturated and saturated zones of the aquifer, the
depth to ground water and the saturated thickness of the saturated zone. IWEM checks
for infeasible parameter combinations after you have entered all Tier 2 parameters and
alerts you if it has found a problem. If IWEM determines that the data you have provided
will cause an excessive degree of ground-water mounding, IWEM will reduce the
allowed infiltration rate.
6.2.3 Tier 2 Parameter Descriptions
This section provides a detailed description of the individual Tier 2 parameters,
including how you may obtain site-specific values. The parameters are organized in
groups, according to the grouping in the IWEM software data entry screens.
6-10
-------
IWEM User's Guide Section 6.0
6.2.3.1 WMU Parameters fcU Sections 3.1, 4.2.1.3, 4.2.5
TBD
WMU Area (m2). This parameter represents the footprint area of the WMU (area
= length x width). This is a required user-input value for a Tier 2 evaluation. The area
must be entered in square meters. To convert other units to square meters, use the
following factors:
1 Acre = 4,046.9 m2
1 Hectare = 10,000 m2
1 ft2 = 0.093 m2
WMU Depth (m). If you select 'Landfill' as the WMU type, you must also enter
the depth of the landfill. This parameter represents the average waste thickness in the
landfill at closure. For landfills this is a required user input value. It does not apply to
waste piles or land application units. For surface impoundments, you must enter an
equivalent parameter, the ponding depth (see below). The landfill depth must be entered
in meters. To convert other units to meters, use the following factors:
1 Foot = 0.305 m
1 Inch = 0.0254 m
Ponding Depth (m). This is a required user input parameter for surface
impoundments only. This parameter represents the average depth of free liquid in the
impoundment. Surface impoundments tend to build up a layer of consolidated 'sludge' at
their bottom; the thickness of the layer, if present, should not be counted as part of the
ponding depth. The ponding depth must be entered in meters. To convert other units to
meters, use the same conversion factors listed above.
Sediment Layer Thickness (m). This is an optional user input value. It is
applicable to surface impoundments only. This parameter represents the average
thickness of accumulated sediment ('sludge') deposited on the bottom of the
impoundment. The sediment layer thickness must be entered in meters. The default
value is 0.2 m. To convert other units to meters, use the same conversion factors listed
above.
Depth of the WMU Base Below Ground Surface (m). This is an optional user
input value. It represents the depth of the base of the unit below the ground surface, as
schematically depicted in Figure 6.2. The depth of the unit below the ground surface
reduces the distance in the unsaturated zone through which leachate constituents have to
travel before they reach ground water. This depth must be entered in meters. The default
value is 0.0 meters, i.e., the base of the unit is level with the ground surface. To convert
-------
IWEM User's Guide Section 6.0
other units to meters, use the same conversion factors listed above. There may be
circumstances in which the base of the WMU is elevated above the ground surface.
IWEM can handle this situation in two ways:
a) If you know the depth to ground water of your site, you can enter the total
vertical distance between the base of the WMU and the water table as the Depth
of the Water Table in the subsurface parameters input screen. In this case, set
the Depth of the WMU Base Below Ground Surface to zero (0.0).
b) If you do not know the depth to the water table, then you can enter the elevation
of the WMU base as a negative value for the Depth of the WMU Base Below
Ground Surface. For instance, if the unit is 1 meter above ground surface, enter
a value of -1 as the depth.
WASTE MANAGEMENT UNIT
K^M
DEPTH OF THE WMU BASE " I/VAVVWJ
VLINER DEPTHTO
WATER TABLE v
SATURAT
THICK
1
GROUND SURFACE
WATER TABLE
ED ZONE
NESS
//&/&/&/&/&^
Figure 6.2 WMU with Base Below Ground Surface.
Operational Life (yr). For waste piles, surface impoundments, or land application
units, the operational life is an optional Tier 2 user input parameter. This parameter does
not apply to landfills because each landfill is assumed closed with waste in place and the
time required to deplete the contaminants in a landfill waste is calculated for the user by
IWEM. See Section 6.1.1 for more details on leaching durations. The operational life
represents the number of years the WMU is in operation, or, more precisely for the
purpose of IWEM, the number of years the unit releases leachate. Default values for this
parameter are as follows:
6-12
-------
IWEM User's Guide Section 6.0
Waste Pile = 20 years
Land Application Unit = 40 years
Surface Impoundment = 50 years
Distance to Nearest Surface Water Body (m). For surface impoundments, IWEM
needs to know whether or not there is a permanent surface water body within 2,000
meters of the WMU, (i.e., a river, pond, or lake). This parameter is used in the
calculation of ground-water mounding to cap the infiltration rate from surface
impoundments. The surface water body does not have to be located in the direction of
ground-water flow and can be in any direction from the WMU unit. If you know the
distance to the nearest surface water body, IWEM will use that value. If the distance is
unknown or known with some uncertainty, IWEM provides the following options:
Distance to surface water body is unknown (IWEM uses 360 m),
Exact distance is unknown but it is less than 2000 m (IWEM uses 360 m), or
Exact distance is unknown but it is greater than 2000 m (IWEM uses 5000 m).
Distance to nearest well (m). This parameter represents the distance, in the
direction of downgradient ground-water flow, to an actual or potential ground-water
exposure location. This exposure location can be represented as a ground-water well.
Figure 6.3 depicts how the well distance is measured. This figure shows a plan view
(upper graph) and a cross-sectional view (lower graph) of a groundwater constituent
plume emanating from a WMU. The WMU is represented as the dark rectangular area in
the figure. The constituent plume is represented by the lighter shaded area. In this figure,
the direction of ground-water flow underneath the WMU is from left to right. The
constituent plume follows the direction of ground-water flow, but as it moves, the plume
also spreads laterally (upper graph) as well as vertically (lower graph). In IWEM, these
processes are modeled by EPACMTP. Figure 6.3 also shows the location of the well.
IWEM always assumes that the well is located along the center line of the plume,
but the software randomly varies the depth of the well intake point (see lower graph)
during the Monte Carlo simulation process. The distance between WMU and the location
of the well is an optional user input parameter at Tier 2. This parameter must be entered
in meters, and has a default value of 150 meters (492 feet). To enter a site-specific value,
determine the direction of ground-water flow, and then the horizontal distance to the
nearest well (or location at which you want to ensure that constituent concentrations in
ground water do not exceed protective levels) along the direction of groundwater flow. If
you are unsure of the ground water flow direction, it will be protective to enter the
shortest distance between the edge of the WMU and the nearest location of concern.
6-13
-------
IWEM User's Guide
Section 6.0
PLAN VIEW
CONTAMINANT
PLUME
CENTERLINE
SECTIONAL VIEW
DOWNGRADIENT DISTANCE
WELL
LOCATION
LAND SURFACE
Figure 6.3 Position of the Modeled Well Relative to the Waste
Management Unit.
For compatibility with the EPACMTP ground-water model and consistency with
related EPA programs, we assume the well is located within 1 mile, or 1,609 meters,
from the WMU. IWEM will not accept larger values.
While IWEM allows you to enter a site-specific value for the distance between the
well and the WMU, the model does not allow you to modify the depth of the well intake
point below the water table. In IWEM evaluations, the depth of the well intake point is
always treated as a 'Monte Carlo' parameter, i.e., the tool will vary the well depth during
the model simulations, from zero (right at the water table), up to a maximum depth of 10
meters (30 feet) below the water table. If the value for the saturated thickness of your
6-14
-------
IWEM User's Guide Section 6.0
aquifer (see section 6.2.3.2) is less than 10 meters, IWEM will use that actual depth as the
maximum value for the well depth. Also, IWEM does not allow you to vary the distance
from the center line of the plume.
6.2.3.2 Subsurface Parameters tsUI Section 4.2.3.1
TBD
The subsurface parameters in IWEM comprise a group of the most important
ground-water modeling parameters. Unfortunately, these parameters are not easily
measured. Obtaining site-specific values for these parameters requires a hydrogeological
site characterization. Such information may be available from WMU planning and siting
studies, environmental impact assessments, and RCRA permit applications. The United
States Geological Survey (www.usgs.gov) and your local state geological survey may also
be good sources of site-specific information.
To assist you in performing a Tier 2 evaluation, the IWEM software provides
multiple options for entering subsurface parameters to assist you in making the best
possible use of information you have. The preferred option is to use accurate site-specific
values for all of the parameters, entering them directly in the appropriate data input
screens. The second option is where you have values for some, but not all of the
parameters. In this case, you enter the parameter values that you know, and IWEM makes
a best estimate of the missing values, utilizing knowledge the software has as to how the
various parameters tend to be correlated from its national ground-water modeling
database. The third, and least desirable, option is where you have no site-specific
subsurface data whatsoever. In this case, IWEM simply assigns parameter values that are
average values from its database.
The individual IWEM parameters in this group are discussed below.
Subsurface Environments. IWEM includes a built-in database of hydrogeological
parameters, organized by 12 different subsurface environments, plus one 'unknown'
category, as follows:
1) Metamorphic and Igneous
2) Bedded Sedimentary Rock
3) Till over Sedimentary Rock
4) Sand & Gravel
5) Alluvial Basins, Valleys & Fans
6) River Valleys and Floodplains with Overbank Deposits
7) River Valleys and Floodplains without Overbank Deposits
8) Outwash
9) Till and Till over Outwash
10) Unconsolidated and Consolidated Shallow Aquifers
645
-------
IWEM User's Guide Section 6.0
Subsurface Environment Descriptions
1) Igneous and Metamorphic Rocks
This hydrogeologic environment is underlain by consolidated bedrock of volcanic origin. This hydrogeologic
environment setting is typically associated with steep slopes on the sides of mountains, and a thin soil cover.
Igneous and metamorphic rocks generally have very low porosities and permeabilities This hydrogeologic
environment can occur throughout the United States, but is most prevalent in the western US.
2) Bedded Sedimentary Rock
Sedimentary rock is formed through erosion of bedrock. Deposited layers of eroded material may later be buried
and compacted to form sedimentary rock. Generally, the deposition is not continuous but recurrent, and sheets of
sediment representing separate events come to form distinct layers of sedimentary rock. Typically, these deposits
are very permeable and yield large quantities of ground water. Examples of this hydrogeologic environment
setting are found throughout the United States.
3) Till Over Sedimentary Rock
This hydrogeologic environment is found in glaciated regions in the northern United States which are frequently
underlain by relatively flat-lying consolidated sedimentary bedrock consisting primarily of sandstone, shale,
limestone, and dolomite. The bedrock is overlain by glacial deposits which, consists chiefly of till, a dense
unsorted mixture of soil and rock particles deposited directly by ice sheets. Ground water occurs both in the
glacial deposits and in the sedimentary bedrock. Till deposits often have low permeability.
4) Sand and Gravel
Sediments are classified into three categories based upon their relative sizes; gravel, consisting of particles that
individually may be boulders, cobbles or pebbles; sand, which may be very coarse, coarse, medium, fine or very
fine; and mud, which may consist of clay and various size classes of silt. Sand and gravel hydrogeologic
environments are very common throughout the United States and frequently overlie consolidated and semi-
consolidated sedimentary rocks. Sand and gravel aquifers have very high permeabilities and yield large
quantities of ground water.
5) Alluvial Basins, Valleys and Fans
Thick alluvial deposits in basins and valleys bordered by mountains typify this hydrogeologic environment.
Alluvium is a general term for clay, silt, sand and gravel that was deposited during comparatively recent geologic
time by a stream or other body of running water. The sediments are deposited in the bed of the stream or on its
flood plain or delta, or in fan shaped deposits at the base of a mountain slope. Alluvial basins, valleys and fans
frequently occupy a region extending from the Puget Sound-Williamette Valley area of Washington and Oregon
to west Texas. This region consists of alternating basins or valleys and mountain ranges. The surrounding
mountains, and the bedrock beneath the basins, consist of granite and metamorphic rocks. Ground water is
obtained mostly from sand and gravel deposits within the alluvium. These deposits are interbedded with finer
grained layers of silt and clay.
6-16
-------
IWEM User's Guide Section 6.0
Subsurface Environment Descriptions (continued)
6) River Alluvium with Overbank Deposits
This hydrogeologic environment is characterized by low to moderate topography and thin to moderately thick sediments of
flood-deposited alluvium along portions of a river valley. The alluvium is underlain by either unconsolidated sediments or
fractured bedrock of sedimentary or igneous/metamorphic origin. Water is obtained from sand and gravel layers which are
interbedded with finer grained alluvial deposits. The alluvium typically serves as a significant source of water. The flood plain
is covered by varying thicknesses of fine-grained silt and clay, called overbank deposits. The overbank thickness is usually
greater along major streams and thinner along minor streams but typically averages 5 to 10 feet.
7) River Alluvium without Overbank Deposits
This hydrogeologic environment is identical to the River Alluvium with Overbank Deposits environment except that no
significant fine-grained floodplain deposits occupy the stream valley. The lack of fine grained deposits may result in
significantly higher recharge in areas with ample precipitation.
8) Outwash
Sand and gravel removed or "washed out" from a glacier by streams is termed outwash. This hydrogeologic environment is
characterized by moderate to low topography and varying thicknesses of outwash that overlie sequences of fractured bedrock of
sedimentary, metamorphic or igneous origin. These sand and gravel outwash deposits typically serve as the principal aquifers
within the area. The outwash also serves as a source of regional recharge to the underlying bedrock.
9) Till and Till Over Outwash
This hydrogeologic environment is characterized by low topography and outwash materials that are covered by varying
thicknesses of glacial till. The till is principally unsorted sediment which may be interbedded with localized deposits of sand
and gravel. Although ground water occurs in both the glacial till and in the underlying outwash, the outwash typically serves as
the principal aquifer because the fine grained deposits have been removed by streams. The outwash is in direct hydraulic
connection with the glacial till and the glacial till serves as a source of recharge for the underlying outwash.
10) Unconsolidated and Semi-consolidated Shallow Surficial Aquifers
This hydrogeologic environment is characterized by moderately low topographic relief and gently dipping, interbedded
unconsolidated and semi-consolidated deposits which consist primarily of sand, silt and clay. Large quantities of water are
obtained from the surficial sand and gravel deposits which may be separated from the underlying regional aquifer by a low
permeability or confining layer. This confining layer typically "leaks", providing recharge to the deeper zones.
11) Coastal Beaches
This hydrogeologic environment is characterized by low topographic relief, near sea-level elevation and unconsolidated deposits
of water-washed sands. The term beach is appropriately applied only to a body of essentially loose sediment. This usually
means sand-size particles, but could include gravel. Quartz particles usually predominate. These materials are well sorted, very
permeable and have very high potential infiltration rates. These areas are commonly ground-water discharge areas although they
can be very susceptible to the intrusion of saltwater.
12) Solution Limestone
Large portions of the central and southeastern United States are underlain by limestones and dolomites in which the fractures
have been enlarged by solution. Although ground water occurs in both the surficial deposits and in the underlying bedrock, the
limestones and dolomites, which typically contain solution cavities, generally serve as the principal aquifers. This type of
hydrogeologic environment is often described as "karst."
13) Unknown Environment
If the subsurface hydrogeological environment is unknown, or it is different from any of the twelve main types used in IWEM,
select the subsurface environment as Type 13. In this case, IWEM will assign values of the hydrogeological parameters (depth
to groundwater, saturated zone thickness, saturated zone hydraulic conductivity, and saturated zone hydraulic gradient) that are
simply national average values.
6-17
-------
IWEM User's Guide Section 6.0
11) Coastal Beaches
12) Solution Limestone
13) Unknown
This User's Guide provides a summary of the geologic and hydrogeologic
characteristic of each environment (see text box). You are cautioned that the assignment
of a subsurface environment is best done by a professional trained in hydrogeology and is
familiar with local site conditions.
Depth to the Water Table (m) This parameter is the vertical distance from the
ground surface to the water table as depicted in Figure 6.2. The water table in this case is
meant to represent the 'natural' water elevation, as it is or would be without the influence
from the WMU. The presence of a WMU, particularly a surface impoundment, may
cause a local rise in the water table called mounding. When you run a Tier 2 evaluation,
IWEM assumes that the depth to water table value you have entered does not include
mounding. The tool will calculate the predicted impact of each liner design on the
ground water as part of the modeling evaluation.
If the water table elevation at your site shows seasonal fluctuation, it is best to
enter an average annual depth to ground-water value. Note that entering a smaller depth
to ground-water value will mean that constituents have less distance to travel before they
reach the ground water, and this will tend to result in a more protective IWEM result (i.e.,
IWEM will tend to predict higher ground-water exposure concentrations and hence return
a lower LCTV). It is also important to remember that the depth to ground water should
be measured from the ground surface, not from the base of the WMU. If the base of the
unit is lower than the ground surface and, therefore, closer to the watertable, you should
enter that value as the Depth of the WMU Base Below the Ground Surface (see section
6.2.3.1 above).
The depth to ground water should be entered in meters. To convert from other
units to meters, use the factors listed in section 6.2.3.1. The default value for this
parameter is a function of the selected subsurface environment. If you selected the
"unknown" subsurface environment, IWEM will use the national average of 5.2 meters.
If you selected one of the twelve subsurface environments and do not specify the depth to
the water table, IWEM will treat the depth to the water table as a Monte-Carlo variable:
IWEM will use a distribution of values that is appropriate for the selected subsurface
environment.
Saturated Zone Thickness (m). This parameter represents the vertical distance
from the watertable down to the base of the aquifer, as shown in the diagram in Figure
6.2. Usually the base is an impermeable layer, e.g., bedrock. This parameter is used in
6-18
-------
IWEM User's Guide Section 6.0
the Tier 2 model simulation to describe the thickness of the ground-water zone over
which the leachate plume can mix with ground water. If your site has a highly stratified
hydrogeology, it may be difficult to precisely define the "base of the aquifer," but in such
cases, the stratification may effectively limit the vertical plume travel distance. In this
case it may be appropriate to enter the maximum vertical extent of the plume as an
"effective" saturated zone thickness in IWEM.
The parameter must be entered in meters. To convert from other units to meters,
use the factors given in section 6.2.3.1. The default saturated zone thickness is a function
of the selected subsurface environment. If you selected the "unknown" subsurface
environment, IWEM will use the national average of 10.1 meters. If you selected one of
the twelve subsurface environments and did not specify the saturated thickness, IWEM
will treat the depth to the saturated thickness as a Monte-Carlo variable and use a
distribution of values that is appropriate for the selected subsurface environment.
Hydraulic Gradient (m/m). For unconfined aquifers, the hydraulic gradient is
simply the slope of the water table in a particular direction. It is calculated as the
difference in the elevation of the water table measured at two locations divided by the
distance between the two locations. In IWEM, this parameter represents the average
horizontal ground-water gradient in the vicinity of the WMU location. The gradient is
meant to represent the 'natural' ground-water gradient as it is, or would be, without
influence from the WMU. The presence of a WMU, particularly a surface impoundment,
may cause local mounding of the water table and associated higher local ground-water
gradients. When you run a Tier 2 evaluation, IWEM assumes that the gradient value you
have entered does not include mounding; rather the software will calculate the predicted
impact on the ground water of each liner design as part of the modeling evaluation.
The hydraulic gradient, together with the hydraulic conductivity (see below),
controls the ground-water flow rate, in accordance with Darcy's Law. The effect of
varying ground-water flow rate on contaminant fate and transport is complex. Intuitively,
it would seem that factors that increase the ground-water flow rate would cause a higher
ground-water exposure level at the receptor well, but this is not always the case. A higher
ground-water velocity will cause leachate constituents to arrive at the well location more
quickly. For constituents that are subject to degradation in ground water, the shorter
travel time will cause the constituents to arrive at the well at higher concentrations as
compared to a case of low ground-water velocity and long travel times. On the other
hand, a high ground-water flow rate will tend to increase the degree of dilution of the
leachate plume, due to mixing and dispersion. This will in turn tend to lower the
magnitude of the concentrations reaching the well. The Tier 1 and Tier 2 evaluations are
based on the maximum constituent concentrations at the well, rather than how long it
6-19
-------
IWEM User's Guide Section 6.0
might take for the exposure to occur, and therefore a higher ground-water flow rate may
result in lower predicted exposure levels at the well.
The hydraulic gradient is a unitless parameter. Its default value depends on the
subsurface environment you selected. If you selected the "unknown" environment,
IWEM will use a nationwide average value of 0.0057. If you selected one of the twelve
subsurface environments and did not specify the hydraulic gradient, IWEM will treat the
hydraulic gradient as a Monte-Carlo variable, and it will use a distribution of values that
is appropriate for the selected subsurface environment.
Hydraulic Conductivity (m/yr). This parameter represents the permeability of the
saturated aquifer in the horizontal direction. The hydraulic conductivity, together with
the hydraulic gradient, controls the ground-water flow rate. For the same reasons as
discussed above, assigning a low hydraulic conductivity value will not necessarily result
in lower predicted ground-water exposures and higher LCTVs. In a broader sense, it
means that siting a WMU in a low permeability aquifer setting is not always more
protective than a high permeability setting. Low ground-water velocity means that it will
take longer for the exposure to occur, and as a result, there is more opportunity for natural
attenuation to degrade contaminants. For long-lived waste constituents, it also means that
little dilution of the plume may occur.
The hydraulic conductivity of aquifers is sometimes reported as a transmissivity
value, which is usually denoted with the symbol'T'. Transmissivity is simply the
product of hydraulic conductivity and saturated thickness. To back-calculate the
hydraulic conductivity, you should divide the transmissivity by the value of the saturated
zone thickness. The hydraulic conductivity parameter in IWEM must be entered in
meters per year. To convert from other units, use the following factors:
1 meter/second = 31,536,000 m/yr
1 foot/second = 9,612,173 m/yr
1 gallon/day/foot2 = 14.89 m/yr
The default value of hydraulic conductivity in IWEM varies with the subsurface
environment you have selected. If you selected the "unknown" subsurface environment,
IWEM will use a nationwide average value of 1,890 m/yr. If you selected one of the
twelve hydrogeologic environments and the hydraulic conductivity as "unknown," IWEM
will treat the hydraulic conductivity as a Monte-Carlo variable, and it will use a
distribution of values that is appropriate for the selected subsurface environment.
Subsurface pH. This parameter represents the alkalinity or acidity of the soil and
aquifer. The pH is one of the most important subsurface parameters controlling the
6^20
-------
IWEM User's Guide Section 6.0
mobility of metals. Most metals are more mobile under acidic (low pH) conditions, as
compared to neutral or alkaline (pH of 7 or higher) conditions. The pH may also affect
the hydrolysis rate of organic constituents; some constituents degrade more rapidly or
more slowly as pH varies. The pH of most aquifer systems is slightly acidic, the primary
exception being aquifers in solution limestone settings. These may also be referred to as
'karst', 'carbonate' or 'dolomite' aquifers. The ground water in these systems is usually
alkaline.
IWEM assumes the subsurface pH value is the same in the unsaturated zone and
saturated zone. The default pH value depends on the hydrogeologic environment you
selected; if you selected "Solution Limestone" (Subsurface Environment 12), the default
pH is 7.5. In all other hydrogeologic environments, the default pH value is 6.2. These
default values represent median values from EPA's Data Storage and Retrieval System,
National Water Quality Database (STORET). If you do not know the hydrogeologic
environment, IWEM will assume that the subsurface environment is of a
non-solution-limestone type with the default pH of 6.2.
6.2.3.3 Infiltration and Recharge Parameters tsUI Section 4.2.2
TBD
In IWEM, the infiltration rate is defined as the rate (annual volume divided by
WMU area) at which leachate flows from the bottom of the WMU (including any liner)
into the unsaturated zone beneath the WMU. Recharge is the regional rate of aquifer
recharge outside of the WMU. For landfills, waste piles, and land application units, the
infiltration rate is primarily determined by the local climatic conditions, especially annual
precipitation, and WMU liner characteristics. For surface impoundments, the infiltration
rate from the unit is a function of the surface impoundment ponding depth, liner
characteristics, and the presence of a 'sludge' layer at the bottom of the impoundment.
The regional recharge rate is a function of the annual precipitation rate, and varies with
geographical location and soil type.
The WMU related parameters are entered in IWEM in the WMU Parameters
group (see Section 6.2.3.1). The location and soil related parameters are entered in the
Infiltration and Recharge Parameters group. Infiltration rate is among the most sensitive
site-specific parameters in an IWEM evaluation, and, therefore, the software gives you
the option to provide a site-specific value in Tier 2. The model is usually much less
sensitive to recharge rate. IWEM determines the appropriate value for you, as a function
of site location and soil type. The specific IWEM parameters in this group are as follows.
Site-specific Infiltration Rate (m/yr). This parameter represents the actual annual
volume of leachate, per unit area of the WMU, which flows from the bottom of the WMU
into the unsaturated zone underneath the WMU. The performance characteristics of a
liner, if present, are among the most important factors controlling the infiltration rate, and
-------
IWEM User's Guide Section 6.0
therefore, the rate of leachate release. IWEM provides you the option to enter a site-
specific infiltration rate to accommodate liner designs that are different from the standard
liner designs (i.e., (1) no liner, (2) single clay liner, or (3) composite liner), and to
evaluate extreme climatic conditions.
IWEM provides default values for infiltration rate, which are a function of WMU
type, liner design, and site location. These values are used in Tier 1 and as defaults in a
Tier 2 evaluation. The default infiltration rates used in IWEM for landfills, waste piles,
and land application units were developed using the Hydrologic Evaluation of Landfill
Performance (HELP) model (Schroeder et. al, 1994). The infiltration rate from a WMU
is difficult to measure directly; if you wish to determine site-specific WMU infiltration
rates for use in IWEM, it is recommended to use a model such as HELP to estimate the
rates.
The infiltration rate in IWEM must be entered in units of meter/year. To convert
from other units, use the following factors:
1 foot/year = 0.305 m/yr
1 inch/year = 0.0254 m/yr
Climate Center. IWEM includes a database of infiltration rates and regional
recharge rates for 102 climate centers located throughout the United States. To ensure
that IWEM will use the most appropriate values (if you choose to let IWEM select a
default value), you must select the climate center which is most appropriate for your site.
Usually this is the nearest climate center. However, this is not always the case. Especially
in coastal and mountain regions, the nearest climate center does not always represent
conditions that most closely approximate conditions at your site. You should therefore
use your judgment and also consider other adjacent climate centers. In the IWEM
software tool, you select the climate center from a drop-down list which can be sorted by
City or by State. Figure 6.4 shows the geographic locations of the 102 climate stations in
the United States.
Regional Soil Type. In order to assign an appropriate recharge rate, IWEM needs
to know the dominant, regional soil type in the vicinity of your site. IWEM provides a
selection of three major soil types, which are representative of most soils in the United
States:
Sandy Loam
Silty Loam
Silty Clay Loam.
6-22
-------
IWEM User's Guide Section 6.0
IWEM also allows you to select the soil type "unknown." In that case, IWEM
will treat the soil type as a Monte-Carlo variable and randomly select from the three
available soil types, in accordance with the relative frequency of occurrence of each type
across the United States. By selecting the soil type, IWEM also assigns the soil
parameters that are used in the modeling of fate and transport in the unsaturated zone of
the aquifer.
Waste Type Permeability This parameter is used only for waste piles. Waste
piles are not typically covered and the permeability of the waste itself is a factor in
determining the rate of leachate released due to water percolating through the WMU. For
waste piles, IWEM recognizes three categories of waste permeability and their associated
infiltration rate: high permeability (0.041 cm/sec); moderate permeability (0.0041
cm/sec); and low permeability (0.00005 cm/sec). The waste permeability is correlated
with the grain size of the waste material, ranging from coarse to five-grained materials.
If you do not specify the waste type for waste piles, IWEM will default to
randomly selecting between the infiltration rates for each of the three waste types in the
Tier 2 Monte Carlo process, with each type having equal probability. That is, IWEM will
use a uniform probability distribution.
6-23
-------
ON
to
;hua
La
-------
IWEM User's Guide Section 6.0
6.2.3.4 Constituent Parameters INd!! Section 5.0
IWEM includes a database of 206 organic constituents and 20 metals. Appendix
A provides a list of these constituents and their properties. The database provides the
following information for each constituent.
Descriptive Data: Name,
CAS Number
Physical and Constituent Properties: Organic Carbon Partition
Coefficient (KJ
Metals sorption isotherm data (kd)
Hydrolysis Rate Constants
Reference Ground-water Concentrations: Maximum Contaminant Level (MCL)
Health Based Numbers (HBN)
To preserve the integrity of the database, IWEM gives you limited flexibility to
modify these data. IWEM does give you the option of specifying an overall constituent
decay rate which can include biodegradation, proving a constituent partitioning
coefficient (kd), and specifying one additional RGC to augment the built-in MCL and
HBN values.
IWEM allows you to add new constituents to its database and this provides an
indirect mechanism to assign different constituent parameter values, by entering a
constituent of interest as a 'new' constituent in the database with its own parameter
values.
The following sections discuss the IWEM constituent parameters.
Descriptive Data
Constituent Name and CAS Number. These parameters are used in IWEM to
identify each constituent. Whereas constituents may have multiple names, the CAS
number is an industry-standard, unique, identification code. If you want to use the "Add
New Constituent" option to assign different fate and transport parameters to an existing
IWEM constituent, it is recommended to use the actual CAS number and enter a new
constituent name.
6-25
-------
IWEM User's Guide Section 6.0
Physical and Constituent Properties fcsU Section 4.2.4
TBD
The physical and constituent properties that affect subsurface fate and transport
include sorption parameters and degradation parameters.
Organic Carbon Partition Coefficient (Koe). This parameter describes the sorption,
or affinity of a constituent to attach itself to soil and aquifer grains. This parameter is
applicable to organic constituents which tend to sorb onto the organic matter in soil or in
an aquifer. Constituents with high Koc values tend to move more slowly through the soil
and ground water. Volatile organics tend to have low Koc values, whereas semi-volatile
organics often have high Koc values. Koc values can be obtained from many constituent
property handbooks, as well as online databases, (e.g., Handbook of Environmental Data
on Organic Constituents, Verschueren, 1983). Sometimes, these references provide an
octanol- water partition coefficient (Kow), rather than a Koc value. Kow and Koc are roughly
equivalent parameters. A number of conversion formulas exist to convert Kow values into
Koc, and can be found in handbooks on environmental fate data (e.g., Verschueren, 1983;
Kollig et. al., 1983). Different conversion formulas exist for different constituents and
environmental media, and there is no single formula that is valid for all organic
constituents; therefore, they should be used with some caution.
In IWEM, Koc has units of liters/kilogram (L/kg) or, equivalently, milliliters/gram
(mL/g).
Metals Isotherm Data. In the case of metals, sorption is expressed in the partition
coefficient kd. IWEM provides a set of kd values calculated using the MINTEQA2
geoconstituent speciation model for each metal. Rather than using a single kd value for
each metal constituent, IWEM includes multiple sets of kd values to reflect the impact of
variations in ground-water pH and other geochemical conditions. Each set of kd values is
referred to as a sorption isotherm. The sorption parameters for metals in IWEM are part
of the software's built-in database and they cannot be modified by the user. Further
information on how the MINTEQ sorption isotherms were developed can be found in the
IWEM Technical Background Document and the EPACMTP Parameters/Data
Background Document.
If you are adding a new constituent to the IWEM database, you can enter a single
kd value to model sorption for the constituent. The kd must be entered in units of L/kg or,
equivalently, mL/g.
Hydrolysis Rate Constants. Hydrolysis refers to the transformation of constituent
constituents through reactions with water. For organic constituents, hydrolysis can be one
of the main degradation processes that occur in soil and ground water. The hydrolysis
6^26
-------
IWEM User's Guide Section 6.0
rate values that are part of the IWEM database have been compiled by the U.S. EPA
Office of Research and Development (Kollig, 1993). For each organic constituent, the
database includes three hydrolysis rate constants: an acid-catalyzed rate constant, a
neutral rate constant, and a base-catalyzed rate constant.
Biodegradation
Biodegradation can be a significant attenuation process for organic constituents in
the subsurface. However, this process is also highly site- and constituent-specific. It is
not possible to provide reliable default biodegradation rates to be used in IWEM.
Evidence of the significance of biodegradation should be carefully considered in
accordance with EPA guidance, such as the OSWER Directive 9200.4-17P on Use of
Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground
Storage Tank Sites. A compendium of EPA bioremediation documents is available
online at www.epa.gov/ORDAVebPubs/biorem.html.
By default, IWEM does not explicitly take into account biodegradation processes,
and the IWEM constituent database does not include biodegradation rates. However, in
Tier 2, the IWEM software allows you to add a constituent-specific biodegradation decay
coefficient to its database, as part of the constituent properties input group8. This decay
coefficient has units of 1/yr. The value of the decay coefficient is related to half-life as:
Decay Coefficient (1/yr) = 0.693 / Half-life (yr)
IWEM stores user-defined decay coefficients in its constituent property database.
You should, however, be careful in using a decay coefficient value which is appropriate
for one site and not appropriate for others.
Reference Ground-Water Concentrations IbUI Section 5.0
TBD
The final set of parameters in the IWEM constituent database is a set of
constituent-specific RGCs, comprising MCLs and risk-based HBNs.
The use of these RGCs in IWEM is discussed in Chapter 7 of this User's Guide.
The derivation of the HBN values is discussed in Section 5 of the IWEM Technical
Background Document. You cannot change existing RGCs in the IWEM database. You
can, however, add a user-specified RGC value for each constituent in the database when
selected for a Tier 2 analysis. IWEM imposes no restrictions on user-specified RGCs,
Strictly speaking this decay coefficient can represent any first-order transformation process other
than hydrolysis, which is already explicitly considered in IWEM.
6^27
-------
IWEM User's Guide Section 6.0
other than that they should be expressed in units of mg/L and an exposure duration is
provided (in years) that is consistent with the way the RGC was derived.
User-specified RGCs may represent either more or less stringent health-based
values, or alternative regulatory standards. IWEM makes no assumptions about user-
specified RGCs and, consequently, the software cannot check whether your value is
correct or not.
If you wish to add constituents to the IWEM database, you will be required to
provide at least one RGC for each new constituent, either a MCL, an ingestion HBN, or
an inhalation HBN. Consult the IWEM Technical Background Document for details on
the derivation of HBN values. This mechanism also provides an indirect way of using
modified MCL and/or HBN values for constituents that are already in the database. In this
case, you can add the constituent to the database as a 'new' constituent and provide your
own HBN values.
6-28
-------
IWEM User's Guide Section 7.0
7.0 Understanding Your IWEM Results
After completing an analysis, IWEM provides a recommendation for a liner
design for a WMU or the appropriateness of land application. Section 7 provides
guidance on how IWEM may assist you in answering the following questions:
What kind of liner will be necessary to safely manage my waste in a landfill,
surface impoundment or waste pile?
Is land application appropriate for my waste?
What are the maximum allowable leachate concentrations for all constituents
in a waste for a particular type of WMU and liner design?
Should you consider a Tier 3 assessment?
The IWEM liner recommendations and determination of maximum allowable
leachate concentrations are based on protective ground-water concentrations at wells. In
Tier 1, IWEM uses the tabulated LCTV values that represent protective national
screening values. In Tier 2, IWEM calculates LCTVs to provide guidance on what
leachate levels need to be achieved, for instance through treatment, to safely allow
disposal in a particular WMU design. To help you understand the IWEM results, we will
discuss LCTVs first.
7.1 Leachate Concentration Threshold Values (LCTVs)
An LCTV is the maximum concentration of a constituent in the waste leachate
that is protective of ground water. That is, if the concentration in the leachate does not
exceed the LCTV, then the concentration in ground water at the well will not exceed the
RGC. IWEM uses the EPACMTP fate and transport model to calculate LCTVs.
EPACMTP is a fate and transport model that simulates the concentration of a constituent
in ground-water, as a function of the constituent's concentration in the waste leachate.
The LCTV is determined by comparing the predicted well concentration against a
selected RGC, i.e., an MCL or HBN. By definition, the LCTV is the value of the leachate
concentration for which the well concentration is equal to the RGC. LCTVs depend on:
1) the combined effects of WMU design characteristics and hydrogeological fate and
transport processes; and 2) the effect of constituent-specific regulatory standards such as
an MCL and constituent toxicity represented by the HBN.
7-1
-------
IWEM User's Guide Section 7.0
Tier 1 LCTVs are different from Tier 2 LCTVs. LCTVs from the Tier 1 analysis
are generally applicable to sites across the country. Tier 2 LCTVs on the other hand, are
based on site-specific data for several sensitive parameters and are not applicable to other
sites.
7.2 Limits on the LCTV
While the LCTVs are based on fate and transport modeling, and regulatory and
risk-based ground-water standards, EPA also considered other factors in developing final
LCTV values for some waste constituents. These are described in this section.
7.2.1 Toxicity Characteristic Rule (TC Rule) Regulatory Levels fcU Section 6.2
TBD
In 1990, EPA adopted the Toxicity Characteristic (TC) Rule making wastes
containing certain constituents at or above listed leachate concentrations a hazardous
waste.
For any waste constituent included in the TC rule, we capped the LCTV at the TC
Rule Regulatory Level. This level is the leachate concentration above which the waste is
considered to be a hazardous waste (U.S. EPA, 1990). TC levels have been determined
for the constituents listed in Table 7.1.
7.2.2 1,000 mg/L Cap fcU Section 6.2
TBD
EPA does not expect leachate concentrations from WMUs covered by this
guidance to exceed 1,000 mg/L for a single constituent, and therefore, has limited the
expected waste constituent leachate concentrations to be less than or equal to 1,000 mg/L.
One of the reasons to cap the leachate concentration in IWEM is that the fate and
transport assumptions in IWEM may not be valid at high concentrations. For instance,
high leachate concentrations may indicate the presence of a free organic phase.
Consequently, all Tier 1 and Tier 2 LCTVs are capped at a maximum value of 1,000
mg/L.
7-2
-------
IWEM User's Guide
Section 7.0
Table 7.1 Toxicity Characteristic Leachate Levels
Waste Constituent
Arsenic
Barium
Benzene
Cadmium
Carbon Tetrachloride
Chlordane
Chlorobenzene
Chloroform
Chromium
o-cresol
m-cresol
p-cresol
2,4-D
1 ,4-dichlorobenzene
1 ,2-dichloroethane
1 , 1 -dichloroethylene
2,4-dinitrotoluene
Endrin
Heptachlor
Hexachlorobenze
TC Rule Leachate
Regulatory Level
(mg/L)
5
100
0.5
1
0.5
0.03
100
6
5
200
200
200
10
7.5
0.5
0.7
0.13
0.02
0.008
0.13
Waste Constituent
Hexachloro-1 ,3-butadiene
Hexachloroethane
Lead
Lindane
Mercury
Methoxychlor
Methyl ethyl ketone
Nitrobenzene
Pentachlorophenol
Pyridine
Selenium
Silver
Tetrachloroethylene
Toxaphene
Trichloroethylene
2,4,5-trichlorophenol
2,4,6-trichlorophenol
2,4,5-TP acid (silvex)
Vinyl chloride
TC Rule Leachate
Regulatory Level
(mg/L)
0.5
3
5
0.4
0.2
10
200
2
100
5
1
5
0.7
0.5
0.5
400
2
1
0.2
7.2.3 Constituents with Toxic Daughter Products
J Section 6.2
TBD
A number of the constituents included in the IWEM constituent database can be
transformed in soil and ground water into one or more toxic daughter products as a result
of hydrolysis reactions. For these constituents, the LCTVs are calculated such that they
accommodate both the parent constituent as well as any toxic daughter products. For
instance, if a parent waste constituent rapidly hydrolyses into a persistent daughter
product, the ground-water exposure caused by the parent itself may be minimal (it has
already degraded before it reaches the well), but the final LCTV for this constituent
would be based on the exposure caused by the daughter product, under the protective
assumption that the parent compound fully transforms into the daughter product. If an
IWEM constituent has more than one toxic daughter product, the final LCTV is based on
the LCTV for the most protective compound in the parent-daughter sequence. If the
7-3
-------
IWEM User's Guide Section 7.0
LCTV of the parent constituent is lower than that of the daughter, the LCTV of the parent
remains unchanged. Additionally, if the daughter constituent has a particular RGC but
the parent constituent does not, the RGC of the daughter product is used to determine the
parent constituent LCTV. This methodology is designed to be protective of downgradient
ground water in terms of both the parent waste constituent and its daughter constituent(s).
The IWEM constituent database includes information on the toxic daughter
products associated which each hydrolyzing constituent, and the user does not need to
know which constituents transform into toxic daughter products. In Tier 1, the capping
the LCTV of parent constituents at the LCTV of their respective daughters is transparent
to the user. The capping of LCTVs is done automatically by the software and are flagged
in the Tier 1 tables and reports.
In a Tier 2 evaluation, if you select a waste constituent that hydrolyses, the IWEM
software will automatically add any toxic daughters products associated with that
constituent to the evaluation. In the Tier 2 input screens, daughter products are listed
immediately after their parent(s) in the Toxicity Standards Screen (Screen 22, see Figure
5.23). Constituents that are included because they are daughter products of constituents
in the waste, are identified as such in the input screens. In the Tier 2 reports, the results
of all waste constituents and any toxic daughter constituents produced by hydrolysis are
shown in the Tier 2 report. Daughter products are listed separately from parent
constituents, but for each daughter product, the parent waste constituent from which it
originated is identified.
Due to the chemical transformation of waste constituents, it is possible the same
constituent is included more than once in the evaluation. A constituent can be selected
because it is present in the waste, but it can also be added by the IWEM software because
it is produced as the result of hydrolysis transformations on one or more other waste
constituents. IWEM evaluates each occurrence of the constituent separately, and the
same constituent may lead to different liner recommendations in the same Tier 2
evaluation. For instance, assume that a constituent is present at low concentration in the
waste itself, but this compound is also produced as the result of hydrolysis of a second
waste constituent which is in the waste at a much higher concentration. IWEM will first
evaluate the constituent as an original waste constituent. In this example, we assumed
that the concentration in the waste is low, and the IWEM software in that case may
recommend a no-liner design as being protective. Next, IWEM will evaluate the ground-
water impact of the same constituent as a daughter product resulting from the
transformation of the second waste constituent. Because this second waste constituent
(the parent) is present in the waste at high concentrations, its transformation may cause
the ground-water concentration of our constituent of concern (which is now evaluated as
a daughter product) to be so high that IWEM determines that a no-liner design is not
7-4
-------
IWEM User's Guide Section 7.0
protective. This example would lead to a result in which the same constituent has two
different liner recommendations.
Even though the chemical compound is the same, IWEM treats these two
instances as if they were different constituents. One of the reasons EPA chose to do this,
is that it allows the user to make waste management decisions in terms of the constituents
that are actually present in the waste. In the example described here, an option may be to
treat the waste to reduce constituent concentrations to acceptable levels. In our example,
the goal should be not to reduce the level of the constituent of concern in the waste (it is
only present at low levels), but rather to reduce the concentration of its parent constituent.
Doing this will automatically reduce the ground-water impact of its daughter product(s).
7.3 IWEM Liner Recommendations Udl Section 6.3
TBD
IWEM makes liner recommendations by identifying the minimum design that is
protective of ground water for all waste constituents. In Tier 1, a liner design is
protective if the expected leachate concentrations for all waste constituents are less than
the LCTV determined by IWEM for the same constituents. In the case of LAUs, land
application of waste is considered appropriate if the leachate concentrations of all
constituents do not exceed LAU LCTVs.
The IWEM Tier 1 software automatically performs the comparisons of leachate
concentration to all of the LCTVs for each waste constituent and liner scenario. The
results of the evaluation are presented in terms of a MCL summary and a HBN summary.
The HBN summary reflects the liner recommendation based on the most protective, that
is the lowest, HBN available for each constituent. The recommendation also takes into
account the possible formation of toxic daughter products, as discussed in Section 7.2.3.
If the leachate concentrations for all constituents are lower than the corresponding
no-liner LCTVs, then no liner is recommended as being sufficiently protective of
groundwater. If any leachate concentration is higher than the corresponding no-liner
LCTV, then a minimum of a single clay liner is recommended. If any leachate
concentration is higher than the corresponding single clay liner LCTV, then a minimum
of a composite liner is recommended. If any concentration is higher than the composite
liner, consider pollution prevention, treatment, or additional controls. For waste streams
with multiple constituents, the recommended liner design is the most protective minimum
recommended liner.
After conducting a Tier 1 analysis, you can choose to implement the Tier 1
recommendation by designing the unit based on the liner recommendations given by the
IWEM software. If you choose to implement the Tier 1 recommendation, consultation
-------
IWEM User's Guide Section 7.0
with state authorities is recommended to ensure compliance with state regulations, which
may require more protective measures than the Tier 1 lookup tables recommend.
Alternatively, if the waste has one or very few "problem" constituents that call for a more
stringent and costly liner system (or which make land application inappropriate), evaluate
pollution prevention, recycling, and treatment efforts for those constituents.
If, after conducting the Tier 1 analysis, you are not satisfied with the resulting
recommendations, or if site-specific conditions seem likely to support the use of a liner
design different from the one recommended (or suggest a different conclusion regarding
the appropriateness of land application of a waste), then you may conduct a Tier 2
analysis or a site-specific groundwater fate and transport analysis (Tier 3).
In a Tier 2 evaluation, IWEM uses the EPACMTP fate and transport model to
determine the ground-water exposure concentration that is expected for each waste
constituent given its leachate concentration. IWEM uses the technique of Monte Carlo
analysis to develop a probability distribution of ground-water well exposure
concentrations for each constituent and liner scenario. Analogous to Tier 1 (which uses a
90th percentile LCTV value), IWEM uses the 90th percentile of the ground-water well
exposure concentration in Tier 2 to make liner recommendations. The software compares
the 90th percentile ground-water exposure concentration to the RGC(s) for that
constituent. IWEM first makes this evaluation for the no-liner scenario. If the ground-
water exposure concentration is less than the applicable RGC(s), then the no-liner
scenario is protective for that constituent. IWEM evaluates all waste constituents in this
manner. If the 90th percentile ground-water exposure concentrations of all waste
constituents are below their respective RGCs, then IWEM recommends the no-liner
scenario as being protective and the evaluation is complete. However, if the ground-
water exposure concentrations of one or more waste constituents exceed their RGCs, then
the no-liner scenario is not protective, and IWEM will evaluate the single clay liner
scenario (unless the WMU is a LAU). If the single clay liner scenario is protective for all
constituents, IWEM will recommend this design. If any waste constituents fail the single
clay liner design, then IWEM will recommend at least a composite liner.
In a Tier 2 evaluation, IWEM also calculates LCTVs. The Tier 2 LCTVs are
different from the Tier 1 values; they represent location-adjusted thresholds. While the
Tier 2 LCTVs are not directly used in IWEM to make liner recommendations, they are
displayed on the detailed results screen, and printed in the IWEM reports. These LCTVs
can be used in the same manner as in Tier 1 to identify pollution prevention, recycling, or
treatment alternatives to reduce the leachate concentrations of "problem" constituents to
levels that allow disposal of a waste in a less stringent WMU design.
7-6
-------
IWEM User's Guide Section 7.0
The Monte Carlo simulations required for a Tier 2 evaluation can be
computationally demanding, and an evaluation of multiple liner designs for a single waste
constituent can take several hours. In order to optimize the computational process,
IWEM will first perform the liner evaluations from least protective (no-liner) to most
protective (composite liner). If during this process, IWEM identifies a liner design that is
protective for all constituents (for instance, a single clay liner), it will stop the evaluation
process, and not evaluate more protective designs (in the example case, it would skip the
composite liner evaluation).
After conducting the Tier 2 Evaluation, you can choose to implement the Tier 2
recommendation by designing the unit based on the liner recommendations given by the
IWEM software or continue to a Tier 3 analysis. If you choose to implement the Tier 2
recommendation, consultation with state authorities is recommended to ensure
compliance with state regulations, which may require more protective measures than the
Tier 2 results recommend.
If after conducting the Tier 2 Evaluation, you are not satisfied with the resulting
recommendations or if site-specific conditions seem likely to support the use of a liner
design different from the one recommended (or suggest a different conclusion regarding
the appropriateness of land application of a waste), then you may conduct a fully
site-specific groundwater fate and transport analysis (Tier 3).
7-7
-------
IWEM User's Guide
Section 8.0
8.0 Trouble Shooting
The IWEM Version 1.0 has been extensively tested on the following
combinations of Windows operating system and Internet Explorer:
Latest versions of MS Windows operating
systems
95 (Version 4.00.950B)
98 Second Edition (Version 4.10.2222A)
NT 4.0 (Service Pack 6 a)
2000 (Service Pack 2)
XP (Version 2002)
Corresponding version of MS Internet
Explorer
Version 5.5 Service Pack 2
Version 6.0
Version 6.0
Version 6.0
Version 6.0
If you encounter any problems during installation, it is likely that your operating
system and/or version of Internet Explorer are not up-to-date. Check the version of your
operating system and Internet Explorer and compare them to the list above. If either of
these two are not up-to-date, visit the Microsoft Support web site at
http://support.microsoft.com, click on the |DCWMLOADSOFTWARE| link, and then click on
either the |MCROSCFT\MNDOV\S UPDATES] link or the (INTERNET EXPLORER link and follow the
prompts to download and install the updates. Check with your system administrator if
you do not have the correct privileges to install software on your computer.
How do I determine what version of Windows I am using?
Right click on the (MYGoivPirTER icon on your desktop and select PROPERTIES from
the pop-up menu. A dialog box will appear and near the top will be the version
information of Windows installed on your computer.
How do I determine what version of Internet Explorer I am using?
Start Internet Explorer, click on I^LP ABOUT INTERNET EXPLORER]. A dialog box will
appear and list first is the version of Internet Explorer installed on your computer.
What do I do if I am still having problems?
If your operating system and Internet Explorer versions are up-to-date and you
still encounter problems installing or running the IWEM software, please contact the
RCRA Information Center in any of the following ways:
8-1
-------
IWEM User's Guide
Section 8.0
E-mail: rcra-docket@epa.gov
Phone: 703-603-9230
Fax: 703-603-9234
In person: Hours: 9:00 am to 4:00 pm, weekdays, closed on Federal Holidays
Location: USEPA
West Building Basement
1300 Constitution Ave., NW
Washington, D.C.
Mail: RCRA Information Center (5305W)
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, NW
Washington, DC 20460-0002
When contacting the RCRA Information Center, please cite RCRA Docket
number: F1999-IDWA-FFFFF.
8-2
-------
IWEM User's Guide Section 9.0
9.0 References
Schroeder, P.R., Dozier, T.S., Zappi, P.A., McEnroe, B.M., Sjostrom, J.W., and Peyton,
R.L., 1994. The Hydrologic Evaluation of Landfill Performance (HELP) Model,
Engineering Document for Version 3, Risk Reduction Engineering Laboratory,
Office of Research and Development, U.S. EPA, Cincinnati, OH 45268,
EPA/600/R-94/168b.
U.S. EPA, 1990. Toxicity Characteristic Final Rule. 55 FR 11796. March 29, 1990.
U.S. EPA, 1991. MINTEQA2/PRODEFA2, A Geochemical Assessment Model for
Environmental Systems: Version 3.0 User's Manual EPA/600/3-91/021, Office of
Research and Development, Athens, Georgia 30605.
U.S. EPA, 1993. Environmental Fate Constants for Organic Chemicals under
Consideration for EPA's Hazardous Waste Identification Projects. Compiled and
edited by Heinz Kollig. Environmental Research Laboratory, Office of Research
and Development, Athens, GA.
U.S. EPA, 1996d. Drinking Water Regulations and Health Advisories. Office of Water,
Washington, DC. October (EPA 822-B-96-002).
U.S. EPA, 1997. Guiding Principles for Monte Carlo Analysis. EPA/630/R-97/1001
Risk Assessment Forum, Washington, DC 20460.
U.S. EPA, 2002a. EPACMTP Technical Background Document. Office of Solid Waste,
Washington, DC.
U.S. EPA, 2002b. EPACMTP Parameters/Data Background Document Office of Solid
Waste, Washington, DC.
U.S. EPA, 2002c. IWEM Technical Background Document.. Office of Solid Waste,
Washington, DC.
U.S. EPA, 2002d. Guide for Industrial Waste Management. Office of Solid Waste,
Washington, DC.
Verschueren, K., 1983. Handbook of Environmental Data on Organic Chemicals. Van
Nostrand Reinhold Co., New York.
9-1
-------
Appendix A
List of Waste Constituents
-------
IWEM User's Guide
Appendix A
Appendix A
List of Waste Constituents
CAS Number
Constituent Name
CAS Number
Constituent Name
Organics
83-32-9
75-07-0
67-64-1
75-05-8
98-86-2
107-02-8
79-06-1
79-10-7
107-13-1
309-00-2
107-18-6
62-53-3
120-12-7
56-55-3
71-43-2
92-87-5
50-32-8
205-99-2
100-51-6
100-44-7
111-44-4
39638-32-9
117-81-7
75-27-4
74-83-9
106-99-0
71-36-3
85-68-7
88-85-7
75-15-0
56-23-5
57-74-9
126-99-8
106-47-8
108-90-7
Acenaphthene
Acetaldehyde [Ethanal]
Acetone (2-propanone)
Acetonitrile (methyl cyanide)
Acetophenone
Acrolein
Acrylamide
Acrylic acid [propenoic acid]
Acrylonitrile
Aldrin
Allyl alcohol
Aniline (benzeneamine)
Anthracene
B enz { a } anthracene
Benzene
Benzidine
Benzo{a}pyrene
Benzofb jfluoranthene
Benzyl alcohol
Benzyl chloride
Bis(2-chloroethyl)ether
Bis(2-chloroisopropyl)ether
Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Bromomethane
Butadiene, 1, 3-
Butanol
Butyl benzyl phthalate
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb)
Carbon disulfide
Carbon tetrachloride
Chlordane
Chloro- 1 ,3-butadiene 2-(Chloroprene)
Chloroaniline p-
Chlorobenzene
510-15-6
124-48-1
75-00-3
67-66-3
74-87-3
95-57-8
107-05-1
218-01-9
108-39-4
95-48-7
106-44-5
1319-77-3
98-82-8
108-93-0
108-94-1
72-54-8
72-55-9
50-29-3
2303-16-4
53-70-3
96-12-8
95-50-1
106-46-7
91-94-1
75-71-8
75-34-3
107-06-2
156-59-2
156-60-5
75-35-4
120-83-2
94-75-7
78-87-5
542-75-6
10061-01-5
Chlorobenzilate
Chlorodibromomethane
Chloroethane [Ethyl chloride]
Chloroform
Chloromethane
Chlorophenol 2-
Chloropropene, 3- (Allyl Chloride)
Chrysene
Cresol m-
Cresol o-
Cresol p-
Cresols
Cumene
Cyclohexanol
Cyclohexanone
DDD
DDE
DDT, p,p '-
Diallate
Dibenz { a,h } anthracene
Dibromo-3-chloropropanel ,2-
Dichlorobenzenel ,2-
Dichlorobenzenel ,4-
Dichlorobenzidine3 ,3 '-
Dichlorodifluoromethane (Freon 12)
Dichloroethane 1,1-
Dichloroethanel ,2-
Dichloroethylene cis-1,2-
Dichloroethylene trans- 1,2-
Dichloroethylene 1,1-
Dichlorophenol 2,4-
Dichlorophenoxyacetic acid 2,4-(2,4-D)
Dichloropropane 1,2-
Dichloropropene l,3-(mixture of isomers)
Dichloropropene cis-1,3-
A-l
-------
IWEM User's Guide
Appendix A
Appendix A (continued)
List of Waste Constituents
CAS Number
10061-02-6
60-57-1
84-66-2
56-53-1
60-51-5
119-90-4
68-12-2
57-97-6
119-93-7
105-67-9
84-74-2
99-65-0
51-28-5
121-14-2
606-20-2
117-84-0
123-91-1
122-39-4
122-66-7
298-04-4
115-29-7
72-20-8
106-89-8
106-88-7
110-80-5
111-15-9
141-78-6
60-29-7
97-63-2
62-50-0
100-41-4
106-93-4
107-21-1
75-21-8
96-45-7
91-20-3
Constituent Name
Dichloropropene trans- 1,3-
Dieldrin
Diethyl phthalate
Diethylstilbestrol
Dimethoate
Dimethoxybenzidine 3,3-
Dimethyl formamide N,N- [DMF]
Dimethylbenzf a} anthracene 7,12-
Dimethylbenzidine 3,3-
Dimethylphenol 2,4-
Di-n-butyl phthalate
Dinitrobenzene 1,3-
Dinitrophenol 2,4-
Dinitrotoluene 2,4-
Dinitrotoluene 2,6-
Di-n-octyl phthalate
Dioxane 1,4-
Diphenylamine
Diphenylhydrazine, 1, 2-
Disulfoton
Endosulfan (Endosulfan I and II, mixture)
Endrin
Epichlorohydrin
Epoxybutane, 1, 2-
Ethoxyethanol 2-
Ethoxyethanol acetate, 2-
Ethyl acetate
Ethyl ether
Ethyl methacrylate
Ethyl methanesulfonate
Ethylbenzene
Ethylene dibromide (1,2-Dibromoethane)
Ethylene glycol
Ethylene oxide
Ethylene thiourea
Naphthalene
CAS Number
206-44-0
50-00-0
64-18-6
98-01-1
319-85-7
58-89-9
319-84-6
76-44-8
1024-57-3
87-68-3
118-74-1
77-47-4
55684-94-1
34465-46-8
67-72-1
70-30-4
110-54-3
7783-06-4
193-39-5
78-83-1
78-59-1
143-50-0
126-98-7
67-56-1
72-43-5
109-86-4
110-49-6
78-93-3
108-10-1
80-62-6
298-00-0
1634-04-4
56-49-5
74-95-3
75-09-2
1746-01-6
Constituent Name
Fluoranthene
Formaldehyde
Formic acid
Furfural
HCH beta-
HCH (Lindane) gamma-
HCH alpha-
Heptachlor
Heptachlor epoxide
Hexachloro- 1 ,3-butadiene
Hexachlorobenzene
Hexachlorocyclopentadiene
Hexachlorodibenzofurans [HxCDFs]
Hexachlorodibenzo-p-dioxins [HxCDDs]
Hexachloroethane
Hexachlorophene
Hexane n-
Hydrogen Sulfide
Indeno{l,2,3-cd}pyrene
Isobutyl alcohol
Isophorone
Kepone
Methacrylonitrile
Methanol
Methoxychlor
Methoxyethanol 2-
Methoxyethanol acetate 2-
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl methacrylate
Methyl parathion
Methyl tert-butyl ether [MTBE]
Methylcholanthrene 3-
Methylene bromide (Dibromomethane)
Methylene Chloride (Dichloromethane)
Tetrachlorodibenzo-p-dioxin, 2,3,7,8-
A-2
-------
IWEM User's Guide
Appendix A
Appendix A (continued)
List of Waste Constituents
CAS Number
98-95-3
79-46-9
55-18-5
62-75-9
924-16-3
621-64-7
86-30-6
10595-95-6
100-75-4
930-55-2
152-16-9
56-38-2
608-93-5
30402-15-4
36088-22-9
82-68-8
87-86-5
108-95-2
62-38-4
108-45-2
298-02-2
85-44-9
1336-36-3
23950-58-5
75-56-9
129-00-0
110-86-1
94-59-7
57-24-9
100-42-5
95-94-3
51207-31-9
Constituent Name
Nitrobenzene
Nitropropane 2-
Nitrosodiethylamine N-
Nitrosodimethylamine N-
Nitroso-di-n-butylamine N-
Nitroso-di-n-propylamine N-
Nitrosodiphenylamine N-
Nitrosomethylethylamine N-
Nitrosopiperidine N-
Nitrosopyrrolidine N-
Octamethyl pyrophosphoramide
Parathion (ethyl)
Pentachlorobenzene
Pentachlorodibenzofurans [PeCDFs]
Pentachlorodibenzo-p-dioxins [PeCDDs]
Pentachloronitrobenzene (PCNB)
Pentachlorophenol
Phenol
Phenyl mercuric acetate
Phenylenediamine 1,3-
Phorate
Phthalic anhydride
Polychlorinated biphenyls (Aroclors)
Pronamide
Propylene oxide [1,2-Epoxypropane]
Pyrene
Pyridine
Safrole
Strychnine and salts
Styrene
Tetrachlorobenzene 1,2,4,5-
Tetrachlorodibenzofuran, 2,3,7,8-
CAS Number
630-20-6
79-34-5
127-18-4
58-90-2
3689-24-5
137-26-8
108-88-3
95-80-7
95-53-4
106-49-0
8001-35-2
75-25-2
76-13-1
120-82-1
71-55-6
79-00-5
79-01-6
75-69-4
95-95-4
88-06-2
93-72-1
93-76-5
96-18-4
121-44-8
99-35-4
126-72-7
108-05-4
75-01-4
108-38-3
95-47-6
106-42-3
1330-20-7
Constituent Name
Tetrachloroethane 1,1,1,2-
Tetrachloroethane 1,1,2,2-
Tetrachloroethylene
Tetrachlorophenol 2,3,4,6-
Tetraethyl dithiopyrophosphate (Sulfotep)
Thiram [Thiuram]
Toluene
Toluenediamine 2,4-
Toluidine o-
Toluidine p-
Toxaphene (chlorinated camphenes)
Tribromomethane (Bromoform)
Trichloro-l,2,2-trifluoro- ethane 1,1,2-
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Trichloroethylene
Trichlorofluoromethane (Freon 11)
Trichlorophenol 2,4,5-
Trichlorophenol 2,4,6-
Trichlorophenoxy)propionic acid 2-
Trichlorophenoxyacetic acid 2,4,5-
Trichloropropane 1,2,3-
Triethylamine
Trinitrobenzene
Tris(2,3-dibromopropyl)phosphate
Vinyl acetate
Vinyl chloride
Xylene m-
Xylene o-
Xylene p-
Xylenes (total)
A-3
-------
IWEM User's Guide
Appendix A
Appendix A (continued)
List of Waste Constituents
CAS Number
Constituent Name
CAS Number
Constituent Name
Metals
7440-36-0
7440-38-2
7440-39-3
7440-41-7
7440-43-9
16065-83-1
18540-29-9
7440-48-4
7440-50-8
16984-48-8
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium (III)
Chromium (VI)
Cobalt
Copper
Fluoride
7439-92-1
7439-96-5
7439-97-6
7439-98-7
7440-02-0
7782-49-2
7440-22-4
7440-28-0
7440-62-2
7440-66-6
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
A-4
-------
Appendix B
Sample Reports From Tier 1 and Tier 2
-------
Tier 1 Evaluation Results
6/20/2002
5:00:55PM
Recommendation :
Composite Liner
Facility Type
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
Landfill
Southern Industries Landfill
122 Industrial Ave
Raleigh
NC
27611
October 31, 1998
List of Constituents Selected by the User
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Minimum Liner Recommendation Based on MCL
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
Minimum Liner Recommendation
No Liner
Single Liner
Single Liner
Minimum Liner Recommendation Based on HBN
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
Minimum Liner Recommendation
Composite Liner
Single Liner
No Liner
1 of 7
-------
In the following tables, the LCTV is generally calculated as LCTV = DAF * RGC. However, in some instances, the DAF is denoted here with an asterisk (*). This occurs
when the ground-water concentration is either exceedingly low, thus capping the LCTV, or the LCTV is capped by some other constraint. In instances where the toxic
daughter cap is applied, the RGC is either absent or denoted by an asterisk. Please refer to Section 7.2 of the IWEM User's Guide (Limits on the Leachate
Concentration Threshold Value) for more details. A brief explanation of LCTV caps is given in this report after the detailed HBN results.
Detailed Results Based on MCL - No Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
MCL (mg/L)
0.005
0.006
0.005
DAF
2.2
2.2
LCTV
(mg/L)
0.011
0.014
0.011
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective ?
Yes
No
No
Detailed Results Based on MCL - Single Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
MCL (mg/L)
0.005
0.006
0.005
DAF
6.1
6.2
LCTV
(mg/L)
0.031
0.04
0.031
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective ?
Yes
Yes
Yes
Detailed Results Based on MCL - Composite Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
MCL (mg/L)
0.005
0.006
0.005
DAF
1 .90E+04
6.20E+05
LCTV
(mg/L)
0.5 (A)
1000(B)
1000(B)
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective?
Yes
Yes
Yes
Detailed Results Based on HBN - No Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
HBN (mg/L)
0.0016
0.0098
0.013
Exposure
Pathway & Effect
Inhalation Cancer
Ingestion Non-cancer
Ingestion Cancer
DAF
2.2
2.2
LCTV
(mg/L)
0.0036
0.023
0.029
Leachate
Cone . (mg/L)
0.01
0.03
0.02
Protective?
No
No
Yes
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
2 of 7
-------
Detailed Results Based on HBN - Single Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
HBN (mg/L)
0.0016
0.0098
0.013
Exposure
Pathway & Effect
Inhalation Cancer
Ingestion Non-cancer
Ingestion Cancer
DAF
6.1
6.2
LCTV
(mg/L)
0.0097
0.068
0.081
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective ?
No
Yes
Yes
Detailed Results Based on HBN - Composite Liner
CAS Number
71-43-2
7440-36-0
75-09-2
Constituent Name
Benzene
Antimony
Methylene Chloride (Dichloromethane)
HBN (mg/L)
0.0016
0.0098
0.013
Exposure
Pathway & Effect
Inhalation Cancer
Ingestion Non-cancer
Ingestion Cancer
DAF
1 .90E+04
6.30E+05
LCTV
(mg/L)
0.5 (A)
1000(B)
1000(B)
Leachate
Cone. (mg/L)
0.01
0.03
0.02
Protective?
Yes
Yes
Yes
CAPS & WARNINGS
A - The LCTV is capped by the Toxicity Characteristic Rule Exit Level (TC LEVEL) of the constituent.
B - The LCTV is capped by 1000 mg/L (EPA Policy).
C - The LCTV exceeds the cited solubility for this constituent.
D - The parent constituent LCTV is derived from the LCTV of a more conservative toxic daughter product(s).
E - The parent constituent does not have a RGC for this exposure pathway and effect, but the toxic daughter product(s) does. The LCTV of the parent is derived from
the LCTV of the toxic daughter product.
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
3 of 7
-------
Constituent Name
Benzene
CAS ID
71-43-2
Physical Properties
Property
Constituent Type
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
78.1134
1.8
0
0
0
1750
282
0.0325
0.0056
Data Source
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA, 2001 a
Calc., based on USEPA, 2001 a
USEPA, 1997c
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
Reference Dose (mg/kg-day)
Reference Concentration (mg/mA3)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.005
0.0018
0.19
0.0016
0.06
0.055
0.027
Data Source
USEPA, 2000h
USEPA, 2001 b
CALEPA, 1999b
USEPA, 2001 b
CALEPA, 2000
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
4 of 7
-------
Constituent Name
Antimony
CAS ID
7440-36-0
Physical Properties
Property
Constituent Type
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Metal
121.76
1.00E+06
Data Source
CambridgeSoft Corporation, 2001
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
Reference Dose (mg/kg-day)
Reference Concentration (mg/mA3)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.006
0.0098
0.0004
Data Source
USEPA, 2000h
USEPA, 2001 b
USEPA, 2001 b
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
5 of 7
-------
Constituent Name
Methylene Chloride (Dichloromethane)
CAS ID
75-09-2
Physical Properties
Property
Constituent Type
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
84.9328
0.93
0
0.001
0.6
1.30E+04
315
0.0394
0.0022
Data Source
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA, 2001 a
Calc., based on USEPA, 2001 a
USEPA, 1997c
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
HBN-lngestion, Cancer (mg/L)
HBN-lnhalation, Non-Cancer (mg/L)
HBN-lnhalation, Cancer (mg/L)
Reference Dose (mg/kg-day)
Reference Concentration (mg/mA3)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.005
1.5
0.013
10
0.028
0.06
3
0.0075
0.0016
Data Source
USEPA, 2000h
USEPA, 2001 b
USEPA, 2001 b
USEPA, 1997a
USEPA, 2001 b
USEPA, 2001 b
USEPA, 1997a
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 1 Evaluation Results
Facility Name: Southern Industries Landfill
Facility Type: Landfill
6/20/2002
6 of 7
-------
References
CalEPA. 1999b. Air Toxics Hot Spots Program Risk Assessment Guidelines: Part III. Technical Support Document for the Determination of Noncancer Chronic
Reference Exposure Levels. SRP Draft. Office of Environmental Health Hazard Assessment, Berkeley, CA. http://www.oehha.org/hotspots/RAGSII.html.
CalEPA. 2000. Air Toxics Hot Spots Program Risk Assessment Guidelines: Part III. Technical Support Document for the Determination of Noncancer Chronic
Reference Exposure Levels. Office of Environmental Health Hazard Assessment, Berkeley, CA. Available online (in 3 sections) at
http://www.oehha.org/air/chronic_rels/22RELS2k.html, http://www.oehha.org/air/chronic_rels/42kChREL.html,
http://www.oehha.org/air/chronic_rels/Jan2001 ChREL.html.
CambridgeSoft Corporation. 2001. ChemFinder.com database and internet searching, http://chemfinder.cambridgesoft.com. Accessed July 2001.
USEPA. 1993a. Environmental Fate Constants for Orgainic Chemicals Under Consideration for EPA's Hazardous Waste Identification Projects, EPA/600/R-93/132,
August 1993.
USEPA. 1997a. Health Effects Assessment Summary Tables (HEAST). EPA-540-R-97-036. FY 1997 Update. Office of Solid Waste and Emergency Response,
Washington, DC.
USEPA. 1997c. Superfund Chemical Data Matrix (SCDM). SCDMWIN 1.0 (SCDM Windows User's Version), Version 1. Office of Solid Waste and Emergency
Response, Washington DC: GPO. http://www.epa.gov/superfund/resources/scdm/index.htm. Accessed July 2001
USEPA. 2000h. Code of Federal Regulations, National Primary Drinking Water Regulations, CFR 40, Part 141, Section 32. www.epa.gov/safewater/regs/cfr141 .pdf.
USEPA. 2001a. WATER9. Office of Air Quality Planning and Standards, Research Triangle Park, NC. http://www.epa.gov/ttn/chief/software/water/index.html.
Accessed July 2001.
USEPA. 2001 b. Integrated Risk Information System (IRIS). National Center for Environmental Assessment, Office of Research and Development, Washington, DC.
http://www.epa.gov/iris/
Calculated from inhalation unit risk factors from USEPA, 2001 b.
Tier 1 Evaluation Results Facility Name: Southern Industries Landfill Facility Type: Landfill 6/20/2002 7 of 7
-------
6/20/2002 5:12:46PM
Tier 2 Evaluation Results
Recommendation: Composite Liner
Facility Type Landfill
Facility name
Street address
City
State
Zip
Date of sample analysis
Name of user
Additional information
Landfill Parameters
Parameter Value
Depth of base of the LF below ground surface (m) 0
Distance to well (m) 150
Landfill area (mA2) [requires site specific value] 1 .23E+04
WMU depth (m) [requires site specific value] 6.5
Subsurface Parameters
Subsurface Environment Sand and Gravel
Parameter Value
Ground-water pH value (metals only) Distribution
Depth to water table (m) Distribution
Aquifer hydraulic conductivity (m/yr) Distribution
Regional hydraulic gradient Distribution
Aquifer thickness (m) Distribution
Data Source
Default
Default
132
zxc
Data Source
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
Monte Carlo [See IWEM TBD 4.2.3.1]
1 of 7
-------
Regional Soil and Climate Parameters
Parameter
Soil Type
Climate Center
No Liner Infiltration Rate (m/yr)
Clay Liner Infiltration Rate (m/yr)
Composite Liner Infiltration Rate (m/yr)
Recharge Rate (m/yr)
Value
Medium-grained soil (silt loam)
Greensboro NC
.3256
.0362
Monte Carlo
0.3256
Constituent Reference Ground-water Concentrations and Constituent Properties
Constituent Name
Acrylonitrile
RGC
(mg/L)
0.0002
RGC Based On Kd* (L/kg)
HBN - Ingestion, Cancer
"If a site-specific value was entered by the user, it will be displayed here; otherwise, the model used the constituent properties listed at the end
Daughter Constituent Reference Ground-water Concentrations and Constituent Properties
Parent Constituent
Acrylonitrile
Acrylonitrile
Decay Coeff* Leachate
(1/yr) Cone. (mg/L)
0.1
of the report.
RGC
Daughter Constituent RGC Based On
(mg/L)
Acrylamide 2.20E-05 HBN - Ingestion, Cancer
Acrylic acid [propenoic acid] 12 HBN - Ingestion, NonCancer
"If a site-specific value was entered by the user, it will be displayed here; otherwise
Detailed Results for Parent Constituents - No Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mg/L)
0.1
DAF
(mg/L)
2.4
the model used the constituent properties listed at the end
Decay Coeff.*
Kd-(Ukg) (*/vr)
of the report.
LCTV RGC
(mg/L) Selected RGC (mg/L)
4.11E-05(D) HBN -Ingestion, Cancer 2.20E-05
90th %tile Exp.
Cone. (mg/L) Protective?
0.0413 No
Detailed Results for Parent Constituents - Clay Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mg/L)
0.1
DAF
(mg/L)
13
LCTV RGC
(mg/L) Selected RGC (mg/L)
0.0003 (D) HBN - Ingestion, Cancer 2.20E-05
90th %tile Exp.
Cone. (mg/L) Protective?
0.0075 No
Detailed Results for Parent Constituents - Composite Liner
Constituent Name
Acrylonitrile
Leachate
Cone. (mg/L)
0.1
DAF
(mg/L)
2.40E+04
LCTV
(mg/L)
4.32
Selected RGC
HBN - Ingestion, Cancer
RGC
(mg/L)
2.20E-05
90th %tile Exp.
Cone. (mg/L)
4.10E-06
Protective?
Yes
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
2 of 7
-------
Detailed Results for Daughter Constituents - No Liner
Constituent Name
Acrylamide
Acrylic acid [propenoic acid]
Leachate
Cone. (mg/L)
0.134
0.1358
DAF
(mg/L)
2.5
2.4
LCTV
(mg/L)
5.50E-05
28.8
Selected RGC
HBN - Ingestion, Cancer
HBN - Ingestion, NonCancer
RGC
(mg/L)
2.20E-05
12
90th %tile Exp.
Cone. (mg/L)
0.0539
0.0562
Protective?
No
Yes
Detailed Results for Daughter Constituents - Clay Liner
Constituent Name
Acrylamide
Acrylic acid [propenoic acid]
Leachate
Cone. (mg/L)
0.134
0.1358
DAF
(mg/L)
17
NA
LCTV
(mg/L)
0.0004
NA
Selected RGC
HBN - Ingestion, Cancer
All Available
RGC
(mg/L)
2.20E-05
90th %tile Exp.
Cone. (mg/L)
0.008
NA
Protective?
No
See No Liner
Detailed Results for Daughter Constituents - Composite Liner
Constituent Name
Acrylamide
Acrylic acid [propenoic acid]
Leachate
Cone. (mg/L)
0.134
0.1358
DAF
(mg/L)
1 .OOE+30
NA
LCTV
(mg/L)
1000
NA
Selected RGC
HBN - Ingestion, Cancer
All Available
RGC
(mg/L)
2.20E-05
90th %tile Exp.
Cone. (mg/L)
0
NA
Protective?
Yes
See No Liner
CAPS & WARNINGS
A - The LCTV is capped by the Toxicity Characteristic Rule Exit Level (TC LEVEL) of the constituent.
B - The LCTV is capped by 1000 mg/L (EPA Policy).
C - The LCTV exceeds the cited solubility for this constituent.
D - The parent constituent LCTV is derived from the LCTV of a more conservative toxic daughter product(s).
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
3 of 7
-------
Constituent Name
Acrylonitrile
CAS ID
107-13-1
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
53.0634
-0.089
500
0
5200
7.40E+04
360
0.0388
0.0001
Data Source
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA, 2001 a
Calc., based on USEPA, 2001 a
USEPA, 1997c
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
Reference Dose (mg/kg-day)
HBN-lngestion, Cancer (mg/L)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
HBN-lnhalation, Non-Cancer (mg/L)
Reference Concentration (mg/mA3)
HBN-lnhalation, Cancer (mg/L)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.025
0.001
0.0002
0.54
0.038
0.002
0.001
0.24
Data Source
USEPA, 1997a
USEPA, 1997a
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
4 of 7
-------
Constituent Name
Acrylamide
CAS ID
79-06-1
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
71 .0786
-0.989
31.5
0.018
0
6.40E+05
337
0.0397
1.00E-09
Data Source
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA, 2001 a
Calc., based on USEPA, 2001 a
USEPA, 1997c
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
Reference Dose (mg/kg-day)
HBN-lngestion, Cancer (mg/L)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
HBN-lnhalation, Non-Cancer (mg/L)
Reference Concentration (mg/mA3)
HBN-lnhalation, Cancer (mg/L)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
0.0049
0.0002
2.20E-05
4.5
5.1
4.6
Data Source
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
Calc, based on USEPA, 2001 b
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
5 of 7
-------
Constituent Name
Acrylic acid [propenoic acid]
CAS ID
79-10-7
Physical Properties
Property
ChemicalType
Molecule Weight (g/mol)
Log Koc (distribution coefficient for organic carbon) (mL/g)
Ka: acid-catalyzed hydrolysis rate constant (1/mol yr)
Kn: neutral hydrolysis rate constant (1/yr)
Kb: base-catalyzed hydrolysis rate constant (1/mol yr)
Solubility (mg/L)
Diffusivity in air (cmA2/sec)
Diffusivity in water (mA2/yr)
Henry's law constant (atm-mA3/mol)
Value
Organic
72.1
-1.84
0
0
0
1 .OOE+06
325
0.0378
1.17E-07
Data Source
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1993a
USEPA, 1997c
Calc., based on USEPA, 2001 a
Calc., based on USEPA, 2001 a
USEPA, 1997c
Reference Ground-water Concentration Values
Property
Maximum Contamination Level (mg/L)
HBN-lngestion, Non-Cancer (mg/L)
Reference Dose (mg/kg-day)
HBN-lngestion, Cancer (mg/L)
Carcinogenic Slope Factor-Oral (1 /mg/kg-day)
HBN-lnhalation, Non-Cancer (mg/L)
Reference Concentration (mg/mA3)
HBN-lnhalation, Cancer (mg/L)
Carcinogenic Slope Factor-Inhalation (1 /mg/kg-day)
Value
12
0.5
15
0.001
Data Source
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
USEPA, 2001 b
Tier 2 Evaluation Results
Facility Name:
Facility Type: Landfill
6/20/2002
6 of 7
-------
References
USEPA. 1993a. Environmental Fate Constants for Orgainic Chemicals Under Consideration for EPA's Hazardous Waste Identification Projects, EPA/600/R-93/132,
August 1993.
USEPA. 1997a. Health Effects Assessment Summary Tables (HEAST). EPA-540-R-97-036. FY 1997 Update. Office of Solid Waste and Emergency Response,
Washington, DC.
USEPA. 1997c. Superfund Chemical Data Matrix (SCDM). SCDMWIN 1.0 (SCDM Windows User's Version), Version 1. Office of Solid Waste and Emergency Response,
Washington DC: GPO. http://www.epa.gov/superfund/resources/scdm/index.htm. Accessed July 2001
USEPA. 2001a. WATER9. Office of Air Quality Planning and Standards, Research Triangle Park, NC. http://www.epa.gov/ttn/chief/software/water/index.html. Accessed
July 2001.
USEPA. 2001 b. Integrated Risk Information System (IRIS). National Center for Environmental Assessment, Office of Research and Development, Washington, DC.
http://www.epa.gov/iris/
Calculated from inhalation unit risk factors from USEPA, 2001 b.
Tier 2 Evaluation Results Facility Name: Facility Type: Landfill 6/20/2002 7 of 7
------- |