Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities, Volume 3, Appendices B and C


xvEPA
           United States
           Environmental Protection
           Agency
           Solid Waste and
           Emergency Response
           (5305W)
EPA530-D-98-001C
July 1998
www.epa.gov/osw
Human Health Risk
Assessment Protocol for
Hazardous Waste
Combustion Facilities
           Volume Three
           Appendices B and C
              Peer Review Draft
                      Printed oh paper that contains at least 20 percent postconsumer fiber

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Human Health Risk Assessment Protocol for
  Hazardous Waste Combustion Facilities
             Volume Three
          Appendices B and C

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                          APPENDIX B




ESTIMATING MEDIA CONCENTRATION EQUATIONS AND VARIABLE VALUES



                   Human Health Risk Assessment Protocol



                             July 1998

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                             APPENDIX B

                          TABLE OF CONTENTS
TABLE
PAGE
SOIL INGESTION EQUATIONS

B-l-1 COPC SOIL LOSS CONSTANT DUE TO ALL PROCESSES 	B-l

B-l-2 COPC SOIL LOSS CONSTANT	 B-12

B-l-3 COPC LOSS CONSTANT DUE TO SOIL EROSION  	>	B-16

B-l-4 COPC LOSS CONSTANTDUE TO RUNOFF  	 B-21

B-l-5 COPC LOSS CONSTANT DUE TO LEACHING 	 B-26

B-l-6 COPC LOSS CONSTANT DUE TO VOLATILIZATION LEACHING	 B-32


CONSUMPTION OF ABOVEGROUND AND BELOWGROUND PRODUCE EQUATIONS

B-2-1 SOIL CONCENTRATION DUE TO DEPOSITION  	 B-38

B-2-2 COPC SOIL LOSS CONSTANT	 B-49

B-2-3 COPC LOSS CONSTANT DUE TO SOIL EROSION  	B-53

B-2-4 COPC LOSS CONSTANT DUE TO RUNOFF  	 B-58

B-2-5 COPC LOSS CONSTANT DUE TO LEACHING	B-63

B-2-6 COPC LOSS CONSTANT DUE TO VOLATILIZATION 	 B-69

B-2-7 ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION . B-75

B-2-8 ABOVEGROUND PRODUCE CONCENTRATION DUE TO AIR-TO-PLANT
     TRANSFER	B-87

B-2-9 ABOVEGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE	B-93

B-2-10 BELOWGROUND PRODUCE COPC CONCENTRATION DUE TO ROOT UPTAKE . B-97
                                 B-i

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                              APPENDIX B




                          TABLE OF CONTENTS
TABLE
PAGE
CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS




B-3-1  SOIL CONCENTRATION DUE TO DEPOSITION 	 B-103




B-3-2  COPC SOIL LOSS CONSTANT	 B-114




B-3-3  COPC LOSS CONSTANT DUE TO SOIL EROSION  	 B-118




B-3-4  COPCLOSS CONSTANT DUE TO RUNOFF 	 B-123




B-3-5  COPCLOSS CONSTANT DUE TO LEACHING	 B-128




B-3-6  COPCLOSS CONSTANT DUE TO VOLATILIZATION	 B-134




B-3-7  FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION	 B-140




B-3-8  FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER  B-151




B-3-9  FORAGE/SILAGE/GRAIN CONCENTRATION DUE TO ROOT UPTAKE 	 B-157




B-3-10 BEEF CONCENTRATION DUE TO PLANT AND SOIL INGESTION 	 B-161




B-3-11 MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION	 B-169




B-3-12 PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION	 B-178




B-3-13 COPC CONCENTRATION IN EGGS	 B-186




B-3-14 CONCENTRATION IN CHICKEN	 B-191
                                 B-ii

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                              APPENDIX B




                          TABLE OF CONTENTS
TABLE
PAGE
CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS




B-4-1 WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION 	.	 B-196




B-4-2 COPC SOIL LOSS CONSTANT	:	 B-207




B-4-3 COPC LOSS CONSTANT DUE TO SOIL EROSION	 B-211




B-4-4 COPCLOSS CONSTANT DUE TO RUNOFF	 B-216




B-4-5 COPCLOSS CONSTANT DUE TO LEACHING	B-221




B-4-6 COPC LOSS CONSTANT DUE TO VOLATILIZATION	 B-227




B-4-7 TOTAL WATER BODY LOAD	 B-233




B-4-8 DEPOSITION TO WATER BODY	 B-236




B-4-9 IMPERVIOUS RUNOFF LOAD TO WATERBODY ..,	 B-239




B-4-10 PERVIOUS RUNOFF LOAD TO WATERBODY 	 B-242




B-4-11 EROSIONLOAD TO WATERBODY		 B-247




B-4-12 DIFFUSION LOAD TO WATERBODY	 B-252




B-4-13 UNIVERSAL SOIL LOSS EQUATION (USLE)	 B-256




B-4-14 SEDIMENT DELIVERY RATIO	 B-261




B-4-15 TOTAL WATERBODY CONCENTRATION	 B-264




B-4-16 FRACTION IN WATER COLUMN AND BENTfflC SEDIMENT	 B-268




B-4-17 OVERALL TOTAL WATER BODY DISSIPATION RATE CONSTANT  	 B-273




B-4-18 WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT 	 B-275




B-4-19 OVERALL COPC TRANSFER RATE COEFFICIENT	 B-279
                                  B-iii

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                              APPENDIX B

                          TABLE OF CONTENTS
TABLE
PAGE
B-4-20 LIQUID-PHASE TRANSFER COEFFICIENT 	 B-283

B-4-21 GAS-PHASE TRANSFER COEFFICIENT 	 B-288

B-4-22 BENTHIC BURIAL RATE CONSTANT	 B-292

B-4-23 TOTAL WATER COLUMN CONCENTRATION	 B-296

B-4-24 DISSOLVED PHASE WATER CONCENTRATION	 B-299

B-4-25 COPC CONCENTRATION SORBED TO BED SEDIMENT 	 B-302

B-4-26 HSH CONCENTRATION FROM BIOCONCENTRATION FACTORS USING
      DISSOLVED PHASE WATER CONCENTRATION	 B-306

B-4-27 FISH CONCENTRATION FROM BIOACCUMULATION FACTORS USING
      DISSOLVED PHASE WATER CONCENTRATION	 B-310

B-4-28 FISH CONCENTRATION FROM BIOTA-TO-SEDIMENT ACCUMULATION
      FACTORS USING COPC SORBED TO BED SEDIMENT	 B-314


DIRECT INHALATION EQUATION

B-5-1  AIR CONCENTRATION	 B-317


ACUTE EQUATION

B-6-1  ACUTE AIR CONCENTRATION EQUATION  	 B-320
                                 B-iv

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                                       APPENDIX B
Pa

Pw
e
a
A
Abeef
•"•chicken
Aegg
Ah
Aht
A,
AL
 pork

AW
Baeggs
BAFfah
Bamilk
Bapork
BCFchicken
BCFegg

BCFflsh

BD
Br.
   ag
Br,
   forage/silage/grain
Br,
   rootveg
 Bs
   LIST OF VARIABLES AND PARAMETERS

Empirical constant (unitless)
Dimensionless viscous sublayer thickness (unitless)
Viscosity of air (g/cm-s)
Viscosity of water corresponding to water temperature (g/cm-s)
Density of air (g/cm3 or g/m3)
Density of water corresponding to water temperature (g/cm3)
Temperature correction factor (unitless)
Bed sediment porosity (L volume/L sediment)—unitless
Soil volumetric water content (mL water/cm3 soil)

Empirical intercept coefficient (unitless)
Surface area of contaminated area (m2)
Concentration of COPC in beef (mg COPC/kg FW tissue)
Concentration of COPC in chicken meat (mg COPC/kg FW tissue)
Concentration of COPC in eggs (mg COPC/kg FW tissue)
Area planted (m2)
Area planted to rth crop (m2).
Impervious watershed area receiving COPC deposition (m2)
Total watershed area receiving COPC deposition (m2)
Concentration of COPC in milk (mg COPC/kg FW tissue)
Concentration of COPC in pork (mg COPC/kg FW tissue)
Water body surface area (m2)

Empirical slope coefficient (unitless)
Biotransfer factor for beef (day/kg FW tissue)
Biotransfer factor for chicken (day/kg FW tissue)
Biotransfer factor for chicken eggs (day/kg FW tissue)
Bioaccumulation fector for COPC in fish (L/kg FW tissue)
Biotransfer factor for milk (day/kg FW tissue)
Biotransfer factor for pork (day/kg FW tissue)
Bioconcentration factor for COPC in chicken
(mg COPC/kg FW tissue)/(mg COPC/kg feed)—unitless
Bioconcentration factor for COPC in eggs
(mg COPC/kg FW tissue)/(mg COPC/kg feed)—unitless
Bioconcentration factor for COPC in fish
(mg COPC/kg FW tissue)/(mg COPC/kg dissolved water)—unitless
Soil bulk density (g soil/cm3 soil)
Plant-soil bioconcentration factor for aboveground produce
(mg COPC/kg DW plant)/(mg COPC/kg soil)—unitless
Plant-soil bioconcentration fector for forage, silage, and grain
(mg COPC/kg DW plB-vant)/(mg COPC/kg soil)—unitless
Plant-soil bioconcentration factor for belowground produce
(mg COPC/kg DW plant)/(mB-vg COPC/kg soil)—unitless
  Soil bioavailability factor (unitless)
                                             B-v

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                                       APPENDIX B
 BSAF
 Bv,,
Bv,
c
C
Ca
C,
CBS
Cs
Cyp
Cyv
Cywv
Da
4,
Ds
dm
Dw
Dydp
Dyt\vp

Dywp
Dywv
Dywwv

4

ER
   LIST OF VARIABLES AND PARAMETERS
 Biota-sediment accumulation factor
 (mg COPC/kg lipid tissue)/(mg COPC/kg sediment)—unitless
 COPC air-to-plant biotransfer factor for aboveground produce
 (mg COPC/kg DW plant)/(mg COPC/kg air)—unitless
 Air-to-plant biotransfer factor for COPC in forage
 (mg COPC/kg DW plant)/(mg COPC/kg air)—unitless

 Junge constant =  l.TxlO"4 (atm-cm)
 USLE cover management factor (unitless)
 Air concentration (ug/m3)
 Acute air concentration (ug/m3)
 Bed sediment concentration (or bed sediment bulk density) (g/cm3 or kg/L)
 Drag coefficient (unitless)
 Dissolved phase water concentration (mg COPC/L water)
 Concentration of COPC in fish (mg COPC/kg FW tissue)
 Unitized hourly air concentration from vapor phase (ug-s/g-m3)
 Unitized hourly air concentration from particle phase (ug-s/g-m3)
 Average soil concentration over exposure duration (mg COPC/kg soil)
 Concentration sorbed to bed sediment (mg COPC/kg sediment)
 Soil concentration at time tD (mg COPC/kg soil)
 Total COPC concentration in water column (mg COPC/L water column)
 Total water body COPC concentration including water column and bed sediment
 (g COPC/m3 water body) or (mg/L)
 Unitized yearly average air concentration from particle phase (ug-s/g-m3)
 Unitized yearly average air concentration from vapor phase (ug-s/g-m3)
 Unitized yearly (water body or watershed) average air concentration from vapor
 phase (ug-s/g-m3)

 Diffusivity of COPC in air (cm2/s)
 Depth of upper benthic sediment layer (m)
 Deposition term (mg COPC/kg soil-yr)
 Depth of water column (m)
 Diffusivity of COPC in water (cm2/s)
 Unitized yearly average dry deposition from particle phase (s/m2-yr)
 Unitized yearly (water body or watershed) average total (wet and dry) deposition
 from particle phase (s/m2-yr)
 Unitized yearly average wet deposition from particle phase (s/m2-yr)
 Unitized yearly average wet deposition from vapor phase (s/m2-yr)
Unitized yearly (water body or watershed) average wet deposition from vapor
 phase (s/m2-yr)
 Total water body depth (m)

 Soil enrichment ratio (unitless)
Average annual evapotranspiration (cm/yr)
                                           B-vi

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 Fd
 flipid
 Fw

• Jwc
 H

 I

 k
 K
 Kds
 KG
 KL
 Koc
  ks
  kse
  ksg
  ksl
  ksr
  ksv
  "•wt
                  APPENDIX B

   LIST OF VARIABLES AND PARAMETERS
Fraction of total water body COPC concentration in benthic sediment (unitiess)
Fraction of diet that is soil (unitiess)
Fraction of plant type / grown on contaminated soil and ingested by the animal
(unitiess)
Fish lipid content (unitiess)  .
Fraction of COPC wet deposition that adheres to plant surfaces (unitiess)
Fraction of total water body COPC concentration in the water column (unitiess)
Fraction of COPC air concentration in vapor phase (unitiess)

Henry's Law constant (atm-m3/mol)

Average annual irrigation (cm/yr)

Von Karman's constant (unitiess)
USLE credibility factor (ton/acre)
Benthic burial rate constant (yr"1)
Bed sediment/sediment pore water partition coefficient
(cm3 water/g bottom sediment or L water/kg bottom sediment)
Soil-water partition coefficient (cm3 water/g soil)
Suspended sediment-surface water partition coefficient
(L water/kg suspended sediment)
Gas phase transfer coefficient (m/yr)
Liquid phase transfer coefficient (m/yr)
Soil organic carbon-water partition coefficient (mL water/g soil)
Octanol-water partition coefficient
(mg COPC/L octanol)/(mg COPC/L octanol}—unitiess
Plant surface loss coefficient (yr"1)
COPC soil loss constant due to all processes (yr"1)
COPC loss constant due to soil erosion (yr"1)
COPC loss constant due to biotic and abiotic degradation (yr"1)
COPC loss constant due to leaching (yr"1)
COPC loss constant due to surface runoff (yr"1)
COPC loss constant due to volatilization (yr"1)
Water column volatilization rate constant (yr"1)
Overall COPC transfer rate coefficient (m/yr)
Overall total water body dissipation rate constant (yr"1)

Total (wet and dry) particle phase and wet vapor phase COPC direct deposition
load to water body (g/yr)
Vapor phase COPC diffusion (dry deposition) load to water body (g/yr)
Soil erosion load (g/yr)
Runoff load from pervious surfaces (g/yr)
Runoff load from impervious surfaces (g/yr)
                                              B-vii

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                                        APPENDIX B
 LT

 LS
M
  vtgefakle
MF
   ltd
P\
P°S
P
PF
Pd


P,
Prk
Pv

Q
R
RCF

RO
RF
Rp

SD
A^r
SF
   LIST OF VARIABLES AND PARAMETERS
Total COPC load to the water body (including deposition, runoff, and erosion)
USLE length-slope factor (unitless)

Mass of a thin (skin) layer of belowground vegetable (g)
Mass of the entire vegetable (g)
Metabolism factor (unitless)

Fraction of organic carbon in bottom sediment (unitless)

Liquid phase vapor pressure of chemical (atm)
Solid phase vapor pressure of chemical (atm)
Average annual precipitation (cm/yr)
USLE supporting practice factor (unitless)
Concentration of COPC in aboveground produce due to direct deposition
(mg COPC/kg DW)
Concentration of COPC in plant type / ingested by the animal (mg/kg DW)
Concentration of COPC in aboveground produce due to root uptake
(mgCOPC/kgDW)
Concentration of COPC in belowground produce due to root uptake
(mg COPC/kg DW)
Concentration of COPC in aboveground produce (forage and silage) due to air-
to-plant transfer Qig COPC/g DW plant tissue or mg COPC/kg DW plant tissue)

COPC emission rate (g/s)
Quantity of plant type / ingested by the animal (kg DW plant/day)
Quantity of soil ingested by the animal (kg/day)

Interception fraction — the fraction of material in rain intercepted by vegetation
and initially retained (unitless)
Universal gas constant (atm-m3/mol-K)
Root concentration factor
(jig COPC/g DW planting COPC/mL soil water)
Average annual surface runoff from pervious areas (cm/yr)
USLE rainfall (or erosivity) factor (yr"1)
Interception fraction of the edible portion of plant (unitless)

Sediment delivery ratio (unitless)
Entropy of fusion [&Sf/R '= 6.79 (unitless)]
Slope factor (mg/kg-day)"1
Whitby's average surface area of particulates (aerosols)
       = S.SxlO"6 cm2/cm3 air  for background plus local sources
       = 1 . 1 x 1 0"s cmVcm3 air  for urban sources
                                           B-viii

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                                         APPENDIX B
Ta
T,
T2
tD
Tm
Tp
TSS

*ia

u

Vdv
Vfx
VG,
VG,
   ag
   rootveg
w
Yh
Yh,
Yp
0.01
lo-6
10-6
0.31536
365
907.18
0.1
0.001
100
1000
4047
1 x 103
3.1536 x 107
    LIST OF VARIABLES AND PARAMETERS
Ambient air temperature (K)
Time period at the beginning of combustion (yr)
Length of exposure duration (yr)
Time period over which deposition occurs (or time period of combustion) (yr)
Melting point of chemical (K)
Length of plant exposure to deposition per harvest of edible portion of plant (yr)
Total suspended solids concentration (mg/L)
Water body temperature (K)
Half-time of COPC (days)

Current velocity (m/s)

Dry deposition velocity (cm/s)
Average volumetric flow rate through water body (m3/yr)
Empirical correction factor for aboveground produce (forage and silage)(unitless)
Empirical correction factor for belowground produce (unitless)

Average annual wind speed (m/s)

Unit soil loss (kg/m2-yr)

Dry harvest yield  = 1.22x10" kg DW, calculated from the 1993 U.S. average
wet weight Yh of 1.35x10" kg (USDA 1994b) and a conversion factor of 0.9
(Fries 1994)
Harvest yield of /th crop (kg DW)
Yield or standing crop biomass of the edible portion of the plant (productivity) (kg
DW/m2)

Soil mixing zone depth (cm)

Units conversion factor (kg cm2/mg-m2)
Units conversion factor (g/ug)
Units conversion factor (kg/mg)
Units conversion factor (m-g-s/cm-ug-yr)
Units conversion factor (days/yr)
Units conversion factor (kg/ton)
Units conversion factor (g-kg/cm2-m2)
Units conversion factor (kg-cm2/mg-m2)
Units conversion factor (mg-cm2/kg-cm2)
Units conversion factor (mg/g)
Units conversion factor (m2/acre)
Units conversion factor (g/kg)
Units conversion factor (s/yr)
                                             B-ix

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TABLE B-l-1
SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 1 of 11)
Description

The equations in this table are used to calculate an average COPC soil concentration resulting from wet and dry deposition of particles and vapors to soil over the exposure duration. COPCs are
assumed to be incorporated only to a finite depth (the soil mixing zone depth, Zs).

The COPC soil concentration averaged over the exposure duration, represented by Cs, should be used for carcinogenic COPCs, where risk is averaged over the lifetime of an individual.
Because the hazard quotient associated with noncarcinogenic COPCs is based on a reference dose rather than a lifetime exposure, the highest annual average COPC soil concentration occurring
during the exposure duration period should be used for noncarcinogenic COPCs. The highest annual average COPC soil concentration would occur at the end of the time period of combustion
and is represented by Cs/D.
The following uncertainties are associated with this variable:

(1)

(2)
The time period for deposition of COPCs resulting from hazardous waste combustion is assumed to be a conservative, long-term value. This assumption may overestimate Cs and
CstD.
Exposure duration values (T2) are based on historical mobility studies and will not necessarily remain constant. Specifically, mobility studies indicate that most receptors that move
remain in the vicinity of the combustion unit; however, it is impossible to accurately predict the probability that these short-distance moves will influence exposure, based on factors
such as atmospheric transport of pollutants.
(3) The use of a value of zero for 7/ does not account for exposure that may have occurred from historic operations and emissions from hazardous waste combustion. This may
underestimate Cs and Cs,D.
(4) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and CstD.
(S) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate Cs and Cs,n.
B-l

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TABLE B-t-1
SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 2 of 11)
Equation for Carcinogens
Soil Concentration Averaged Over Exposure Duration
Cs
Ds-tD-Cs.n\ [ Cs,

- exp (-fa (T3-tD
CT2-r,)
•for Tl
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TABLE B-l-1
SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 3 of 11)
Highest Annual Average Soil Concentration
Equation for Noncarcinogens
Ds • [1 - exp (-ks •;£))]
ks
where
Ds = m'Q .[pv (0.31536 • Vdv • Cyv + Dywv) + (Dydp+Dywp) • (1 - F,)]
Z_ • BD
For mercury modeling
Ds =
10°
Z ' BD
-[Fv (0.31536 • Vdv • Cyv + Dywv) + (Dydp+Dywp) • (1 - Fv)]
Use 0.48Q for total mercury and Fv = 0.85 in the mercury modeling equation to calculate Ds. The calculated Ds value is apportioned into the divalent mercury (Kg2*) and methyl mercury
(MHg) forms based on the assumed 98% Hg2* and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg°) occurs in very small amounts in the vapor phase and does not
exist in the particle or particle-bound phase. Therefore, elemental mercury deposition onto soils is assumed to be negligible or zero. Elemental mercury is evaluated for the direct inhalation
pathway only (Table B-5-1).

0.98 Ds
0.02Ds
0.0

Evaluate divalent and methyl mercury as individual COPCs. Calculate Cs for divalent and methyl mercury using the corresponding (1) fate and transport parameters for mercuric chloride
(Kg2*) and methyl mercury provided in Appendix A-3, and (2) Ds (Hg2*) and Ds (MHg) as calculated above.
B-3
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TABLE B-l-1
SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 4 of 11)
Variable
Cs
Cs,
ID
Ds
Description
Average soil concentration over
exposure duration
Soil concentration at time tD
Deposition term
Units
rag COPC/kg
soil
mg COPC/kg
soil
mg COPC/kg
soil-yr
Vake
Varies
U.S. EPA (1994a) and NC DEHNR (1997) recommend incorporating the use of a deposition term into the Cs equation.

Uncertainties associated with this variable include the following:

(1) Four of the variables in the equation for Ds (Q Cywv, Dywv, Dydp, and Dywp) are COPC- and site-specific.
Values of these variables are estimated on the basis of modeling. The direction and magnitude of any
uncertainties should not be generalized.
(2) Based on the narrow recommended ranges, uncertainties associated with Vdv, Fm and BD are expected to be
low.
(3) Values for Zs vary by about one order of magnitude. Uncertainty is greatly reduced if it is known whether soils
are tilled or untilled.
tD
Time period over which deposition
occurs (time period of combustion)
100
U.S. EPA (1990a) specifies that this period of time can be represented by periods of 30,60 or 100 years. U.S. EPA OSW
recommends that facilities use the conservative value of 100 years unless site-specific information is available indicating
that this assumption is unreasonable (see Chapter 6 of the HHRAP).
ks
COPC soil loss constant due to all
processes
yr'
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-l-2. The COPC soil loss
constant is the sum of all COPC removal processes.

Uncertainty associated with this variable includes the following:

COPC-specific values for ksg (one of the variables in the equation in Table B-l-2) are empirically determined
from field studies. No information is available regarding the application of these values to the site-specific
conditions associated with affected facilities.
B-4
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TABLE B-l-1
SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 5 of 11)
VarfcMe
, Description
Vnife
Value
Length of exposure duration
6,30, or 40
U.S. EPA OSW recommends reasonable maximum exposure (RME) values for T2:
Exposure Duration
Child Resident
Subsistence Farmer Child
Subsistence Fisher Child

Adult Resident and
Subsistence Fisher
RME
6 years
30 years
(6 child and 24 adult)
Reference
U.S. EPA (1990b)
U.S. EPA (1990b)
U.S. EPA (1994b)
Subsistence Farmer 40 years

U.S. EPA (1994c) recommended the following unreferenced values:

. Exposure Duration Years
Subsistence Fanner 40
Adult Resident 30
Subsistence Fisher 30
Child Resident 9

Uncertainties associated with this variable include the following:

(1) Exposure duration rates are based on historical mobility rates and may not remain constant. This assumption
may overestimate or underestimate Cs and Cs,D.
(2) . Mobility studies indicate that most receptors that move remain in the vicinity of the emission sources.
However, it is impossible to accurately predict the likelihood that these short-distance moves will influence
exposure, based on factors such as atmospheric transport of pollutants. This assumption may overestimate or
underestimate Cs and Cs,D.
Time period at the beginning of
combustion
Consistent with U.S. EPA (1994c), U.S. EPA OSW recommends a value of 0 for T,.

The following uncertainty is associated with this variable:

The use of a value of 0 for T{ does not account for exposure that may have occurred from historical operations
or emissions from the combustion of hazardous waste. This may underestimate Cs and CstD.
B-5
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TABLE B-l-1
SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 6 of 11)
Variable
100
Description
Units conversion factor
COPC-specific emission rate
Units
mg-cm2/kg-cm2
g/s
Value
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 of the HHRAP for guidance regarding the calculation of
this variable. Uncertainties associated with this variable are site-specific.
Soil mixing zone depth
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Unfilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S.EPA(1990a)andU.S.EPA(1993a)
U.S. EPA (1990a) did not include a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1992).

The following uncertainties are associated with this variable:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting a greater
mixing depth. This uncertainty may overestimate Cs and Cs,D.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of
other residues. This uncertainty may underestimate Cs and CstD.
3D
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and
clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990a). A range of 0.83 to 1.84 was originally cited in
Hoffman and Baes (1979). U.S. EPA (1994c) recommended a default BD value of 1.5 g soil/cm3 soil, based on a mean
value for loam soil that was obtained from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g soil/cm3
soil also represents the midpoint of the "relatively narrow range" for5D of 1.2 to 1.7 g soil/cm3 soil (U.S. EPA 1993a).

The following uncertainty is associated with this variable:

The recommended BD value may not accurately represent site-specific soil conditions; and may under- or
overestimate site-specific soil conditions to an unknown degree.
B-6
-------
TABLE B-l-1

SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)
(Page 7 of 11)
Variable
Description
Value
Fraction of COPC air concentration
in vapor phase
unitless
Otol
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.
This range is based on the values presented in Appendix A-3. Values are also presented in U.S. EPA (1994c) and NC
DEHNR(1997).

Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fv = 0 for all metals (except mercury).

The following uncertainties are associated with this variable:

(1) It is based on the assumption of a default Rvalues for background plus local sources, rather than anSr
value for urban sources. If a specific site is located in an urban area, the use of the latter ST value may be
more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than that
for background plus local sources, and it would result in a lower calculated Fv value; however, the Fv value
is likely to be only a few percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant) is
constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from
the particle surface and the heat of vaporization of the liquid-phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value
of c is used to calculate Fv.
U.S. EPA (1994c) recommended the use of 3 cm/s for the dry deposition velocity, based on median dry deposition
velocity for HN03 from an unspecified U.S. EPA database of dry deposition velocities for HNO3, ozone, and SO2. HNO3
was considered the most similar to the COPCs recommended for consideration in the HHRAP. The value should be
applicable to any organic COPC with a low Henry's Law Constant.

The following uncertainty is associated with this variable:

HN03 may not adequately represent specific COPCs; therefore, the use of a single value may under- or
overestimate estimated soil concentration.
Cyv
Unitized yearly average air
concentration from vapor phase
ug-s/g-m3
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
B-7
-------
TABLE B-W
SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 8 of 11)
Variable
Dywv
Dydp
Dywp
Description
Unitized yearly average wet
deposition from vapor phase
Unitized yearly average dry
deposition from particle phase
Unitized yearly average wet
deposition from particle phase
Until
s/m2-yr
s/m2-yr
s/m2-yr
Value
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
B-8
-------
TABLE B-l-1

SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 9 of 11)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

This reference is for the statement that the equation used to calculate the fraction of air concentration in vapor phase (Fv) assumes that the variable c (the Junge constant) is constant for
all chemicals. However, this document notes that the value of c depends on the chemical (sorbate) molecular weight, the surface concentration for monolayer coverage, and the difference
between the heat of desorption from the particle surface and the heat of vaporization of the liquid phase sorbate. The following equation, presented in this document, is cited by U.S. EPA
(1994b) and NC DEHNR (1997) for calculating the variable Fv:
F:. = 1 -
c • ST
P°L-c-ST
where

Fv = Fraction of chemical air concentration in vapor phase (unitless)
c = Junge constant = 1.7 x 10"04 (atm-cm)
ST = Whitby's average surface area of particulates = 3.5 x 10"06 cmVcm3 air (corresponds to background plus local sources)
P°L = Liquid-phase vapor pressure of chemical (atm) (see Appendix A-3)

If the chemical is a solid at ambient temperatures, the solid-phase vapor pressure is converted to a liquid-phase vapor pressure as follows:

F\ AS, (r, - Ta)
P°s R Ta
where
P°

Solid-phase vapor pressure of chemical (atm) (see Appendix A-3)

Entropy of fiision over the universal gas constant = 6.79 (unitless)

Melting point of chemical (K) (see Appendix A-3)
Ambient air temperature = 284 K (11 °C)
B-9
-------
TABLE B-1-1

SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 10 of 11)

Carsel, R.F., R.S. Parrish, R.L. Jones, JJL Hansen, and RX. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology. Vol.
2. Pages 11-24.

This reference is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value, BD, of 1.5 g soil/cm3 soil for loam soil.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

This document is cited by U.S. EPA (1990a) for the statement that soil bulk density, BD, is affected by the soil structure, such as looseness or compaction of the soil, depending on the
water and clay content of the soil.

Hoffman, P.O., and C.F. Baes, 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NOREG/TM-882.

This document presents a soil bulk density range, BD, of 0.83 to 1.84.

Junge, C.E. 1977. Fateof Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is one of the source documents for the equation in Table B-1-1. This document also recommends the use of (1) a deposition term, Ds, and (2) COPC-specific Fv (fraction of COPC
air concentration in vapor phase) values.

Research Triangle Institute (RTI). 1992. Preliminary Soil Action Level for Superfund Sites. Draft Interim Report. Prepared for U.S. EPA Hazardous Site Control Division, Remedial Operations
Guidance Branch. Arlington, Virginia. EPA Contract 68-W1-0021. Work Assignment No. B-03, Work Assignment Manager Loren Henning. December.

This document is a reference source for COPC-specific Fv (fraction of COPC air concentration hi vapor phase) values.

U.S. EPA. 1990a. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office. Office of
Research and Development. EPA 600-90-003. January.

This document is a reference source for the equation in Table B-1-1, and it recommends that (1) the time period over which deposition occurs (time period for combustion), tD, be
represented by periods of 30,60, and 100 years, and (2) undocumented values for soil mixing zone depth, Zs, for tilled and unfilled soil.

U.S. EPA. 1990b. Exposure Factors Handbook March.

This document is a reference source for values for length of exposure duration, T2.

U.S.EPA. 1992. Estimating Exposure to Dioxin-Like Compounds. DraftReport. Office of Research and Development. Washington, D.C. EPA/600/6-88/005b.

This document is cited by U.S. EPA (1993a) as the source of values for soil mixing zone depth, Zn for tilled and unfilled soils.
B-10
-------
TABLE B-l-1

SOIL CONCENTRATION DUE TO DEPOSITION
(SOIL INGESTION EQUATIONS)

(Page 11 of 11)

U.S. EPA. 1993a. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November.

This document is a reference for recommended values for soil mixing zone depth, Zy for tilled and untilled soils; it cites U.S. EPA (1992) as the source of these values. It also
recommends a "relatively narrow" range for soil bulk density, BD, of 1.2 to 1.7 g soil/cm3 soil.

U.S. EPA. 1993b. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid
Waste. Office of Research and Development. Washington, D.C. September 24.

This document is a reference for the equation in Table B-l-1. It recommends using a deposition term, Ds, and COPC-specific Fv values (fraction of COPC air concentration in vapor
phase) in the Cs equation.

U.S. EPA 1994a. Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. April 15.

This document is a reference for the equation in Table B-l-1; it recommends that the following be used in the Cs equation: (1) a deposition term, Ds, and (2) a default soil bulk density
value of 1.5 g soil/cm3 soil, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).

U.S.EPA. 1994b. Estimating Exposure to Dioxin-Like Compounds. Volumelll: Site-Specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document recommends values for length of exposure duration, T2, for the subsistence farmer.

U.S. EPA. 1994c. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Office of Emergency and Remedial Response.
Office of Solid Waste. December 14.

The value for dry deposition velocity is based on median dry deposition velocity for HN03 from a U.S. EPA database of dry deposition velocities for HNO3 ozone, and SO2. HNO3 was
considered the most similar to the constituents covered and the value should be applicable to any organic compound having a low Henry's Law Constant. The reference document for
this recommendation was not cited. This document recommends the following:

Values for the length of exposure duration, T2
Value of 0 for the time period of the beginning of combustion, T,
Fv values (fraction of COPC air concentration in vapor phase) that range from 0.27 to 1 for organic COPCs
Vdv value (dry deposition velocity) of 3 cm/s (however, no reference is provided for this recommendation)
Default soil bulk density value of 1.5 g soil/cm3 soil, based on a mean for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
Vdv value of 3 cm/s, based on median dry deposition velocity for HN03 from an unspecified U.S. EPA database of dry deposition velocities for HN03, ozone, and SO2. HN03
was considered the most similar to the COPCs recommended for consideration in the HHRAP.

(Page 1 of 4)
Description
This equation calculates the COPC soil loss constant, which accounts for the loss of COPCs from soil by several mechanisms.
Uncertainties associated with this equation include the following:

(1)

(2)
COPC-specific values for ksg are empirically determined from field studies; no information is available regarding the application of these values to the site-specific conditions
associated with affected facilities.
The source of the equations in Tables B-l-3 through B-l-6 have not been identified.
Equation
ks = ksg + kse + ksr + ksl + ksv
Variable
Description
Units
Value
ks
COPC soil loss constant due to all
processes
yr'
>7j*i >. -
ksg
COPC loss constant due to biotic
and abiotic degradation
yr-'
Varies
This variable is COPC-specific and should be determined from the COPC tables in Appendix A-3.

"Degradation rate" values are also presented in NC DEHNR (1997); however, no reference or source is provided for the values.
U.S. EPA (1994a) and U.S. EPA (1994b) state that ksg values are COPC-specific; however, all ksg values are presented as zero
(U.S. EPA 1994a) or as "NA" (U.S. EPA 1994b); the basis of these assumptions is not addressed.

The following uncertainty is associated with this variable:

COPC-specific values for ksg are empirically determined from field studies; no information is available regarding the
application of these values to the site-specific conditions associated with affected facilities.
B-12
-------
TABLE B-l-2
COPC SOIL LOSS CONSTANT
(SOIL INGESTION EQUATIONS)

(Page 2 of 4)
Variable
Description
Value
kse
COPC loss constant due to soil
erosion
yr'
This variable is COPC- and site-specific, and is further discussed in Table B-1-3. Consistent with U.S. EPA (1994a), U.S. EPA
(1994b) and NC DEHNR (1997), U.S. EPA OSW recommends that the default value assumed for kse is zero because of
contaminated soil eroding onto the site and away from the site.

Uncertainties associated with this variable include the following:

(1) The source of the equation in Table B-1-3 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting a greater mixing
depth. This uncertainty may overestimate fee.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate kse.
ksr
COPC loss constant due to surface
runoff
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-l-4. No reference document is cited
for this equation; however, the use of this equation is consistent with U.S. EPA (1993). U.S. EPA (1994a).states that all ksr values
are zero but does not explain the basis for this assumption.

Uncertainties associated with this variable (calculated by using the equation in Table B-l-4) include the following:

(1) The source of the equation in Table B-l-4 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting a greater mixing
depth. This uncertainty may overestimate ksr.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate ksr.
ksl
COPC loss constant due to leaching
yr-'
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-l-5. The use of this equation is
consistent with U.S. EPA (1993), U.S. EPA (1994b), and NC DEHNR (1997). U.S. EPA (1994a) states that all M values are zero
but does not explain the basis of this assumption.

Uncertainties associated with this variable (calculated by using the equation in Table B-l-S) include the following:

(1) The source of the equation in Table B-l-5 has not been identified.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate ksl.
B-13
-------
f
TABLE B-l-2
Description
COPC loss constant due to
volatilization
Units
yr1
COPC SOIL LOSS CONSTANT
(SOIL INGESTION EQUATIONS)

(Page 3 of 4)
Value
This variable is COPC- and site-specific, and is further discussed in Table B-1-6. Consistent with U.S. EPA guidance (1994a) and
based on the need for additional research to be conducted to determine the magnitude of the uncertainty introduced for modeling
volatile COPCs from soil, U.S. EPA OSW recommends that, until identification and validation of more applicable models, the
constant for the loss of soil resulting from volatilization (ksv) should be set equal to zero.

Uncertainties associated with this variable include the following:
(1)
(2)

(3)
The source of the equation in Table B-1-6 has not been identified.
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting a greater mixing
depth. This uncertainty may overestimate ksv.
Deposition to hard surfaces may result in dust residues that have negligible dilution, (as a result of potential mixing with
tofliatof other residues. This uncertainty may underestimate fcsv. _
B-14
-------
TABLE B-l-2

COPC SOIL LOSS CONSTANT
(SOIL INGESTION EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NC DEHNR. 1997. Final NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the reference documents for the equations in Tables B-l-4, B-l-5, and B-l-6. This document is also cited as (1) the source for a range of COPC-specific
degradation rates (ksg), and (2) one of the sources that recommend using the assumption that the loss resulting from erosion (kse) is zero because of contaminated soil eroding onto the
site and away from the site.

U.S. EPA. 1993. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Office of Health and Environmental
Assessment. Office of Research and Development. EPA-600-AP-93-003. November 10.

This document is one of the reference documents for the equations in Tables B-l-3 and B-l-5.

U.S. EPA. 1994a. Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. April 15.

This document is cited as a source for the assumptions that losses resulting from erosion (kse), surface runoff (ksr), degradation (ksg), leaching (ksl), and volatilization (ksv) are all zero.

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document is one of the reference documents for the equations in Tables B-l-4, B-l-5, and B-l-6. This document is also cited as one of the sources that recommend using the
assumption that the loss resulting from erosion (kse) is zero and the loss resulting from degradation (ksg) is "NA" or zero for all compounds.
B-15
-------
TABLE B-l-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(SOIL INGESTION EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the constant for COPC loss resulting from erosion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), U.S. EPA OSW recommends
that the default value assumed for kse is zero because of contaminated soil eroding onto the site and away from the site. In site-specific cases where the permitting authority considers it
appropriate to calculate a kse, the following equation presented in this table should be considered along with associated uncertainties. Additional discussion on the determination of kse can be
obtained from review of the methodologies described in U.S. EPANCEA document, Methodology for Assessing Health Risks Associated with Multiple Exposure Pathways to Combuslor
Emissions (In Press). Uncertainties associated with this equation include:

(1) For soluble COPCs, leaching might lead to movement below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate kse.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate kse.
Equation
kse =
0.l-Xe-SD-ER
BD-Z.
Kd-BD
Variable
Description
Units
Value
kse
COPC loss constant due to soil
erosion
yr'
Unit soil loss
kgAn2-yr
Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), U.S. EPA OSW recommends that the default
value assumed for kse is zero because of contaminated soil eroding onto the site and away from the site.
uncertainty may overestimate kse.
Varies
This variable is site-specific and is calculated by using the equation in Table B-4-13.

The following uncertainty is associated with this variable:

All of the equation variables are site-specific. Use of default values rather than site-specific values for any or all of
these variables will result in unit soil loss (Xe) estimates that are under- or overestimated to some degree. Based on
default values, Xe estimates can vary over a range of less than two orders of magnitude.
B-16
-------
TABLE B-l-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(SOIL INGESTION EQUATIONS)

(Page 2 of 5)
Variable
Description
Units
Value
SD
Sediment delivery ratio
unitless
Varies
This value is site-specific, and is calculated by using the equation in Table B-4-14.

Uncertainties associated with this variable include the following:

(1) The recommended default values for the empirical intercept coefficient, a, are average values that are based on
studies of sediment yields from various watersheds. Therefore, those default values may not accurately represent
site-specific watershed conditions. As a result, use of these default values may under- or overestimate SD.
(2) The recommended default value for the empirical slope coefficient, b, is based on a review of sediment yields from
various watersheds. This single default value may not accurately represent site-specific watershed conditions. As
a result," use of this default value may under- or overestimate SD.
ER
Soil enrichment ratio
unitless
Inorganics: 1
Organics: 3
COPC enrichment occurs because (1) lighter soil particles erode more than heavier soil particles, and (2) concentration of
organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded material
than in in-situ soil (U.S. EPA 1993). In the absence of site-specific data, U.S. EPA OSW recommends a default value of 3
for organic COPCs and 1 for inorganic COPCs. This is consistent with other U.S. EPA guidance (1993), which recommends
a range of 1 to 5 and a value of 3 as a "reasonable first estimate." This range has been used for organic matter, phosphorus,
and other soil-bound COPCs (U.S. EPA 1993); however, no sources or references were provided for this range. ER is
generally higher in sandy soils than in silty or loamy soils (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The default ER value may not accurately reflect site-specific conditions; therefore, kse may be over- or
underestimated to an unknown extent. The extent of any uncertainties will be reduced by using county-specific ER
values.
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffman
and Baes (1979). U.S. EPA (1994b) recommended a default BD value of 1.5 g soil/cm3 soil, based on a mean value for loam
soil that was taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g soil/cm3 soil also represents
the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g soil/cm3 soil (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-17
-------
TABLE B-l-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(SOIL INGESTION EQUATIONS)

(Page 3 of 5)
Variable
Description
Units
Value
Soil mixing zone depth
cm
Ito20
U.S. EPA currently recommends the following values for this variable:
Soil
Unfilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate kse.
Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other
residues. This uncertainty may underestimate kse.
Kd,
Soil-water partition coefficient
mL water/g
soil
(or cm3
water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kdt values are calculated as described in
Appendix A-3.
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable is site-specific, and depends on the available water and on soil structure; 6^, can be estimated as the midpoint
between a soil's field capacity and wilting point, if a representative watershed soil can be identified. However, U.S. EPA
OSW recommends the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to
0.3 (heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and is
consistent with U.S. EPA (1994b).

The following uncertainty is associated with this variable:

The default Qm value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
B-18
-------
TABLE B-l-3

COPC LOSS CONSTANT DUE TO SOIL EROSION
(SOIL INGESTION EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

Carsel, R.F., R.S. Parish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hvdrolosv Vol
2. Pages 11-24.

This document is cited by U.S. EPA (1994b) as the source for a mean soil bulk density, BD, value of 1.5 g soil/cm3 soil for loam soil.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

This document is cited by U.S. EPA (1990) for the statement that soil bulk density, BD, is affected by the soil structure, such as looseness or compaction of the soil, depending on the
water and clay content of the soil.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionudides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NCDEHNR. 1997. Final NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the sources that recommend using the assumption that the loss resulting from erosion (kse) is zero because of contaminated soil eroding onto the site and away
from the site.

This document is one of the reference documents for the equations in Tables B-l-3 and B-l-5.

U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office. Office of
Research and Development. EPA 600-90-003. January.

This document presents a range of values for soil mixing zone depth, ZB for tilled and unfilled soil. The basis or source of these values is not identified.

U.S. EPA. 1993. Addendum to the Methodologyfor Assessing Health Risks Associated-with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November 1993.

This document is the source of a range of COPC enrichment ratio, ER, values. The recommended range, 1 to 5, has been used for organic matter, phosphorous, and other soul-bound
COPCs. This document recommends a value of 3 as a "reasonable first estimate," and states that COPC enrichment occurs because lighter soil particles erode more than heavier soil
particles. Lighter soil particles have higher ratios of surface area to volume and are higher in organic matter content. Therefore, concentration of organic COPCs, which is a function of
the organic carbon content of sorbing media, is expected to be higher in eroded material than in insitu soil.

This document is also a source of the following:
B-19
-------
TABLE B-l-3

COPC LOSS CONSTANT DUE TO SOIL EROSION
(SOIL INGESTION EQUATIONS)

(Page 5 of 5)

« A "relatively narrow range" for soil bulk density, 3D, of 12 to 1.7 g soft/cm3 soil
• COPC-specific (inorganic COPCs only) Kd, values used to develop a proposed range (2 to 280,000 mL water/g soil) of Kd, values
• A range of soil volumetric water content (9W) values of 0.1 mL water/cm3 soil (very sandy soils) to 03 mL water/cm3 soil (heavy loam/clay soils) (however, no source or
reference is provided for this range)
• A range of values for soil mixing zone depth, Zn for tilled and unfilled soil

U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities, April 15.

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume HI: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development
Washington, D.C. EPA/600/6-88/005Cc. June.

This document is the source of values for soil mixing zone depth, Zs, for tilled and unfilled soil, as cited in U.S. EPA (1993).

This document recommends (1) a default soil bulk density value of 1.5 g soil/cm3 soil, based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb
(1988), and (2) a default soil volumetric water content, 0^, value of 0.2 mL water/cm3 soil, based on U.S. EPA (1993).
B-20
-------
TABLE B-l-4
COPC LOSS CONSTANT DUE TO RUNOFF
(SOIL INGESTION EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the COPC loss constant due to runoff of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might result in movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate for.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestimate for.
Equation
ksr
RO
Variable
ksr
COPC loss constant due to runoff
yr'
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994b), and NC DEHNR (1997), average annual
surface runoff, RO, can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and
Troise 1973). According to NC DEHNR (1997), estimates can also be made by using more detailed, site-specific procedures
for estimating the amount of surface runoff, such as those based on the U.S. Soil Conservation Service curve number equation
(CNE). U.S. EPA (1985) is cited as an example of such a procedure.

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual surface runoff information is not available, default or
estimated values may not accurately represent site-specific or local conditions. As a result, ksl may be under- or
overestimated to an unknown degree.
B-21
-------
TABLE B-l-4
COPC LOSS CONSTANT DUE TO RUNOFF
(SOIL INGESTION EQUATIONS)

(Page 2 of5)
Variable
Description
Units
Value
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable depends on the available water and soil structure; if a representative watershed soil can be identified, 0,,, can be
estimated as the midpoint between a soil's field capacity and wilting point U.S. EPA OSW recommends the use of 02
mL/cm3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils), which
is recommended by U.S. EPA (1993) (no source or reference is provided for this range), and is consistent with U.S. EPA
(1994b) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The default 6^, value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kds values are calculated as described in Appendix
A-3.
B-22
-------
TABLE B-l-4
Variable
, Description
COPC LOSS CONSTANT DUE TO RUNOFF
(SOIL INGESTION EQUATIONS)
(Page 3 of 5)
Value
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). The proposed range was originally cited in Hoffinan
and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean
value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 (g soil/cm3 soil) also
represents the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 (g soil/cm3 soil) (U.S. EPA 1993).

The following uncertainty is associated with this variable:

^_____Tjj[ej:ecommended soil bujkdensjty_yajuemaj; not accurately represent site-specific soil conditions.
B-23
-------
TABLE B-l-4

COPC LOSS CONSTANT DUE TO RUNOFF
(SOIL INGESTION EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology. Vol.
2. Pages 11-24,

This document is cited by U.S. EPA (1994b) as the source of a mean soil bulk density, BD, value of 1.5 (g soil/cm3 soil) for loam soil.

Geraghty, J.J., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center, Port Washington, New York.

This document is cited by U.S. EPA (1993), U.S. EPA (1994), and NC DEHNR (1997) as a reference to calculate average annual runoff, RO. This reference provides maps with isolines
of annual average surface water runoff, which is defined as all flow contributions to surface water bodies, including direct runoff shallow interflow, and ground water recharge. Because
these values are total contributions and not only surface runoff, U.S. EPA (1994) recommends that the volumes be reduced by 50 percent in order to estimate surface runoff.

Hillel,D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of Table B-l-4; however, this document is not the original source of this equation (this source is unknown). This
document also recommends the following:

• Estimation of annual current runoff, RO (cm/yr), by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) or site-specific procedures,
such as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.
• Default value of 02 (mL water/cm3 soil) for soil volumetric water content (6^,)

U.S. EPA. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventional Pollutants in Surface and Ground Water—Part I (Revised. 1985). Environmental Research
Laboratory. Athens, Georgia. EPA/600/6-85/002a. September.

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate site-specific surface runoff

U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associatedwith Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office. Office of
Research and Development EPA 600-90-003. January.

This document presents a range of values for soil mixing zone depth, Zs, for tilled and untilled soil; the basis for, or sources of, these values is not identified.
B-24
-------
TABLE B-l-4

COPC LOSS CONSTANT DUE TO RUNOFF
(SOIL INGESTION EQUATIONS)

(Page 5 of 5)

U.S. EPA. 1993. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November.

This document recommends the following:

A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)
A range of soil volumetric water content, 0^, values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) (the original source of, or reference for, these values is not
identified)
A range of values for soil mixing depth, Za for tilled and unfilled soil (the original source of, or reference for, these values is not identified)
A range (2 to 280,000 [mL water/g soil]) of Kds values for inorganic COPCs
Use of the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) to calculate average annual runoff, RO

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document presents a range of values for soil mixing zone depth, Zs, for tilled and unfilled soil as cited in U.S. EPA (1993).

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Offices of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the following:

• Estimation of average annual runoff, RO, by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973)
• Default soil bulk density, BD, value of 1.5 g soil/cm3 soil, based on the mean for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
• Default soil volumetric water content, O^, value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993)
B-25
-------
TABLE B-l-5
COPC LOSS CONSTANT DUE TO LEACHING
(SOIL INGESTION EQUATIONS)

(Page 1 of 6)
Description
This equation calculates the constant for COPC loss resulting from leaching of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainly may overestimate ksl.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate ksl.
(3) The original source of this equation has not been identified. U.S. EPA (1993) presents the equation as shown here. U.S. EPA (1994b) and NC DEHNR (1997) replaced the numerator
as shown with "q", defined as average annual recharge (cm/yr).
ksl
Equation
P + / - RO - E,,
Variable
Description
Units
Value
ksl
COPC loss constant due leaching
yr'
*
Average annual precipitation
cm/yr
18.06 to 164.19
This variable is site-specific. This range is based on information presented in U.S. EPA (1990), representing data for 69
selected cities (U.S. Bureau of Census 1987; Baes, Sharp, Sjoreen and Shor 1984). The 69 selected cities are not identified;
however, they appear to be located throughout the continental United States. U.S. EPA OSW recommends that site-specific
data be used.

The following uncertainty is associated with this variable:

To the extent that a site is not located near an established meteorological data station, and site-specific data are not
available, default average annual precipitation data may not accurately reflect site-specific conditions. As a result,
ksl may be under- or overestimated. However, average annual precipitation data are reasonably available; therefore,
uncertainty introduced by this variable is expected to be minimal.
B-26
-------
TABLE B-l-5
COPC LOSS CONSTANT DUE TO LEACHING
(SOIL INGESTION EQUATIONS)

(Page 2 of 6)
Variable
Bescriptioa "
Vala«
Average annual irrigation
cm/yr
0 to 100
This variable is site-specific. This range is based on information presented in U.S. EPA (1990), representing data for 69
selected cities (Baes, Sharp, Sjoreen, and Shor 1984). The 69 selected cities are not identified; however, they appear to be
located throughout the continental United States.

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual irrigation information is not available, default values
(generally based on the closest comparable location) may not accurately reflect site-specific conditions. As a result,
ksl may be under- or overestimated to an unknown degree.
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994b), and NC DEHNR (1997), average annual
surface runoff can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise
1973). According to NC DEHNR (1997), this estimate can also be made by using more detailed, site-specific procedures,
such as those based on the U.S. Soil Conservation Service CNE. U.S. EPA (1985) is cited as an example of such a procedure.

The following uncertainty is associated with this variable:

COPC LOSS CONSTANT DUE TO LEACHING
(SOIL INGESTION EQUATIONS)

(Page 3 of 6)
Variable
Description
Units
Value
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable is site-specific, and depends on the available water and on soil structure; if a representative watershed soil can
be identified, 6W can be estimated as the midpoint between a soil's field capacity and wilting point U.S. EPA OSW
recommends the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the range of 0.1 (very sandy soils) to 0.3
(heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and is consistent
with U.S. EPA (1994b) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The default 0OT value may not accurately reflect site-specific or local conditions; therefore, ksl may be under- or
overestimated to a small extent, based on the limited range of values.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Depth (cm) Reference
1 U.S.EPA(1990a)andU.S.EPA(1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993c) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(Page 4 of 6)
Variable
Description
Units
Value
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffman
and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value of 1.5 g/cm3, based on a mean value for
loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also represents the midpoint of the
"relatively narrow range" forBD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
Kd.
Soil-water partition coefficient
cm3water/g
soil
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kds values are calculated as described in Appendix
A-3. '
B-29
-------
TABLE B-1-5

COPC LOSS CONSTANT DUE TO LEACHING
(SOIL INGESTION EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

Baes, C.R., RJX Sharp, A.L. Sjoreen and R.W. Shor. 1984. "A Review and Analysis of Parameters for Assessing Transport of Environmentally Released Radionuclides through Agriculture."
Prepared for the U.S. Department of Energy under Contract No. DEAC05-840R21400.

For the continental United States, as cited in U.S. EPA (1990), this document is the source of a series of maps showing: (1) average annual precipitation (P), (2) average annual irrigation
(I), and (3) average annual evapotranspiration isolines.

This document is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value, BD, of 1.5 g soil/cm3 soil for loam soil.

Geraghty, JJ., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center, Port Washington, New York.

This document is cited by U.S. EPA (1993), U.S. EPA (1994b), and NC DEHNR (1997) as a reference for calculating average annual runoff, RO. This document provides maps with
isolines of annual average surface runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge.
Because these volumes are total contributions and not only surface runoff, U.S. EPA (1994b) recommends that the volumes be reduced by 50 percent in order to estimate average annual
surface runoff.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

Hillel,D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of the equation in Table B-1-5. However, the document is not the original source of this equation. This document also
recommends the following:

• Estimation of average annual surface runoff, RO(cm/yr), by using the Water Atlas of the United States (Getagtfy, Miller, Van der Leeden, and Troise 1973) or site-specific
procedures, such as using the U.S. Soil Conservation Service ONE; U.S. EPA 1985 is cited as an example of such a procedure.
• A default value of 0.2 (mL water/cm3 soil) for soil volumetric water content, Qm
B-30
-------
TABLE B-l-5

COPC LOSS CONSTANT DUE TO LEACHING
(SOIL INGESTION EQUATIONS)

(Page 6 of 6)

U.S. Bureau of the Census. 1987. Statistical Abstract of the United States: 1987. 107th edition. Washington, D.C.

This document is a source of average annual precipitation (P) information for 69 selected cites, as cited in U.S. EPA (1990); these 69 cities are not identified.

U.S. EPA. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventional Pollutants in Surface and Groundwater. Part I (Revised 1985). Environmental Research
Laboratory. Athens, Georgia. EPA/600/6-85/002a. September.

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate RO.

This document presents ranges of (1) average annual precipitation, (2) average annual irrigation, and (3) average annual evapotranspiration. This document cites Baes, Sharp, Sjoreen,
and Shor (1984) and U.S. Bureau of the Census (1987) as the original sources of this information.

This document is one of the reference sources for the equation in Table B-l-5; this document also recommends the following:

• A range of soil volumetric water content, 8^, values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils); the original source or reference for these values is not identified.
• A range of values for soil mixing depth, Za for tilled and unfilled soil; the original source reference for these values is not identified.
• A range (2 to 280,000 [mL water/g soil]) of Kds values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1,2 to 1.7 (g soil/cm3 soil)

This document is one of the reference source documents for the equation in Table B-l-5. The original source of this equation is not identified. This document also presents a range of
values for soil mixing depth, Z, for tilled and untilled soil; the original source of these values is not identified. Finally, this document presents several COPC-specific Kd, values that
were used to establish a range (2 to 280,000 [mL water/g soil]) of Kd, values.

This document presents values for soil mixing depth, Zn for tilled and untilled soil, as cited in U.S. EPA (1993).

This document recommends (1) a default soil volumetric water content, 8^ value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993), and (2) a default soil bulk density, BD, value of
1.5 (g soil/cm3 soil), based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).
B-31
-------
TABLE B-l-S
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(SOIL INGESTION EQUATIONS)

(Page Iot6)
Description
This equation calculates the COPC loss constant from soil due to volatilization. Consistent with U.S. EPA guidance (1994) and based on the need for additional research to be conducted to
determine the magnitude of the uncertainty introduced for modeling volatile COPCs from soil, U.S. EPA OSW recommends that, until identification and validation of more applicable models,
the constant for the loss of soil resulting from volatilization (ksv) should be set equal to zero. In cases where high concentrations of volatile organic compounds are expected to be present in the
soil and the permitting authority considers calculation of ksv to be appropriate, the equation presented in this table should be considered. U.S. EPA OSW also recommends consulting the
methodologies described in U.S. EPA NCEA document, Methodology for Assessing Health Risks Associated wilh Multiple Exposure Pathways to Combustar Emissions (In Press).
Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate ksv.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate ksv.
ksv
3.1536 • 107-g[
Zs'Kds-R-Ta-BD\
Equation
0.482-
i -0.67
-0.11
Variable
Definition
Units
Value
ksv
COPC loss constant due to
volatilization
yr'
Consistent with U.S. EPA guidance (1994) and based on the need for additional research to be conducted to
determine the magnitude of the uncertainty introduced for modeling volatile COPCs from soil, U.S. EPA OSW
recommends that, until identification and validation of more applicable models, the constant for the loss of soil
resulting from volatilization (ksv) should be set equal to zero.
0.482
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
0.78
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
-0.67
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
-0.11
Empirical constant
3.7535 x Wm
Units conversion factor
unitless
This is an empirical constant calculated during the development of this equation.
s/yr
B-32
-------
TABLE B-l-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(SOIL INGESTION EQUATIONS)

(Page 2 of6)
Variable
Definition
\ tlaifet
Value
H
Henry's Law constant
atm-mVmol
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented
in Appendix A-3.

The following uncertainty is associated with this variable:

Values for this variable, estimated by using the parameters and algorithms in Appendix A-3, may
under- or overestimate the actual COPC-specific values. As a result, ksv may be under- or
overestimated.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Reference
U.S.EPA(1990a)andU.S.EPA(1993a)
U.S.EPA(1990a)andU.S.EPA(1993a)
Depth (cm)

U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kd, values are calculated as described
in Appendix A-3.
R
Universal gas constant
atm-m3/mol-K
8.205x10*
There are no uncertainties associated with this parameter.
B-33
-------
I
TABLE B-l-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(SOIL INGESTION EQUATIONS)

(Page 3 of 6)
Variable
Definition
Units
Value
T.
Ambient air temperature
K
298
This variable is site-specific. U.S. EPA (1990) also recommends an ambient air temperature of 298 K.

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for the variable are not available, default values may not
accurately represent site-specific conditions. The uncertainty associated with the selection of a single
value from within the temperature range at a single location is expected to be more significant than
the uncertainty associated with choosing a single ambient temperature to represent all localities.
3D
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the
water and clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84
was originally cited in Hoffinan and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density
value of 1.5 g/cm3, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).
The value of 1.5 g/cm3 also represents the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g/cm3
(U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
Average annual wind speed
m/s
3.9
Consistent with U.S. EPA (1990), U.S. EPA OSW recommends a defeult value of 3.9 m/s. See Chapter 3 for
guidance regarding the references and methods used to determine a site-specific value that is consistent with air
dispersion modeling.

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for this variable are not available, defeult values may
not accurately represent site-specific conditions. The uncertainty associated with the selection of a
single value from within the range of windspeeds at a single location may be more significant than the
uncertainty associated with choosing a single windspeed to represent all locations.
B-34
-------
TABLE B-l-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(SOIL INGESTION EQUATIONS)
Definition
Value
Viscosity of air
g/cm-s
1.81 x 10-04
U.S. EPA OSW recommends the use of this value, based on Weast (1980). This value applies at standard
conditions (20°C or 298 K and 1 atm or 760 mm Hg).

The viscosity of air may vary slightly with temperature.
Density of air
g/cm3
0.0012
U.S. EPA OSW recommends the use of this value, based on Weast (1980). This value applies at standard
conditions (20°C or 298 K and 1 atm or 760 mm Hg).

The density of air will vary with temperature.
Da
Diffusivity of COPC in air
cm2/s
Varies
This value is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

The default Da values may not accurately represent the behavior of COPCs under site-specific
conditions. However, the degree of uncertainty is expected to be minimal.
Surface area of contaminated area
m2
1.0
Sgjj3iapjCT5Jbrjgijdance regarding the calculation of this value.
B-35
-------
TABLE B-l-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(SOIL INGESTION EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

Carsel, R.F., R.S, Parrish, R.L. Jones, J.L. Hansen, and RX. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils," Journal of Contaminant Hydrology. Vol.
2. Pages 11-24.

This document is cited by U.S. EPA (1994b) as the source of a mean soil bulk density value, BD, of 1.5 (g soil/cm3 soil) for loam soil.

Hillel.D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionudides, ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NCDEHNR. 1997. NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of the equation in Table B-l-6.

U. S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office. Office of
Research and Development. EPA 600-90-003. January.

This document recommends the following:

• A range of values for soil mixing zone depth, £„ for tilled and unfilled soil; however, the source or basis for these values is not identified
• A default ambient air temperature of 298 K
• An average annual wind speed of 3.9 m/s; however, no source or reference for this value is identified.

This document is one of the reference source documents for the equation in Table B-l-6; however, the original reference for this equation is not identified.

This document also presents the following:

• A range of values for soil mixing depth, Za for tilled and unfilled soil; however, the original source of these values is not identified.
• COPC-specific Kds values that were used to establish a range (2 to 280,000 [mL water/g soil]) of Kds values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(SOIL INGESTION EQUATIONS)

(Page 6 of 6)

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-specific Assessment Procedures External Review Draft. Office of Research and Development: Washington,
D.C. EPA/600/6-88/005CC. June.

This document presents value for soil, mixing depth, Zs, for tilled and untilled soil as cited in U.S. EPA (1993).

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends a default soil density, BD, value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb
(1988).

Weast,R.C. 1980. Handbook of Chemistry and Physics. 61st Edition. CRC Press, Inc. Cleveland, Ohio.

This document is cited by NC DEJJNR (1997) as the source recommended values for viscosity of air, /ua, and density of air, pa.
B-37
-------
TABLE B-2-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 11)
Description

The COPC soil concentration averaged over the exposure duration, represented by Cs, should be used for carcinogenic COPCs, where the risk is averaged over the lifetime of an individual.
Because the hazard quotient associated with noncarcinogenic COPCs is based on a reference dose rather than a lifetime exposure, the highest annual average COPC soil concentration occurring
during the exposure duration period should be used for noncarcinogenic COPCs. The highest annual average COPC soil concentration would occur at the end of the time period of combustion
and is represented by Cs,D.

The following uncertainties are associated with this variable:

(1) The time period for deposition of COPCs resulting from hazardous waste combustion is assumed to be a conservative, long-term value. This assumption may overestimate Cs and

(2) Exposure duration values (T2) are based on historical mobility studies and will not necessarily remain constant. Specifically, mobility studies indicate that most receptors that move
remain in the vicinity of the combustion unit; however, it is impossible to accurately predict the probability that these short-distance moves will influence exposure, based on factors
such as atmospheric transport of pollutants.
(3) The use of a value of zero for Tj does not account for exposure that may have occurred from historic operations and emissions from hazardous waste combustion. This may
underestimate Cs and Cs,D.
(4) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils and, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs(D.
(5) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate Cs and Cs,p.
B-38
-------
TABLE B-2-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 11)
Equation for Carcinogens
Soil Concentration Averaged Over Exposure Duration
Dfs-tD-Cs.n\ I Cs,
- exp (-fa (T2-tD
Cs =
Ds
ks • (tD - T,)
(- ks • r,)
~ks
B-39
-------
TABLE B-2-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 of 11)
Highest Annual Average Soil Concentration
Equation for Noncarcinogens
[I - exp (-ks-tD)]
ks
where
Ds = ' -[F (0.31536 • Vdv • Cyv + Dywv) + (Dydp + Dywp) • (1 - FJ\
ZS-BD
For mercury modeling
Ds =
= 100 "(0.480 .
Z-BD
S
Use 0.48Q for total mercury and Fv = 0.85 in the mercury modeling equation to calculate Ds. The calculated Ds value is apportioned into the divalent mercury (Hg*+) and methyl mercury
(MHg) forms based on the assumed 98% Hg2+ and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg°) occurs in very small amounts in the vapor phase and does not
exist in the particle or particle-bound phase. Therefore, elemental mercury deposition onto soils is assumed to be negligible or zero. Elemental mercury is evaluated for the direct inhalation
pathway only (Table B-5-1).
0.98 Ds
O.Q2Ds
0.0

Evaluate divalent and methyl mercury as individual COPCs. Calculate Cs for divalent and methyl mercury using the corresponding (1) fate and transport parameters for mercuric chloride
Cdivalent mercunrt and methvl mercurv orovided in Aooendix A-3, and (2) Ds (He2*) and Ds (MHg) as calculated above.
B-40
-------
TABLE B-2-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of 11)
Variable
Cs
CslD
Ds
tD
ks
> . J Description.
Average soil concentration over
exposure duration
Soil concentration at time tD
Deposition term
Time period over which deposition
occurs (time period of combustion)
COPC soil loss constant due to all
processes
' " Unite. „
mg COPC/kg soil
mg COPC/kg soil
mg COPC/kg soil-
yr
yr
yr'
1 -." J. , '* Value ' . ' ":-,";' >•-''•'"--' ",.-•-"">-•-.:••' 'c '-'!--"','"^'t '-::'""-

Varies
U.S. EPA (1994a) and NC DEHNR (1991) recommend incorporating the use of a deposition term into the Cs equation.
Uncertainties associated with this variable include the following:
(1) Five of the variables in the equation for Ds (Q, Cyv, Dywv, Dywp, and Dydp) are COPC- and site-specific.
Values of these variables are estimated on the basis of modeling. The direction and magnitude of any
uncertainties should not be generalized.
(2) Based on the narrow recommended ranges, uncertainties associated with Vdv, F^ and BD are expected to be
low.
(3) Values for Zj vary by about one order of magnitude. Uncertainty is greatly reduced if it is known whether
soils are tilled or untilled.
100
U.S. EPA (1990a) specifies that this period of time can be represented by periods of 30, 60 or 100 years. U.S. EPA
OSW recommends that facilities use the conservative value of 100 years unless site-specific information is available
indicating that this assumption is unreasonable (see Chapter 6 of the HHRAP Protocol).
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-2-2. The COPC soil loss
constant is the sum of all COPC removal processes.
Uncertainty associated with this variable includes the following:
COPC-specific values for ksg (one of the variables in the equation in Table B-2-2) are empirically
determined from field studies. No information is available regarding the application of these values to the
site-specific conditions associated with affected facilities.
B-41
-------
I
TABLE B-2-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 5 of 11)
Variable
Description
Units
Value
Length of exposure duration
yr
6,30, or 40
U.S. EPA OSW recommends the following reasonable maximum exposure (RME) values for T?.
Exposure Duration
Child Resident
Subsistence Farmer Child
Subsistence Fisher Child

Adult Resident and
Subsistence Fisher
6 years
30 years
(6 child and 24 adult)
Reference
U.S. EPA (1990b)
U.S.EPA(1990b)
Subsistence Farmer 40 years U.S. EPA (1994b)

U.S. EPA (1994c) recommended the following unreferenced values:

Exposure Duration Years
Subsistence Farmer 40
Adult Resident 30
Subsistence Fisher 30
ChildResident 9

Uncertainties associated with this variable include the following:

(1) Exposure duration rates are based on historical mobility rates and may not remain constant. This assumption
may overestimate or underestimate Cs and Cs,D.
(2) Mobility studies indicate that most receptors that move remain in the vicinity of the emission sources;
however, it is impossible to accurately predict the likelihood that these short-distance moves will influence
exposure, based on factors such as atmospheric transport of pollutants. This assumption may overestimate or
underestimate Cs and Cs,D.
T,
Time period at the beginning of
combustion
yr
0
Consistent with U.S. EPA (1994bc), U.S. EPA OSW recommends a value of 0 for T,.

The following uncertainty is associated with this variable:

The use of a value of 0 for Tl does not account for exposure that may have occurred from historical operation
or emissions from the combustion of hazardous waste. This may underestimate Cs and Cs,D.
B-42
-------
TABLE B-2-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 6 of 11)
Variable
700
Units conversion factor
mg-cm2/kg-cm2
COPC emission rate
g/s
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 of the HHRAP for guidance regarding the calculation
of this variable.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Depth (cm) Reference
1 U.S.EPA(1990a)andU.S.EPA(1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990a) does not include a reference for these values.

The following uncertainties are associated with this variable:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting a
greater mixing depth. This uncertainty may overestimate Cs and Cs,D.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of
other residues. This uncertainty may underestimate Cs and Cs,D.
BD
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and
clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990a). A range of 0.83 to 1.84 was originally cited
in Hoffman and Baes (1979). U.S. EPA (1994c) recommended a default BD value of 1.5 g/cm3, based on a mean value
for loam soil that was obtained from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also
represents the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993a).

The following uncertainty is associated with this variable:

The recommended BD value may not accurately represent site-specific soil conditions; and may under- or
overestimate site-specific soil conditions to an unknown degree.
B-43
-------
TABLE B-2-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(PageTofll)
Variable
F*
0.31536
Vdv
Cyv
Description
Fraction of COPC air concentration
in vapor phase
Units conversion factor
Dry deposition velocity
Unitized yearly average air
concentration from vapor phase
Units
unitless
m-g-s/cm-ng-yr
cm/s
Hg-s/g-m3
Value
Otol
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.
This range is based on the values presented in Appendix A-3. Values are also presented in U.S. EPA (1994c) and NC
DEHNR(1997).
Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fv = 0 for all metals (except mercury).
The following uncertainties are associated with this variable:
(1) It is based on the assumption of a default Sr value for background plus local sources, rather than an ST
value for urban sources. If a specific site is located in an urban area, the use of the latter 5r value may be
more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than
that for background plus local sources, and it would result in a lower calculated Fv value; however, the Fv
value is likely to be only a few percent lower.
(2) According to Bidleman (1 988), the equation used to calculate Fv assumes that the variable c (Junge constant)
is constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from
the particle surface and the heat of vaporization of the liquid phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value
of c is used to calculate Fv.

3
U.S. EPA (1994c) recommended the use of 3 cm/s for the dry deposition velocity, based on median dry deposition
velocity for HNO3 from an unspecified U.S. EPA database of dry deposition velocities for HNO3, ozone, and SO2.
HNO3 was considered the most similar to the COPCs recommended for consideration in the HHRAP. The value
should be applicable to any organic COPC with a low Henry's Law Constant.
The following uncertainty is associated with this variable:
HN03 may not adequately represent specific COPCs; therefore, the use of a single value may under- or
overestimate estimated soil concentration.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
B-44
-------
TABLE B-2-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 8 of 11)
Variable
Dywv
Etydp
Dywp
, , ' > Beieriirtioii ^ V , -
Unitized yearly average wet
deposition from vapor phase
Unitized yearly average dry
deposition from particle phase
Unitized yearly average wet
deposition from particle phase
: , ', twts "
s/m2-yr
s/m2-yr
s/m2-yr
" r ' ' ^ jVninii ' < \ *" ", > % >
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
B-45
-------
TABLE B-2-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(PagePofll)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes," Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

This reference is for the statement that the equation used to calculate the fraction of air concentration in vapor phase (F"v) assumes that the variable c (the Junge constant) is constant for
all chemicals. However, this document notes that the value of c depends on the chemical (sorbate) molecular weight, the surface concentration for monolayer coverage, and the difference
between the heat of desorption from the particle surface and the heat of vaporization of the liquid-phase sorbate. The following equation, presented in this document, is cited by U.S
EPA (1994b) and NC DEHNR (1997) for calculating the variable Fv:
1 -
c-ST
P°L + C ' ST
where

Fv = Fraction in vapor phase (unitless)
c = Junge constant = 1.7 x 10"04 (atm-cm)
ST = Whitby's average surface area of particulates = 3.5 x 10"06 cm2/cm3 air (corresponds to background plus local sources)
P"L = Liquid-phase vapor pressure of chemical (atm) (see Appendix A-3)

If the chemical is a solid at ambient temperatures, the solid phase vapor pressure is converted to a liquid-phase vapor pressure as follows:
where
Solid-phase vapor pressure of chemical (atm) (see Appendix A-3)

Entropy of fusion over the universal gas constant = 6.79 (unitless)

Melting point of chemical (K) (see Appendix A-3)
Ambient air temperature = 284 K (11 °C)
B-46
-------
TABLE B-2-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

{Page 10 of 11)

This reference is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value, BD, of 1.5 (g soil/cm3 soil) for loam soil.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

Hoffman, P.O., and C.F. Baes, 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NOREG/TM-882.

This document presents a soil bulk density range, BD, of 0.83 to 1.84.

Junge, C.E. 1977. Fate ofPollutants in Air and Water Environments, Parti. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is one of the source documents for the equation in Table B-l-1. This document also recommends the use of (1) a deposition term, Ds, and (2) COPC-specific Fv (fraction of COPC
air concentration in vapor phase) values.

Research Triangle Institute (RTI). 1992. Preliminary Soil Action Level for Superfund Sites. Draft Interim Report. Prepared for U.S. EPA Hazardous Site Control Division, Remedial Operations
Guidance Branch. Arlington, Virginia. EPA Contract 68-Wl-0021. Work Assignment No. B-03, Work Assignment Manager Loren Henning. December.

This document is a reference source for COPC-specific Fv (fraction of COPC air concentration in vapor phase) values.

This document is a reference source for the equation in Table B-2-1, and it recommends that (1) the time period over which deposition occurs (time period for combustion ), tD, be
represented by periods of 30,60 and 100 years, and (2) undocumented values for soil mixing zone depth, Zn for tilled and unfilled soil.

U.S. EPA. 1990b. Exposure Factors Handbook March.

This document is a reference source for values for length of exposure duration, T2.

U.S. EPA. 1992. Estimating Exposure to Dioxin-Like Compounds. Draft. Office of Research and Development. Washington, D.C. EPA/600/6-88/005b.

This document is cited by U.S. EPA (1993a) as the source of values for soil mixing zone depth, Zs, for tilled and unfilled soils.
B-47
-------
TABLE B-2-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Pagellofll)

U.S. EPA. 1993a. Addendum to the Methodologyfor Assessing Health Risks Associatedwith Indirect Exposure to Combustor Emissions, External Review Draft. Office of Research and
Development Washington, D.C. November.

This document is a reference for recommended values for soil mixing zone depth, Z, for tilled and untilled soils; it cites U.S. EPA (1992) as the source of these values. It also
recommends a "relatively narrow" range for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil).

U.S.EPA. 1993b. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid
Waste. Office of Research and Development Washington, D.C. September 24.

This document is a reference for the equation in Table B-2-1. It recommends using a deposition term, Ds, and COPC-specific Fv values (fraction of COPC air concentration in vapor
phase) in the Cs equation.

U.S. EPA. 1994a. Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilitit.i. Office of Emergency and Remedial Response. Office of Solid Waste. April 15.

This document is a reference for the equation in Table B-2-1; it recommends that the following be used in the Cs equation: (1) a deposition term, Ds, and (2) a default soil bulk density
value of 1.5 g/cm3, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).

U.S.EPA. 1994b. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-Specific Assessment Procedures. External Review Draft. Office of Research and Development
Washington, D.C. EPA/600/6-88/005Cc. June.

This document recommends values for length of exposure duration, T2, for the subsistence farmer.

U.S. EPA. 1994c. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Office of Emergency and Remedial Response.
Office of Solid Waste. December 14.

The value for dry deposition velocity is based on median dry deposition velocity for HNO3 from a U.S. EPA database of dry deposition velocities for HN03 ozone, and SO2. HNO3 was
considered the most similar to the constituents covered and the value should be applicable to any organic compound having a low Henry's Law Constant. The reference document for
this recommendation was not cited. This document recommends the following:

Values for the length of exposure duration, T2
Value of 0 for the time period of the beginning of combustion, T,
Fv values (fraction of COPC air concentration in vapor phase) that range from 0.27 to 1 for organic COPCs
Vdv value (dry deposition velocity) of 3 cm/s (however, no reference is provided for this recommendation)
Default soil bulk density value of 1.5 g/cm3, based on a mean for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
Vdv value of 3 cm/s, based on median dry deposition velocity for HNO3 from an unspecified U.S. EPA database of dry deposition velocities for HNO3, ozone, and S02. HNO3
was considered the most similar to the COPCs recommended for consideration in the HHRAP.

U.S.EPA. 1997. Mercury Study Report to Congress. Volume UI: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-48
-------
TABLE B-2-2
COPC SOIL LOSS CONSTANT
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the COPC soil loss constant, which accounts for the loss of COPCs from soil by several mechanisms. !

Uncertainties associated with this equation include the following:

(1) COPC-specific values for ksg are empirically determined from field studies; no information is available regarding the application of these values to the site-specific conditions
associated with affected facilities.
(2) The source of the equations in Tables B-2-3 through B-2-6 have not been identified.
Equation

ks = ksg + kse + ksr + ksl + ksv
Variable
Description
Units
>^j^,i::'V.<&V~'Vr^!^^ •.A.-X-'.VTi^ v;"..-v 4',v^;T
ks
COPC soil loss constant due to all
processes
ksg
COPC loss constant due to biotic
and abiotic degradation
Varies
This variable is COPC-specific and should be determined from the COPC in Appendix A-3.

The following uncertainty is associated with this variable:

COPC SOIL LOSS CONSTANT
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 4)
Units
Value
kse
COPC loss constant due to soil
yr1
erosion
This variable is COPC- and site-specific, and is further discussed in Table B-2-3. Consistent with U.S. EPA (1994a), U.S. EPA
(1994b) and NC DEHNR (1997), U.S. EPA OSW recommends that the default value assumed for kse is zero because of
contaminated soil eroding onto the site and away from the site.

Uncertainties associated with this variable include the following:

(1) The source of the equation in Table B-2-3 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting a greater mixing
depth. This uncertainty may overestimate kse.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate kse.
ksr
COPC loss constant due to surface
runoff
yr'
Varies
This variable is COPC- and site-specific, and is calculated by using the equation hi Table B-2-4. No reference document is cited
for this equation. The use of this equation is consistent with U.S. EPA (1994b) and NC DEHNR (1997). U.S. EPA (1994a) states
that all ksr values are zero but does not explain the basis of this assumption.

Uncertainties associated with this variable (calculated by using the equation hi Table B-2-4) include the following:

(1) The source of the equation hi Table B-2-4 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate ksr.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate far.
fa/
COPC loss constant due to leaching
yr-'
Varies
This variable is COPC- and site-specific, and is calculated by using the equation hi Table B-2-5. The use of this equation is
consistent with U.S. EPA (1993), U.S. EPA (1994b), andNC DEHNR (1997). U.S. EPA (1994a) states that all fa/ values are zero
but does not explain the basis of this assumption.

Uncertainties associated with this variable (calculated by using the equation in Table B-2-5) include the following:

(1) The source of the equation in Table B-2-5 has not been identified.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) hi comparison to that of other residues. This uncertainty may underestimate fa/.
B-50
-------
TABLE B-2-2
COPC SOIL LOSS CONSTANT
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 of 4)
Variable
Description
Value ,
ksv COPC loss constant due to
volatilization
yr'
This variable is COPC- and site-specific, and is further discussed in Table B-2-6. Consistent with U.S. EPA guidance (1994a) and
based on the need for additional research to be conducted to determine the magnitude of the uncertainty introduced for modeling
volatile COPCs from soil, U.S. EPA OSW recommends that, until identification and validation of more applicable models, the
constant for the loss of soil resulting from volatilization (ksv) should be set equal to zero.

Uncertainties associated with this variable include the following:

(1) The source of the equation in Table B-2-6 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting a greater mixing
depth. This uncertainty may overestimate ksv.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution, (as a result of potential mixing with
in-situ materials) in comparison to that of other residues. This uncertainty may underestimate ksv.
B-51
-------
TABLE B-2-2

COPC SOIL LOSS CONSTANT
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the reference documents for the equations in Tables B-2-4, B-2-5, and B-2-6. This document is also cited as (1) the source for a range of COPC-specific
degradation rates (ksg), and (2) one of the sources that recommend using the assumption that the loss resulting from erosion (kse) is zero because of contaminated soil eroding onto the
site and away from the site.

This document is one of the reference documents for the equations in Tables B-2-3 and B-2-5.

This document is cited as a source for the assumptions that losses resulting from erosion (kse), surface runoff (far), degradation (ksg), leaching (hi), and volatilization (ksv) are all zero.

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document is one of the reference documents for the equations in Tables B-2-4, B-2-5, and B-2-6. This document is also cited as one of the sources that recommend using the
assumption that the loss resulting from erosion (kse) is zero and the loss resulting from degradation (ksg) is "NA" or zero for all compounds.
B-52
-------
TABLE B-2-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the constant for COPC loss resulting from erosion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), U.S. EPA OSW recommends
that the default value assumed for kse is zero because of contaminated soil eroding onto the site and away from the site. In site-specific cases where the permitting authority considers it
appropriate to calculate a kse, the following equation presented in this table should be considered along with associated uncertainties. Additional discussion on the determination of kse can be
obtained from review of the methodologies described in U.S. EPA NCEA document, Methodology for Assessing Health Risks Associated with Multiple Exposure Pathways to Combustor
Emissions (In Press). Uncertainties associated with this equation include:

(1) For soluble COPCs, leaching might lead to movement below 1 centimeter in unfilled soils, resulting in a greater mixing depth. This uncertainty may overestimate kse.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate kse. , ^
Equation
kse =
O.l-X-SD-ER
Kd-BD
Variable
Description
'Unit;
Value
kse
COPC loss constant due to soil
erosion
yr'1
0
Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), U.S. EPA OSW recommends that the default
value assumed for kse is zero because of contaminated soil eroding onto the site and away from the site.
uncertainty may overestimate kse.
Xe
Unit soil loss
kg/m2-yr
Varies
This variable is site-specific and is calculated by using the equation in Table B-4-13.

The following uncertainty is associated with this variable:

All of the equation variables are site-specific. Use of default values rather than site-specific values for any or all of
these variables will result in unit soil loss (Xe) estimates that are under- or overestimated to some degree. Based on
default values, Xe estimates can vary over a range of less than two orders of magnitude.
B-53
-------
TABLE B-2-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 5)
Vwiable
Description
Units
Value
SD
Sediment delivery ratio
unitless
Varies
This value is site-specific and is calculated by using the equation in Table B-4-14.

Uncertainties associated with this variable include the following:

(1) The recommended default values for the empirical intercept coefficient, a, are average values that are based on
studies of sediment yields from various watersheds. Therefore, those default values may not accurately represent
site-specific watershed conditions. As a result, use of these default values may under- or overestimate SD.
(2) The recommended default value for the empirical slope coefficient, b, is based on a review of sediment yields from
various watersheds. This single default value may not accurately represent site-specific watershed conditions. As
a result, use of this default value may under- or overestimate SD.
ER
Soil enrichment ratio
unitless
Inorganics: 1
Organics: 3
COPC enrichment occurs because (1) lighter soil particles erode more than heavier soil particles, and (2) concentration of
organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded material
than in in-situ soil (U.S. EPA 1993). In the absence of site-specific data, U.S. EPA OSW recommends a default value of 3
for organic COPCs and 1 for inorganic COPCs. This is consistent with other U.S. EPA guidance (1993), which recommends
a range of 1 to 5 and a value of 3 as a "reasonable first estimate." This range has been used for organic matter, phosphorus,
and other soil-bound COPCs (U.S. EPA 1993); however, no sources or references were provided for this range. ER is
generally higher in sandy soils than in silty or loamy soils (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The default ER value may not accurately reflect site-specific conditions; therefore, kse may be over- or
underestimated to an unknown extent. The extent of any uncertainties will be reduced by using county-specific ER
values.
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffman
and Baes (1979). U.S. EPA (1994b) recommended a default BD value of 1.5 g/cm3, based on a mean value for loam soil that
was taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also represents the midpoint of the
"relatively narrow range" forBD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-54
-------
TABLE B-2-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 of 5)
Variable
Description
llttitg
Value
Soil mixing zone depth
cm
U.S. EPA recommends the following values for this variable:
Ito20
Soil
Unfilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate kse.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other
residues. This uncertainty may underestimate foe.
Kd.
Soil-water partition coefficient
mL water/g
soil
(or cm3
water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Rvalues are calculated as described in
Appendix A-3.
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable is site-specific, and depends on the available water and on soil structure; Qm can be estimated as the midpoint
between a soil's field capacity and wilting point, if a representative watershed soil can be identified. However, U.S. EPA
OSW recommends the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to
0.3 (heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and is
consistent with U.S. EPA (1994b).

The following uncertainty is associated with this variable:

The default 9^, value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
B-55
-------
TABLE B-2-3

COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of5)

REFERENCES AND DISCUSSION

This document is cited by U.S. EPA (1994b) as the source for a mean soil bulk density, BD, value of 1.5 (g soil/cm3 soil) for loam soil.

Hillel.D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

Hofrman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

This document presents a range of values for soil mixing zone depth, Zs, for tilled and unfilled soil. The basis or source of these values is not identified.

This document is also a source of the following:

• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)
• COPC-specific (inorganic COPCs only) Kds values used to develop a proposed range (2 to 280,000 [mL water/g soil]) of Kds values
A range of soil volumetric water content (0J values of 0.1 (mL water/cm3 soil) (very sandy soils) to 0.3 (mL water/cm3 soil) (heavy loam/clay soils) (however, no source or
reference is provided for this range)
• A range of values for soil mixing zone depth, Zn for tilled and unfilled soil

U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. April 15.
B-56
-------
TABLE B-2-3

COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 5 of 5)

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development
Washington, D.C. EPA/600/6-88/005Cc. June.

This document is the source of values for soil mixing zone depth, Zs, for tilled and untilled soil, as cited in U.S. EPA (1993).

This document recommends (1) a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb
(1988), and (2) a default soil volumetric water content, 6^, value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993).
B-57
-------
I
TABLE B-2-4
COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the COPC loss constant due to runoff of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might result in movement to below 1 centimeter in unfilled soils, resulting in a greater mixing depth. This uncertainty may overestimate ksr.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestimate ksr.
Equation
ksr =
RO
Variable
Description
Units
Value
ksr
COPC loss constant due to runoff
"4*^^4^*^^ A ., -
*>^^M*fc^^^#.^.
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994b), andNC DEHNR (1997), average annual
surface runoff, RO, can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and
Troise 1973). According to NC DEHNR (1997), estimates can also be made by using more detailed, site-specific procedures
for estimating the amount of surface runoff, such as those based on the U.S. Soil Conservation Service curve number equation
(CNE). U.S. EPA (1985) is cited as an example of such a procedure.

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual surface runoff information is not available, default or
estimated values may not accurately represent site-specific or local conditions. As a result, ksl may be under- or
overestimated to an unknown degree.
B-58
-------
TABLE B-2-4
COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 5)
Variable
Description
Units
Value
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable depends on the available water and soil structure; if a representative watershed soil can be identified, 0^, can be
estimated as the midpoint between a soil's field capacity and wilting point. U.S. EPA OSW recommends the use of 0.2
mL/cm3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils), which
is recommended by U.S. EPA (1993) (no source or reference is provided for this range), and is consistent with U.S. EPA
(1994b) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The default 0^ value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Unfilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate ksr.
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in-situ materials) in comparison to that of other residues. This uncertainty may underestimate ksr.
Kds
Soil-water partition coefficient
mL water/g
soil
(or cm3
water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kds values are calculated as described in
Appendix A-3.
B-59
-------
r
TABLE B-2-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 of 5)
Variable
Description
Unite
Value
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). The proposed range was originally cited in Hoffman
and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value of (1.5 g soil/cm3 soil), based on a mean
value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 (g soil/cm3 soil) also
represents the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 (g soil/cm3 soil) (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value mav not accurately reoresent site-snecific soil conditions
B-60
-------
TABLE B-2-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

This document is cited by U.S. EPA (1994b) as the source of a mean soil bulk density, ED, value of J.5 (g soil/cm3 soil) for loam soil.

Geraghty, J.J., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of'the United States. Water Information Center, Port Washington, New York.

This document is cited by U.S. EPA (1993), U.S. EPA (1994), and NC DEHNR (1997) as a reference to calculate average annual runoff, RO. This reference provides maps with isolines
of annual average surface water runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because
these values are total contributions and not only surface runoff, U.S. EPA (1994) recommends that the volumes be reduced by SO percent in order to estimate surface runoff.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.
•7
NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of Table B-2-4; however, this document is not the original source of this equation (this source is unknown). This
document also recommends the following:

• Estimation of annual current runoff, RO (cro/yr), by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) or site-specific procedures,
such as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.
• Default value of 0.2 (mL water/cm3 soil) for soil volumetric water content (Q^)

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate site-specific surface runoff.

This document presents a range of values for soil mixing zone depth, Za for tilled and untilled soil; the basis for, or sources of, these values is not identified.
B-61
-------
TABLE B-2-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 5 of 5)

U.S. EPA. 1954a. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-specific Assessment Procedures. External Review Draft Office of Research and Development
Washington, D.C. EPA/600/6-88/005Cc June..

This document presents a range of values for soil mixing zone depth, Z^ for tilled and unfilled soil as cited in U.S. EPA (1993).

This document recommends the following:

A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)
A range of soil volumetric water content, 0^ values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) (the original source of, or reference for, these values is not
identified)
A range of values for soil mixing depth, Z5, for tilled and unfilled soil (the original source of, or reference for, these values is not identified)
A range (2 to 280,000 [mL water/g soil) ofKd, values for inorganic COPCs
Use of the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) to calculate average annual runoff, RO.

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Offices of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the following:

• Estimation of average annual runoff, RO, by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973)
• Default soil bulk density, BD, value of 1.5 (g soil/cm3 soil), based on the mean for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
• Default soil volumetric water content, 0^, value of 0.2 (mL water/cm3soil), based on U.S. EPA (1993)
B-62
-------
TABLE B-2-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 6)
Description
This equation calculates the constant for COPC loss resulting from leaching of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate ksl.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate ksl.
(3) The original source of this equation has not been identified. U.S. EPA (1993) presents the equation as shown here. U.S. EPA (1994b) and NC DEHNR (1997) replaced the numerator
as shown with "q", defined as average annual recharge (cm/yr).
ksl =
Equation
P + I - RO - E..
Variable
DescriptioB
Value
ksl
COPC loss constant due to leaching
Average annual precipitation
cm/yr
18.06 to 164.19
This variable is site-specific. This range is based on information presented in U.S. EPA (1990), representing data for 69
selected cities (U.S. Bureau of Census 1987; Baes, Sharp, Sjoreen and Shor 1984). The 69 selected cities are not identified;
however, they appear to be located throughout the continental United States. U.S. EPA OSW recommends that site-specific
data be used.

The following uncertainty is associated with this variable:

(1) To the extent that a site is not located near an established meteorological data station, and site-specific data are not
available, default average annual precipitation data may not accurately reflect site-specific conditions. As a result,
ksl may be under- or overestimated. However, average annual precipitation data are reasonably available; therefore,
uncertainty introduced by this variable is expected to be minimal.
B-63
-------
TABLE B-2-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 6)
Variable
Description
Units
Value
Average annual irrigation
cm/yr
0 to 100
This variable is site-specific. This range is based on information presented in U.S. EPA (1990), representing data for 69
selected cities (Baes, Sharp, Sjoreen, and Shor 1984). The 69 selected cities are not identified; however, they appear to be
located throughout the continental United States.

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual irrigation information is not available, default values
(generally based on the closest comparable location) may not accurately reflect site-specific conditions. As a
result, ksl may be under- or overestimated to an unknown degree. ^^^
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994). and NC DEHNR (1997), average annual
surface runoff; RO, can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and
Troise 1973). According to NC DEHNR (1997), this estimate can also be made by using more detailed, site-specific
procedures, such as those based on the U.S. Soil Conservation Service CNE.

The following uncertainty is associated with this variable:

(Page 3 of 6)
Variable
Units
Value
Soil volumetric water content
(mL
water/cm3
soil)
0.2
This variable is site-specific, and depends on the available water and on soil structure; if a representative watershed soil can
be identified 0OT can be estimated as the midpoint between a soil's field capacity and wilting point. U.S. EPA OSW
recommends the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the range of 0.1 (very sandy soils) to 0.3
(heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and is consistent
with U.S. EPA (1994b) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The default 0^ value may not accurately reflect site-specific or local conditions; therefore, ksl may be under- or
overestimated to a small extent, based on the limited range of values.
Soil mixing zone depth
cm
1 to 20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Reference
U.S.EPA(1990a)andU.S.EPA(1993a)
U.S. EPA (1990a) and U.S. EPA (1993a)
Depth (cm)

U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate ksr. .
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in-situ materials) in comparison to that of other residues. This uncertainty may underestimate ksl.
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffman
and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean
value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 (g soil/cm3 soil) also represents
the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 (g soil/cm3 soil) (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended sgil bulk density value may not accurately represent site-specific soil conditions.
B-65
-------
r
TABLE B-2-5

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of 6)
Variable
Kd.

Description
Soil-water partition coefficient

Units
cm3water/g
soil

Value
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.
The following uncertainty is associated with this variable:
Uncertainties associated with this parameter will be limited if Rvalues are calculated as described in
Appendix A-3.
B-66
-------
TABLE B-2-5

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

Baes, C.F., R.D. Sharp, A.L. Sjoreen and R.W. Shor. 1984. "A Review and Analysis of Parameters for Assessing Transport of Environmentally Released Radionuclides through Agriculture."
Prepared for the U.S. Department of Energy under Contract No. DEAC05-840R21400.

This document is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value, ED, of 1.5 g/cm3 for loam soil.

Geraghty, J.J., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center, Port Washington, New York.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose of Radionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of the equation in Table B-l-5. However, the document is not the original source of this equation. This document also
recommends the following:

Estimation of average annual surface runoff, RO (cm/yr), by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) or site-specific
procedures, such as using the U.S. Soil Conservation Service CNE; U.S. EPA 1985 is cited as an example of such a procedure.
• A default value of 0.2 (mL water/cm3 soil) for soil volumetric water content, 9^,
B-67
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TABLE B-2-5

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 6 of 6)

U.S. Bureau of the Census. 1987. Statistical Abstract of the United Slates: 1987. 107th edition. Washington, D.C.

This document is a source of average annual precipitation (f) information for 69 selected cites, as cited in U.S. EPA (1990); these 69 cities are not identified.

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate RO.

This document is one of the reference sources for the equation in Table B-l-5; this document also recommends the following:

• A range of soil volumetric water content, 0^,, values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils); the original source or reference for these values is not identified.
• A range of values for soil mixing depth, Z0 for tilled and untilled soil; the original source reference for these values is not identified.
• A range (2 to 280,000 [mL water/g soil]) of Kds values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)

This document is one of the reference source documents for the equation in Table B-l-5. The original source of this equation is not identified. This document also presents a range of
values for soil mixing depth, Z, for tilled and untilled soil; the original source of these values is not identified. Finally, this document presents several COPC-specific.Ktf, values that
were used to establish a range (2 to 280,000 [mL water/g soil]) of Kds values.

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-specific Assessment Procedures. External Review Draft Office of Research and Development. Washington,
D.C. EPA/600/6-88/005CC June..

This document presents values for soil mixing depth, Zs, for tilled and untilled soil, as cited in U.S. EPA (1993).

This document recommends (1) a default soil volumetric water content, 0^, value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993), and (2) a default soil bulk density, BD, value of
1.5 (g soil/cm3 soil), based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).
B-68
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TABLE B-2-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 6)
Description
This equation calculates the COPC loss constant from soil due to volatilization. Consistent with U.S. EPA guidance (1994) and based on the need for additional research to be conducted to
determine the magnitude of the uncertainty introduced for modeling volatile COPCs from soil, U.S. EPA OSW recommends that, until identification and validation of more applicable models,
the constant for the loss of soil resulting from volatilization (ksv) should be set equal to zero. In cases where high concentrations of volatile organic compounds are expected to be present in the
soil and the permitting authority considers calculation of ksv to be appropriate, the equation presented in this table should be considered. U.S. EPA OSW also recommends consulting the
methodologies described in U.S. EPA NCEA document, Methodology for Assessing Health Risks Associated with Multiple Exposure Pathways to Combustor Emissions (In Press).
Uncertainties associated with this equation include the following:
(1)
(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate ksv.
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate ksv.
ksv =
3.1536 • Itf-H
Z-Kd-R-T-BD
Equation
0.482- W™-
I -0.67
?.'*>.
4A_
rc
-0.11
Variable
Unite
ksv
COPC loss constant due to
volatilization
yr1
Consistent with U.S. EPA guidance (1994) and based on the need for additional research to be conducted to
determine the magnitude of the uncertainty introduced for modeling volatile COPCs from soil, U.S. EPA OSW
recommends that, until identification and validation of more applicable models, the constant for the loss of soil
resulting from volatilization (ksv) should be set equal to zero.
0.482
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
0.78
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
-ft 67
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
-0.11
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
B-69
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TABLE B-2-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 6)
Variable
Definite
Unit*
Value
H
Henry's Law constant
atm-mVmol
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented
in Appendix A-3.

The following uncertainty is associated with this variable:

Values for this variable, estimated by using the parameters and algorithms in Appendix A-3, may
under- or overestimate the actual COPC-specific values. As a result, fev may be under- or
overestimated.
Z,
Soil mixing zone depth
cm
I to 20
U.S. EPA OSW recommends the following values for this variable:
Soil
Unfilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting
in a greater mixing depth. This uncertainty may overestimate ksr.
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of
potential mixing with in situ materials) in comparison to that of other residues. This uncertainty may
underestimate ksv.
Soil-water partition coefficient
cm3 water/g soil
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented
in Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Rvalues are calculated as described
in Appendix A-3.
Universal gas constant
atm-m3/mol-K
8.205x10-*
There are no uncertainties associated with this parameter.
B-70
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TABLE B-2-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 of6)
Variable
Definition
Unite
Value
Ambient air temperature
K
298
This variable is site-specific. U.S. EPA (1990) also recommends an ambient air temperature of 298 K.

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for the variable are not available, default values may not
accurately represent site-specific conditions. The uncertainty associated with the selection of a single
value from within the temperature range at a single location is expected to be more significant than
the uncertainty associated with choosing a single ambient temperature to represent all localities.
BD
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the
water and clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84
was originally cited in Hoffman and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density
value of 1.5 g/cm3, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).
The value of 1.5 g/cm3 also represents the midpoint of the "relatively narrow range" forBD of 1.2 to 1.7 g/cm3
(U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
W
Average annual wind speed
m/s
3.9
Consistent with U.S. EPA (1990), U.S. EPA OSW recommends a default value of 3.9 m/s. See Chapter 3 for
guidance regarding the references and methods used to determine a site-specific value that isconsistent with air
dispersion modeling.

The following uncertainty is associated with this variable:

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of 6)
Variable
ft
P«
D.
A
Definition
Viscosity of air
Density of air
Diffiisivity of COPC in air
Surface area of contaminated area
Units
g/cm-s
g/cm3
cnrVs
m2
Value
1.81 x 10-"
U.S. EPA OSW recommends the use of this value, based on Weast (1980). This value applies at standard
conditions (20°C or 298 K and 1 atm or 760 mm Hg).
The viscosity of air may vary slightly with temperature.
0.0012
U.S. EPA OSW recommends the use of this value, based on Weast (1980. This value applies at standard
conditions (20°C or 298 K and 1 atm or 760 mm Hg).
The density of air will vary slightly with temperature.
Varies
This value is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.
The following uncertainty is associated with this variable:
The default Da values may not accurately represent the behavior of COPCs under site-specific
conditions. However, the degree of uncertainty is expected to be minimal.
1.0
See Chapter 5 for guidance regarding the calculation of this value.
B-72
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TABLE B-2-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

Carsel, R.F., R.S, Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology. Vol.

This document is cited by U.S. EPA (1994b) as the source of a mean soil bulk density value, BD, of 1.5 (g soil/cm3 soil) for loam soil.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of the equation in Table B-l-6; however, the original source of this equation is not identified.

U. S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office. Office of
Research and Development. EPA 600-90-003. January.

This document recommends the following:

• A range of values for soil mixing zone depth, Zs, for tilled and untilled soil; however, the source or basis for these values is not identified
• A default ambient air temperature of 298 K
• An average annual wind speed of 3.9 m/s; however, no source or reference for this value is identified.

This document is one of the reference source documents for the equation in Table B-l-6; however, the original reference for this equation is not identified.

This document also presents the following:

• A range of values for soil mixing depth, Zs, for tilled and untilled soil; however, the original source of these values is not identified.
• COPC-specific Kds values that were used to establish a range (2 to 280,000 [mL water/g soil]) of Kd, values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 6 of 6)

This document presents value for soil, mixing depth, Zn for tilled and unfilled soil as cited in U.S. EPA (1993).

This document recommends a default soil density, BD, value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb
(1988).

Weast,R.C. 1980. Handbook of Chemistry and Physics. 61st Edition. CRC Press, Inc. Cleveland, Ohio.

This document is cited by NC DEHNR (1997) as the source recommended values for viscosity of air, \j.v and density of air, pa.
B-74
-------
TABLE B-2-7

ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 12)
Description
This equation calculates the COPC concentration in aboveground vegetation, due to wet and dry deposition of COPCs onto plant surfaces. The limitations and uncertainty in calculating this
value include the following:

(1) Uncertainties associated with the variables Q, Dydp, and Dywp are site-specific.
(2) The calculation of kp values does not consider chemical degradation processes. Inclusion of chemical degradation process would decrease the amount of time that a chemical remains
on plant surfaces (half-time) and thereby increase kp values. Pd decreases with increased kp values. Reduction of half-time from the assumed 14 days to 2.8 days, for example, would
decrease Pd about 5-fold.
(3) The calculation of other parameter values (for example, Fw and Rp) is based directly or indirectly on studies of vegetation other than aboveground produce (primarily grasses). To the
extent that the calculated parameter values do not accurately represent aboveground produce-specific values, uncertainty is introduced.
(4) The uncertainties associated with the variables Fv Tp, and Yp are not expected to be significant.

As highlighted above, Pdis most significantly affected by the values assumed for kp and the extent to which parameter values (assumed based on studies of pasture grass) accurately reflect
aboveground produce-specific values.
Pd =
Equation
1000 • Q • (1 - Fv) • [Dydp + (Fw • Dywp)} • Rp • [1.0 - exp (-kp • Tp)]
For mercury modeling
Pd =
1000 • 0.480 • (1 - Fv) • [Dydp + (Fw • Dywp)] • Rp • [1.0 - exp (-kp • Tp)]
Yp-kp
Use 0.48Q for total mercury and Fv = 0.85 in the mercury modeling equation to calculate Pd. The calculated Pd value is apportioned into the divalent mercury (Hg2*) and methyl mercury
(MHg) forms based on the 78% Kg2* and 22% MHg speciation split in aboveground produce (see Chapter 2).

0.78 Pd
0.22 Pd

Evaluate divalent and methyl mercury as individual COPCs. Calculate Pd for divalent and methyl mercury using the corresponding values.
B-75
-------
r
TABLE B-2-7
ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 12)
Variable
Description
Units
Value
Pd
1000
Concentration of COPC in
aboveground produce due to direct
(wet and dry) deposition
mgCOPC/kg
DW
Units conversion factor
mg/g
fi
COPC-specific emission rate
g/s
Varies
This value is COPC- and site-specific and is determined by air dispersion modeling. See Chapters 2 and 3 for
guidance regarding the calculation of this variable. Uncertainties associated with this variable are also COPC- and
site-specific.
Fraction of COPC air concentration
in vapor phase
unitless
Otol
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values is presented in
Appendix A-3. This range is based on values presented hi Appendix A-3. Values are also presented in U.S. EPA
(1994b) and NC DEHNR (1997).

Fv was calculated using an equation presented hi Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fv = 0 for all metals (except mercury).

The following uncertainties are associated with this variable:

(1) It is based on the assumption of a default ST value for background plus local sources, rather than an 5T
value for urban sources. If a specific site is located in an urban area, the use of the latter ST value may be
more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than
that for background plus local sources, and it would result in a lower calculated/^ value; however, the Fv
value is likely to be only a few percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge
constant) is constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular
weight, the surface concentration for monolayer coverage, and the difference between the heat of desorption
from the particle surface and the heat of vaporization of the liquid phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value
of c is used to calculate Fv.
(3) Based on U.S. EPA (1994a), the Fv value for dioxins (PCDD/PCDF) is intended to represent 2,3,7,
8-TCDD TEQs by weighting data for all dioxin and fiiran congeners with nonzero TEFs. Uncertainty is
introduced, because U.S. EPA has been unable to verify the recommended Fv value for dioxins.
Dydp
Unitized yearly average dry
deposition from particle phase
s/m2-yr
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are site-specific.
B-76
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TABLE B-2-7
ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 of 12)
Variable
Description
Units
Value
Rp
Interception fraction of the edible
portion of plant
unitless
0.39
U.S. EPA OSW recommends the use of this default Rp value because it represents the most current information
available; specifically, productivity and relative ingestion rates.

Baes, Sharp, Sjoreen, and Shor (1984) proposed using the same empirical relationship developed by Chamberlain
(1970) for other vegetation classes. Class-specific estimates of the empirical constant, y, were developed by forcing
an exponential regression equation through several points, including average and theoretical maximum estimates of
Rp and Yp (Baes, Sharp, Sjoreen, and Shor 1984). The class-specific Rp estimates were then weighted, by relative
ingestion of each class, to arrive at the weighted average Rp value of 0.39.

U.S. EPA (1994b) and U.S. EPA (1995) recommended a weighted average Rp value of 0.05. However, the relative
ingestion rates used in U.S. EPA (1994b) and U.S. EPA (1995) to weight the average Rp value were derived from
U.S. EPA (1992) and U.S. EPA (1994b). The most current guidance available for ingestion rates of homegrown
produce is the 1997 Exposure Factors Handbook (U.S. EPA 1997). The default Rvalue of 0.39 was weighted by
relative ingestion rates of homegrown exposed fruit and exposed vegetables found in U.S. EPA (1997).

Uncertainties associated with this variable include the following:

(1) The empirical relationship developed by Chamberlain (1970) on the basis of a study of pasture grass may
not accurately represent aboveground produce.
(2) The empirical constants developed by Baes, Sharp, Sjoreen, and Shor (1984) for use in the empirical
relationship developed by Chamberlain (1970) may not accurately represent site-specific mixes of
aboveground produce.
B-77
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TABLE B-2-7
ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page4ofl2)
Variable
Description
Units
Value
Fw
Fraction of COPC wet deposition
that adheres to plant surfaces
unitless
0.2 for anicms
0.6 for cations and most organics
U.S. EPA OSW recommends using the chemical class-specific values of 0.2 for anions and 0.6 for cations and most
organics and estimated by U.S. EPA (1994b) and U.S. EPA (1995). These values are the best available information,
based on a review of the current scientific literature, with the following exception: U.S. EPA OSW recommends
using an Fw value of 0.2 for the three organic COPCs that ionize to anionic forms. These include (1) 4-chloroaniline,
(2) n-nitrosodiphenylamine, and (3) n-nitrosodi-n-proplyamine (see Appendix A-3).

The values estimated by U.S. EPA (1994b) and U.S. EPA (1995) are based on information presented in Hoffman,
Thiessen, Frank, and Blaylock (1992), which presented values for a parameter (r) termed the "interception fraction."
These values were based on a study in which soluble radionuclides and insoluble particles labeled with radionuclides
were deposited onto pasture grass via simulated rain. The parameter (r) is defined as "the fraction of material in rain
intercepted by vegetation and initially retained" or, essentially, the product of Rp and Fw, as defined:

r = Rp • Fw

The r values developed by Hoffinan, Thiessen, Frank, and Blaylock (1992) were divided by an Rp value of 0.5 for
forage (U.S. EPA 1994b). The Fw values developed by U.S. EPA (1994b) are 0.2 for anions and 0.6 for cations and
insoluble particles. U.S. EPA (1994b) and U.S. EPA (1995) recommends using the Fw value calculated by using the
r value for insoluble particles to represent organic compounds; however, no rationale for this recommendation is
provided.

Interception values (r)—as defined by Hoffinan, Thiessen, Frank, and Blaylock (1992)—have not been
experimentally determined for aboveground produce. Therefore, U.S. EPA (1994b) and U.S. EPA (1995) apparently
defaulted and assumed mat the Fw values calculated for pasture grass (similar to forage) also apply to aboveground
produce. The rationale for this recommendation is not provided.
Uncertainties associated with this variable include the following:

(1)

(2)
Values ofr developed experimentally for pasture grass may not accurately represent aboveground
produce-specific r values.
Values ofr assumed for most organic compounds, based on the behavior of insoluble polystryene
microspheres tagged with radionuclides, may not accurately represent the behavior of organic compounds
under site-specific conditions.
Dywp
Unitized yearly wet deposition in
particle phase
s/m2-yr
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are site-specific.
B-78
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TABLE B-2-7
ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 5 of 12)
Variable
Units
Value
.Plant surface loss coefficient
yr-1
18
U.S. EPA OSW recommends the kp value of 18 recommended by U.S. EPA (1993) and U.S. EPA (1994b). The kp
value selected is the midpoint of a possible range of values (7.44 to 90.36). U.S. EPA (1990) identified several
processes—including wind removal, water removal, and growth dilution—that reduce the amount of COPC that has
been deposited on a plant surface. The term kp is a measure of the amount of contaminant lost to these physical
processes over time. U.S. EPA (1990) cites Miller and Hoffman (1983) for the following equation used to estimate
kp:
kp = (In 2 / tla) • 365 days/yr
where
t1/2 = half-time (days)
Miller and Hoffinan (1983) report half-time values ranging from 2.8 to 34 days for a variety of COPCs on herbaceous
vegetation. These half-time values result in kp values of 7.44 to 90.36 (yr'1). U.S. EPA (1993) and U.S. EPA (1994b)
recommend a kp value of 18, based on a generic 14-day half-time, corresponding to physical processes only. The
14-day half-time is approximately the midpoint of the range (2.8 to 34 days) estimated by Miller and Hoffman (1983).

Uncertainties associated with this variable include the following:

(1) Calculation of kp does not consider chemical degradation processes. The addition of chemical degradation
processes would decrease half-times and thereby increase kp values; plant concentration decreases as kp
increases. Therefore, use of a kp value that does not consider chemical degradation processes is
conservative.
(2) The half-time values reported by Miller and Hoffinan (1983) may not accurately represent the behavior of
compounds on aboveground produce.
(3) Based on this range (7.44 to 90.36), plant concentrations could range from about 1.8 times higher to about 5
times lower than the plant concentrations, based on a kp value of 18.
B-79
-------
r
TABLE B-2-7

ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 6 of 12)
Variable
Description
Unit!
Value
Tp Length of plant exposure to
deposition per harvest of edible
portion of plant
yr
0.164
U.S. EPA OSW recommends using a Tp value of 0.164 years; this is consistent with U.S. EPA (1990), U.S. EPA
(1993), U.S. EPA (1994b), and NC DEHNR (1997), which recommended treating Tp as a constant, based on the
average period between successive hay harvests. Belcher and Travis (1989) estimated this period at 60 days. Tp is
calculated as follows:
60 days *. 365 days/year

The following uncertainty is associated with this variable:
0.164 years
The average period between successive hay harvests (60 days) may not reflect the length of the growing
season or the length between successive harvests for site-specific aboveground produce crops. Pd will be
(1) underestimated if the site-specific value of Tp is less than 60 days, or (2) overestimated if the
site-specific value of Tp is more than 60 days.
B-80
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TABLE B-2-7
ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 7 of 12)
Variable
Description
Value
Yp Yield or standing crop biomass of
the edible portion of the plant
(productivity)
kgDW/m2
Aboveground Produce: 2.24
U.S. EPA OSW recommends using the Yp value of 2.24. Based on a review of the available literature, this value
appears to be representative of the most complete and thorough information.

U.S. EPA (1990) states that the best estimate of Yp is productivity. Baes, Sharp, Sjoreen, and Shor (1984) and Shor,
Baes, and Sharp (1982) define Yp as follows as:
where
Yh,
Ah,
Yp =
= Harvest yield of ith crop (kg DW)
= Area planted to ith crop (m )
U.S. EPA (1994a) and NC DEHNR (1997) recommended using this equation. Class-specific Yp values were
estimated by using average U.S. values for Yh and Ah for a variety of fruits and vegetables for 1993 (USDA 1994a
and USDA 1994b). Yh values were converted to dry weight by using average conversion factors for fruits, fruiting
vegetables, legumes, and leafy vegetables (Baes, Sharp, Sjoreen, and Shor 1984).

Class-specific Yp values were grouped to reflect exposed fruits or exposed vegetables. Exposed fruit and exposed
vegetable Yp values were then weighted by relative ingestion rates derived from the homegrown produce tables in
U.S. EPA (1997). The average ingestion-weighted Yp value was 2.24. U.S. EPA (1994b) and U.S. EPA (1995)
recommend a Yp value of 1.6; however, the produce classes and relative ingestion rates used to derive this Yp value
are inconsistent with U.S. EPA (1997).

The following uncertainty is associated with this variable:

The harvest yield (Yh) and area planted (Ah) may not reflect site-specific conditions. This may under- or
overestimate Yp.
B-81
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TABLE B-2-7

ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 8 of 12)
REFERENCES AND DISCUSSION

Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radiomclides through Agriculture.
ORNL-5786. Oak Ridge National Laboratory. Oak Ridge, Tennessee. September.

This document proposed using the same empirical relationship developed by Chamberlain (1970) for other vegetation classes. Class-specific estimates of the empirical constant, y, were
developed by forcing an exponential regression equation through several points, including average and theoretical maximum estimates of Rp and Yp.

The class-specific empirical constants developed are as follows:

Exposed produce — 0.0324
Leafy vegetables — 0.0846
Silage — 0.769

Belcher, G.D., and C.C. Travis. 1989. "Modeling Support for the RURA and Municipal Waste Combustion Projects: Final Report on Sensitivity and Uncertainty Analysis for the Terrestrial Food
Chain Model." Interagency Agreement No. 1824-A020-A1, Office of Risk Analysis, Health and Safety Research Division, Oak Ridge National Laboratory. Oak Ridge, Tennessee.
October.

This document recommends Tp values based on the average period between successive hay harvests and successive grazing.

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Pages 361-367. November 4.

This document is cited by U.S. EPA (1994a) and NC DEHNR (1997) as the source of the following equations for calculating Fr For discussion, see References and Discussion,
Table B-l-1.

Chamberlain, A.C. 1970. "Interception and Retention of Radioactive Aerosols by Vegetation." Atmospheric Environment. 4:57 to 78.

Experimental studies of pasture grasses identified a correlation between initial Rp values and productivity (standing crop biomass [Yp]):

Rp = l-e-frP

where

y = Empirical constant; range provided as 2.3 to 3.3
Yp = Yield or standing crop biomass (productivity) (kg DW/m2)

Hoffman, P.O., K.M. Thiessen, M.L. Frank, and B.G. Blaylock. 1992. "Quantification of the Interception and Initial Retention of Radioactive Contaminants Deposited on Pasture Grass by
Simulated Rain." Atmospheric Environment. Vol. 26A. 18:3313 to 3321.
B-82
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TABLE B-2-7

ABOVEGROUND PRODUCE CONCENTRATION DUE TO DDIECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 9 of 12)

This document developed values for a parameter (r) that it termed "interception fraction," based on a study in which soluble gamma-emitting radionuclides and insoluble particles tagged
with gamma-emitting radionuclides were deposited onto pasture grass (specifically, a combination of fescues, clover, and old field vegetation, including fescue) via simulated rain. The
parameter, r, is defined as "the fraction of material in rain intercepted by vegetation and initially retained" or, essentially, the product ofRp and Fw, as defined for the HHRAP:
r = Rp • Fw
Experimental r values obtained include the following:
• A range of 0.006 to 0.3 for anions (based on the soluble radionuclide iodide-131 [I3II]); when calculating Rp values for anions, U.S. EPA (1994a) used the highest geometric
mean r value (0.08) observed in the study.
• A range of 0.1 to 0.6 for cations (based on the soluble radionuclide beryllium-7 [7Be]; when calculating^? values for cations, U.S. EPA (1994a) used the highest geometric
mean r value (0.28) observed in the study.
• A geometric range of values from 0.30 to 0.37 for insoluble polystyrene microspheres (IPM) ranging in diameter from 3 to 25 micrometers, labeled with cerium-141 [MICe],
f'NJb, and strontium-85 85Sr; when calculating Rp values for organics (other than three organics that ionize to anionic forms: 4-chloroaniline, n-nitrosodiphenylamine, and
n-nitrosodi-n-propylamine [see Appendix A-3]), U.S. EPA (1994a) used the geometric mean r value for IPM with a diameter of 3 micrometers; however, no rationale for this
selection was provided.

The authors concluded that, for the soluble I31I anion, interception fraction r is an inverse function of rain amount, whereas for the soluble cation 'Be and the IPMs, r depends more on
biomass than on amount of rainfall. The authors also concluded that (1) the anionic 13II is essentially removed with the water after the vegetation surface has become saturated, and
(2) the cationic 7Be and the IPMs are adsorbed to or settle out onto the plant surface. This discrepancy between the behavior of the anionic and cationic species is consistent with a
negative charge on the plant surface.

As summarized in U.S. EPA (1994a), this document is the source of the recommended Fv value of 0.27 for dioxins (polychlorinated dibenzodioxins/polychlorinated dibenzofurans
[PCDD/PCDF]). This value is intended to represent 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) equivalents (TEQ) by weighting all dioxin and furan congeners with nonzero
toxicity equivalency factors (TEF). U.S. EPA is investigating the appropriateness of the use of recommended Fv value for PCDD/PCDFs.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

Miller, C.W. and P.O. Hoffman. 1983. "An Examination of the Environmental Half-Time for Radionuclides Deposited on Vegetation." Health Physics. 45 (3): 731 to 744.

This document is the source of the equation used to calculate kp:

kp = (ln2////2) • 365 days/year

where

ti/2 = half-time (days)

The study reports half-time values ranging from 2.8 to 34 days for a variety of COPCs on herbaceous vegetation. These half-time values result in calculate lip values from 7.44 to
B-83
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TABLE B-2-7

ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 10 of 12)
NCOEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units, January.

This is one of the source documents for the equation in Table B-2-7.

Shor, R.W., C.F. Baes, and R.D. Sharp. 1982. Agricultural Production in the United States by County: A Compilation of Information from the 1974 Census of Agriculture for Use in Terrestrial
Food-Chain Transport and Assessment Models. Oak Ridge National Laboratory Publication. ORNL-5786.

This document is the source of the equation used to calculate Yp:

Yp ~ P, = Yh/Ah,
where
P, = productivity of «th crop (kilogram dry weight [kg DW]/square meter [m2])
Yh, = harvest yield of ith crop (kg DW)
Ah, = area planted to crop / (m^)

using the following information:

Produce Category

Exposed Fruits
Exposed Vegetables
Leafy Vegetables
Fruiting Vegetables

The use of the empirical relationship developed by Baes, Sharp, Sjoreen, and Shor (1984) to estimate Rp based on Yp requires that Yp term to be in whole-weight units. However, in Equation B-2-
7, the Yp term should be in dry-weight units.

For exposed vegetables, Rp was derived from a weighted average of leafy vegetable and fruiting vegetable Rp values. This weighted average was based on whole-weight Yp values for
leafy and fruiting vegetables. In addition, the exposed vegetable Yp value, both whole- and dry-weight, was derived by the following:
Empirical
Constant
(unitless)
0.0324
-
0.0846
0.0324
Rp
(unitless)
0.053
0.982
0.215
0.996
Yp
(kgDW/m2-)
0.252
5.660
0.246
10.52
Yp
(keWW/nrt
1.68
89.4
2.86
167
Intake
(g/kg-dav)
0.19
0.11
-
—
"Exposed Vegetables
j^fy Vegetables
Vegetables
,,
Vegetables ^"Frmfmg Vegetables
B-84
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TABLE B-2-7
ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)
(Page 11 of 12)
The following produce items were included in each category:
Exposed Fruits—apple, apricot, berry, cherry, cranberry, grape, peach, pear, plum/prune, strawberry
Exposed Vegetables—asparagus, cucumber, eggplant, sweet pepper, tomato, snap beans, broccoli, brussel sprouts, cauliflower, celery, lettuce, and spinach

The ingestion rates for exposed fruits and exposed vegetables were based on U.S. EPA (1997), homegrown intake rates.

However, U.S. EPA has reviewed Baes, Sharp, Sjoreen, and Shor (1984), which also presents and discusses this equation.

U.S. Department of Agriculture (USDA). 1994a. Vegetables 1993 Summary. National Agricultural Statistics Service, Agricultural Statistics Board. Washington, D.C. Vg 1-2 (94).

USDA. 1994b. Noncitnis Fruits and Nuts 1993 Summary. National Agricultural Statistics Service, Agricultural Statistics Board, Washington, D.C. FrNt 1-3 (94).

One of the sources of Yh (harvest yield) and Ah (area planted for harvest) values for fruits, fruiting vegetables, legumes, and leafy vegetables used to calculate Yp (yield or standing crop
biomass). Yh values were converted (for use in the equations) to dry weight by using average conversion factors for these same aboveground produce classes, as presented in Baes, Sharp,
Sjoreen, and Shor (1984). The fruits and vegetables considered in each category are as follows:

Exposed fruits—apple, apricot, berry, cherry, cranberry, grape, peach, pear, plum/prune.and strawberry
Exposed vegetables—asparagus, cucumber, eggplant, sweet pepper, tomato, snap beans, broccoli, brussel sprouts, cauliflower, celery, lettuce, and spinach

This is one of the source documents for the equation in Table B-2-7. This document also states that the best estimate of Yp (yield or standing crop biomass) is productivity, as defined
under Shor, Baes, and Sharp (1982).

U.S. EPA. 1992. Technical Support Documentfor Land Application ofSewage Sftwfee, Volumes I and II. Office of Water. Washington, D.C. EPA 822/R-93-001a.

This document is the source of ingestion rates (g DW/day) for aboveground produce classes—fruiting vegetables (4.2), leafy vegetables (2.0), and legumes (8.8)—used to calculate Rp
and Yp.

This is one of the source documents for the equation in Table B-2-7.

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-Specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This is the source of ingestion rate for fruits, based on whole weight (88 g/day) and converted to dry weight by using an average whole-weight to dry-weight conversion factor for fruits
(excluding plums/prunes, which had an extreme value) of 0.15 taken from Baes, Sharp, Sjoreen, and Shor (1984), used to calculate Rp and Yp.

B-85
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TABLE B-2-7

ABOVEGROUND PRODUCE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 12 of 12)

This is one of the source documents for the equation in Table B-2-7.

This document also recommended weighted average Rp and Yp values of 0.05 and 1.6, respectively, based on the empirical relationships identified by Chamberlain (1970) and Shor,
Baes, and Sharp (1982).
Rp
7 - e-
where
y = Empirical constant; range provided as 2.3 to 3.3
Yp = Standing crop biomass (productivity) (kg DW/m2)

and Shor, Baes, and Sharp (1982):

Yp = Yh,/Ah,

where

Yht = Harvest yield of flh crop (kgDW)
Aht = Area planted to crop / (m2)

U.S.EPA. 1995. Review Draft Development of Human Health-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project Volumes I and II. Office of Solid
Waste. March 3.

This is one of the source documents for the equation in Table B-2-7.

U.S.EPA. 1997. Exposure Factors Handbook. Office of Research and Development. EPA/600/P-95/002F. August.

This document is the source of relative ingestion rates.
B-86
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TABLE B-2-8

ABOVEGROUND PRODUCE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page! of 6)
Description

This equation calculates the COPC concentration in aboveground produce resulting from wet and dry deposition of COPCs onto plant surfaces.

The limitations and uncertainty introduced in calculating this value include the following:

(1)
(2)
The range of values for the variable Bv (air-to-plant biotransfer factor) is about 19 orders of magnitude for organic COPCs (this range may change on the basis of the tables in
Appendix A-3). COPC-specific Bv values for nondioxin-like compounds may be overestimated by up to one order of magnitude, based on experimental conditions used to develop the
algorithm used to estimate Bv values.
The algorithm used to calculate values for the variable Fv assumes a default value for the parameter ST (Whitby's average surface area of participates [aerosols]) of background plus
local sources, rather than an ST value for urban sources. If a specific site is located in an urban area, the use of the latter ST value may be more appropriate. The ST value for urban
sources is about one order of magnitude greater than that for background plus local sources and would result in a lower Fv value; however, the Fv value is likely to be only a few
percent lower.
As highlighted by uncertainties described above, Pv is most affected by the value calculated for Bv.
B-87
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TABLE B-2-8
ABOVEGROUND PRODUCE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 6)
Equation
Cyv • Bva •
= Q . F . _£ °JL
For mercury modeling
Pv = (0.480 '
Cw • Bv ' VG
^ ag - -
Pa
Use 0.48Q for total mercury and Fv = 0.85 in the mercury modeling equation to calculate Pv. The calculated Pv value is apportioned into the divalent mercury (Hg24) and methyl mercury
(MHg) forms based on the 78% Hg2* and 22% MHg speciation split in abovegroundproduce.
0.78 Pv
Pi>(Mhg) = 0.22 Pv

Evaluate divalent and methyl mercury as individual COPCs. Calculate Pv for divalent and methyl mercury using the corresponding values.
Variable
Descrintion
Pv
Concentration of COPC in
aboveground produce due to air-to-
plant transfer
jigCOPC/gDW
(equivalent to
mg COPC/kg
DW)
COPC-specific emission rate
g/s
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling. See Chapters 2 and 3 of the
HHRAP for guidance regarding the calculation of this variable. Uncertainties associated with this variable are
site-specific.
B-88
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TABLE B-2-8
ABOVEGROUND PRODUCE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 off 6)
Variable
Description
Units
Value
Fraction of COPC air concentration
in vapor phase
unitless
Otol
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values is presented in
Appendix A-3. This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA
(1994b) and NC DEHNR (1997).

Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fv = 0 for all metals (except mercury).

The following uncertainties are associated with this variable:

(1) It is based on the assumption of a default ST value for background plus local sources, rather than an ST value for
urban sources. If a specific site is located in an urban area, the use of the latter SV value may be
more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than that
for background plus local sources, and it would result in a lower calculated F, value; however, the F, value
is likely to be only a few percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant) is
constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from
the particle surface and the heat of vaporization of the liquid phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value
of c is used to calculate F...
Cyv
Unitized yearly average air
concentration from vapor phase
ug-s/g-m3
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are site-specific.
Bvm
COPC air-to-plant biotransfer
factor for aboveground produce
unitless

([mgCOPC/g
DW plant]/[(mg
COPC/g air])
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

Uncertainty associated with this variable include the following:

(1) The studies that formed the basis of the algorithm used to estimate Bv values were conducted on azalea leaves
and grasses, and may not accurately represent Bv for aboveground produce other than leafy vegetables.
B-89
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I
TABLE B-2-8
ABOVEGROUND PRODUCE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of 6)
Variable
Description
Units
Value
VGm Empirical correction factor for
aboveground produce
unitless
0.01 or 1.0
U.S. EPA OSW recommends that a VG^ value of 0.01 for COPCs with a log K^ greater than 4 and a value of 1.0 for
COPCs with a log K,,w less than 4.

This variable is an empirical correction factor that reduces aboveground produce concentration. The equation in this
table was developed to estimate the transfer of COPCs into leafy vegetation rather than into bulkier aboveground
produce, such as apples. Because of the protective outer skin, size, and shape of bulky produce, transfer of lipophilic
COPCs (log K,,w greater than 4) to the center of the produce is not likely. In addition, typical preparation techniques,
such as washing, peeling, and cooking, will further reduce residues.

U.S. EPA (1994b) recommended a value of 0.01, based on U.S. EPA (1994a), but made no distinction between fruits,
vegetables, and leafy vegetation. NC DEHNR (1997), also citing U.S. EPA (1994a), recommends values of (1) 0.01 for
fruits and fruiting vegetables, and (2) 1.0 for leafy vegetables. The values cited from U.S. EPA (1994a) are also based
on information from Riederer (1990) and Wipf, Homberger, Neuner, Ranalder, Vetter, and Vuilleumier (1982).

Uncertainties associated with this variable include the following:

(1) U.S. EPA (1994a) assumes an insignificant translocation of compounds deposited on the surface of
aboveground vegetation to inner parts of aboveground produce. This may underestimate Pv.
(2) U.S. EPA (1994a) assumes that die density of the skin and the whole vegetable are equal. This may
overestimate Pv.
(3) U.S. EPA (1994a) assumes that the thickness of vegetable skin and broadleaf tree skin are equal. The effect of
this assumption of Pv is unknown.
Pa
Density of air
g/m3
1200.0
U.S. EPA OSW recommends the use of this value based on Weast (1986). This reference indicates that air density varies
with temperature. The density of air at both 20°C and 25°C (rounded to two significant figures) is 1.2 x 10+3.

U.S. EPA (1990) also recommends this value, but states that is was based on a temperature of 25°C. U.S. EPA (1994b)
andNC DEHNR (1997) recommend this same value but state that it was calculated at standard conditions (20°C and 1
atmosphere). Both documents cite Weast (1981).
B-90
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TABLE B-2-8

ABOVEGROUND PRODUCE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

For discussion, see References and Discussion in Table B-l-1.

This is the reference for the statement that the equation used to calculate the fraction of air concentration in vapor phase (Fv) assumes that the variable c (the Junge constant) is constant
for all chemicals. However, this reference notes that the value of c depends on the chemical (sorbate) molecular weight, the surface concentration for monolayer coverage, and the difference
between the heat of desorption from the particle surface and the heat of vaporization of the liquid-phase sorbate.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is one of the source documents for the equation in Table B-2-8. This document also recommends that (1) Fv values be based on the work of Bidleman (1988), and (2) an empirical
correction factor (VGas) be used to reduce concentrations of COPCs in specific vegetation types—specifically, a VGag value of 0.5 is recommended for silage. However, no rationale is
provided for this value. This factor is used to reduce estimated COPC concentrations in specific vegetation types, because (l)5v was developed for azalea leaves, and (2) it is assumed
that there is insignificant translocation of compounds deposited on the surface of some vegetation types to the inner parts of this vegetation because of the lipophilicity of the COPC.

Riederer, M. 1990. "Estimating Partitioning and Transport of Organic Chemicals in the Foliage/Atmosphere System: Discussion of a Fugacity-Based Model." Environmental Science and
Technology. 24: 829 to 837.

This is the source of the leaf thickness estimate used to estimate the empirical correction factor (VGag).

This document is a source of air density values.

Based on attempts to model background concentrations of dioxin-like compounds in beef on the basis of known air concentrations, this document recommends reducing, by a factor of 10,
Bv values calculated by using the Bacci, Cerejeira, Gaggi, Chemello, Calamari, and Vighi (1992) algorithm The use of this factor "made predictions [of beef concentrations] come in line
with observations."

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume II: Properties, Sources, Occurrence, and Background Exposures. External Review Draft. Office of Research and
Development. Washington, DC. EPA/600/6-88/005CC. June.
B-91
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TABLE B-2-8

ABOVEGROUND PRODUCE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 6 of 6)
This document recommends an empirical correction factor of 0.01 to reduce estimated vegetable concentrations on the basis of the assumption that there is insignificant translocation of
compounds deposited on the surface of aboveground vegetation to inner parts for aboveground produce. The document provides no reference or discussion regarding the validity of this
assumption.

The factor of 0.01 is based on a similar correction factor for belowground produce (VG^, which is estimated on the basis of a ratio of the vegetable skin mass to vegetable total mass.
The document assumes that the densities of the skin and vegetable are equal. The document also assumes an average vegetable skin leaf that is based on Rierderer (1990). Based on
these assumptions, U.S. EPA (1994a) calculated YGbg for carrots and potatoes of 0.09 and 0.03, respectively. By comparing these values to contamination reduction research completed
by Wipf, Homberger, Neuner, Ranalder, Vetter, and Vuilleumier (1982), U.S. EPA (1994a) arrived at the recommended VG^ value of 0.01.

This is one of the source documents for the equation in Table B-2-8. This document also presents a range (0.27 to 1) of Fv values for organic COPCs, based on the work of Bidleman
(1988); Fv for all inorganics is set equal to zero.

U.S.EPA. 1995. Review Draft Development of Human Health-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and II Officeof Solid
Waste. March 3.

U.S.EPA. 1997. Mercury Study Report to Congress. Volume HI: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development EPA 452/R-97-005. December.

Weast,R.C. 1981. Handbook of 'Chemistry and Physics. 62nd Edition. Cleveland, Ohio. CRC Press.

This document is a reference for air density values.

Weast,R.C. 1986. Handbook of Chemistry and Physics. 66th Edition. Cleveland, Ohio. CRC Press.

This document is a reference for air density values, and is an update of Weast (1981).

Wipf, H.K., E. Homberger, N. Neuner, U.B. Ranalder, W. Vetter, and J.P. Vuilleumier. 1982. "TCDD Levels in Soil and Plant Samples from the Seveso Area." In: Chlorinated Dioxins and
Related Compounds: Impact on the Environment. Eds. Hutzinger, O. et al. Pergamon, NY.
B-92
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TABLE B-2-9
ABOVEGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the COPC concentration in aboveground produce due to direct uptake of COPCs from soil through plant roots. The limitations and uncertainty introduced in calculating
this value include the following:

(1) The availability of site-specific information, such as meteorological data, will affect the accuracy of Cs estimates.
(2) Estimated COPC-specific soil-to-plant bioconcentration factors (Br) do not reflect site-specific conditions. This may be especially true for inorganic COPCs for which estimates of Br
would be more accurately estimated by using site-specific BCFs rather than BCFs presented in Baes, Sharp, Sjoreen, and Shor (1984). Hence, U.S. EPA OSW recommends the use of
plant uptake response slope factors derived in U.S. EPA (1992) for arsenic, cadmium, selenium, nickel, and zinc. ___^^_
Equation
Br
ag
For mercury modeling, aboveground produce concentration due to root uptake is calculated using the respective Cs and Br values for divalent mercury (Kg2*) and methyl mercury (MHg).
Pr
rr
ag(MHg)
Rr
Dr
ag(MHg)
Variable
Prm
Concentration of COPC in
aboveground produce due to root
uptake
mgCOPC/kgDW
Average soil concentration over
exposure duration
mg COPC/kg soil
Varies
This value is COPC-and site-specific and should be calculated using the equation in Table B-2-1. Uncertainties
associated with this variable are site-specific.
B-93
-------
r
TABLE B-2-9

ABOVEGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 2 of 4)
Variable
JP
-------
TABLE B-2-9

ABOVEGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 3 of 4)

REFERENCES AND DISCUSSION

Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionudides through Agriculture.
ORNL-5786. Oak Ridge National Laboratory. Oak Ridge, Tennessee. September.

Element-specific bioconcentration factors (BCF) were developed by Baes, Sharp, Sjoreen, and Shor (1984)—for both vegetative (stems and leaves) portions of food crops (Bv) and
nonvegetative (reproductive—fruits, seeds, and tubers) portions of food crops (Br)—on the basis of a review and compilation of a wide variety of measured, empirical, and comparative
data. Inorganic-specific Br values were calculated as a weighted average of vegetative (Bv) and reproductive (Br) BCFs. U.S. EPA recommends that inorganic-specific Br values be
calculated as a weighted average of vegetative and reproductive BCFs. Relative ingestion rates determined from U.S. EPA (1997a) are 75 percent reproductive and 25 percent vegetative
for homegrown produce. However, for exposed fruits only the reproductive BCFs should be used.

NCDEHNR. 1997. NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is one of the source documents for the equation in Table B-2-9.

Travis, C.C. and A.D. Arms. 1988. "Bioconcentration of Organics in Beef, Milk, and Vegetation." Environmental Science and Technology. 22:271 to 274.

Based on paired soil and plant concentration data for 29 organic compounds, this document developed a regression equation relating soil-to-plant5CF (Br) to K^;

log Br= 1.588- 0.578 logKm

This is one of the source documents for the equation in Table B-2-9.

U.S. EPA. 1992. Technical Support Document for Land Application of Sewage Sludge, Volumes I and II. Office of Water. Washington, D.C. EPA 822/R-93-00 la.

Source of plant uptake response factors for arsenic, cadmium, nickel, selenium, and zinc. Plant uptake response factors are converted to BCFs by multiplying the plant uptake response
factor by 2.

U.S. EPA. 1994. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-Specific Assessment Procedures. External Review Draft. Office of Research and Development. Washington,
D.C. EPA/600/6-88/005Cc. June.

This is the source for ingestion rate for fruits, based on whole weight (88 g/day), and converted to dry weight by using an average whole-weight to dry-weight conversion factor for fruits
(excluding plums/prunes, which had an extreme value) of 0.15 from Baes, Sharp, Sjoreen, and Shor (1984)—used to calculate Br.

U.S. EPA. 1995. Review Draft Development of'Human Health-BasedandEcologically-BasedExit Criteria for the Hazardous Waste Identification Project. Volumes I and II. Office of Solid
Waste. March 3.
B-95
-------
TABLE B-2-9

ABOVEGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ABOVEGROUND PRODUCE EQUATIONS)

(Page 4 of4)

This document recommends using the BCFs, Bv, and Br from Baes, Sharp, Sjoreen, and Shor (1984) for calculating the uptake of inorganics into vegetative growth (stems and leaves) and
nonvegetative growth (fruits, seeds, and tubers), respectively.

Although most BCFs used in this document come from Baes, Sharp, Sjoreen, and Shor (1984), values for some inorganics were apparently obtained from plant uptake response slope
factors. These uptake response slope factors derived from U.S. EPA (1992).

U.S. EPA. 1997a. Exposure Factors Handbook. Office of Research and Development. EPA/600/P-95/002F. August.

This document is the source for relative intake rate split of 75 percent reproductive and 25 percent vegetative for homegrown produce.

U.S. EPA. 1997b. Mercury Study Report to Congress. Volume HI: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-96
-------
TABLE B-2-10
BELOWGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF BELOWGROUND PRODUCE EQUATIONS)

(Page 1 of 6)
Description
This equation calculates the COPC concentration in belowground vegetation due to direct uptake of COPCs from soil. The limitations and uncertainty introduced in calculating this value
include the following:

(1) The availability of site-specific information, such as meteorological data, will affect the accuracy of Cs estimates.
(2) Estimated COPC-specific soil-to-plant biotransfer factors (Br) not reflect site-specific conditions. This may be especially true for inorganic COPCs for which estimates of Br would be
more accurately estimated by using site-specific BCFs from Baes, Sharp, Sjoreen, and Shor (1984). Hence, for arsenic, cadmium, selenium, nickel, and zinc, U.S. EPA OSW
recommends the use of plant uptake response slope factors derived from U.S. EPA (1992).
Brrootveg • VGrootveg
Br
rootveg
RCF
Kd
For mercury modeling, belowground produce concentration due to root uptake is calculated using the respective Cs and Br values for divalent mercury (Hg24) and methyl mercury (MHg).
Variable
Description
Pr,,,
Cs
Concentration of COPC in
belowground produce due to root
uptake
Average soil concentration over
exposure duration
mg COPC/kg soil
Varies
This value is COPC-and site-specific and should be calculated using the equation in Table B-2-1. Uncertainties
associated with this variable are site-specific.
B-97
-------
r
TABLE B-2-1Q

BELOWGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF BELOWGROUND PRODUCE EQUATIONS)

(Page 2 of 6)
Variable
Description
Units
Value
Br,
Plant-soil bioconcentration factor
for belowground produce
unitless

([mgCOPC/kg
plant DW]/[mg
COPC/
kg soil])
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

Uncertainties associated with this variable include the following:

(1) Estimates of Br for some inorganic COPCs, based on plant uptake response slope factors, may be more
accurate than those based on BCFs from Baes, Sharp, Sjoreen, and Shor (1984).
(2) U.S. EPA OSW recommends that uptake of organic COPCs from soil and the transport of COPCs to
belowground produce be calculated on the basis of a regression equation developed by Briggs et al (1982).
This regression equation may not accurately represent the behavior of all classes of organic COPCs under
site-specific conditions.
B-98
-------
TABLE B-2-10
BELOWGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF BELOWGROUND PRODUCE EQUATIONS)

(Page 3 of 6)
Variable
Description ,'.
Unite
Value
VG,
rootveg
Empirical correction factor for
belowground produce
unitless
0.01 or 1.0
U.S. EPA OSW recommends that a VGrooneg value of 0.01 be used for COPCs with a log Km greater than 4 and that a
VGnaMg value of 1.0 be used for COPCS with a log K^ less than 4.

This variable is an empirical correction factor that reduces produce concentration. Because of the protective outer
skin, size, and shape of bulky produce, transfer of lipophilic COPCs (log Km greater than 4) to the center of the
produce is not likely. In addition, typical preparation techniques, such as washing, peeling, and cooking, will further
reduce residues.

U.S. EPA (1994) recommended a VGromeg value of 0.01 for lipophilic COPCs (log Km greater than 4) to reduce
estimated belowground produce concentrations. This estimate for unspecified vegetables is based on:
VG.
rootveg
where

M«*i = Mass of thin (skin) layer of an below ground vegetable (g)
MvegaMc = Mass of entire vegetable (g)

If it is assumed that the density of the skin and the whole vegetable are the same, this equation can become a ratio of
the volume of the skin to that of the whole vegetable. With this assumption, U.S. EPA (1994) calculated VGroot,eg
values of 0.09 and 0.03 for carrots and potatoes, respectively. U.S. EPA (1994) identified other processes, such as
peeling, cooking, and cleaning, that will further reduce the vegetable concentration. Because of these other processes,
U.S. EPA recommended a VGrooHeg value of 0.01 for lipophilic COPCs.

The following uncertainty is associated with this variable:

U.S. EPA (1994) assumes that the density of the skin and the whole vegetable are equal. This may
overestimate Pr. However, based on the limited range of VGroatnig (compared to Br), it appears that in most
cases, these uncertainties will have a limited impact on the calculation ofPr and, ultimately, risk.
B-99
-------
TABLE B-2-10
BELOWGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF BELOWGROUND PRODUCE EQUATIONS)

(Page 4 of6)
Variable
Kd,
Description
Soil-water partition coefficient
Units
cm3 water/g soil
Value
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.
The following uncertainty is associated with this variable:
Uncertainties associated with this parameter will be limited if #4 values are calculated as described in
Appendix A-3.
B-100
-------
TABLE B-2-10

BELOWGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF BELOWGROUND PRODUCE EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionuclides through Agriculture.
ORNL-5786. Oak Ridge National Laboratory. Oak Ridge, Tennessee. September.

For discussion, see References and Discussion in Table B-2-10.

Briggs, G.G., R.H. Bromilow, and A.A. Evans. 1982. Relationships between lipophilicity and root uptake and translocation of non-ionized chemicals by barley. Pesticide Science 13:495-504.

This document presents the relationship between RCFand Km presented in the equation in Table B-2-10..

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is a source document for the equation in Table B-2-10.

Travis, C.C. and A.D. Arms. 1988. "Bioconcentration of Organics in Beef, Milk, and Vegetation." Environmental Science and Technology. 22:271 to 274.

Based on paired soil and plant concentration data for 29 organic compounds, this document developed a regression equation relating soil-to-plantflCF (Br) to Km

log Br = 1.588 - 0.578 log Km

U.S. EPA. 1992. Technical Support Document for Land Application of'Sewage S7«rfgE, Volumes I and II. Office of Water. Washington, D.C. EPA 822/R-93-001a.

Source of plant uptake response factors for arsenic, cadmium, nickel, selenium, and zinc. Plant uptake response factors are converted to BCFs by multiplying the plant uptake response
factor by 2.

This document is a source of COPC-specific Kd, values.

This is a source document for Vgroomg values. • . '

U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and II. Office of Solid
Waste. March 3.

B-101
-------
TABLE B-2-10

BELOWGROUND PRODUCE CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF BELOWGROUND PRODUCE EQUATIONS)

(Page 6 of 6)

Although roost BCFs used in this document come from Baes, Sharp, Sjoreen, and Shor (1984), values for some inorganics were apparently obtained from plant uptake response slope
factors. These uptake response slope factors were calculated from field data, such as metal methodologies. References used to calculate the uptake response slope factors are not clearly
identified.

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 11)
Description

The COPC soil concentration averaged over the exposure duration, represented by Cs, should be used for carcinogenic COPCs, where the risk is averaged over the lifetime of an individual
Because the hazard quotient associated with noncarcinogenic COPCs is based on a reference dose rather than a lifetime exposure, the highest annual average COPC soil concentration occurring
during the exposure duration period should be used for noncarcinogenic COPCs. The highest annual average COPC soil concentration would occur at the end of the time period of combustion
and is represented by Cs,D.

The following uncertainties are associated with this variable:

(1) The time period for deposition of COPCs resulting from hazardous waste combustion is assumed to be a conservative, long-term value. This assumption may overestimate Cs and
Cs,D.
(2) Exposure duration values (T2) are based on historical mobility studies and will not necessarily remain constant. Specifically, mobility studies indicate that most receptors that move
remain in the vicinity of the combustion unit; however, it is impossible to accurately predict the probability that these short-distance moves will influence exposure, based on factors
such as atmospheric transport of pollutants.
(3) The use of a value of zero for T, does not account for exposure that may have occurred from historic operations and emissions from hazardous waste combustion This may
underestimate Cs and Cs,D.
(4) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils and, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs,D.
(5) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate Cs and Cs,D.
B-103
-------
TABLE B-3-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(PageZofll)
Soil Concentration Averaged Over Exposure Duration
Cs
ks
Cs =
Ds
ks-(tD - T,)
Equation for Carcino*gens
h
(-fa (r. - a>))]
(T2 -
(D + exp (- fa • tD )
As
•for T}
-------
TABLE B-3-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 11)
Highest Annual Average Soil Concentration
Equation for Noncarcinogens
Ds • [1 - exp (-ks • tD)]
Jb
where
Ds = 10Q ' Q - [F; (0.31536 • Vdv • Cyv * Dywv) + (Dydp + Dywp) • (1 - F )]
Z/JRD
For mercury modeling
Ds = 100'(0.480 .[Fv (0.31536 • Vdv • Cyv + Dywv) + (Dydp + Dywp) - (1 - Fv)]
Use 0.4Sg for total mercury and Fv = 0.85 in the mercury modeling equation to calculate Ds. The calculated Ds value is apportioned into the divalent mercury (Kg*1) and methyl mercury
(MHg) forms based on the assumed 98% Hg2* and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg°) occurs in very small amounts in the vapor phase and does not
exist in the particle or particle bound phase. Therefore, elemental mercury deposition onto soils is assumed to be negligible or zero. Elemental mercury is evaluated for the direct inhalation
pathway only (Table B-5-1).
£)j(Mhg)
0.98 Ds
0.02 Ds
0.0
Evaluate divalent and methyl mercury as individual COPCs. Calculate Cs for divalent and methyl mercury using the corresponding (1) fate and transport parameters for mercuric chloride
(divalent mercury) and methyl mercury provided in Appendix A-3, and (2) Ds (Hg2*) and Ds (MHg) as calculated above.
Variable
Average soil concentration over
exposure duration
B-105
-------
TABLE B-3-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 11)
Variable
Cs,
'ID
Description
Soil concentration at time tD
Units
mg COPC/kg soil
Value
Ds
Deposition term
tng COPC/kg soil-
Varies
U.S. EPA (1994a) andNC DEHNR (1991) recommend incorporating the use of a deposition term into the Cs equation.

Uncertainties associated with this variable include the following:

(1) Five of the variables in the equation for Ds (Q, Cyv, Dywv, Dywp, and Dydp) are COPC- and site-specific.
Values of these variables are estimated on the basis of modeling. The direction and magnitude of any
uncertainties should not be generalized.
(2) Based on the narrow recommended ranges, uncertainties associated with Vdv, Fn and BD are expected to be
low.
(3) Values for Z, vary by about one order of magnitude. Uncertainty is greatly reduced if it is known whether
soils are tilled or untilled.
tD
Time period over which deposition
occurs (time period of combustion)
100
U.S. EPA (1990a) specifies that this period of time can be represented by periods of 30,60 or 100 years. U.S. EPA
OSW recommends that facilities use the conservative value of 100 years unless site-specific information is available
indicating that this assumption is unreasonable (see Chapter 6 of the HHRAP Protocol).
ks
COPC soil loss constant due to all
processes
yr1
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-3-2. The COPC soil loss
constant is the sum of all COPC removal processes.

Uncertainty associated with this variable includes the following:

COPC-specific values for ksg (one of the variables in the equation in Table B-3-2) are empirically
determined from field studies. No information is available regarding the application of these values to the
site-specific conditions associated with affected facilities.
B-106
-------
TABLE B-3-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of 11)
Variable
Description
Units
Value
Length of exposure duration
6,30, or 40
U.S. EPA OSW recommends the following reasonable maximum exposure (RME) values for T2:
Exposure Duration
Child Resident
Subsistence Farmer Child
Subsistence Fisher Child

Adult Resident and
Subsistence Fisher

Subsistence Farmer
RME
6 years
30 years
(6 child and 24 adult)

40 years
Reference
U.S.EPA(1990b)
U.S. EPA (1990b)
U.S. EPA (1994b)
U.S. EPA (1994c) recommended the following unreferenced values:
Exposure Duration
Subsistence Farmer
Adult Resident
Subsistence Fisher
Child Resident
Years
40
30
30
9
Uncertainties associated with this variable include the following:

(1) Exposure duration rates are based on historical mobility rates and may not remain constant. This assumption
may overestimate or underestimate Cs and Cs,D.
(2) Mobility studies indicate that most receptors that move remain in the vicinity of the emission sources;
however, it is impossible to accurately predict the likelihood that these short-distance moves will influence
exposure, based on factors such as atmospheric transport of pollutants. This assumption may overestimate or
underestimate Cs and CslD.
T,
Time period at the beginning of
combustion
0
Consistent with U.S. EPA (1994bc), U.S. EPA QSW recommends a value of 0 for Tj.

The following uncertainty is associated with this variable:

The use of a value of 0 for Tj does not account for exposure that may have occurred from historical operation
or emissions from the combustion of hazardous waste. This may underestimate Cs and Cs,D.
B-107
-------
r
TABLE B-3-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page6ofll)
Variable
700
Description
Units conversion factor
COPC emission rate
Units
mg-cnrVkg-cm2
g/s
Value
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 of the HHRAP for guidance regarding the calculation
of this variable. Uncertainties associated with this variable are site-specific.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Unfilled
Tilled
Depth fern) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990a) does not include a reference for these values.

The following uncertainties are associated with this variable:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled, resulting a greater
mixing depth. This uncertainty may overestimate Cs and Cs,jy.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of
other residues. This uncertainty may underestimate Cs and Cs,D.
BD
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and
clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990a). A range of 0.83 to 1.84 was originally cited
in Hoffman and Baes (1979). U.S. EPA (1994c) recommended a default BD value of 1.5 g/cm3, based on a mean value
for loam soil that was obtained from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also
represents the midpoint of the "relatively narrow range" for.BZ> of 12 to 1.7 g/cm3 (U.S. EPA 1993a).

The following uncertainty is associated with this variable:

The recommended BD value may not accurately represent site-specific soil conditions; and may under- or
overestimate site-specific soil conditions to an unknown degree.
B-108
-------
TABLE B-3-1
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 7 of 11)
Variable
Fv
0.31536
Vdv
Cyv
Description
Fraction of COPC air concentration
in vapor phase
Units conversion factor
Dry deposition velocity
Unitized yearly average air
concentration from vapor phase
Units .
unitless
m-g-s/cm-ug-yr
cm/s
Hg-s/g-m3
, ,./ > Vatae ->",<• <"
Otol
This variable is COPC-specific. Discussion of this variable and COPC-specific values is presented in Appendix A-3.
This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA (1994b) and NC
DEHNR(1997).
Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fv = 0 for all metals (except mercury).
The following uncertainties are associated with this variable:
(1) It is based on the assumption of a default ST value or background plus local sources, rather than an ST
value for urban sources. If a specific site is located in an urban area, the use of the latter Sr value may be
more appropriate. Specifically, the SV value for urban sources is about one order of magnitude greater than
that for background plus local sources, and it would result in a lower calculated Rvalue; however, the Fv
value is likely to be only a few percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant)
is constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from
the particle surface and the heat of vaporization of the liquid-phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value
of c is used to calculate Fv.

3
U.S. EPA (1994c) recommended the use of 3 cm/s for the dry deposition velocity, based on median dry deposition
velocity. for HN03 from an unspecified U.S. EPA database of dry deposition velocities for HN03, ozone, and S02.
HNO3 was considered the most similar to the COPCs recommended for consideration in the HHRAP. The value
should be applicable to any organic COPC with a low Henry's Law Constant
The following uncertainty is associated with this variable:
HN03 may not adequately represent specific COPCs; therefore, the use of a single value may under- or
overestimate estimated soil concentration.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
B-109
-------
TABLE B-3-i
SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 8 of 11)
Variable
Dywv
Dydp
Dywp
Description
Unitized yearly average wet
deposition from vapor phase
Unitized yearly average dry
deposition from particle phase
Unitized yearly average wet
deposition from particle phase
Units
s/m2-yr
s/m2-yr
s/m2-yr
Value
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
B-110
-------
TABLE B-3-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 9 of 11)
REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

Fv = Fraction of chemical air concentration in vapor phase (unitless)
c = Junge constant = 1.7 x 10"04 (atm-cm)
ST = Whitby's average surface area of particulates = 3.5 x 10"06 (cm2/cm3 air) (corresponds to background plus local sources)
P°L = Liquid phase vapor pressure of chemical (atm) (see Appendix A-3)

If the chemical is a solid at ambient temperatures, the solid-phase vapor pressure is converted to a liquid-phase vapor pressure as follows:
r, - ra)
where
r s
AS,
~F
= Solid-phase vapor pressure of chemical (atm) (see Appendix A-3)

= Entropy effusion over the universal gas constant = 6.79 (unitless)

= Melting point of chemical (K) (see Appendix A-3)
= Ambient air temperature = 284 K (11 °C)
Carsel, R.F., R.S. Parrish,.R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology. Vol.
~27Pages 11-24.

B-lli
-------
TABLE B-3-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 10 of 11)
This reference is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value of 1.5 (g soil/cm3 soil) for loam soil

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

This document is cited by U.S. EPA (1990s) for the statement that soil bulk density, BD, Is affected by the soil structure, such as looseness or compaction of the soil, depending on the
water and clay content of the soil.

Hoffman, P.O., and C.F. Baes, 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadiomtclides. ORNL/NOREGTM-882.

This document presents a soil bulk density range, BD, of 0.83 to 1.84.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NC DEHNR. 1997. NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is one of the source documents for the equation in Table B-1-1. This document also recommends the use of (1) a deposition term, Ds, and (2) COPC-specific Fy (fraction of COPC
air concentration in vapor phase) values.

Research Triangle Institute (RTI). 1992. Preliminary Soil Action Level for Super/and Sites. Draft Interim Report. Prepared for U.S. EPA Hazardous Site Control Division, Remedial Operations
Guidance Branch. Arlington, Virginia. EPA Contract 68-W1-0021. Work Assignment No. B-03, Work Assignment Manager Loren Henning. December.

This document is a reference source for COPC-specific Fv (fraction of COPC air concentration in vapor phase) values.

This document is a reference source for the equation in Table B-3-1, and it recommends that (1) the time period over which deposition occurs (time period for combustion ), tD, be
represented by periods of 30,60 and 100 years, and (2) undocumented values for soil mixing zone depth, Zs, for tilled and unfilled soil.

U.S. EPA. 1990b. Exposure Factors Handbook. March.

This document is a reference source for values for length of exposure duration, T2.

U.S. EPA. 1992. Estimating Exposure to Dioxin-Like Compounds. Draft Report. Office of Research and Development. Washington, D.C. EPA/600/6-88/005b.

This document is cited by U.S. EPA (1993a) as the source of values for soil mixing zone depth, Zs, for tilled and untilled soils.

U.S. EPA. 1993a. Addendum to the Methodology for Assessing Health Risks Associatedwith Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November.
B-112
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TABLE B-3-1

SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 11 of 11)
This document is a reference for recommended values for soil mixing zone depth, Zs for tilled and unfilled soils; it cites U.S. EPA (1992) as the source of these values. It also
recommends a "relatively narrow" range for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil).

U.S.EPA. 1993b. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid
Waste. Office of Research and Development. Washington, D.C. September 24.

This document is a reference for the equation in Table B-3-1. It recommends using a deposition term, Ds, and COPC-specific Fv values (fraction of COPC air concentration in vapor
phase) in the Cs equation.

U.S. EPA 1994a. Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. April 15.

This document is a reference for the equation in Table B-3-1; it recommends that the following be used in the Cs equation: (1) a deposition term, Ds, and (2) a default soil bulk density
value of 1.5 g/cm3, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).

U.S.EPA. 1994b. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-Specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document recommends values for length of exposure duration, T2, for the subsistence farmer.

Values for the length of exposure duration, T2
Value of 0 for the time period of the beginning of combustion, T,
Fv values (fraction of COPC air concentration in vapor phase) that range from 0.27 to 1 for organic COPCs
Vdv value (dry deposition velocity) of 3 cm/s (however, no reference is provided for this recommendation)
Default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
Vdv value of 3 cm/s, based on median dry deposition velocity for HNO3 from an unspecified U.S. EPA database of dry deposition velocities for HN03, ozone, and S02. HN03
was considered the most similar to the COPCs recommended for consideration in the HHRAP.

(Page 1 of 4)
Description
This equation calculates the COPC soil loss constant, which accounts for the loss of COPCs from soil by several mechanisms. Uncertainties associated with this equation include the following:

(1) COPC-specific values for ksg are empirically determined from field studies; no information is available regarding the application of these values to the site-specific conditions
associated with affected facilities.
(2) The source of the equations in Tables B-3-3 through B-3-6 has not been identified.
Equation

ks = ksg + kse + ksr + ksl + ksv
Variable
Description
Unite
Value
ks
COPC soil loss constant due to all
processes
yr-'
ksg
COPC soil loss constant due to
biotic and abiotic degradation
yr'
Varies
This variable is COPC-specific and should be determined from the COPC tables in Appendix A-3.

The following uncertainty is associated with this variable:

COPC-specific values for ksg are empirically determined from field studies; no information is available regarding the
application of these values to the site-specific conditions associated with affected facilities.
B-114
-------
TABLE B-3-2
COPC SOIL LOSS CONSTANT
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 4)
Variable
^ -."I Description /
Units
Value
kse
COPC loss constant due to soil
erosion
yr'
0
This variable is COPC- and site-specific, and is further discussed in Table B-3-3. Consistent with U.S. EPA (1994a), U.S. EPA
(1994b) and NC DEHNR (1997), U.S. EPA OSW recommends that the default value assumed for kse is zero because of
contaminated soil eroding onto the site and away from the site.

Uncertainties associated with this variable include the following:

(1) The source of the equation in Table B-3-3 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting a greater mixing
depth. This uncertainty may overestimate kse.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate kse.
ksr
COPC loss constant due to surface
runoff
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-3-4. No reference document is cited
for this equation; the use of this equation is consistent with U.S. EPA (1994b) and NC DEHNR (1997). U.S. EPA (1994a) states
that all ksr values are zero but does not explain the basis of this assumption.

Uncertainties associated with this variable (calculated by using the equation in Table B-3-4) include the following:

(1) The source of the equation in Table B-3-4 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate ksr.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate ksr.
ksl
COPC loss constant due to leaching
yr'
Varies
This variable is COPC- and site-specific, and is calculated by the using equation in Table B-3-5. The use of this equation is
consistent with U.S. EPA (1993) and U.S. EPA (1994b), and NC DEHNR (1997). U.S. EPA (1994a) states that all ksl values are
zero but does not explain the basis of this assumption.

Uncertainties associated with this variable (calculated by using the equation in Table B-3-5) include the following:

(1) The source of the equation in Table B-3-5 has not been identified.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate ksl.
B-115
-------
I
TABLE &3-2
COPC SOIL LOSS CONSTANT
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 4)
V«rub!e
Dttctiption
Units
Value
ksv
COPC loss constant due to
volatilization
yr<
This variable is COPC- and site-specific, and is further discussed in Table B-3-6. Consistent with U.S. EPA guidance (1994a) and
based on the need for additional research to be conducted to determine the magnitude of the uncertainty introduced for modeling
volatile COPCs from soil, U.S. EPA OSW recommends that, until identification and validation of more applicable models, the
constant for the loss of soil resulting from volatilization (ksv) should be set equal to zero.

Uncertainties associated with this variable include the following:

(1) The source of the equation in Table B-3-6 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting a greater mixing
depth. This uncertainty may overestimate Asv.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution, (as a result of potential mixing with
in-situ materials) in comparison to that of other residues. This uncertainty may underestimate fav.
B-116
-------
TABLE B-3-2

COPC SOIL LOSS CONSTANT
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the reference documents for the equations in Tables B-3-4, B-3-5, and B-3-6. This document is also cited as (1) the source for a range of COPC-specific
degradation rates (ksg), and (2) one of the sources that recommend using the assumption that the loss resulting from erosion (kse) is zero because of contaminated soil eroding onto the
site and away from the site.

U.S. EPA. 1993c. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Office of Health and Environmental
Assessment. Office of Research and Development. EPA-600-AP-93-003. November 10.

This document is one of the reference documents for the equations in Tables B-3-3 and B-3-5.

This document is cited as a source for the assumptions that losses resulting from erosion (kse), surface runoff (ksr), degradation (ksg), leaching (ksl), and volatilization (ksv) are all zero.

This document is one of the reference documents for the equations in Tables B-3-4, B-3-5, and B-3-6. This document is also cited as one of the sources that recommend using the
assumption that the loss resulting from erosion (kse) is zero and the loss resulting from degradation (ksg) is "NA" or zero for all compounds.
B-117
-------
TABLE E-3-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the constant for COPC loss resulting from erosion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), andNC DEHNR (1997), U.S. EPA OSW recommends
that the default value assumed for fee is zero because of contaminated soil eroding onto the site and away from the site. In site-specific cases where the permitting authority considers it
appropriate to calculate a fee, the following equation presented in this table should be considered along with associated uncertainties. Additional discussion on the determination of fee can be
obtained from review of the methodologies described in U.S. EPA NCEA document, Methodology for Assessing Health Risks Associated with Multiple Exposure Pathways to Combustor
Emissions (In Press). Uncertainties associated with this equation include:

(1) For soluble COPCs, leaching might lead to movement below 1 centimeter in unfilled soils, resulting in a greater mixing depth. This uncertainty may overestimate foe.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate fee.
Equation
fee =
0.l-Xe-SD-ER
BD-Z.
Kd-BD
Variable
Description
Units
Value;
fee
COPC loss constant due to soil
erosion
yr'
0
Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), U.S. EPA OSW recommends that the default
value assumed for fee is zero because of contaminated soil eroding onto the site and away from the site.
uncertainty may overestimate fee.
Unit soil loss
kg/m2-yr
Varies
This variable is site-specific and is calculated by using the equation in Table B-4-13.

The following uncertainty is associated with this variable:

All of the equation variables are site-specific. Use of default values rather than site-specific values for any or all of
these variables will result in unit soil loss (Xe) estimates that are under- or overestimated to some degree: Based on
default values, Xe estimates can vary over a range of less than two orders of magnitude.
B-118
-------
TABLE B-3-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 5)
Variable
Vahfe
SD
Sediment delivery ratio
unitless
Varies
This value is site-specific and is calculated by using the equation in Table B-4-14.

Uncertainties associated with this variable include the following:

(1) The recommended default values for the empirical intercept coefficient, a, are average values that are based on
studies of sediment yields from various watersheds. Therefore, those default values may not accurately represent
site-specific watershed conditions. As a result, use of these default values may under- or overestimate SD.
(2) The recommended default value for the empirical slope coefficient, b, is based on a review of sediment yields from
various watersheds. This single default value may not accurately represent site-specific watershed conditions. As
a result, use of this default value may under- or overestimate SD.
ER
Soil enrichment ratio
unitless
Inorganics: 1
Organics: 3
COPC enrichment occurs because (1) lighter soil particles erode more than heavier soil particles, and (2) concentration of
organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded material
than in in-situ soil (U.S. EPA 1993). In the absence of site-specific data, U.S. EPA OSW recommends a default value of 3
for organic COPCs and 1 for inorganic COPCs. This is consistent with other U.S. EPA guidance (1993), which recommends
a range of 1 to 5 and a value of 3 as a "reasonable first estimate." This range has been used for organic matter, phosphorus,
and other soil-bound COPCs (U.S. EPA 1993); however, no sources or references were provided for this range. ER is
generally higher in sandy soils than in silty or loamy soils (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The default ER value may not accurately reflect site-specific conditions; therefore, kse may be over- or
underestimated to an unknown extent. The extent of any uncertainties will be reduced by using county-specific ER
values.
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffinan
and Baes (1979). U.S. EPA (1994b) recommended a default BD value of 1.5 (g soil/cm3 soil), based on a mean value for
loam soil that was taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 (g soil/cm3 soil) also
represents the midpoint of the "relatively narrow range" forBD of 1.2 to 1.7 (g soil/cm3 soil) (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-119
-------
TABLE B-3-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 5)
Variable
Description
Units
Value
Soil mixing zone depth
cm
Ito20
U.S. EPA currently recommends the following values for this variable:
SoU
Unfilled
Tilled
Pepm (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate kse.
Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other
residues. This uncertainty may underestimate kse.
Kd,
Soil-water partition coefficient
mL water/g
soil
(or cm3
water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if AT4 values are calculated as described in
Appendix A-3. :
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable is site-specific, and depends on the available water and on soil structure; 6, can be estimated as the midpoint
between a soil's field capacity and wilting point, if a representative watershed soil can be identified. However, U.S. EPA
recommends the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3
(heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and is
consistent with U.S. EPA (1994b).

The following uncertainty is associated with this variable:

The default 0^, value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
B-120
-------
TABLES 3-3

COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 5)
REFERENCES AND DISCUSSION

This document is cited by U.S. EPA (1994b) as the source for a mean soil bulk density, BD, value of 1.5 (g soil/cm3 soil) for loam soil.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

Hoffinan, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

This document presents a range of values for soil mixing zone depth, Zs, for tilled and unfilled soil. The basis or source of these values is not identified.

This document is the source of a range of COPC enrichment ratio, ER, values. The recommended range, 1 to 5, has been used for organic matter, phosphorous, and other soil-bound
COPCs. This document recommends a value of 3 as a "reasonable first estimate," and states that COPC enrichment occurs because lighter soil particles erode more than heavier soil
particles. Lighter soil particles have higher ratios of surface area to volume and are higher in organic matter content. Therefore, concentration of organic COPCs, which is a function of
the organic carbon content of sorbing media, is expected to be higher in eroded material than in in situ soil.

This document is also a source of the following: -

• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)
• COPC-specific (inorganic COPCs only) Kd, values used to develop a proposed range (2 to 280,000 [mL water/g soil]) of Kd, values
• A range of soil volumetric water content (0W) values of 0.1 (mL water/cm3 soil) (very sandy soils) to 0.3 (mL water/cm3 soil) (heavy loam/clay soils) (however, no source or
reference is provided for this range)
• A range of values for soil mixing zone depth, Za for tilled and unfilled soil

COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of 5)

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds, Volume 111: Site-specific Assessment Procedures, External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document is the source of values for soil mixing zone depth, Zn for tilled and untilled soil, as cited in U.S. EPA (1993). U.S. EPA is reviewing the document to verity the original
source of, or reference for, the recommended mixing zone values.

This document recommends (1) a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb
(1988), and (2) a default soil volumetric water content, 6^, value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993).
B-122
-------
TABLE B-3-4
COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the COPC loss constant due to runoff of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate ksr.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestimate ksr.
Equation
ksr =
RO
Variable
Description
'.(tfhMs •
ksr
COPC loss constant due to runoff
yr'
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994b), and NC DEHNR (1997), average annual
surface runoff, RO, can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and
Troise 1973). According to NC DEHNR (1997), estimates can also be made by using more detailed, site-specific procedures
for estimating the amount of surface runoff, such as those based on the U.S. Soil Conservation Service curve number equation
(CNE). U.S. EPA (1985) is cited as an example of such a procedure.

The following uncertainty is associated with this variable:

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 5)
Variable
Description
Units
Value
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable is depends on the available water and soil structure; if a representative watershed soil can be identified, 6W can
be estimated as the midpoint between a soil's field capacity and wilting point U.S. EPA OSW recommends the use of 0.2
(mL water/cm3 soil) as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam/clay
soils), which is recommended by U.S. EPA (1993) (no source or reference is provided for this range), and is consistent with
U.S. EPA (1994b) andNC DEHNR (1997).

The following uncertainty is associated with this variable:

The default 6^ value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate far.
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate for.
Soil-water partition coefficient
mL water/g
soil
(or cm3
water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are'presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kds values are calculated as described in
Appendix A-3.
B-124
-------
TABLE B-3-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 5)
Variable
Description
Value
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). The proposed range was originally cited in Hof&nan
and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value of 1.5 g/cm3, based on a mean value for
loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also represents the
midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-125
-------
TABLE B-3-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

Carsel, R.F., R.S, Fairish, R.L. Jones, J.L. Hansen, and RX. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology. Vol.
2. Pages 11-24.

This document is cited by U.S. EPA (1994b) as the source of a mean soil bulk density, BD, value of 1.5 (g soil/cm3 soil) for loam soil.

Geraghty, J.J., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center, Port Washington, New York.

This document is cited by U.S. EPA (1993), U.S. EPA (1994), and NC DEHNR (1997) as a reference to calculate average annual runoff, RO. This reference provides maps with isolines
of annual average surface water runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because
these values are total contributions and not only surface runoff, U.S. EPA (1994) recommends that the volumes be reduced by 50 percent in order to estimate surface runoff.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

Hoffman, F.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of Table B-3-4; however, this document is not the original source of this equation (this source is unknown). This
document also recommends the following:

• Estimation of annual current runoff, RO (cm/yr), by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) or site-specific procedures,
such as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.
• Default value of 0.2 (mL water/cm3 soil) for soil volumetric water content (d^

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate site-specific surface runoff.

This document presents a range of values for soil mixing zone depth, Zs, for tilled and untilled soil; the basis for, or sources of, these values is not identified.
B-126
-------
TABLE B-3-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of 5)

This document recommends the following:

A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil./cm3 soil)
A range of soil volumetric water content, 6^, values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) (the original source of, or reference for, these values is not
identified)
A range of values for soil mixing depth, Zs, for tilled and unfilled soil (the original source of, or reference for, these values is not identified)
A range (2 to 280,000 [mL water/g soil]) of Kds values for inorganic COPCs
Use of the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) to calculate average annual runoff, RO.

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume HI: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document is the source of values for soil mixing zone depth, Za for tilled and unfilled soil, as cited in U.S. EPA (1993). U.S. EPA is reviewing the document to verify the original
source of, or reference for, the recommended mixing zone values.

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Offices of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the following:

• Estimation of average annual runoff, RO, by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973)
• Default soil bulk density, BD, value of 1.5 (g soil/cm3 soil), based on the mean for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
• Default soil volumetric water content, 6^, value of (0.2 mL water/cm3 soil), based on U.S. EPA (1993)
B-127
-------
TABLE B-3-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 6)
Description
This equation calculates the COPC loss constant due to leaching of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPGs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate hi.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with insitu materials) in comparison to that of other residues. This
uncertainty may underestimate ksl.
(3) The original source of this equation has not been identified. U.S. EPA (1993) presents the equation as shown here. U.S. EPA (1994b) and NC DEHNR (1997) replaced the numerator
as shown with "q", defined as average annual recharge (cm/yr).
ksl
Equation
P + / - RO - E.,
Variable
Description
Units
Value
ksl
Constant for COPC loss due to soil
leaching

Average annual precipitation
cm/yr
18.06 to 164.19
This variable is site-specific. This range is based on information presented in U.S. EPA (1990), representing data for 69
selected cities (U.S. Bureau of Census 1987; Baes, Sharp, Sjoreen and Shor 1984). The 69 selected cities are not identified;
however, they appear to be located throughout the continental United States. U.S. EPA OSW recommends that site-specific
data be used.

The following uncertainty is associated with this variable:

(1) To the extent that a site is not located near an established meteorological data station, and site-specific data are not
available, default average annual precipitation data may not accurately reflect site-specific conditions. As a result,
ksl may be under- or overestimated. However, average annual precipitation data are reasonably available; therefore,
uncertainty introduced by this variable is expected to be minimal.
B-128
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TABLE B-3-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 6)
Variable
Description >"
Units
Value
Average annual irrigation
cm/yr
0 to 100
This variable is site-specific. This range is based on information presented in U.S. EPA (1990), representing data for 69
selected cities (Baes, Sharp, Sjoreen, and Shor 1984). The 69 selected cities are not identified; however, they appear to be
located throughout the continental United States.

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual irrigation information is not available, default values
(generally based on the closest comparable location) may not accurately reflect site-specific conditions. As a result,
ksl may be under- or overestimated to an unknown degree.
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994b), and NC DEHNR (1997), average annual
surface runoff, RO, can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and
Troise 1973). According to NC DEHNR (1997), this estimate can also be made by using more detailed, site-specific
procedures, such as those based on the U.S. Soil Conservation Service CNE. U.S. EPA (1985) is cited as an example of such
a procedure.

The following uncertainty is associated with this variable:

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 6)
Variable
Description
Units
Vtloe
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable is site-specific, and depends on the available water and on soil structure; if a representative watershed soil can
be identified &„ can be estimated as the midpoint between a soil's field capacity and wilting point. U.S. EPA OSW
recommends the use of 0.2 (mL soil/cm3 water) as a default value. This value is the midpoint of the range of 0.1 (very sandy
soils) to 0.3 (heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and
is consistent with U.S. EPA (1994b) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The default Qm value may not accurately reflect site-specific or local conditions; therefore, ksl may be under- or
overestimated to a small extent, based on the limited range of values.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Reference
U.S.EPA(1990a)andU.S.EPA(1993a)
U.S. EPA (1990a) and U.S. EPA (1993a)
Depth (cm)

U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate ksr.
(2) Deposition to hard surfaces may result hi dust residues that have negligible dilution (as a result of potential mixing
with in-situ materials) in comparison to that of other residues. This uncertainty may underestimate ksl.
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffman
and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean
value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 (g soil/cm3 soil) also represents
the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 (g soil/cm3 soil) (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-130
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TABLE B-3-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 6)
Variable
Kd,
Description
Soil-water partition coefficient
.Units
cm3
water/g soil
• „ > * > ' Value
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.
The following uncertainty is associated with this variable:
Uncertainties associated with this parameter will be limited if Kd, values are calculated as described in
Appendix A-3.
B-131
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TABLE B-3-5

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of6)
REFERENCES AND DISCUSSION

Baes, C.F., R.D. Sharp, AJL Sjoreen and R.W. Shor. 1984. "A Review and Analysis of Parameters for Assessing Transport of Environmentally Released Radionudides through Agriculture."
Prepared for the U.S. Department of Energy under Contract No. DEAC05-840R21400.

This document is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value, 3D, of 1.5 g soil/cm3 soil for loam soil.

Geraghty, J.J., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center, Port Washington, New York.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, F.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose of Radionudides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

• Estimation of average annual surface runoff, RO (cm/yr), by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) or site-specific
procedures, such as using the U.S. Soil Conservation Service CNE; U.S. EPA 1985 is cited as an example of such a procedure.
• A default value of 02 (mL water/cm3 soil) for soil volumetric water content, Qm
B-132
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TABLE B-3-5

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 6 of 6)
U.S. Bureau of the Census. 1987. StatisticalAbstract of'the UnitedStates: 1987. 107th edition. Washington, D.C.

This document is a source of average annual precipitation (P) information for 69 selected cites, as cited in U.S. EPA (1990); these 69 cities are not identified.

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate RO.

U.S.EPA. 1993. Addendum to the Methodology for Assessing Health Risks Associatedwith Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November.

This document is one of the reference sources for the equation in Table B-l-5; this document also recommends the following:

• A range of soil volumetric water content; 0^, values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils); the original source or reference for these values is not identified.
• A range of values for soil mixing depth, Zs, for tilled and unfilled soil; the original source reference for these values is not identified.
• A range (2 to 280,000 [mL water/g soil]) of Ai^ values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like-Compounds. Volume III: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document is the source of values for soil mixing zone depth, Za for tilled and untilled soil, as cited in U.S. EPA (1993).

This document recommends (1) a default soil volumetric water content, O^ value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993), and (2) a default soil bulk density, BD, value of
1.5 (g soil/cm3 soil), based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).

B-133
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TABLE B-3-S
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater mixing depth. This uncertainty may overestimate fov.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues. This
uncertainty may underestimate ksv.
Equation
ksv =
3.1536 • 107-tf
Z -Kd -R-T -BD
0.482-
I -0.67
-0.11
Variable
Definition "-
Units
fev
COPC loss constant due to
volatilization
yr1
Consistent with U.S. EPA guidance (1994) and based on the need for additional research to be conducted to
determine the magnitude of the uncertainty introduced for modeling volatile COPCs from soil, U.S. EPA OSW
recommends that, until identification and validation of more applicable models, the constant for the loss of soil
resulting from volatilization (ksv) should be set equal to zero.
0.482
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
0.78
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
-0.67
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
-0.11,
3.1536 x W
Empirical constant
unitless
This is an empirical constant calculated during the development of this equation.
Units conversion factor
s/yr
B-134
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TABLE B-3-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 6)
Variable
. Definition
Units
Value
H
Henry's Law constant
atm-mVmol
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific variables are
presented in Appendix A-3.

The following uncertainty is associated with this variable:

Values for this variable, estimated by using the parameters and algorithms in Appendix A-3, may
under- or overestimate the actual COPC-specific values. As a result, ksv may be under- or
overestimated.
2,
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Depth (cm) Reference
1 U.S.EPA(1990a)andU.S.EPA(1993a)
20 U.S.EPA(1990a)andU.S.EPA(1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting
in a greater mixing depth. This uncertainty may overestimate ksr.
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of
potential mixing with in situ materials) in comparison to that of other residues. This uncertainty may
underestimate ksv.
Kd,
Soil-water partition coefficient
cm3 water/g soil
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented
in Appendix A-3.

The following uncertainty is associated with this variable:

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 6)
Vtriable
Definition
Units
Value
Ambient air temperature
K
298
This variable is site-specific. U.S. EPA (1990) recommends an ambient air temperature of 298 K.

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for the variable are not available, default values may not
accurately represent site-specific conditions. The uncertainly associated with the selection of a single
value from within the temperature range at a single location is expected to be more significant than
the uncertainty associated with choosing a single ambient temperature to represent all localities.
BD
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the
water and clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84
was originally cited in Hoffman and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density
value of 1.5 g/cm3, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).
The value of 1.5 g/cm3 also represents the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g/cm3
(U.S. EPA 1993).

The following uncertainty is associated with this variable:

The following uncertainty is associated with mis variable:

To the extent that site-specific or local values for this variable are not available, default values may
not accurately represent site-specific conditions. The uncertainty associated with the selection of a
single value from within the range of windspeeds at a single location may be more significant than the
uncertainty associated with choosing a single windspeed to represent all locations.
B-136
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TABLE B-3-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of6)
Variable
. Definition
Unit*
Value
Viscosity of air
g/cm-s
1.81x10^
U.S. EPA OSW recommends the use of this value, based on Weast (1980. This value applies at standard
conditions (25°C or 298 K and 1 atm or 760 mm Hg).

The viscosity of air may vary slightly with temperature.
Density of air
g/cm3
0.0012
U.S. EPA recommends the use of this value, based on Weast (1980). This value applies at standard conditions
(25°C or 298 K and 1 atm or 760 mm Hg).

The density of air will vary with temperature.
D.
Diffusivity of COPC in air
cm2/s
Varies
This value is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

The default Da values may not accurately represent the behavior of COPCs under site-specific
conditions. However, the degree of uncertainty is expected to be minimal.
Surface area of contaminated area
1.0
See Chapter 5 for guidance regarding the calculation of this value
B-137
-------
TABLE B-3-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of 6)
REFERENCES AND DISCUSSION

Carsel, R.F., R.S, Parrish, R.L. Jones, J.L. Hanson, and R.L, Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils," Journal of Contaminant Hydrology, VoL
2. Pages 11-24.

This document is cited by U.S. EPA (1994b) as the source of a mean soil bulk density value, BD, of 1.5 (g soil/cm3 soil) for loam soil.

Hillel.D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionucIides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of the equation in Table B-l-6; however, the original source of this equation is not identified.

U. S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office. Office of
Research and Development EPA 600-90-003. January.

This document recommends the following:

• A range of values for soil mixing zone depth, Za for tilled and unfilled soil; however, the source or basis for these values is not identified
• A default ambient air temperature of 298 K
• An average annual wind speed of 3.9 m/s; however, no source or reference for this value is identified.

This document is one of the reference source documents for the equation in Table B-l-6; however, the original reference for this equation is not identified.

This document also presents the following:

• A range of values for soil mixing depth, Zw for tilled and unfilled soil; however, the original source of these values is not identified.
• COPC-specific Kd, values that were used to establish a range (2 to 280,000 [mL water/g soil]) of Kd, values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)

B-138
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TABLE B-3-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 6 of 6)

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume in: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document is the source of values for soil mixing zone depth, £„ for tilled and untilled soil, as cited in U.S. EPA (1993).

This document recommends a default soil density, BD, value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb
(1988).

Weast,R.C. 1980. Handbook of Chemistry and Physics. 61st Edition. CRC Press, Inc. Cleveland, Ohio.

This document is cited by NC DEHNR (1997) as the source recommended values for viscosity of air, //„, and density of air, pa.
B-139
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TABLE B-3-7
FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 11)
Description
This equation calculates the COPC concentration in forage and silage (aboveground vegetation) due to wet and dry deposition of COPCs onto plant surfaces. The limitations and uncertainty
introduced in calculating this variable include the following:

(1) Variables Q, Dydp, and Dywp are COPC- and site-specific. Uncertainties associated with these variables are site-specific.
(2) In calculating the variable Fw, values of r assumed for most organic compounds—based on the behavior of insoluble polystyrene microspheres tagged with radionuclides— may
accurately represent the behavior of organic compounds under site-specific conditions.
(3) The empirical relationship used to calculate the variable Sp, and the empirical constant for use in the relationship, may not accurately represent site-specific silage types.
(4) The recommended procedure for calculating the variable Ap does not consider chemical degradation processes. This conservative approach contributes to the possible overestimation
of plant concentrations.
(5) The harvest yield (YK) and area planted (Ah) values used to estimate the variable Yp may not reflect site-specific conditions.
Equation
Pd =
1000 • [Q • (1 - Fv) • [Dydp + (Fw • Dywp)] • Rp • [1.0-exp(-fo • Tp)}
__
For mercury modeling
Pd =
1000 • (0.480 • (1 - Fv) • [Dydp + (Fw - Dywp)] • Rp • [1.0-exp(-fo • Tp}]
—_
Forage and silage concentration due to direct deposition is calculated using 0.48Q for total mercury and Fv = 0.85 in the mercury modeling equation. The calculated Pd value is apportioned into
the divalent and methyl mercury forms based on the 78% divalent mercury (Hg2*) and 22% methyl mercury (MHg) speciation split in aboveground produce and forage.

0.78 Pd
0.22 Pd
Concentration of COPC in forage
and silage due to direct deposition
B-140
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TABLE B-3-7
FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 11)
Variable
1000
Q
Dydp
Description
Units conversion factor
COPC-specific emission rate
Unitized yearly average dry
deposition from particle phase
Unitt .
mg/g
g/s
s/m2-yr
Value ' [i'\\,~ ;,•;>;-, •'*; '•'' ' '-, v.

Varies
This value is COPC- and site-specific, and is determined by air dispersion modeling. See Chapters 2 and 3 for guidance
regarding the calculation of this variable. Uncertainties associated with this variable are site-specific.
Varies
This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are site-specific.
B-141
-------
r
TABLE B-3-7
FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 11)
Variable
Description
Units
Value
Fw Fraction of COPC wet deposition
that adheres to plant surfaces
unitless
0.2 for anions
0.6 for cations and most organics
U.S. EPA OSW recommends using the chemical class-specific values of 0.2 for anions and 0.6 for cations and most organics
and estimated by U.S. EPA (1994b) and U.S. EPA (1995). These values are the best available information, based on a
review of the current scientific literature, with the following exception: U.S. EPA OSW recommends using an Fw value of
0.2 for the three organic COPCs that ionize to anionic forms. These include (1) 4-chloroaniline, (2) n-
nitrosodiphenylamine, and (3) n-nitrosodi-n-proplyamine (see Appendix A-3).

The values estimated by U.S. EPA (1994b) and U.S. EPA (1995) are based on information presented in Hoffinan, Thiessen,
Frank, and Blaylock (1992), which presented values for a parameter (r) termed the "interception fraction." These values
were based on a study in which soluble radionuclides and insoluble particles labeled with radionuclides were deposited
onto pasture grass via simulated rain. The parameter (r) is defined as "the fraction of material in rain intercepted by
vegetation and initially retained" or, essentially, the product of Rp and Fw, as defined:

r = Rp • Fw

The r values developed by Hoffinan, Thiessen, Frank, and Blaylock (1992) were divided by an Rp value of 0.5 for forage
(U.S. EPA 1994b). The Fw values developed by U.S. EPA (1994b) are 0.2 for anions and 0.6 for cations and insoluble
particles. U.S. EPA (1994b) and U.S. EPA (1995) recommends using the Fw value calculated by using the r value for
insoluble particles to represent organic compounds; however, no rationale for this recommendation is provided.

Interception values (r)—as defined by Hoffinan, Thiessen, Frank, and Blaylock (1992)—have not been experimentally
determined for aboveground produce. Therefore, U.S. EPA (1994b) and U.S. EPA (1995) apparently defaulted and
assumed that the Fw values calculated for pasture grass (similar to forage) also apply to aboveground produce. The
rationale for this recommendation is not provided.

Uncertainties associated with this variable include the following:

(1) Values of r developed experimentally for pasture grass may not accurately represent aboveground produce-specific
r values.
(2) Values of r assumed for most organic compounds, based on the behavior of insoluble polystryene microspheres
tagged with radionuclides, may not accurately represent the behavior of organic compounds under site-specific
conditions.
B-142
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TABLE B-3-7
FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 11)
Variable
Units
Value
Fraction of COPC air concentration
in vapor phase
unitless
Otol
This variable is COPC-specific. Discussion of this variable and COPC-specific values is presented in Appendix A-3. This
range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA (1994b) and NC DEHNR
(1997).

Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs. U.S.
EPA (1994c) states that Fv = 0 for all metals (except mercury).

The following uncertainties are associated with this variable:

(1) It is based on the assumption of a default ST value for background plus local sources, rather than an ST value for
urban sources. If a specific site is located in an urban area, the use of the latter ST value may be more appropriate.
Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus
local sources, and it would result in a lower calculated Fv value; however, the Fv value is likely to be only a few
percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant) is
constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from the particle
surface and the heat of vaporization of the liquid phase sorbate. To the extent that site- or COPC-specific
conditions may cause the value of c to vary, uncertainty is introduced if a constant value of c is used to calculate
Fv.
Dywp
Unitized yearly average wet
deposition from particle phase
s/m -yr
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are site-specific.
B-143
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TABLE R-3-7
FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(PageSofll)
Variable
Units
Value
Rp
Interception fraction of the edible
portion of plant
unitless ,
Forage: 0.5
Silage: 0.46
U.S. EPA OSW recommends the use of these default Rp values because it represents the most current information available;
specifically, productivity and relative ingestion rates.

As summarized in Baes, Sharp, Sjoreen, and Shor (1984), experimental studies of pasture grasses identified a correlation
between initial Rp values and productivity (standing crop biomass [Yp]) (Chamberlain 1970):
where
Rp =
Y '
Rp = l-e-^Yp
Interception fraction of the edible portion of plant (unitless)
Empirical constant. Chamberlain (1970) presents a range of 2.3 to 3.3; Baes, Sharp, Sjoreen, and Shor
(1984) uses 2.88, the midpoint for pasture grasses.
Yield or standing crop biomass (productivity) (kg DW/m2)
Baes, Sharp, Sjoreen, and Shor (1984) proposed using the same empirical relationship developed by Chamberlain (1970)
for other vegetation classes. Class-specific estimates of the empirical constant, y, were developed by forcing an exponential
regression equation through several points, including average and theoretical maximum estimates of .Rp and Yp (Baes,
Sharp, Sjoreen, and Shor 1984). The class-specific Rp estimates were then weighted, by relative ingestion of each class, to
arrive at the weighted average Rp value of 0.5 for forage and 0.46 for silage.

U.S. EPA (1994b) and U.S. EPA (1995) recommend a weighted average Rp value of 0.05. However, the relative ingestion
rates used in U.S. EPA (1994b) and U.S. EPA (1995) to weight the average Rp value were derived from U.S. EPA (1992)
and U.S. EPA (1994b). The most current guidance available for ingestion rates of homegrown produce is the 1997
Exposure Factors Handbook (U.S. EPA 1997). The default Rp values of 0.5 for forage and 0.46 for silage were weighted
by relative ingestion rates of homegrown exposed fruit and exposed vegetables found hi U.S. EPA (1997).

Uncertainties associated with this variable include the following:

(1) The empirical relationship developed by Chamberlain (1970) on the basis of a study of pasture grass may not
accurately represent aboveground produce.
(2) The empirical constants developed by Baes, Sharp, Sjoreen, and Shor (1984) for use in the empirical relationship
developed by Chamberlain (1970) may not accurately represent site-specific mixes of aboveground produce.
B-144
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TABLE B-3-7
FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 6 of 11)
Description
.Value
kp
Plant surface loss coefficient
yr'
18
This value is site-specific. U.S. EPA (1990) identified several processes—including wind removal, water removal, and
growth dilution—that reduce the amount of COPC that has been deposited onto plant surfaces. The term kp is a measure of
the amount of COPC lost to these physical processes over time. U.S. EPA (1990) cites Miller and Hoffman (1983) for the
following equation used to estimate kp:
kp = (In II tlfl) • 365 days/year
where
'1/2
half-time (days)
Miller and Hoffman (1983) report half-time values ranging from 2.8 to 34 days for a variety of COPCs on herbaceous
vegetation. These half-time values converted to kp values of 7.44 to 90.36 yr1. U.S. EPA (1993) and U.S. EPA (1994b)
recommend a kp value of 18, based on a generic 14-day half-time, corresponding to physical processes only. The 14-day
half-time is approximately the midpoint of the range (2.8 to 34 days) estimated by Miller and Hoffman (1983).

U.S. EPA OSW recommends the use of the previously identified kp value of 18; this kp value selected is the midpoint of a
possible range of values. Based on this range (7.44 to 90.36), plant concentrations could range from about 1.8 times higher
to about 48 times lower than the plant concentrations, based on a kp value of 18.

Uncertainties associated with this variable include the following:

(1) Calculation of kp does not consider chemical degradation processes. The addition of chemical degradation
processes would decrease half-times and thereby increase kp values; plant concentration decreases as kp increases.
Therefore, use of a kp value that does not consider chemical degradation processes is conservative.
(2) The half-time values reported by Miller and Hoffman (1983) may not accurately represent the behavior of
compounds on aboveground produce.
(3) Based on this range (7.44 to 90.36), plant concentrations could range from about 1-8 times higher to about 5 times
lower than the plant concentrations, based on a kp value of 18.
B-145
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I
TABLE B-3-7

FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 7 of 11)
Variable
Description
Units
Value
Tp Length of plant exposure to
deposition per harvest of edible
portion of plant
Forage: 0.12
Silage: 0.16
This variable is site-specific. U.S. EPA OSW recommends the use of these default values in the absence of site-specific
information. U.S. EPA (1990), U.S. EPA (1994b), and NC DEHNR (1997) recommended treating Tp as a constant, based
on the average periods between successive hay harvests and successive grazing.

For forage, the average of the average period between successive hay harvests (60 days) and the average period between
successive grazing (30 days) is used (that is, 45 days). Tp is calculated as follows:

Tp = (60 days + 30 days)/ 2 •*• 365 days/yr = 0.12 yr

These average periods are from Belcher and Travis (1989), and are used when calculating the COPC concentration in cattle
forage.

When calculating the COPC concentration in silage fed to cattle, the average period between successive hay harvests (60
days) is used (Belcher and Travis 1989). Tp is calculated as follows:

Tp = 60 days * 365 days/year = 0.16 year

The following uncertainty is associated with this variable:

The use of hay harvest cycles to estimate silage Tp values may underestimate COPC uptakes if silage types differ
significantly from hay and have longer actual harvest cycles (for example, if grains or other feeds with longer
harvest cycles are used as silage). This underestimation will increase as actual harvest cycles increase, up to
about 3 months. Beyond that tune frame, if the kp value remains unchanged at 18, higher Tp values will have
little effect on predicted COPC concentrations in plants.
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TABLE B-3-7
FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 8 of 11)
Variable
jPWts
Value
Yield or standing crop biomass of
the edible portion of the plant
kgDW/m2
' Forage: 0.24
Silage: 0.8
This variable is site-specific. U.S. EPA OSW recommends the use of these default values in the absence of site-specific
information. U.S. EPA (1990) states that the best estimate of Yp is productivity, which Baes, Sharp, Sjoreen, and Shor
(1984) and Shor, Baes, and Sharp (1982) define as follows:
Yp* Yh,/Ah,
where
th,
Ah,
Harvest yield of ith crop (kg DW)
Area planted to crop i (m2)
U.S. EPA (1994b) and NC DEHNR (1997) recommend using either previously calculated Yp values or the equation
presented above to calculate a Yp value.

U.S. EPA OSW recommends that the forage Yp value be calculated as a weighted average of pasture grass and hay Yp
values. Weights (0.75 for forage and 0.25 for hay) are based (1) on the fraction of a year during which cattle are assumed to
be pastured and eating grass (9 mo/yr), and (2) the fraction of a year during which cattle are assumed to not be pastured and
to be fed hay (3 mo/yr). An unweighted Yp value for pasture grass of 0.15 kg DW/m2 is assumed (U.S. EPA 1994b). An
unweighted Yp value for hay of 0.5 kg DW is calculated by the above equation, using the following dry harvest yield (Yh)
and area harvested (Ah) values:
Yh

Ah
1.22 x 10+" kg DW; from 1993 U.S. average wet weight Yh of 1.35 x 10" kg (USDA 1994)
and conversion factor of 0.9 (Agricultural Research Service 1994)
2.45 x 10+" m2; from 1993 U.S. average for hay (USDA 1994).

The unweighted pasture grass and hay Yp values are multiplied by 3/4 and 1/4, respectively. They are then added to
calculate the weighted forage Yp of 0.24 kg DW. U.S. EPA recommends that a production weighted U.S. average Yp of 0.8
be assumed for silage (Shor, Baes, and Sharp 1982).

The following uncertainty is associated with this variable:

The harvest yield (Yh) and area planted (Ah) may not reflect site-specific conditions. This may under- or
overestimate Yp.
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TABLE B-3-7

FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 9 of 11)

REFERENCES AND DISCUSSION

Agricultural Research Service. 1994. Personal communication regarding the dry weight fraction value for hay between G.F. Fries, and Glenn Rice and Jennifer Windholz, U.S. EPA Office of
Research and Development March 22.

This communication is cited by NC DEHNR (1997) for the fraction of 0.9 used to convert wet weight to dry weight for hay.

Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. Review and Analysis of Parameters and Assessing Transport ofEnvironmentally Released Radionuclides through Agriculture.
ORNL-5786. Oak Ridge National Laboratory. Oak Ridge, Tennessee. September.

This document proposes using the empirical relationship developed by Chamberlain (1970) (see reference and equation below) that identifies a correlation between initial Rp values and
productivity (standing crop biomass [Yp]). It uses this relationship to calculate Rp values for forage and silage.

Belcher, G.D., and C.C. Travis. 1989. Modeling Support for the RURA and Municipal Waste Combustion Projects: Final Report on Sensitivity and Uncertainty Analysis for the Terrestrial Food
Chain Model. Interagency Agreement No. 1824-A020-A1, Office of Risk Analysis, Health and Safety Research Division, Oak Ridge National Laboratory. Oak Ridge, Tennessee.
October.

This document recommends Tp values based on the average period between successive hay harvests and successive grazing.

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

For discussion, see References and Discussion, Table B-l-1.

Chamberlain, A.C. 1970. "Interception and Retention of Radioactive Aerosols by Vegetation." Atmospheric Environment. 4:57 to 78.

Experimental studies of pasture grasses identified a correlation between initial Rp values and productivity (standing crop biomass [Yp]):
where
y = Empirical constant; range provided as 2.3 to 3.3
Yp = Yield or standing crop biomass (productivity) (kg DW/m2)
Hoffman, F.O., K.M. TMessen, M.L. Frank, and E.G. Blaylock. 1992. "Quantification of the Interception and Initial Retention of Radioactive Contaminants Deposited on Pasture Grass by
'simulated Rain." Atmospheric Environment. Vol. 26A, 18:3313 to 3321.

FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 10 of 11)

r = Sp • Fw

Experimental r values obtained include the following:

• An r range of 0.006 to 0.3 for anions (based on the soluble radionuclide iodide-131 [13II]; when calculating Rp values for anions, U.S. EPA (1994a) used the highest geometric
mean r value (0.08) observed in the study.
• An r range of 0.1 to 0.6 for cations (based on the soluble radionuclide beryllium-7 fBe]; when calculating Rp values for cations, U.S. EPA (1994a) used the highest geometric
mean r value (0.28) observed in the study.
• A geometric range of r values from 0.30 to 0.37 for IPMs ranging in diameter from 3 micrometers, to 25 micrometers labeled with I4lCe, 95Nb, and 85Sr; when calculating Rp
values for organics (other than three organics that ionize to anionic forms: 4-chloroaniline, n-nitrosodiphenylamine, and n-nitrosodi-n-propylamine [see Appendix A-3]). U.S.
EPA (1994a) used the geometric mean r value for IPM with a diameter of 3 micrometers; however, no rationale for this selection is provided.

The authors concluded that, for the soluble I3II anion, interception fraction (r) is an inverse function of rain amount, whereas for the soluble cation 'Be and the IPMs, r depends more on
biomass than on amount of rainfall. The authors also concluded that (1) the anionic I3II is essentially removed with the water after the vegetation surface has become saturated, and
(2) the cationic 'Be and the IPMs are adsorbed to or settle out onto the plant surface. This discrepancy between the behavior of the anionic and the cationic species is consistent with a
negative charge on the plant surface.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Parti. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

Miller, C.W., and P.O. Hoffman. 1983. "An Examination of the Environmental Half-Time for Radionuclides Deposited on Vegetation." Health Physics. 45 (3): 731 to 744.

This document is the source of the equation used to calculate Itp:

lip = (In 21 tl/2) x 365 days/year

where ,

t,a = half-time (days)

The study reports half-time values ranging from 2.8 to 34 days for a variety of contaminants on herbaceous vegetation. These half-time values convert to kp values of 7.44 to 90.36 years'1.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This a source document for the equation in Table B-3-7.

This document also recommends the following:

• Rp values of 0.5 (forage) and 0.46 (silage), based on the correlation from Chamberlain (1970)
• Treating Tp as a constant, based on the average periods between successive hay harvests and successive grazing
• Bidleman (1988) as source of equation for calculating Fv

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TABLE B-3-7

FORAGE AND SILAGE CONCENTRATION DUE TO DIRECT DEPOSITION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 11 of 11)

For discussion, see References and Discussion in Table B-2-7.

U.S. Department of Agriculture (USDA). 1994. Vegetables 1993 Summary. National Agricultural Statistics Service, Agricultural Statistics Board. Washington, D.C. Vg 1-2 (94).

This document is cited by NC DEHNR (1997) as the source for the average wet weight harvest yield (Yh) for hay.

This is one of the source documents for the equation in Table B-3-7. This document also states that the best estimate of Yp (yield or standing crop biomass) is productivity, as defined
above under Shor, Baes, and Sharp (1982).

U.S. EPA. 1993. ReviewDrqft Addendum to the Methodology for Assessing Health Risks Associated'with Indirect Exposure to Combustor Emissions. Office of Health and Environmental
Assessment. Office of Research and Development. EPA/600/AP-93/003. November.

This is one of the source documents for the equation in Table B-3-7. This document also recommends a kp value of 18, based on a generic 14-day half-time, corresponding to physical
processes only. This 14-day half-time is approximately the midpoint of the range (2.8 to 34 days) estimated by Miller and Hoffinan (1983).

This document recommends an unweighted estimate of yield or standing crop biomass of 0.15 kg DW/m2 for pasture grass.

This is one of the source documents for the equation in Table B-3-7. This document also (1) developed and recommends Fw values of 0.2 for anions and 0.6 for cations and insoluble
particles, based on dividing "r" values developed by Hoffinan, Thiessen, Frank, and Blaylock (1992) and an Rp value of 0.5 for forage; (2) recommends Rp values of 0.5 (forage) and 0.46
(silage); (3) recommends a lip value of 18, based on a generic 14-day half-time, corresponding to physical processes only, (4) recommends treating Tp as a constant .based on the average
periods between successive hay harvests and successive grazing, and (5) cites Bidleman (1988) as the source of the equation for calculating Fv.

U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and H. OfficeofSolid
Waste. March 3.

This is one of the source documents for the equation in Table B-2-6. This document also recommends (1) using the Fw value calculated by using the r value for insoluble particles (see
Hoflman, Thiessen, Frank, and Blaylock 1992) to represent organic compounds; however, no rationale for this recommendation is provided, and (2) Rp values of 0.5 (forage) and 0.46
(silage), based on the correlation from Chamberlain (1970).

U.S. EPA. 1997. Exposure Factors Handbook. "Food Ingestion Factors". Volume n. SAB Review Draft. EPA/600/P-95/002F. August.

B-150
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TABLE B-3-8
FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 6)
Description
This equation calculates the COPC concentration in forage and silage (aboveground vegetation) resulting from direct uptake of vapor phase COPCs onto plant surfaces.

Uncertainties associated with the use of this equation include the following:

(1) The range of values for the variable Bv (air-to-plant biotransfer factor) is about 19 orders of magnitude for organic COPCs. COPC-specific Bv values for nondioxin-like compounds
may be overestimated by up to one order of magnitude, based on experimental conditions used to develop the algorithm used to estimate Bv values.
(2) The algorithm used to calculate values for the variable Fv assumes a default value for the parameter ST (Whitby's average surface area of particulates [aerosols]) of background plus
local sources, rather than an SV value for urban sources. If a specific site is located in an urban area, the use of the latter SV value may be more appropriate. The ST value for urban
sources is about one order of magnitude greater than that for background plus local sources and would result in a lower PVvalue; however, the Fv value is likely to be only a few
percent lower.
Equation

Cvv • Bvf • VG
Pv = Q • F - forage a
Pa
For mercury modeling
Pv = (0.480 • F
Cyv • Bv
VG
Aboveground produce concentration due to air-to-plant transfer is calculated 0.48Q for total mercury and Fv = 0.85 in the mercury modeling equation. The calculated Pv value is apportioned
into the divalent and methyl mercury forms based on the 78% divalent mercury (Hg2*) and 22% methyl mercury (MHg) speciation split in aboveground produce and forage.
Pv(Mhg)
0.78 Pv
0.22 Pv
Variable
Description
Units
Pv
Forage and silage concentration
due to air-to-plant transfer
ugCOPC/gDW
plant tissue
(equivalent to
mg/kgDW)
B-151
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TABLE B-3-8
FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 6)
Variable
Q
Fv
Cyv
Description
COPC-specific emission rate
Fraction of COPC air concentration
in vapor phase
Unitized yearly average air
concentration from vapor phase
Units
g/s
unitless
ug-s/g-m3
Value
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 for guidance regarding the calculation of this
variable. Uncertainties associated with this variable are also COPC- and site-specific.
Otol
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values is presented in
Appendix A-3. This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA
(1994b) and NC DEHNR (1997).
Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fy = 0 for all metals (except mercury).
The following uncertainties are associated with this variable:
(1) It is based on the assumption of a default ST value for background plus local sources, rather than an ST
value for urban sources. If a specific site is located in an urban area, the use of the latter Sy value may be
more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than
that for background plus local sources, and it would result in a lower calculated Fv value; however, the Fv
value is likely to be only a few percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge
constant) is constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular
weight, the surface concentration for monolayer coverage, and the difference between the heat of desorption
from the particle surface and the heat of vaporization of the liquid-phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value
of c is used to calculate Fv
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3).
Uncertainties associated with this variable are site-specific.
B-152
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TABLE B-3-8
FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 6)
Variable
Unite
Value
Bv,
'forage
Air-to-plant biotransfer factor for
forage and silage
(rag COPC/g plant
tissue DW)/
(mg COPC/g air)
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-

Uncertainty associated with this variable include the following:

The studies that formed the basis of the algorithm used to estimate Bv values were conducted on azalea
leaves and grasses, and may not accurately represent Bv for aboveground produce other than leafy
vegetables.
VGal
Empirical correction factor for
forage and silage
unitless
Forage: 1.0
Silage: 0.5
This variable is site-specific. U.S. EPA OSW recommends the use of VGag values of 1.0 for forage and 0.5 for silage
in the absence of site-specific information.

U.S. EPA (1994a), U.S. EPA (1994b), andNC DEHNR (1997) recommend an empirical correction factor to reduce
estimated concentrations of constituents in specific vegetation types. This factor is used to reduce estimated bulky
silage concentrations, because (1) Bv was developed for azalea leaves, and (2) it is assumed that there is insignificant
translocation of compounds deposited on the surface of specific vegetation types (such as bulky silage) to the inner
parts of this vegetation.

U.S. EPA (1994a) and U.S. EPA (1994b) recommends a VGag of 1.0 for pasture grass and other leafy vegetation
because of a direct analogy to exposed azalea and grass leaves. Pasture grass is described as "leafy vegetation."

U.S. EPA (1994a) and U.S. EPA (1994b) does not recommend a VGag value for silage. NC DEHNR (1997)
recommends a VGag factor of 0.5 for bulky silage but does not present a specific rationale for this recommendation.
U.S. EPA (1995) notes that a volume ratio of outer surface area volume to whole vegetation volume could be used to
assign a value to VGag for silage, if specific assumptions concerning the proportions of each type of vegetation of
which silage may consist of were known (for example, corn and other grains). In the absence of specific assumptions
concerning hay/silage/grain intake, however, U.S. EPA (1995) recommends assuming a VGag of 0.5 for silage without
rigorous justification.

The following uncertainty is associated with this variable:

(1) It is recommended that the VGa? value of 0.5 for silage be used without vigorous justification. Depending
on the composition of site-specific silage, the recommended VGag value may under- or overestimate the
actual value.
B-153
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TABLE B-3-8
FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of6)
Variable
Description
Units
Value
Density of air
g/m3
0.0012
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of site-specific
information. U.S. EPA (1990) recommends the same value, but states that it is based on a temperature of 25°C; no
reference was provided.

U.S. EPA (1994b) and NC DEHNR (1997) recommend this same value, but state that it was calculated at standard
conditions (20°C and 1 atmosphere)(Weast 1981). A review of Weast (1986) indicates that air density varies with
temperature. An air density of 1.2 x 10^ (rounded to two significant figures) applies to both 20°C and 25°C.
B-154
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TABLE B-3-8

FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

Bideltnan, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367

For discussion, see References and Discussion in Table B-l-1.

NCDEHNR. 1997. NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is a source document for the equation in Table B-3-8. This document also recommends (1) that Fv values be based on the work of Bidleman (1988), and (2) the use of an empirical
correction factor (FG^) to reduce concentrations of COPCs in some vegetation types- (specifically, a VGag value of 0.5 is recommended for silage; however, no rationale is provided for
this value). This factor is used to reduce estimated COPC concentrations in specific vegetation types, because (1) Bv was developed for azalea leaves, and (2) it is assumed that there is
significant translocation of compounds deposited on the surface of specific vegetation types to the inner parts of this vegetation.

Riederer, M. 1990. "Estimating Partitioning and Transport of Organic Chemicals in the Foliage/Atmosphere: Discussion of a Fugacity-Based Model." Environmental Science and Technology.
24: 829 to 837.

This is the source of the leaf thickness used to estimate the empirical correction factor (VGag).

This is one of the source documents for the equation in Table B-3-8.

U.S. EPA. 1993. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combuster Emissions. Office of Health and Environmental
Assessment. Office of Research and Development. EPA-600-AP-03-003. November 10.

This document recommends reducing Bv values calculated by using the Bacci, Cerejeira, Gaggi, Chemello, Calamari, and Vighi (1992) algorithm by a factor of 10 based on attempts to
model background concentrations. The use of this factor "made predictions [of beef concentrations] come in line with observations."

U. S. EPA 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume II: Properties, Sources, Occurrence, and Background Exposures. External Review Draft. Office of Research and
Development. Washington, D.C. EPA/600/6-88/005Cb. June.

This document recommends an empirical correction factor of 0.01 to reduce estimated vegetable concentrations, based on the assumption that there is insignificant translocation of
compounds deposited on the surface of aboveground vegetation to inner parts for aboveground produce. The document provides no reference or discussion regarding the validity of this
assumption.

The factor of 0.01 is based on a similar correction factor for below ground produce (VGag), which is estimated based on a ratio of the vegetable skin mass to vegetable total mass. The
document assumes that the density of the skin and vegetable are equal. The document also assumes an average vegetable skin leaf based on Rierderer (1990). Based on these
B-155
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TABLE B-3-8

FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-PLANT TRANSFER
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 6 of6)

assumptions, U.S, EPA (1994a) calculated VGn for carrots and potatoes of 0.09 and 0.03, respectively. By comparing these values to contamination reduction research completed by
Wipf, HourbergemNeuner, Ranalder, Vetter, andUilleurnier (1982), U.S. EPA (1994a) arrived at the recommended VG^ of 0.01.

This is one of the source documents for the equation in Table B-3-8. This document also presents a range (0.27 to 1) of Fv values for organic COPCs, calculated on the basis of Bidleman
(1988); F, for all inorganics is set equal to zero.

U.S. EPA. 1995. Review Draft Development of Human-Health Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and II. Office of Solid
Waste. March 3.

This document presents estimated VGag values. U.S. EPA (1995) notes that a volume ratio of outer surface area volume to whole vegetation volume could be used to assign a value to
VGag for silage, if specific assumptions (concerning the proportions of each type of vegetation of which silage may consist of) were known (for example, corn and other grains). In the
absence of specific assumptions concerning hay/silage/grain intake, however, U.S. EPA (1995) recommends assuming a VGas value of 0.5 for silage (for COPCs with a log K^ greater
than 4) without rigorous justification.

Weast,R.C. 1981. Handbook of Chemistry and Physics. 62nd Edition. Cleveland, Ohio. CRC Press.

This document is a reference for air density values.

Weast,R.C. 1986. Handbook of Chemistry and Physics. 66th Edition. Cleveland, Ohio. CRC Press.

This document is a reference for air density values, and is an update of Weast (1981).

Wipf, H.K., E. Hamberger, N. Neuner, U.B. Ranalder, W. Vetter, and J.P. Vuilleumier. 1982 "TCDD Levels in Soil and Plant Samples from the Seveso Area." In: ChlorinatedDioxins and
Related Compounds: Impact on the Environment. Eds. Hutzinger, O. et al. Perganon. New York.
B-156
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TABLE B-3-9
FORAGE/SILAGE/GRAIN CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the COPC concentration in forage/silage/grain (aboveground produce), due to direct uptake of COPCs from soil through plant roots. Uncertainties associated with the
use of this equation include the following:

(1) The availability of site-specific information, such as meteorological data, will affect the accuracy of Cs estimates.
(2) Estimated COPC-specific soil-to-plant bioconcentration factors (Br) do not reflect site-specific conditions. This may especially be true for inorganic COPCs for which estimates of Br
would be more accurately estimated by using site-specific bioconcentration factors rather than bioconcentration factors from Baes, Sharp, Sjoreen, and
Shor (1984). Hence, U.S. EPA OSW recommends the use of plant uptake response-slope factors derived from U.S. EPA (1992) for arsenic, cadmium, selenium, nickel, and zinc.
Equation
Pr =
rr
Rr
or
forage
For mercury modeling, forage/silage/grain concentration due to root uptake is calculated for divalent mercury (Hg*1) and methyl mercury (MHg) using their respective Cs and Br values.
2* • Br
forage(Hg2t)
Pr
rr
MHg
Rr
Dr
forage(MHg)
Variable
Description •
, , Units
Pr
Concentration of COPC in
forage/silage/grain due to root
uptake
mgCOPC/kgDW
plant tissue
Average soil concentration over
exposure duration
mg/kg
Varies
This value is COPC and site-specific, and should be calculated using the equation in Table B-3-1. Uncertainties
associated with this variable are site-specific.
B-157
-------
TABLE B-3-9
FORAGE/SILAGE/GRAIN CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 4)
Variable
Description
Plant-soil bioconcentration factor
for forage, silage, and grain
Units
unitless

[(mgCOPC/kg
plant DW)/
(mg COPC/kg
soil)]
Value
Varies
This variable is COPC-specific, Discussion of this variable and COPC-specific values are presented in Appendix A-3.

Uncertainties associated with this variable include the following:

(1) Estimates of Br for some inorganic COPCs, based on plant uptake response slope factors, may be more
accurate than those based on BCFs from Baes, Sharp, Sjoreen, and Shor (1984).
(2) U.S. EPA OSW recommends that uptake of organic COPCs from soil and transport of the COPCs to
aboveground plant parts be calculated on the basis of a regression equation developed in a study of the uptakfi
of 29 organic compounds. This regression equation, developed by Travis and Arms (1988), may not
accu^tely_rep^entfliebe^morof all classes of organic COPCs under site-specific conditions.
B-158
-------
TABLE B-3-9

FORAGE/SILAGE/GRAIN CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 4)

REFERENCES AND DISCUSSION

Baes, C.F. R.D. Sharp, A.L. Sjoreen, and R.W. Shot. 1984. Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionuclides Through Agriculture.
ORNL-5786. Oak Ridge National Laboratory, Oak Ridge, Tennessee. September.

This document presents inorganic-specific transfer factors (Br) for both vegetative (Bv) portions of food crops and nonvegetative (reproductive—fruits, seeds, and tubers) portions (Br) of
food crops. These bioconcentration factors were developed based on review and compilation of a wide variety of measured, empirical, and comparative data.

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is a source document for the equation in Table B-3-9.

Travis, C.C., and A.O. Arms. 1988. "Bioconcentration of Organics in Beef, Milk, and Vegetation." Environmental Science and Technology. 22:271 to 274.

This document developed the following regression equation relating soil-to-plant bioconcentration factor (Br) to K^, based on varied soil and plant concentration data:

logBr= 1.588 - 0.578 • logKm

U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustion Emissions. Environmental Criteria and Assessment Office. Office of
Research and Development. EPA/000/6-90/003. January.

This is one of the source documents for the equation in Table B-3-9. This document also notes:

(1) the uptake of organic compounds from soil and transport of these compounds into forage,
(2) and that grain is dependent on the solubility of compounds in water, which is inversely proportional to the octanol-water partition coefficient (K^,).

U.S. EPA. 1992. Technical Support Document for Land Application of Sewage Sludge. Volumes I and II. Office of Water. Washington, D.C. EPA 822/R-93-001a.

Source of plant uptake response factors for arsenic, cadmium, nickel, selenium, and zinc. Plant uptake response factors can be converted to BCFs by multiplying the plant uptake
response factor by a factor of 2. •

U.S. EPA. 1995. Review Draft Development of Human Health Based and Ecologically Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and II. Office of Solid
Waste. March 3.

This document recommends using the bioconcentration factors Bv and Br from Baes, Sharp, Sjoreen, and Shor (1984) for calculating the uptake of inorganics into vegetative and
nonvegetative growth, respectively.
B-159
-------
r
TABLE B-3-9

FORAGE/SILAGE/GRAIN CONCENTRATION DUE TO ROOT UPTAKE
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 4)

Although most bioconcentration factors employed in this document came from Baes, Sharp, Sjoreen, and Shor (1984), values for some inorganics were apparently obtained from plant
uptake response slope fectors. These uptake response slope factors were calculated from field data, such as metal loading rates and soil metal concentrations. However, the
methodologies and references used to calculate the uptake response slope factors are not clearly identified.

(Page 1 of 8)
Description
This equation first estimates the daily amount of COPCs by cattle through the ingestion of contaminated plant and soil material. The equation then recommends the use of biotransfer factors to
transform the daily animal intake of a COPC (mg COPC/day) into an animal COPC tissue concentration (mgCOPC/kg FW tissue).

The limitations and uncertainty introduced in calculating this variable include the following:

(1) Variables P, and Cs are COPC- and site-specific. Uncertainties associated with these variables are site-specific.
(2) Uncertainties associated with the variables Ft Qs, and Qp, are expected to be minimal.
(3) The use of a single Babetf value for each COPC may not accurately reflect site-specific conditions. It is not clear whether the default values are likely to under - or overestimate A^.

Based on the information below, Ahe^ is dependent on the concentrations of COPCs estimated in plant feeds and soil, and the biotransfer factor estimated for each constituent.
Equation
For mercury modeling, beef concentration due to plant and soil ingestion is calculated for divalent mercury (Hg24) and methyl mercury (MHg) using their respective P,, Cs, and Babetf values.
Variable
Description '
Units
V;.CAX>v^:4''^^ ;,,,v v.y •' *< •#;•„&::••',- v^ ;• *"
Concentration of COPC in beef
mg COPC/kg
FW tissue
Fraction of plant type (i) grown on
contaminated soil and ingested by
the animal
unitless
1
This variable is site- and plant type-specific. Plant types for cattle are typically identified as grain, forage, and silage.
U.S. EPA OSW recommends that a default value of 1.0 be used for all plant types when site-specific information is not
available. This is consistent with U.S. EPA (1990), U.S. EPA (1994a), U.S. EPA (1994b) andNC DEHNR (1997),
which recommend that 100 percent of the plant materials ingested by cattle be assumed to have been grown on soil
contaminated by emissions.

The following uncertainty is associated with this variable:

(1) 100 percent of the plant materials eaten by cattle are assumed to be grown on soil contaminated by emissions.
This may overestimate Abetf.
B-161
-------
TABLE B-3-1G
BEEF CONCENTRATION DUE TO PLANT AND SOIL DIGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 8)
Variable
Description
Units
Value
Qp, Quantity of plant type (i) ingested
by the animal per day
kgDW
plant/day
Forage: 8.8
Silage: 2.5
Grain: 0.47
This variable is site- and plant type-specific; plant types for cattle are typically identified as grain, forage, and silage.
U.S. EPA OSW recommends that cattle raised by subsistence beef farmers be evaluated by using the following values
for Qp: forage (8.8), silage (2.5), and grain (0.47). These values are consistent with U.S. EPA (1990), U.S. EPA
(1994c), and NC DEHNR (1997).

Although not typically recommended by U.S. EPA —because subsistence beef farmers rely on a higher
percentage of forage and silage to feed cattle, whereas typical beef farmers rely on greater amounts of grain to
feed cattle—it may be appropriate in site-specific cases to evaluate cattle raised by typical beef farmers by
using the following values for Qp: forage (3.8), silage (1.0), and grain (3.8). These values are also consistent
with U.S. EPA (1990), U.S. EPA (1994c), and NC DEHNR (1997).

The reference documents cite Boone, Ng, and Palms (1981), NAS (1987), McKone and Ryan (1989), and Rice (1994) as
primary references for plant ingestion rates.

Uncertainties introduced by this variable include the following:

(1) The recommended daily grain ingestion rate of 0.47 kg dry weight (DW)/day is calculated indirectly from (1) a
recommended total daily dry matter intake of 11.8 kg DW plant/day, based on NAS (1987) and McKone and
Ryan (1989), as cited in EPA (1990), and (2) daily ingestion rates of forage (8.8 kg/day) and silage (2.5 kg
DW/day), recommended by Boone, Ng, and Palms (1981). However, Boone, Ng, and Palms (1981)
recommended an alternative daily grain ingestion rate of 1.9 kg DW/day, about four times higher than the rate
recommended by U.S. EPA. As shown in Equations in Tables B-3-7 through B-3-9, the concentrations of
COPCs in forage, silage, and grain are calculated similarly. Therefore, the relative amounts of forage, silage,
and grain ingested daily have a limited effect on the intake of COPCs, if the total daily intake of dry matter is
held constant. Therefore, limited uncertainty is introduced.
(2) The daily ingestion rates (total and plant type-specific) recommended may not accurately represent site-specific
or local conditions. Therefore, A^nasy be under- or overestimated, but limited degree.
B-162
-------
TABLE B-3-10
BEEF CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)
(Page 3 of 8)
Variable
P,
Description
Concentration of COPC in plant
type ft) ingested by the animal
Unite ..
mg/kgDW
Value
Varies
This variable is COPC-, site-, and plant type-specific; plant types for cattle are typically identified as grain, forage, and
silage. Values forPd, Pv, and Pr are calculated by using the equations in Tables B-3-7, B-3-8, and B-3-9; and then
summed for each plant type to determine Pt.

Uncertainties introduced by this variable include the following:

Some of the variables in the equations in Tables B-3-7, B-3-8, and B-3-9—including Cs, Cyv, Q, Dydp, and
Dywp—are COPC- and site-specific. Uncertainties associated with these variables are site-specific.
In the equation in Table B-3-7, uncertainties associated with other variables include the following: Fv (values
for organic compounds estimated on the basis of the behavior of polystyrene microspheres), Rp (estimated on
the basis of a generalized empirical relationship), ty (estimation process does not consider chemical
degradation), and Yp (estimated on the basis of national harvest yield and area planted values). All of these
uncertainties contribute to the overall uncertainty associated with/*,.
In the equation in Table B-3-8, COPC-specific Bv values for nondioxin-like compounds may be overestimated
by up to one order of magnitude, based on experimental conditions used to develop the algorithm to estimate
Bv values.
In the equation in Table B-3-9, COPC-specific plant-soil biotransfer factors (Br) may not reflect
site-specific conditions. This may be especially true for inorganic COPCs for which estimates of fir would be
more accurately estimated by using plant uptake response slope factors.
(1)

(2)

(3)

(4)
Quantity of soil ingested by the
animal
kg/day
0.5
This variable is site-specific. U.S. EPA OSW recommends that the soil ingestion rate of 0.5 kg/day be used This is
consistent with NC DEHNR (1997) and U.S. EPA (1994c), which cite USDA (1994), Rice (1994), and NAS (1987).
These references are described below.

Although not typically recommended by U.S. EPA —because subsistence beef farmers rely on a higher percentage forage
to feed cattle, whereas typical beef farmers rely on greater amounts of grain to feed cattle—it may be appropriate in site-
specific cases to evaluate cattle raised by typical beef farmers by using a value for Qs of 0.25 kg/day. This is consistent
with NC DEHNR (1997), which cites Rice (1994) as the source of this value. These references are described below.

Uncertainties introduced by this variable include the following:

(1) The recommended soil ingestion rate may not accurately represent site-specific or local conditions. However,
any differences between the recommended value and site-specific or local soil ingestion rates are expected to'
be small. Therefore, any uncertainty introduced is also expected to be limited.
B-163
-------
TABLE B-3-10
BEEF CONCENTRATION DUE TO PLANT AND SOIL BSfGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 8)
Variable
Description
Units
Value
Cs
Average soil concentration over
exposure duration
mgCOPC/kg
soil
Varies
This variable is COPC- and site-specific, and should be calculated by using the equation in Table B-3-1. Uncertainties
introduced by this variable are site-specific.
Bs
Soil bioavailability factor
unitless
1.0
The soil bioavailability factor, Bs, can be thought of as the ratio between bioconcentration (or biotransfer) factors for soil
and vegetation for a given contaminant The efficiency of transfer from soil may differ from efficiency or transfer from
plant material for some COPCs. If the transfer efficiency is lower for soils, than this ratio would be less than 1.0. If it is
equal or greater than that of vegetation, the Bs would be equal to or greater than 1.0.

Since there is not enough data regarding bioavailability from soil, U.S. EPA OSW recommends a default value of 1.0 for
Bs, until more COPC data becomes available for this parameter. There is a fair amount of uncertainty associated with
the use of this default value, because some COPCs may be much less bioavailable from soil than from plant tissues.
Biotransfer factor for beef
day/kg FW
tissue
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.
Baberf is defined as the ratio of the COPC concentration in animal tissue (mg COPC/kg animal tissue) to the daily intake
of the COPC (mg COPC/day) by the animal.

Uncertainties introduced by this variable include the following:

(1) U.S. EPA OSW recommends that Ba^ values for organic COPCs other than dioxins and furans be calculated
by using the regression equation developed on the basis of a study of 29 organic compounds. Values calculated
by using this regression equation may not accurately represent the behavior of organic COPCs under
site-specific conditions. Therefore, estimates of Ba^ and, therefore, /^ may be under- or overestimated to
some degree.
(2) . U.S. EPA OSW recommends use of Bataf values for dioxins and furans developed by U.S. EPA (1995). These
values were developed by using experimental data for a single cow from McLachlan, Thoma, Reissinger, and
Hutzinger (1990). The uptake and distribution of dioxins and furans in this single animal may not accurately
represent the behavior of these compounds in livestock under site-specific conditions. Therefore, Ba,^ and
Aiuf value may be under- or overestimated to some degree.
(3) U.S. EPA recommended that Babaf values for metals be calculated by using single COPC-specific uptake
factors developed by Baes, Sharp, Sjoreen, and Shor (1984). These uptake factors may not accurately represent
the behavior of inorganic COPCs under site-specific conditions; therefore, Ba^ and, therefore, Abaf value may
be under- or overestimated to some degree. ^^
B-164
-------
TABLE B-3-10
BEEF CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of 8)
Variable
MF
<-\ 'v>. Description J
Metabolism factor
,' , Wtt " '•
unitless
• " Value • a, ' " *
0.01 and 1.0
This variable is COPC-specific. Based on a study by Jkeda et al. (1980), U.S. EPA (1995a) recommended using a
metabolism factor to account for metabolism in animals to offset the amount of bioaccumulation suggested by biotransfer
factors. MF applies only to beef, milk, and pork. It does not apply to direct exposures to air, soil, or water, or to
ingestion of produce, chicken, or fish. U.S. EPA (1995b) recommended an MF of 0.01 for bis(2-ethylhexyl)phthalate
(BEHP) and 1.0 for all other contaminants.
B-165
-------
TABLE B-3-10

BEEF CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 6 of8)

REFERENCES AND DISCUSSION

Baes, C.F., RD. Sharp, AJL Sjoreen, and R.W. Shor. 1984. "Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionuclides Through Agriculture." Oak
Ridge National Laboratory, Oak Ridge, Tennessee.

U.S. EPA (1994c) recommends Baes Sharp, Sjoreen, and Shor (1984) as a source of Ba^ values for inorganics.

Boone, F.W., Yook C. Ng, and John M. Palms. 1981. "Terrestrial Pathways of Radionuclide Particulates." Health Physics, Vol. 41, No. 5, pp. 735-747. November.

This document is identified as a source of plant ingestion rates. Boone, Ng, and Palms (1981) reports forage, grain, and silage ingestion rates of 8.8,1.9, and 2.5 kg DW/day,
respectively, for subsistence beef cattle.

Ikeda, G.J., P.P. Sapenza, and J.L. Couvillion. 1980. "Comparative distribution, excretion, and metabolism of di(2-ethylhexyl)phthalate in rats, dogs, and pigs." Food Cosmet. Toxicology.
18:637- 642.

McKone, T.E., and P.B. Ryan. 1989. Human Exposures to Chemicals Through Food Chains: An Uncertainty Analysis. Livermore, California: Lawrence Livermore National Laboratory Report.
UCRL-99290.

This document is cited as a source of plant ingestion rates. According to U.S. EPA (1990), McKone and Ryan (1989) report an average total subsistence ingestion rate of 12 kg DW/day
for the three plant feeds, which is consistent with the total recommended by other guidance documents for subsistence cattle (that is, forage, grain, and silage total of 11.8 kg DW/day).

McLachlan, M.S., H. Thoma, M. Reissinger, and 0. Hutzinger. 1990. "PCDD/F in an Agricultural Food Chain, Part 1: PCDD/F Mass Balance of a Lactating Cow." Chemosphere, Vol. 20, Nos.
7-9, pp. 1013-1020.

This document is identified as a source of cow milk experimental data used hi the U.S. EPA (1992) dioxin document to calculate bioconcentration factors with units of kilograms
feed/kilogram tissue. As described for U.S. EPA (1995) below, these bioconcentration factors were converted to Ba^ values.

National Academy of Sciences (NAS). 1987. Predicting Feed Intake of Food-Producing Animals. National Research Council, Committee on Animal Nutrition, Washington, D.C.

This document is identified as a source of food ingestion rates. NC DEHNR (1997) and U.S. EPA (1994c) note that NAS (1987) reports a daily dry matter intake that is 2 percent of an
average beef cattle body weight of 590 kilograms. This results in a daily total intake rate of 11.8 kg DW/day, and the daily soil ingestion rate of approximately 0.5 kg soil/day (based on
USDA [1994]).

NC DEHNR. 1997. Final NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is a reference source for the equation in Table B-3-10. This document also recommends the following:

• Forage, grain, and silage ingestion rates of 3.8,3.8, and 1.0 kg DW/day, respectively, for typical farmer beef cattle, based on Rice (1994)
• ' Use of regression equation from Travis and Arms (1988) to calculate biotransfer factors for beef, Babs^
B-166
-------
TABLE B-3-10

BEEF CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 7 of 8)

NC DEHNR (1997) recommends forage, grain, and silage ingestion rates of 3.8,3.8, and 1.0 kg dry weight/day, respectively, for typical farmer beef cattle. NC DEHNR (1997) reports
Rice (1994) as a references for these variable.

Travis, C.C., and A.D. Arms. 1988. "Bioconcentration of Organics in Beef, Milk, and Vegetation." Environmental Science and Technology. 22:271-274

For organic COPCs, U.S. EPA (1990 and 1994c):

(1) recommend that the regression equation from this document (see below) be used to calculate biotransfer factors for beef (Ba^
(2) report a positive correlation between log K^ and Ba^ values, and
(3) recommend using log Km to calculate Babe^ values for organic compounds, as presented in the following regression equation:

where

Bate!f = Biotransfer factor for beef (day/kg)
Km = Octanol-water partition coefficient (unitless) (see Appendix A-3)

This document recommends fat content values for beef and milk of 25 and 3.08 percent, respectively.

U.S. Department of Agriculture (USDA). 1994. Personal Communication Between G.F. Fries, and Glenn Rice and Jennifer Windholtz, U.S. Environmental Protection Agency, Office of Research
and Development. Agricultural Research Service. March 22.

NC DEHNR (1997) and U.S. EPA (1994c) note that this reference reports soil ingestion for cattle to be 4 percent of the total daily dry matter intake.

This document recommends an F, value of 1; this value assumes that 100 percent of the plant materials ingested by cattle have been grown on soil contaminated by emissions.

U.S. EPA. 1993. Technical Support Document for Land Application of Sewage Sludge. Volumes I and II. EPA 822/R-93-001a. Office of Water. Washington, D.C.

U.S. EPA (1995) recommended.that bioconcentration factors for the metals cadmium, mercury, selenium, and zinc presented in this document be used to derive Bateif values. Following
the method recommended by U.S. EPA (1992) for dioxins, the bioconcentration factors—with units of (kilograms feed DW/kilogram tissue DW—are divided by feed ingestion rates
(kilogram feed DW/day]) to calculate 5awvalues (day/kilogram tissue DW). A feed ingestion rate of 20 kg DW/day is recommended by U.S. EPA (1993).

U.S. EPA. 1994a. Estimating Exposures to Dioxin-like Compounds. Volume III: Site-specific Assessment Procedures. Office of Research and Development. EPA/600/6-88/005Cc. External
Review Draft. June.

B-167
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TABLE B-S-IO

BEEF CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 8 of 8)

This document recommends an F, value of 1; this value assumes that 100 percent of the plant materials ingested by cattle have been grown on soil contaminated by emissions.

U.S. EPA. 1994b. Draft Exposure Assessment Guidancefor RCRA Hazardous Waste Combustion Facilities. Office of Solid Waste and Emergency Response. EPA-530-R-94-021. April.

This document recommends an F, value of 1; this value assumes that 100 percent of the plant materials ingested by cattle have been grown on soil contaminated by emissions.

U.S. EPA. 1994c. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document is one of the reference source documents for the equation in Table B-3-10. This document also recommends the following:

• An F, value of 100 percent
• Qp, values for forage, silage, and grain of 8.8,2.5 and 0.47 kg dry weight/day, respectively, based on Boone, Ng, and Palms (1981), NAS (1987), McKone and Ryan (1989), and
Rice (1994)
A soil ingestion rate for cattle (6W) of 0.5 kg/day, based on USDA (1994), Rice (1994), and NAS (1987)
• A range (l.lx 10"09 to 4.8 day/kg animal tissue) of Bataf values-based on Baes, Sharp, Sjoreen, and Shor (1984), McLachlan, Thoma, Reissinger, and Hutzinger (1990), and
Travis and Arms (1988).

U.S. EPA. 1995a. Further Issues for Modeling the Indirect Exposure Impacts from Combustor Emissions. Office of Research and Development Washington, D.C. January 20.

U.S. EPA (1995)a does not recommend using the Travis and Arms (1988) equation to calculate Babetf values for dioxin-like compounds. U.S. EPA (1995a) notes that cow milk
experimental data derived by McLachlan (1990) was used in the U.S. EPA (1992) dioxin exposure document to calculate biotransfer factors with units of (kilogram feed/kilogram tissue).
U.S. EPA (1995a) then divides these biotransfer factors by feed ingestion rates (kilogram feed/day) to calculate Ba^.m values for dioxin and furan compounds. U.S. EPA (1995a) then
recommends that Ba^ be extrapolated from these dioxin and furan Ba^ values. The BamiUc values are converted to Bate^by assuming the fat contents of beef and milk. U.S. EPA
(1992) assumes that milk is 3.5 percent fat and that beef is 19 percent fat. Therefore, U.S. EPA (1995a) concludes thatBaw would be 5.4 times higher (19/3.5) than Ba^j.

This document recommends using BCF for the metals cadmium, mercury, selenium, and zinc, presented in U.S. EPA (1993), to calculate Ba^ values for these metals. Specifically, the
BCFs from U.S. EPA (1993)—which are in units of kilogram feed DW/kilogram tissue DW are divided by a feed ingestion rate of 20 kilograms DW/day to arrive at Ba^ values in units
of day/kilogram tissue DW, according to the methodology developed for dioxins (U.S. EPA 1992).

U.S. EPA. 1995b. "Waste Technologies Industries Screening Human Health Risk Assessment (SHHRA): Evaluation of Potential Risk from Exposure to Routine Operating Emissions." Volume
V. External Review Draft. U.S. EPA Region 5, Chicago, Illinois.

U.S. EPA. 1997a. Exposure Factors Handbook. "Food Ingestion Factors". Volume H. SAB Review Draft. EPA/600/P-95/002F. August.

U.S. EPA. 1997b. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-168
-------
TABLE B-3-11
MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of 9)
Description
This equation first estimates the daily amount of COPCs taken in by cattle through the ingestion of contaminated plant and soil material. The equation then recommends the use of biotransfer
factors to transform the daily animal intake of a COPC (mg COPC/day) into an animal (dairy cattle) milk COPC concentration (mg COPC/kg FW tissue).

The limitations and uncertainty introduced in calculating this variable include the following:

(1) Variables P, and Cs are COPC- and site-specific. Uncertainties associated with these variables are site-specific.
(2) Uncertainties associated with the variables F,, Qs, and Qp, are expected to be minimal.
(3) 5
-------
I
TABLE B-3-11
MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 9)
Variable
Description
Units
Value
Quantity of plant type (i) ingested
by the animal per day
kgDW
plant/day
Forage: 13.2
Silage: 4.1
Grain: 3.0
This variable is site- and plant type-specific; plant types for cattle are identified as grain, forage, and silage. U.S. EPA
OSW recommends that cattle raised by subsistence milk fanners be evaluated by using the following values for Qp:
forage (13.2), silage (4.1), and grain (3.0).

The recommended plant type-specific Qp, values were calculated as follows. First, total dry matter intake (DMI) was
estimated as 20 kg DW/day, based on information presented in NAS (1987). Second, data from Boone, Ng, and
Palms (1981) were used to separate the total DMI into plant type-specific fractions. Finally, the
recommended plant type-specific Qp, values were calculated by multiplying the estimated total DMI (20 kg DW/day) by
the plant type-specific fractions. For example, the Qp, for forage was calculated as 20 kg DW/day • 0.65 = 13.2
kg DW/day. These values are consistent with U.S. EPA (1990), U.S. EPA (1993), U.S. EPA (1994b), and U.S. EPA
(1995), and NC DEHNR (1997). These reference documents cite Boone, Ng, and Palms (1981), NAS (1987), McKone
and Ryan (1989), and Rice (1994) as primary references for plant ingestion rates.

Although not typically recommended by U.S. EPA—because subsistence milk farmers rely on a higher percentage of
forage and silage to feed cattle, whereas typical milk farmers rely on a greater amount of grain to feed cattle—it may be
appropriate in site-specific cases to evaluate cattle raised by typical milk farmers by using the following values for Qp:
forage (6.2), silage (1.9), and grain (12.2), as presented in Rice (1994). These values are also consistent with U.S. EPA
(1990), U.S. EPA (1993), U.S. EPA (1994b), and NC DEHNR (1996).

Uncertainties introduced by this variable include the following:

(1) The plant type-specific Qp, values were calculated based on a total DMI of 20 kg DW/day (NAS 1987) rather
than the total DMI of 17 kg DW/day presented in Boone, Ng, and Palms (1981) and McKone and Ryan (1989).
Site-specific total DM values may vary.
(2) The plant type-specific fractions calculated from Boone, Ng, and Palms (1981) may not accurately represent
site-specific or local plant type-specific fractions.
B-170
-------
TABLE B-3-11
MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of9)
Variable
Description <..
Unite .
Value
P, Concentration of COPC in plant
type (i) ingested by the animal
rag/kg DW
Varies
This variable is COPC-, site-, and plant type-specific; plant types for cattle are identified as grain, forage, and silage.
Values forPd, Pv, and Pr are calculated by using the equations in Tables B-3-7, B-3-8, and B-3-9; and then summed for
each plant type to determine P,.

Uncertainties introduced by this variable include the following:

(1) Some of the variables in the equations in Tables B-3-7, B-3-8, and B-3-9—including Cs, Cyv, Q. Dydp, and
Dywp—are COPC- and site-specific. Uncertainties associated with these variables are site-specific.
(2) In the equation in Table B-3-7, uncertainties associated with other variables include the following: Fv (values
for organic compounds estimated on the basis of the behavior of polystyrene microspheres), Rp (estimated on
the basis of a generalized empirical relationship), kp (estimation process does not consider chemical
degradation), and Yp (estimated on the basis of national harvest yield and area planted values). All of these
uncertainties contribute to the overall uncertainty associated with/',.
(3) In the equation in Table B-3-8, COPC-specific Bv values for nondioxin-like compounds may be overestimated
by up to one order of magnitude, based on experimental conditions used to develop the algorithm to estimate
Bv values.
(4) In the equation in Table B-3-9, COPC-specific plant-soil biotransfer factors (Br) may not reflect
site-specific conditions. This may be especially true for inorganic COPCs for which estimates of Br would be
more accurately estimated by using plant uptake response slope factors.
B-171
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TABLE B-3-11
MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 9)
Variable
Description
Units
Value
Quantity of soil ingested by the
animal
kg/day
0.4
This variable is site-specific. U.S. EPA OSW recommends the 0.4 kg/day soil ingestion rate be used. This is consistent
with NC DEHNR (1997) and U.S. EPA (1994b), which cite USDA (1994), Rice (1994), and NAS (1987). Briefly, the
recommended Qs value was calculated as follows. First, a total DMI was estimated as 20 kg DW/day based on
information presented in NAS (1987). Second, USDA (1994) estimates that Qs equals 2 percent of the total DMI.
Finally, the recommended Qs value was calculated as 20 kg DW/day • 0.02 = 0.4 kg DW /day.

Although not typically recommended by U.S. EPA—because subsistence milk farmers rely on a higher percentage forage
to feed cattle, while typical milk farmers rely on greater amounts of grain to feed cattle—it may be appropriate in site-
specific cases to evaluate cattle raised by typical milk farmers using a value for Qs of 0.25 kg/day. This is consistent
with NC DEHNR (1997), which cites Rice (1994) as the source of this value.

Uncertainties introduced by this variable include:

(1) The recommended Qs value was based on a total DMI of 20 kg DW/day NAS (1987) rather than the total DM
of 17 kg DW/day presented in Boone, Ng, and Palms (1981) and McKone and Ryan (1989). To the extent that
site-specific or local total DM values may vary, Amllt may be under- or overestimated to a limited degree.
(2) USDA (1994) states that Qs equals 2 percent of the total DM for dairy cattle on a subsistence farm. Although
the basis of the estimate of 2 percent is not known, it is apparent that to the extent that site-specific or local Qs
values are different than 2 percent, AMt may be under- or overestimated to some degree.
Cs
Average soil concentration over
exposure duration
mg COPC/kg
soil
Varies
This variable is COPC- and site-specific, and should be calculated by using the equation in Table B-3-1. Uncertainties
are site-specific.
Bs
Soil bioavailability factor
unitless
1.0
The soil bioavailability factor, Bs, can be thought of as the ratio between bioconcentration (or biotransfer) factors for soil
and vegetation for a given COPC. The efficiency of transfer from soil may differ from efficiency or transfer from plant
material for some COPCs. If the transfer efficiency is lower for soils, than this ratio would be less than 1.0. If it is equal
or greater than that of vegetation, the Bs would be equal to or greater than 1.0.

(Page 5 of 9)
Variable
Units
Value
Biotransfer factor for milk
day/kg FW
tissue
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3. Ba^ is defined as the ratio of the COPC concentration in milk (mg COPC/kg tissue) to the daily intake
of the COPC (mg COPC/day) by the animal.

Uncertainties introduced by this variable include the following:

(1) U.S. EPA OSW recommends that Ba^lk values for organic COPCs other than dioxins and fiirans be calculated
by using the regression equation developed on the basis of a study of 29 organic compounds. Values calculated
by using this regression equation may not accurately represent the behavior of organic COPCs under
site-specific conditions. Therefore, estimates ofBa^n and, therefore, Amm may be under- or overestimated to
some degree.
(2) U.S. EPA OSW (1994c) recommends use of Ua^ values for dioxins and fiirans developed by U.S. EPA
(1995). These values were developed by using experimental data for a single cow from McLachlan, Thoma,
Reissinger, and Hutzinger (1990). The uptake and distribution of dioxins and fiirans in this single animal may
not accurately represent the behavior of these compounds in livestock under site-specific conditions. Therefore,
BaMh and Amttk value may be under- or overestimated to some degree.
(3) U.S. EPA recommended that BamlK values for metals be calculated by using single COPC-specific uptake
factors developed by Baes, Sharp, Sjoreen, and Shor (1984). These uptake factors may not accurately represent
the behavior of inorganic COPCs under site-specific conditions; therefore, Bamttk and, therefore, Amttk value may
be under- or overestimated to some degree.
MF
Metabolism factor
unitless
0.01 and 1.0
This variable is COPC-specific. Based on a study by Ikeda et al. (1980), U.S. EPA (1995a) recommended using a
metabolism factor to account for metabolism in animals to offset the amount of bioaccumulation suggested by biotransfer
factors. MF applies only to beef, milk, and pork. It does not apply to direct exposures to air, soil, or water, or to
ingestion of produce, chicken, or fish. U.S. EPA (1995b) recommended an MF of 0.01 for bis(2-ethylhexyl)phthalate
(BEHP) and 1.0 for all other COPCs. __^_
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TABLE B-3-11

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(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 6 of 9)

REFERENCES AND DISCUSSION

Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radiomclides through Agriculture, Oak
Ridge National Laboratory, Oak Ridge, Tennessee.

U.S. EPA (1994c) recommends Baes, Sharp, Sjoreen, and Shor (1984) as a source of (1) BaM values for inorganics, and (2) water content of 0.9 for cow's milk, which can be used to
convert BaMt values in dry weight to wet weight

Belcher, G.D., and C.C. Travis. 1989. Modeling Support for the RUM and Municipal Waste Combustion Project Final Report on Sensitivity and Uncertainty Analysis for the Terrestrial Food
Chain Model. Prepared under IAG-1824-A020-A1 by Oak Ridge National Laboratory for U.S. EPA Office of Health and Environmental Assessment, Environmental Criteria and
Assessment Office. Cincinnati, Ohio.

This document was cited by U.S. EPA (1990) as the source ofBanUt values for cadmium.

Boone, F.W., Yook C. Ng, and John M. Palms. 1981. "Terrestrial Pathways of Radionuclide Particulates." Health Physics. Vol. 41, No. 5, pages 735-747. November.

This document is identified as a source of plant ingestion rates. Boone, Ng, and Palms (1981) reports a total forage, grain, and silage ingestion rate of 17 kg DW/day for subsistence
dairy cattle. Also, this document states that this total DMI of 17 kg DW/day is made up of the following plant type-specific fractions: forage (65 percent), grain (15 percent), and silage
(20 percent).

USDA. 1994. Personal Communication Regarding Soil Ingestion Rate for Dairy Cattle. Between G.F. Fries, Agricultural Research Service, and Glenn Rice and Jennifer Windholtz, U.S. EPA,
Office of Research and Development. March 22.

NC DEHNR (1997) and EPA (1994c) note that USDA (1994) reports soil ingestion to be 2 percent of the total DM for dairy cattle on subsistence farms.

Ikeda, G.J., P.P. Sapenza, and J.L. Couvillion. 1980. "Comparative distribution, excretion, and metabolism of di(2-ethylhexyl)phthalate hi rats, does, and pigs." Food Cosmet Toxicolosv
18:637- 642.

McKone, T.E., and P.B. Ryan. 1989. Human Exposures to Chemicals Through Food Chains: An Uncertainty Analysis. Livermore, California: Lawrence Livermore National Laboratory Report
UCRL-99290.

This document is cited as a source of plant ingestion rates. According to EPA (1990), McKone and Ryan (1989) report an average total subsistence ingestion rate of 17 kg dry weight/day
for the three plant feeds, which is consistent with the total recommended by Boone, Ng, and Palms (1981) for subsistence cattle.

McLachlan, M.S., H. Thoma, M. Reissinger, and O. Hutzinger. 1990." PCDD/F in an Agricultural Food Chain, Part 1: PCDD/F Mass Balance of a Lactating Cow." Chemosphere Vol 20 Nos
7-9, pp. 1013-1020.

This document is identified as a source of cow milk experimental data used in the U.S. EPA (1992) dioxin document to calculate bioconcentration factors with units of (kg feed/kg milk).
This study inventoried the dioxins and furans ingested by a single lactating cow, and the dioxins and furans emitted through the milk. The volume of milk generated by the cow was also
given.
B-174
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TABLE B-3-11

MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 7 of 9)

NAS. 1987. Predicting Feed Intake of Food-Producing Animals. National Research Council, Committee on Animal Nutrition. Washington, D.C.

NC DEHNR (1997) and U.S. EPA (1994c) note that this document reports a daily DMI equal to 3.2 percent of an average dairy cattle body weight of 630 kilograms; this results in a daily
DMI of 630 kg DW • 0.032 = 20.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

Grains such as corn may be grown specifically as cattle feed. COPC uptake into these feed materials may occur through root uptake, wet and dry deposition of particulate-bound COPCs
on plants, and vapor-phase uptake of COPCs through plant foliage. Plants are classified as "protected" if they have an outer covering that acts as a barrier to direct deposition and vapor
uptake of air contaminants. NC DEHNR (1997) classifies grains as protected, and recommends that only root uptake of COPCs be evaluated for grains. Because silage may consist of
. forage materials that have been stored and fermented, it should be treated as forage (that is, as unprotected).

This document is a reference source for the equation in Table B-3-1 1 . This document also recommends the following:

(1) AnF, value of 1
(2) Forage, silage, and grain ingestion rates (gpi) of 13.2, 4.1, and 3.0 kg DW/day for subsistence dairy farmer cattle, respectively, based on a total DMI of 20 kg DW/day
calculated from NAS (1987) and plant type-specific fractions from Boone, Ng, and Palms (1981)
(3) Forage, silage, and grain ingestion rates (Qp j of 6.2, 1 .9, and 12.2 kg DW/day, respectively for typical dairy farmer cattle based on USDA (1 994)
(4) A Qs value of 0.4 kg/day, based on NAS (1987) and USDA (1994)
(5) Bamm values ranging from 3.5 x 10-l° to 4.8, based on Baes, Sharp, Sjoreen, and Shor (1984) and Travis and Arms (1988).

NC DEHNR (1997) recommends forage, grain, and silage ingestion rates of 3.8, 3.8, and 1.0 kg dry/day, respectively, for typical farmer milk cattle.

Travis, C.C., and A.D. Arms. 1988. "Bioconcentration of Organics in Milk, and Vegetation". Environmental Science and Technology. 22:271-274

For organic COPCs, NC DEHNR (1997), U.S. EPA (1990), and U.S. EPA (1994c) recommend that the regression equation from Travis and Arms (1988) be used to calculate biotransfer
factors for milk (Ba raM). Travis and Arms (1988) reports a positive correlation between log A^, and BO^R values and recommends using log Km to calculate Bamilk values for organic
compounds. Specifically, the following regression equation is recommended:
where
A
Biotransfer factor for milk (day/kg FW tissue)
Octanol-water partition coefficient (unitless) (see Appendix A-3)
B-175
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TABLE B-3-11

MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 8 of 9)

U.S. EPA. 1990. Interim Final Methodologyfor Assessing Health Risks Associatedwith Indirect Exposure to Combtistor Emissions. Environmental Criteria and Assessment Office. Officeof
Research and Development EPA/600/6-90/003. January.

This document is a reference source for the equation in Table B-3-10. This document also recommends the following:

(1) An F, value of 1
(2) Forage, silage, and grain ingestion rates (QpD of 11.0,3.3, and 2.6 kg DW/day; these are reportedas average ingestion rates and are based on a total DMI of 17 kg DW/day, as
reported in Boone, Ng, and Palms (1981), and McKone and Ryan (1989)
(3) Bamm values for organics, calculated by using the regression equation developed by Travis and Arms (1988), and aflout value for cadmium from Belcher and Travis (1989).

U.S. EPA. 1992. Technical Support Document for Land Application of Sewage Sludge. Volumes I andH. EPA 822/R-93-001a. Office of Water. Washington, D.C.

U.S. EPA (1995) recommends that bioconcentration factors for the metals cadmium, mercury, selenium, and zinc, cited by U.S. EPA (1993), be used to derive BamM values. Following
the method recommended by U.S. EPA (1992) for dioxins, the bioconcentration factors, with units of (kg feed DW/kg tissue DW), are divided by feed ingestion rates (kg feed DW/day) to
calculate BaMk values (day/kg FW tissue). A feed ingestion rate of 20 kg DW/day is recommended by U.S. EPA (1993). It is likely that the feed ingestion rate from U.S. EPA (1993) is
based on NAS (1987).

U.S. EPA. 1994a. Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Solid Waste and Emergency Response. EPA-530-R-94-021. April.

This document recommends a F, value of 1, assuming that 100 percent of the plant materials ingested by cattle have been grown on soil contaminated by combustion unit emissions.

This document is a reference source for the equation in Table B-3-11. This document also recommends the following:

(1) An Rvalue of 1
(2) A forage ingestion rate (Qpj) value of 13.2 kg DW/day, from NAS (1987) and Boone, Ng, and Palms (1981)
(3) -A quantity of soil ingested (0s) value of 0.4 kg/day, based on NAS (1987) and USDA (1994)
(4) BamUt values ranging from 3.5 x 10'10 to 4.8, based on Baes, Sharp, Sjoreen, and Shor (1984), and Travis and Arms (1988)

U.S. EPA. 1994c. Estimating Exposures to Dioxin-Like Compounds. Volume III: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development.
EPA/600/6-88/005CC. June.

This document reported bioconcentration factors for dioxin-like compounds (dioxin and furan congeners) calculated on the basis of experimental data derived by McLachlan, Thoma,
Reissinger, and Hutzinger (1990).

U.S. EPA. 1995a. Further Issuesfor Modeling the Indirect Exposure Impacts from Combustor Emissions. Office of Research and Development Washington, D.C. January.
B-176
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MILK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 9 of 9)

U.S. EPA (1995a) does not recommend using the Travis and Arms (1988) equations to calculate Bamllk values for dioxin-like compounds. U.S. EPA (1995a) notes that cow milk
experimental data derived by McLachlan (1990) was used in the U.S. EPA (1992) dioxin exposure document to calculate biotransfer factors with units of [kg feed/kg tissue]. U.S. EPA
(1995a) then divides these biotransfer factors by feed ingestion rates (kg feed/day) to calculate Ba^n values for dioxin and furan compounds.

(Page 1 of 8)
Description
This equation first estimates the daily intake of COPCs through the ingestion of contaminated plant and soil material. The equation then recommends the use of biotransfer factors to transform
the daily animal intake of a COPC (mg COPC/day) into an animal COPC tissue concentration (mg COPC/kg tissue).

The limitations and uncertainty introduced in calculating this variable include the following:

(1) Uncertainties associated with the variables P, and Cs are COPC- and site-specific.
(2) Uncertainties associated with the variables F> Q, and Qp, are expected to be minimal.
(3) Uncertainties associated with Ba^ values may be significant for two primary reasons: (a) Ba^ for dioxins are calculated from Sam,tt values that are based on metabolism of dioxins
rather than a sow, and (b) the source or methodology used to calculate the Ba^ values for organics other than dioxins and inorganics other than cadmium, mercury, selenium, and zinc
as reported in NC DEHNR (1997) is not known. Therefore, the magnitude and direction of the associated uncertainties cannot be specified.

Based on the information below, ApoA is dependent on the concentrations of COPCs estimated in plant feeds and soil, and the biotransfer factor estimated for each COPC.
Equation
Bapork - MF
For mercury modeling, pork concentration due to plant and soil ingestion is calculated for divalent mercury (Hg*1) and methyl mercury (MHg) using then- respective Ph Cs, and Ba^ values.
Variable
Description
Units
Value
Concentration of COPC in pork
mg COPC/kg FW
tissue
Fraction of plant type (i) grown on
contaminated soil and ingested by
the animal
unitless
1.0
This variable is site- and plant type-specific; plant types for swine are typically identified as grain and silage. U.S.
EPA OSW recommends that a default value of 1.0 be used for all plant types. This is consistent with U.S. EPA
(1990), U.S. EPA (1994a), U.S. EPA (1994c), andNC DEHNR (1996), which recommend that 100 percent of the
plant materials ingested by swine be assumed to have been grown on soil contaminated by emissions.

The following uncertainty is associated with this variable:

(1) 100 percent of the plant materials ingested by cattle are assumed to be grown on soil contaminated by
facility emissions. This may overestimate A^
B-178
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TABLE B-3-12
PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 8)
Variable
Description '
Units
Value
Quantity of plant type (i) ingested
by the animal each day
kg DW plant/day
Silage: 1.4
Grain: 3.3
This variable is site- and plant type-specific; plant types for swine are typically identified as grain and silage. U.S.
EPA OSW recommends that swine raised by subsistence farmers be evaluated by using the following
values for Qp: silage (1.4) and grain (3.3). These Qp, values are based on a total DMI value of 4.7 kg
DW/day, and plant type-specific diet fractions (70 percent grain and 30 percent silage) are based on
U.S. EPA (1982).

NC DEHNR (1997) and U.S. EPA (1990) recommend silage and grain ingestion rates of 1.3 and 3.0 kg
dry/day, respectively, for swine. NC DEHNR (1997) references U.S. EPA (1990) as the source of these ingestion
rates. The difference between the default Qp, values and values recommended by NC DEHNR (1997) and U.S.
EPA (1990) is the total DMI upon which they are based. Specifically, U.S. EPA OSW recommends the use of a
total DMI for swine of 4.7 kg DW/day, based on U.S. EPA (1995), whereas NC DEHNR (1997) and U.S. EPA
(1990) recommend a.total DMI of 4.3 kg dry weight/day.

NCDEHNR (1997) and U.S. EPA (1990) do not differentiate between subsistence and typical hog farmers as they
do for cattle, because it is assumed that forage is not a significant portion of a hog's diet.

Uncertainties introduced by this variable include the following:

(1) The recommended grain and silage ingestion rates may not accurately represent site-specific or
local conditions. Therefore, Qp, and A^* values may be under- or overestimated to some degree.
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TABLE B-3-12

PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 8)
Variable
Description
Units
Value
P,
Concentration of COPC in plant
type (i) ingested by the animal
mg/kgDW
Varies
This variable is COPC-, site-, and plant type-specific; plant types for swine are identified as grain and silage.
Values for Pd, Pv, and Pr are calculated by using the equations in Tables B-3-7, B-3-8, and B-3-9; and then
summed for each plant type to determin Pt.

Uncertainties introduced by this variable include the following:

(1) Some of the variables in the equations in Tables B-3-7, B-3-8, and B-3-9—including Cs, Cyv, Q, Dydp,
and Dywp—are COPC- and site-specific. Uncertainties associated with these variables are site-specific.
(2) In the equation in Table B-3-7, uncertainties associated with other variables include: Fw (values for
organic compounds based on behavior of polystyrene microspheres), Rp (estimated on the basis of a
generalized empirical relationship), kp (estimation process does not consider chemical
degradation) and Yp (estimated based on national harvest yield and area planted values). All of
these uncertainties contribute to the overall uncertainty associated with/*,.
(3) In the equation in Table B-3-8, COPC-specific Bv values for nondioxin-like compounds may be
overestimated by up to one order of magnitude, based on experimental conditions used to develop the
algorithm to estimate Bv values.
(4) In the equation in Table B-3-9, COPC-specific soil-to-plant biotransfer factors (Br) may not reflect
site-specific conditions. This may be especially true for inorganic COPCs for which estimates of
Br would be accurately estimated by using plant uptake response slope factors.
Quantity of soil ingested by the
animal
kg/day
0.37
This variable is site-specific. U.S. EPA OSW recommends that the soil ingestion rate 0.37 kg/day be used.

U.S. EPA (1990) states that sufficient data are not available to estimate swine soil ingestion rates.
NC DEHNR (1997) recommends a soil ingestion rate for swine of 0.37 kg/day. This is estimated by assuming
a soil intake of 8 percent of the total DM. NC DEHNR (1997) does not specify the total DMI used to estimate Qs.
However, mathematically, Qs appears to be based on a total DMI of 4.7 kg DW/day (4.7- 0.08 = 0.37), which is
consistent with U.S. EPA (1995).

The following uncertainty is associated with this variable:

(1) The recommended soil ingestion rate may not accurately represent site-specific or local conditions.
Therefore, Qs and A^ values, may be under- or overestimated to some degree.
Average soil concentration over
exposure duration
mg COPC/kg soil
Varies
This variable is COPC- and site-specific, and should be calculated by using the equation in Table B-3-1.
Uncertainties are site-specific.
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TABLE B-3-12
PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 8)
Variable
Description
Value
Bs
Soil bioavailability factor
unitless
1.0
The soil bioavailability factor, Bs, can be thought of as the ratio between bioconcentration (or biotransfer) factors
for soil and vegetation for a given COPC. The efficiency of transfer from soil may differ from efficiency or transfer
from plant material for some COPCs. If the transfer efficiency is lower for soils, than this ratio would be less than
1.0. If it is equal or greater than that of vegetation, the Bs would be equal to or greater than 1.0.

Due to limited data regarding bioavailability from soil, U.S. EPA OS W recommends a default value of 1.0 for Bs,
until more COPC-specific data is available for this parameter. Some COPCs may be much less bioavailable from
soil than from plant tissues. This uncertainty may overestimate Bs.
Ba,
•pork
Biotransfer factor for pork
day/kg FW tissue
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3. Ba^ is defined as the ratio of the COPC concentration in animal tissue (mg COPC/kg FW tissue)
to the daily intake of the COPC (mg COPC/day) by the animal.

Uncertainties introduced by this variable include the following:

(1) U.S. EPA OSW recommends that Ba^ values for organic COPCs other than dioxins and furans
be calculated by using the regression equation developed on the basis of a study of 29 organic
compounds. Values calculated by using this regression equation may not accurately represent the
behavior of organic COPCs under site-specific conditions. Therefore, estimates of Ba^ and, therefore,
4»r* may be under- or overestimated to some degree.
(2) U.S. EPA OSW recommends use of Ba^ values for dioxins and furans developed by U.S. EPA (1995).
These values were developed by using experimental data for a single cow from McLachlan, Thoma,
Reissinger, and Hutzinger (1990). The uptake and distribution of dioxins and furans in this single
animal may not accurately represent the behavior of these compounds in livestock under site-specific
conditions. Also, using the pork-to-milk fat content ratio to estimate Ba^ values from Bamilk values
assumes that (1) COPCs bioconcentrate in the fat tissues, and (2) there are no differences in metabolism
or feeding characteristics between beef cattle and pigs. Due to uncertainties associated with these
assumptions, Ba^ and Apork values may be under- or overestimated to some degree.
(3) The sources or methodology used to support or estimate Ba^* values presented in NC DEHNR (1997)
are not known. Therefore, the degree to which these values represent the behavior of COPCs under site-
specific conditions cannot be determined.
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TABLE B-3-12
PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of8)
Variable
MF
Description
Metabolism factor
Units
unitless
Value
0.01 and 1.0
This variable is COPC-specific. Based on a study by Bceda et al. (1980), U.S. EPA (1995a) recommended using a
metabolism factor to account for metabolism in animals to offset the amount of bioaccumulation suggested by
biotransfer factors. MF applies only to beef, milk, and pork. It does not apply to direct exposures to air, soil, or
water, or to ingestion of produce, chicken, or fish. U.S. EPA (1995b) recommends an MF of 0.01 for bis(2-
ethylhexyl)phthalate (BEHP) and 1.0 for all other COPCs.
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TABLE B-3-12

PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 6 of 8)

REFERENCES AND DISCUSSION

Boone, F.W., Yook C. Ng, and John M. Palms. 1981. "Terrestrial Pathways of Radionuclide Particulates." Health Physics, Vol. 41, No. 5, pp. 735-747. November.

This document is cited as the source of a total DMI for hogs of 3.4 kg DW/day.

Ikeda, G.J., P.P. Sapenza, and J.L. Couvillion. 1980. "Comparative distribution, excretion, and metabolism of di(2-ethylhexyl)phthalate in rats, dogs, and pigs." Food Cosmet Toxicology
18:637- 642.

McLachlan, M.S., H. Thoma, M. Reissinger, and O. Hutzinger. 1990. "PCDD/F In An Agricultural Food Chain, Part 1:PCDD/F Mass Balance of a Lactating Cow." Chemosphere Vol 20 Nos
7-9, pp. 1013-1020. '

This document presents cow milk experimental data used in U.S. EPA (1994b) to calculate biotransfer factors relating concentrations of dioxins and fiirans in feed to concentrations of
dioxins and furans in cow milk. Specifically, this study inventoried the dioxins and furans ingested by a single lactating cow, the dioxins'and furans emitted through the milk, and the
volume of milk generated by the cow.

U.S. EPA (1995) cited this study as a credible basis for calculating Babe¥ values from Bamllk values based on the ratio of fat content in beef versus milk. NC DEHNR (1997) suggests that
this same methodology can be used to calculate Bapark values for dioxins and furans.

NAS. 1987. Predicting Feed Intake of Food-Producing Animals. National Research Council, Committee on Animal Nutrition, Washington, D.C.

This document presents a total DMI for lactating sows of 5.2 kg DW/day. This document is also cited by U.S. EPA (1995) as the source of a total DMI for swine of 4.7 kg DW/day. As
presented in this document, the value of 4.7 kg DW/day represents the average of specific total DMI values for gilts (young sows) and for lactating sows.

Ng, Y.C., C.S. Colsher, and S.E. Thomson. 1982. Transfer Coefficients for Assessing the Dose from Radionuclides in Meat and Eggs. U.S. Nuclear Regulatory Commission. Final Report.
NUREG/CR-2976.

This document is cited as the source of biotransfer factors (Ba^ for several inorganic COPCs. However, U.S. EPA (1995) notes that "a large degree of uncertainty" exists in many of
the experiments used in this document to develop the biotransfer factors. The biotransfer factors developed by Ng, Colsher, and Thompson (1982) are not recommended for use by U S
EPA.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

Grains such as corn may be grown specifically as swine feed. COPC uptake into these feed materials may occur through root uptake, wet and dry deposition of particulate-bound
constituents on plants, and vapor-phase uptake of COPCs through plant foliage. Plants are classified as "protected" if they have an outer covering that acts as a barrier to 'direct deposition
and vapor uptake of air contaminants. NC DEHNR (1997) classifies grains as protected, and recommends that only root uptake of COPCs be evaluated for grains; because silage may
consist of forage materials that have been stored and fermented, it should be treated as forage (that is, as unprotected).

This document also recommends the following:
B-183
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TABLE B-3-12

PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 7 of 8)

An F, value of 1, assuming that 100 percent of the plant material eaten by swine have been grown on soil contaminated by combustion unit emissions.
Plant type-specific Qp, values for hogs of 3.0 and 1.3 kg DW/day for grain and silage, respectively. This document cites U.S. EPA (1990) as the source of these ingestion rates.
A quantity of soil ingested (Qs) value of 0.37 kg DW/day. This value is calculated as 8 percent of the total DMI (U.S. EPA 1993a). The total DM1 of 4.3 kg DW/day comes
from U.S. EPA (1990).
A range of Bapark values (1.3 x lO^09 to 5.8 day/kg wet tissue); however, the sources of or methodology used to estimate, these values are not identified.
fla^t values for dioxins and furans may be estimated from BaMk values (derived from a study of a single lactating sow, McLachlan, Thoma, Reissinger, Hutzinger 1990) based
on the ratio of fat content (23 percent) of pork (Pennington 1993) and the fat content (3.5 percent) of milk (U.S. EPA 1994b). This methodology is consistent with the approach
recommended by U.S. EPA (1995) for calculating Ba^ values from Bamllt values.
• The source or methodology used to estimate Ba^* values for organics other than dioxins is not identified. However, the following correlation equation correlating Ba^ values
with COPC-specific Km values can be back-calculated from the COPC-specific Ba^ values presented in the document:

log Baport- -7.523 + log Km

Pennington, J.A.T. 1989. Food Values of Portions Commonly Used. 15th ed. Harper and Row. New York.

Cited by NC DEHNR (1997)—actually NC DEHNR (1997) cities "Pennington (1993)" but presents only this document (Pennington 1989) in the reference section—for the estimated fat
content of pork, 23 percent

U.S. EPA. 1982. "Pesticides Assessment Guidelines Subdivision O." Residue Chemistry. Office of Pesticides and Toxic Substances, Washington, D.C. EPA/540/9-82-023.

This document is cited by U.S. EPA (1990) as the source of the assumption that 70 percent of the total DMI for swine is grain and 30 percent is silage.

This document represents total dry matter intake (DMI) rates for hogs and lactating sows of 3.4 and 5.2 kg DW/day, respectively, and recommends ihe average of these two rates (4.3 kg
DW/day) as the total DM. U.S. EPA (1990) cites Boone, Ng, and Palms (1981) as the source of the hog ingestion rate and NAS (1987) as the source of the iactating sow ingestion rate.

This document then assumes that 70 percent of the total DMI for swine is grain and 30 percent is silage; fractions then are used to arrive at the recommended grain ingestion rate of 3.0
kg DW/day (4.3 kg DW/day • 0.70) and the recommended silage ingestion rate of 1.3 kg DW/day (4.3 kg DW/day • 0.30). U.S. EPA (1990) cites U.S. EPA (1982) as the source of the
grain and silage fractions.

This document also recommends an F, value of 1. This assumes that 100 percent of the plant material eaten by swine is grown on soil contaminated by combustion unit emissions.

U.S. EPA. 1992. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November.

This document recommends that the quantity of soil (Qs) eaten by swine be estimated as 8 percent of the total DMI. This document states "Fries of USDA notes pigs exhibit 'rooting'
behavior and assumes a maximum soil ingestion intake of 8 percent of dry matter based on a 2 to 8 percent range noted in his earlier PCB work." However, this document provides no
citations of work performed by Fries or personal communications with Fries.

B-184
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TABLE B-3-12

PORK CONCENTRATION DUE TO PLANT AND SOIL INGESTION
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 8 of 8)

U.S. EPA. 1994a. Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Solid Waste and Emergency Response. EPA-530-R-94-021. April.

This document recommends an F, value of 1. This assumes that 100 percent of the plant material ingested by swine has been grown on soil contaminated by combustion unit emissions.

U.S. EPA. 1994b. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-Specific Assessment Procedures. External Review Draft. Office of Research and Development.
Washington, D.C. EPA/600/6-88/005Cc. June.

This document states that milk is 3.5 percent fat. This document also uses experimental data derived by McLachlon, Thoma, Reissinger, and Hutzinger (1990) to calculate biotransfer
factors with units of (kg feed/kg tissue).

U.S. EPA. 1994c. RevisedDraft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends an F, value of 1. This assumes that 100 percent of the plant material eaten by swine has been grown on soil contaminated by combustion unit emissions.

U.S. EPA. 1995a. Further Issues for Modeling the Indirect Exposure Impacts from Combustor Emissions. Office of Research and Development. Washington, D.C. January20.

This document calculates Ba^ values for cadmium, mercury, selenium, and zinc by dividing uptake slope factors ([mg COPC/kg tissue DW]/[mg COPC/kg feed DW]) from U.S. EPA
(1993b) - 0.003 (cadmium), 0.0234 (mercury), 2.94 (selenium), and 0.002 (zinc)—by a daily feed ingestion rate for pork of 4.7 kg DW/day (NAS 1987). This approach is similar to that
recommended by U.S. EPA (1994b) for dioxins. The calculated biotransfer factors are 6.0 x 10-04 (cadmium); 0.0051 (mercury); 6.255 x 10-°' (selenium); and 4.0 x 10"04 (zinc).

This document also recommends that Babeefvalues for dioxins and furans be extrapolated from Bamttt values for dioxins and furans. Specifically, Bam!lk values are multiplied by the ratio of
the fat content (19 percent) for beef and the fat content (3.5 percent) of milk. NC DEHNR (1997) states that Ba^ values for dioxins and furans can be calculated in a similar manner.

U.S. EPA. 1995b. "Waste Technologies Industries Screening Human Health Risk Assessment (SHHRA): Evaluation of Potential Risk from Exposure to Routine Operating Emissions."
Volume V. External Review Draft. U.S. EPA Region 5, Chicago, Illinois.

(Page 1 of 5)
Description

This equation calculates the COPC concentration in eggs due to ingestion of contaminated soil and grain by free-range chickens.

Uncertainties associated with this equation include the following:

(1) This pathway has typically been applied only to PCDDs and PCDFs. However, concentrations in chicken eggs for other organics and metals can be calculated using biotransfer factors
in a similar approach as was used to calculate concentrations in animal tissue.
(2) The assumption that 10 percent of a chicken's diet is soil may not represent site-specific conditions. Stephens, Petreas, and Hayward (1995) suggest that the percentage of soil in the
diet of chickens raised under field conditions may be greater than 10 percent. Therefore, the concentration of COPCs in eggs,Aegg, may be underestimated.
(3) Estimated COPC-specific soil-to-plant biotransfer factors (Br) may not reflect site-specific or local conditions. Therefore, estimates of Pr and Aets may be under- or overestimated to
some degree.
(4) The recommended BCFs used in calculation ofBaegg may not accurately represent the behavior of COPCs under site-specific and local conditions. For example, Stephens, Petreas, and
Hayward (1995) note that chickens raised under field conditions and probably had a higher than 10 percent soil in their diet, showed larger apparent BCFs. Therefore, the
recommended BCFs may underestimate the concentration of COPCs in eggs, Aegg.
(5) The recommended BCFs are based on incomplete experimental results. Stephens, Petreas, and Hayward (1995) present complete experimental results. This study includes results
from a high-dose group and a low-dose group; results are based on the full exposure period. A brief comparison of the results from Stephens, Petreas, and Hayward (1992) with those
from Stephens, Petreas, and Hayward (1995) indicates that BCFs from the high-dose group are generally higher than BCFs from the low-dose group. Therefore, use of the currently
recommended BCFs may underestimate the COPC concentration in eggs, Aesg.
Equation
Aegg = ( E (F, ' Qp, • />,) + Qs ' Gi • BS ) • Baegg
For mercury modeling, the concentration of COPC in eggs is calculated for divalent mercury (Hg*1) and methyl mercury (MHg) using their respective Ph Cs, and Baegss values.
Variable
A^
Description
Concentration of COPC in eggs
Units
mg
COPC/kg
FW tissue
Value

B-186
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TABLE B-3-13
COPC CONCENTRATION IN EGGS
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 5)
Variable
Description, "
Units
VaTue.
Fraction of plant type / (grain)
grown on contaminated soil and
ingested by the animal
unitless
1.0
This variable is site- and plant type-specific. F, for chickens is estimated for grain feed only. U.S. EPA OSW recommends
that a default value of 1.0 be used for all plant types. This is consistent with U.S. EPA (1990), U.S. EPA (1994a), U.S.
EPA (1994b) and NC DEHNR (1997), which recommend that 100 percent of the plant materials ingested be assumed to
have been grown on soil contaminated by facility emissions.

The following uncertainty is associated with this variable:

(1) 100 percent of the plant materials eaten by chickens are assumed to be grown on soil contaminated by facility
emissions. This may overestimate Aegg.
OPt
Quantity of plant type i (grain)
ingested by the animal
kgDW
plant/day
0.2
Qpt for chicken is estimated for grain feed only, as recommended by NC DEHNR (1997) and U.S. EPA (1990).

Uncertainties associated with this variable include the following:

(1) . Actual grain ingestion rates can vary from site to site; this can over- or underestimate Qpt.
P,
Concentration of COPC in plant
type/(grain)
mg COPC/kg
DW
Varies
This variable is COPC-, site-, and plant type-specific. Values for Pi are calculated for grain by using the equations in
Table B-3-9.

Uncertainties introduced by this variable include the following:

(1) Some of the variables in the equation in Table B-3-9—including Cs, Cyv, Q, Dydp, and Dywp—are COPC- and
site-specific. Uncertainties associated with these variables are site-specific.
(2) In the equation in Table B-3-9, COPC-specific plant-soil biotransfer factors (Br) may not reflect
site-specific conditions. This may be especially true for inorganic COPCs for which estimates of Br would be
more accurately estimated by using plant uptake response slope factors.
Quantity of soil ingested by the
animal
kg/day
0.022
This variable is site-specific. U.S. EPA OSW recommends that the soil ingestion rate of 0.022 kg/day be used. This is
consistent with Stephens, Petreas, and Hayward (1995).

Uncertainties introduced by this variable include the following:

(Page 3 of 5)
Variable
Description
Units
Value
Cs
Average soil concentration over
exposure duration
mg COPC/kg
soil
Varies
This variable is COPC- and site-specific, and should be calculated by using the equation in Table B-3-1. Uncertainties are
site-specific.
Bs
Soil bioavailability factor
unitless
1.0
The soil bioavailability factor, Bs, can be thought of as the ratio between bioconcentration (or biotransfer) factors for soil
and vegetation for a given COPC. The efficiency of transfer from soil may differ from efficiency or transfer from plant
material for some COPCs. If the transfer efficiency is lower for soils, than this ratio would be less than 1.0. If it is equal or
greater than that of vegetation, the Bs would be equal to or greater than 1.0.

Due to limited data regarding bioavailability from soil, U.S. EPA OSW recommends a default value of 1.0 for Bs, until
more COPC-specific data is available for this parameter. Some COPCs may be much less bioavailable from soil than from
plant tissues. This uncertainty may overestimate Bs.
Baee
Biotransfer factor for chicken eggs
day/kg FW
tissue
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainties are associated with this variable:

(1) U.S. EPA OSW recommends that Bacgg values for organic COPCs other than dioxins and furans be calculated by
using the regression equation developed on the basis of a study of 29 organic compounds. Values calculated by
using this regression equation may not accurately represent the behavior of organic COPCs under site-specific
conditions. Therefore, estimates ofBaegg and, therefore, Aesg may be under- or overestimated to some degree.
(2) The recommended BCFs may not accurately represent the behavior of COPCs under site-specific or local
conditions. For example, Stephens, Petreas, and Hayward (1995) note that chickens raised under field conditions,
and which probably had a more than 10 percent soil in their diet, showed larger apparent BCFs. Therefore, the
recommended BCFs may underestimate the concentration of COPCs in eggs, Aegg.
(3) The recommended BCFs are based on incomplete experimental results. Stephens, Petreas, and Hayward (1995)
include results from a high-dose group and as a low-dose group; results are based on the full exposure period. A
brief comparison of the results from Stephens, Petreas, and Hayward (1992) and those from Stephens, Petreas,
and Hayward (1995) indicates that BCFs from the high-dose group are generally higher thanSCF* from the
low-dose group. Therefore, use of the currently recommended BCFs may underestimate the COPC concentration
in eggs, .<4L_
B-188
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TABLEB-3-13

COPC CONCENTRATION IN EGGS
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

California Environmental Protection Agency (CEPA). 1993." Parameter Values and Ranges for CALTOX." Draft. Office of Scientific Affairs. California Department of Toxics Substances
Control. Sacramento, CA. July.

Chang, R.R., D. Hayward, L. Goldman, M. Hamly, J. Flattery, and R.D. Stephens. 1989. "Foraging Farm Animals as Biomonitors for Dioxin Contamination." Chemosphere. Volume 19:
481-486.

This document appears to be cited by Stephens, Petreas, and Hayward (1992) as support for the assumption that soil represents 10 percent of the diet of free-range chickens.

NCDEHNR. 1997. NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is a reference source for the equation in Table B-3-13. This document also cites Stephens, Petreas, and Hayward (1992) as the source of estimates of the fraction of diet
that is soil (Fd), and BCFegg for dioxins and furans.

Petreas, M.X., L.R, Goldman, D.G. Hayward, R. Chang, J. Flattery, T. Wiesmuller, R.D. Stephens, D.M. Fry, and C. Rappe. 1991. "Biotransfer and Bioaccumulation of PCDD/PCDFs from Soils:
Controlled Exposure Studies of Chickens." Chemosphere. Volume 23:1731-1741.

This document appears to be cited by Stephens, Petreas, and Hayward (1992) and Stephens, Petreas, and Hayward (1995) as support for the assumption that soil represents 10 percent of
the diet of free-range chickens. '

This document is cited as the source of the assumption that free- range chickens ingest soil as 10 percent of their diet and as the source of the dioxin and furan congener-specific BCFs.
However, this document does not clearly reference or document the assumption that soil represents 10 percent of a free-range chicken diet. The document appears to cite two other
documents as supporting this assumption, Chang, Hayward, Goldman, Harnly, Flattery, and Stephens (1989) and Petreas, Goldman, Hayward, Chang, Flattery, Wiesmuller, Stephens,
Fry, and Rappe (1992). Also, this document presents dioxin and furan congener-specific BCFs (egg yolk) for the low-exposure group after 80 days of a 178-day exposure period. The
chickens in the low-dose group were fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 42 parts per trillion (ppt) I-TEQ. Chickens in the high-dose group were
fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 458 ppt I-TEQ; BCF results were not presented for this group.

Stephens, R.D., M.X. Petreas, and D.G. Hayward. 1995. "Biotransfer and Bioaccumulation of Dioxins and Furnas from Soil: Chickens as a Model for Foraging Animals." The Science of the
Total Environment. Volume 175: 253-273.

This document is an expansion of the results originally presented in Stephens, Petreas, and Hayward (1992). In particular, this document suggests that the percentage of soil in the diet of
chickens raised under field conditions is likely to be greater than 10 percent, the value that was used in the experimental study presented in this document.

This document also presents dioxin and furan congener-specific BCFs (egg yolk) under two exposure schemes: low exposure and high exposure. The white leghorn (Babcock D 300)
chickens in the low group were fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 42 ppt I-TEQ. Chickens in the high group were fed a diet consisting of
B-189
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TABLE B-3-13

COPC CONCENTRATION IN EGGS
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of 5)

10 percent soil with a PCDD/PCDF concentration of 460 ppt I-TEQ (some congeners were fortified by spiking). The BCFs presented for low- and high-dose groups both represent
averages of results from Day-80, Day-160, and Day-178 (the end of the exposure duration).

This document is a reference source for the equation in Table B-3-9; and an F, value of 1.0.

U.S. EPA. 1992. Technical Support Document for Land Application of 'Sewage S/wrfge. Volumes I and H. EPA 822/R-93-001a. Office of Water. Washington, D.C.

U.S. EPA (1995) recommends that uptake slope factors for the metals cadmium, selenium, and zinc cited by this document be used to derive Ba^ values.

U.S.EPA. 1995. Further Issues for Modeling the Indirect Exposure Impacts from Combustor Emissions. Office of Research and Development. Washington, D.C. January20.

U.S. EPA. 1997a. Exposure Factors Handbook. "Food Ingestion Factors". Volume D. EPA/600/P-95/002F. August.

U.S. EPA. 1997b. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. Office of Ah- Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-190
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TABLE B-3-14
CONCENTRATION IN CHICKEN
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 1 of5)
Description
This equation calculates the COPC concentration (AcUchn) in chicken meat due to ingestion of contaminated soil and grain by the free-range chickens.

Uncertainties associated with this equation include the following:

(1) This pathway has typically been applied only to PCDDs and PCDFs. However, concentrations in chickens for other organics and metals can be calculated using biotransfer factors
using a similar approach as was used to calculate concentrations in other animal tissue.
(2) The assumption that 10 percent of a chicken's diet is soil may not represent site-specific or local conditions of chickens raised on subsistence farms. Stephens, Petreas, and Hayward
(1995) suggests that the percentage of soil in the diet of chickens raised under field conditions may be greater than 10 percent. Therefore, the concentration of COPCs in chicken,
Achidam maY De underestimated.
(3) The recommended BCFs are based on incomplete experimental results. Stephens, Petreas, and Hayward (1995) presents results for a high-dose group and low-dose group (results are
based on the full 178-day exposure period). A comparison of the results from Stephens, Petreas, and Hayward (1992) with those from Stephens, Petreas, and Hayward (1995) shows
that BCPs from the high dose group are generally higher than BCFs from the low dose group. Therefore, use of the currently recommended BCFs may underestimate the COPC
concentration in chicken, AcHckal.
Equation
' CS ' BS } • ^chicken
For mercury modeling, the concentration of COPC in chicken is calculated for divalent mercury (Kg*1) and methyl mercury (MHg) using their respective P,, Cs, and BaMcken values.
Variable
Description
-'.;Units,,
Concentration of COPC in
chicken meat
mg COPC/kg
FW tissue
Fraction of plant type i (grain)
grown on contaminated soil and
ingested by the animal
unitless
1.0
This variable is site- and plant type-specific. Ft for chickens is estimated for grain feed only. U.S. EPA OSW
recommends that a default value of 1.0 be used for all plant types. This is consistent with U.S. EPA (1990), U.S. EPA
(1994a), U.S. EPA (1994b) and NC DEHNR (1997), which recommend that 100 percent of the plant materials ingested
be assumed to have been grown on soil contaminated by facility emissions.

The following uncertainty is associated with this variable:

(1) 100 percent of the plant materials eaten by chickens are assumed to be grown on soil contaminated by facility
emissions. This may overestimate AMcta,.
B-191
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TABLE B-3-14
CONCENTRATION IN CHICKEN
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 2 of 5)
Variable
Description
Units
Value
OP,
Quantity of plant type / (grain)
ingested by the animal
kgDW
plant/day
0.2
Qp, for chicken is estimated for grain feed only, as recommended by NC DEHNR (1997) and U.S. EPA (1990).

Uncertainties associated with this variable include the following:

(1) Actual grain ingestion rates can vary from site to site; this can over- or underestimate Qp,.
P,
Concentration of COPC in plant
type/(grain)
mg COPC/kg
DW
Varies
This variable is COPC-, site-, and plant type-specific. Values for Pi are calculated for gram by using the equations in
Table B-3-9.

Uncertainties introduced by this variable include the following:.

(1) Some of the variables hi the equation in Table B-3-9—including Cs, Cyv, Q, Dydp, and Dywp—are COPC-
and site-specific. Uncertainties associated with these variables are site-specific.
(2) In the equation hi Table B-3-9, COPC-specific plant-soil biotransfer factors (Br) may not reflect
site-specific conditions. This may be especially true for inorganic COPCs for which estimates of Br would be
more accurately estimated by using plant uptake response slope factors.
Quantity of soil ingested by the
animal
kg/day
0.022
This variable is site-specific. U.S. EPA OSW recommends that the soil ingestion rate of 0.022 kg/day be used. This is
consistent with Stephens, Petreas, and Hayward (1995).

Uncertainties introduced by this variable include the following:

(1) The recommended soil ingestion rate may not accurately represent site-specific or local conditions.
(2) Empirical data to support soil ingestion rates of chickens are limited.
Cs
Average soil concentration over
exposure duration
mg COPC/kg
soil
Varies
This variable is COPC- and site-specific, and should be calculated by using the equation in Table B-3-1. Uncertainties
are site-specific.
B-192
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TABLE B-3-14
CONCENTRATION IN CHICKEN
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 3 of 5)
Variable
Description .
Value
Bs
Soil bioavailability factor
unitless
1.0
The soil bioavailability factor, Bs, can be thought of as the ratio between bioconcentration (or biotransfer) factors for soil
and vegetation for a given COPC. The efficiency of transfer from soil may differ from efficiency or transfer from plant
material for some COPCs. If the transfer efficiency is lower for soils, than this ratio would be less than 1.0. If it is
equal or greater than that of vegetation, the Bs would be equal to or greater than 1.0.

Due to limited data regarding bioavailability from soil, U.S. EPA OSW recommends a default value of 1.0 for Bs, until
more COPC-specific data is available for this parameter. Some COPCs may be much less bioavailable from soil than
from plant tissues. This uncertainty may overestimate Bs.
Biotransfer factor for chicken
day/kg FW
tissue
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.
BdcHcixn is defined as the ratio of the COPC concentration in fresh weight tissue (mg COPC/kg FW tissue) to the daily
intake of the COPC (mg COPC/day) from chicken feed.

Uncertainties associated with this variable include the following:

(1) U.S. EPA OSW recommends that BaMck,, values for organic COPCs other than dioxins and furans
be calculated by using the regression equation developed on the basis of a study of 29 organic compounds.
Values calculated by using this regression equation may not accurately represent the behavior of
organic COPCs under site-specific conditions. Therefore, estimates ofBachickn and, therefore, A^^, may be
under- or overestimated to some degree.
(2) The beef-to-chicken fat content ratio method which is used to estimate Ba^n, values from Babaf values for
organics (except PCDDs and PCDFs) is based on the assumptions that (1) COPCs bioconcentrate in the fat
tissues, and (2) there are no differences in metabolism or feeding characteristics between beef cattle and
chicken. Due to uncertainties associated with these assumptions, BacHdaan and A^.^ value may be under- or
overestimated to some degree.
(3) The recommended BCFs may not accurately represent the behavior of COPCs under site-specific or local
conditions. For example, Stephens, Petreas, and Hayward (1995) note that chickens raised under field
conditions, and which probably had more than 10 percent soil in their diet, showed larger apparent BCFs.
Therefore, use of the recommended BCFs may underestimate the concentration of COPCs in chicken, AAlclim,
to some extent.
(4) The recommended BCFs are based on incomplete experimental results. Stephens, Petreas, and Hayward
(1995) presents results that are based on the full 178-day exposure period. A comparison of the results from
Stephens, Petreas, and Hayward (1992) with those from Stephens, Petreas, and Hayward (1995) shows that
BCFs from the high-dose group are generally higher than BCFs from the low-dose group. Therefore, use of the
currently recommended BCFs may underestimate the COPC concentration in chicken, AMckm.
B-193
-------
TABLE B-3-14

CONCENTRATION IN CHICKEN
(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

Chang, R.R., D. Hayward, L. Goldman, M. Harnly, J. Flattery, and R.D. Stephens. 1989. "Foraging Farm Animals as Biomonitors for Dioxin Contamination." Chemosphere. Volume 19; 481-
486.

This document appears to be cited by Stephens, Petreas, and Hayward (1992) as support for the assumption that soil represents 10 percent of the diet of free-range chickens.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is the reference source for the equation in Table B-3-14. This document also cites Stephens, Petreas, and Hayward (1992) as the source for the recommended fraction of
diet that is soil (Fa) and BCFakh!n for dioxins and furan congeners.

Petreas, MX., L. R. Goldman, D. G. Hayward, R. Chang, J. Flattery, T. Wiesmuller, R.D. Stephens, D.M. Fry, and C. Rappe. 1991. "Biotransfer and Bioaccumulation of PCDD/PCDFs from
Soils: Controlled Exposure Studies of Chickens." Chemosphere. Volume 23:1731-1741.

Stephens, R.D., M.X. Petreas, and D.G. Hayward. 1992. "Biotransfer and Bioaccumulation of Dioxins and Dibenzofurans from Soil." Hazardous Materials Laboratory, California Department of
Health Services. Berkeley, California. Presented at the 12th International Symposium on Dioxins and Related Compounds. August 24 through 28. University of Tampere, Tampere,
Finland.

This document is cited as the source of the assumption that free-range chickens ingest soil as 10 percent of their diet and as the source of the dioxin and furan congeners-specific BCFs
recommended by NC DEHNR (1997). However this document does not clearly reference or document the assumption that soil represents 10 percent of a free-range chicken's diet. The
document appears to cite two other documents as supporting its assumption, (1) Change, Hayward, Goldman, Harnly, Flattery and Stephens (1989) and (2) Petreas, Goldman, Hayward,
Chang, Flattery, Wiesmuller, Stephens, Fry, and Rappe (1992).

This document also presents dioxin and furan congener-specific BCFs (thigh) for the low- exposure group after 80 days of a 178-day total exposure period. The chickens in the low-dose
group were fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 42 ppt I-TEQ. Chickens in the high-dose group were fed a diet containing 10 percent soil with a
PCDD/PCDF concentration of 458 ppt I-TEQ; BCF results were not presented from the high-dose group.

Stephens, R.D., M.X. Petreas, and D.G. Hayward. 1995. "Biotransfer and Bioaccumulaton of Dioxins and Furans from Soil: Chickens as a Model for Foraging Animals." The Science of the Total
Environment. Volume 175: 253-273.

CONCENTRATION IN CHICKEN

(CONSUMPTION OF ANIMAL PRODUCTS EQUATIONS)

(Page 5 of5)

This document also presents dioxin and fiiran congener-specific BCFs (thigh) under two exposure schemes—low exposure and high exposure. The white leghorn (Babcock D 300)
chickens in the low group were fed a diet containing 10 percent soil with a PCDD/PCDF concentrations of 42 ppt I-TEQ. Chickens in the high group were fed a diet containing
10 percent soil with a PCDD/PCDF concentration of 460 ppt I-TEQ (some congeners were fortified by spiking).

The BCFs presented for low- and high-dose groups both represent averages of results from Day-80 and Day-164 of a total 178-day exposure period.

U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office Office of
Research and Development. EPA/600/6-90/003. January.

This document is a reference source for the equation in Table B-3-9; and an F, value of 1.0.

U.S.EPA. 1992. Technical Support Documentfor Land Application ofSewage Sludge. Volumes I andfl. EPA 822/R-93-001a. Office of Water. Washington, D.C.

U.S. EPA (1995) recommends that uptake slope factors for the metals cadmium, selenium, and zinc cited by this document be used to derive BaMctxn values.

U.S.EPA. 1995. Further Issues for Modeling the Indirect Exposure Impacts from Combustor Emissions. Office of Research and Development. Washington, D.C. January 20.

U.S.EPA. 1997a. Exposure Factors Handbook. "Food Ingestion Factors". Volume II. EPA/600/P-95/002F. August.

U.S.EPA. 1997b. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-195
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TABLE B-4-1
WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 11)
Description

The following uncertainties are associated with this variable:

(1) The time period for deposition of COPCs resulting from hazardous waste combustion is assumed to be a conservative, long-term value. This assumption may overestimate Cs and
Cs,D.
(2) Exposure duration values (T2) are based on historical mobility studies and will not necessarily remain constant. Specifically, mobility studies indicate that most receptors that move
remain in the vicinity of the combustion unit; however, it is impossible to accurately predict the probability that these short-distance moves will influence exposure, based on factors
such as atmospheric transport of pollutants.
(3) The use of a value of zero for T, does not account for exposure that may have occurred from historic operations and emissions from hazardous waste combustion. This may
underestimate Cs and Cs,D.
(4) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils and, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs,D.
(5) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to mat of other residues. This
uncertainty mav underestimate Cs and C*s«n.
B-196
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TABLE B-4-1
WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 11)
Equation for Carcinogens
Soil Concentration Averaged Over Exposure Duration
Cs =
Ds-tD-Cs
.n
fa
• for T}
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TABLE B-4-1
WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 11)
Highest Annual Average Soil Concentration
Equation for Noncarcinogens
_ Ds • [1 - exp (-ks-tP)]
where
Ds =
10°
Zx • BD
[F (0.31536 • Vdv - Cywv + Dywwv ) + Dytwp • (1 - F)]
For mercury modeling
= 100'(°-486) .[F (0.31536 • Vdv • Cyv + Dywv) + (Dydp + Dywp) - (1 - F )]
Z-BD
S
Use 0.48Q for total mercury and F, = 0.85 in the mercury modeling equation to calculate Ds. The calculated Ds value is apportioned into the divalent mercury (Kg*1) and methyl mercury
(MHg) forms based on the assumed 98% Hg2* and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg*) occurs in very small amounts in the vapor phase and does not
exist in the particle or particle bound phase. Therefore, elemental mercury deposition onto soils is assumed to be negligible or zero. Elemental mercury is evaluated for the direct inhalation
pathway only (Table B-5-1).

0.98 Ds
0.02 Ds
0.0

Evaluate divalent and methyl mercury as individual COPCs. Calculate Cs for divalent and methyl mercury using the corresponding (1) fate and transport parameters for mercuric chloride
(divalent mercury) and methyl mercury provided in Appendix A-3, and (2) Ds (Hg2*) and Ds (MHg) as calculated above.
D.s(Mhg)
Variable
Description
Units
Value
Cs
Average soil concentration over
exposure duration
mg COPC/kg soil

^ -*
B-198
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TABLE B-4-1

WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 11)
Variable j
Description ,
Deposition term
mg COPC/kg soil-
yr
Varies
U.S. EPA (1994a) and NC DEHNR (1991) recommend incorporating the use of a deposition term into the Cs equation.

Uncertainties associated with this variable include the following:

(1) Five of the variables in the equation for Ds (Q, Cyv, Dywv, Dywp, and Dydp) are COPC- and site-specific.
Values of these variables are estimated on the basis of modeling. The direction and magnitude of any
uncertainties should not be generalized.
(2) Based on the narrow recommended ranges, uncertainties associated with Vdv, Fn and BD are expected to be
low.
(3) Values for Z, vary by about one order of magnitude. Uncertainty is greatly reduced if it is known whether
soils are tilled or untilled.
tD
Time period over which deposition
occurs (time period of combustion)
yr
100
U.S. EPA (1990a) specifies that this period of time can be represented by periods of 30, 60 or 100 years. U.S. EPA
OSW recommends mat facilities use the conservative value of 100 years unless site-specific information is available
indicating that this assumption is unreasonable (see Chapter 6 of the HHRAP Protocol).
ks
COPC soil loss constant due to all
processes
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-2. The COPC soil loss
constant is the sum of all COPC removal processes.

Uncertainty associated with this variable includes the following:

COPC-specific values for ksg (one of the variables in the equation in Table B-4-2) are empirically
determined from field studies. No information is available regarding the application of these values to the
site-specific conditions associated with affected facilities.
B-199
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r
TABLE B-4-1

WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(PagcSofll)
Vnriohfp
Units
Value
Length of exposure duration
6,30, or 40
U.S. EPA OSW recommends the following reasonable maximum exposure (RME) values for T2:
Exposure Duration
Child Resident
Subsistence Farmer Child
Subsistence Fisher Child

Adult Resident and
Subsistence Fisher
RME
6 years
30 years
(6 child and 24 adult)
Subsistence Farmer 40 years

U.S. EPA (1994c) recommended the following unreferenced values:
Reference
U.S.EPA(1990b)
U.S.EPA(1990b)

U.S. EPA (1994b)
Exposure Duration
Subsistence Fanner
Adult Resident
Subsistence Fisher
Child Resident
Years
40
30
30
9
Uncertainties associated with this variable include the following:

(1) Exposure duration rates are based on historical mobility rates and may not remain constant. This assumption
may overestimate or underestimate Cs and Cs,D.
(2) Mobility studies indicate that most receptors that move remain in the vicinity of the emission sources;
however, it is impossible to accurately predict the likelihood that these short-distance moves will influence -
exposure, based on factors such as atmospheric transport of pollutants. This assumption may overestimate or
underestimate Cs and Cs,D.
Time period at the beginning of
combustion
0
Consistent with U.S. EPA (1994c), U.S. EPA OSW recommends a value of 0 for T,.

The following uncertainty is associated with this variable:

(Page 6 of 11)
Variable
Description
Units
Value
100
Units conversion factor
mg-cm2/kg-cm2
COPC emission rate
g/s
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 of the HHRAP for guidance regarding the calculation
of this variable. Uncertainties associated with this variable are site-specific.
Soil mixing zone depth
cm
Ito20
Soil
Untilled
Tilled
Reference
U.S.EPA(1990a)andU.S.EPA(1993a)
U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA OSW recommends the following values for this variable:

Depth (cm)

U.S. EPA (1990a) does not include a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1992).

The following uncertainties are associated with this variable:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting a
greater mixing depth. This uncertainty may overestimate Cs and CstD.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of
other residues. This uncertainty may underestimate Cs and CslD.
BD
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and
clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990a). A range of 0.83 to 1.84 was originally cited
in Hoffinan and Baes (1979). U.S. EPA (1994c) recommended a default BD value of 1.5 g/cm3, based on a mean value
for loam soil that was obtained from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also
represents the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993a).

The following uncertainty is associated with this variable:

The recommended BD value may not accurately represent site-specific soil conditions; and may under- or
overestimate site-specific soil conditions to an unknown degree.
B-201
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TABLE B-4-1
WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 7 of 11)
Variable
Deserforion
Value
Vdv
Fraction of COPC air concentration
in vapor phase
unitless
Otol
This variable is COPC-specific. Discussion of this variable and COPC-specific values is presented in Appendix A-3.
This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA (1994b) and NC
DEHNR(1997).

Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fv = 0 for all metals (except mercury).

The following uncertainties are associated with this variable:

(1) It is based on the assumption of a default ST value for background plus local sources, rather than an ST
value for urban sources. If a specific site is located in an urban area, the use of the latter ST value may be
more appropriate. Specifically, the 5V value for urban sources is about one order of magnitude greater than
that for background plus local sources, and it would result in a lower calculated F, value; however, the Fv
value is likely to be only a few percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant)
is constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from
the particle surface and the heat of vaporization of the liquid-phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value
of c is used to calculate Fv.
Dry deposition velocity
cm/s
U.S. EPA (1994c) recommended the use of 3 cm/s for the dry deposition velocity, based on median dry deposition
velocity for HNO3 from an unspecified U.S. EPA database of dry deposition velocities for HNO3, ozone, and SO*
HNO3 was considered the most similar to the COPCs recommended for consideration in the HHRAP. The value
should be applicable to any organic COPC with a low Henry's Law Constant.

The following uncertainty is associated with this variable:

(1) HN03 may not adequately represent specific COPCs; therefore, the use of a single value may under- or
overestimate estimated soil concentration.
Cywv
Unitized yearly (water body or
watershed) average air
concentration from vapor phase
ug-s/g-m3
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific. ^^^
B-202
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TABLE B-4-1
WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 8 of 11)
Variable
Dywwv
Dytwp
Description
Unitized yearly (water body or
watershed) average wet deposition
from vapor phase
Unitized yearly (water body or
watershed) average total (wet and
dry) deposition from particle phase
tfatt*
i
s/m2-yr
s/m2-yr
Value
=====
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
B-203
-------
TABLE B-4-1

WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 9 of 11)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

For discussion, see References and Discussion, Table B-l-1.

This reference is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value, BD, of 1.5 g soil/cm3 soil for loam soil.

Hillel.D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, F.O., and C.F. Baes, 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NOREG/TM-882.

This document presents a soil bulk density range, BD, of 0.83 to 1.84.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This is one of the source documents for the equation in Table B-4-1. This document also recommends the use of (1) a deposition term,I>s, and (2) COPC-specific Fv (fraction of COPC
air concentration in vapor phase) values.

This document is a reference source for COPC-specific F, (fraction of COPC air concentration in vapor phase) values.

This document is a reference source for the equation in TableB-4-1, and it recommends that (1) the time period over which deposition occurs (time period for combustion), tD, be
represented by periods of 30,60 and 100 years, and (2) undocumented values for soil mixing zone depth, ZS) for tilled and unfilled soil.

U.S. EPA. 1990b. Exposure Factors Handbook. March.

B-204
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TABLE B-4-1

WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 10 of 11)

This document is a reference source for values for length of exposure duration, T2.

U.S. EPA. 1992. Estimating Exposure to Dioxin-Like Compounds. Draft Report. Office of Research and Development. Washington, D.C. EPA/600/6-88/005b.

This document is cited by U.S. EPA (1993a) as the source of values for soil mixing zone depth, Za for tilled and unfilled soils.

This document is a reference for recommended values for soil mixing zone depth, Za for tilled and untilled soils; it cites U.S. EPA (1992) as the source of these values. It also
recommends a "relatively narrow" range for soil bulk density, BD, of 1.2 to 1.7 g soil/cm3 soil.

This document is a reference for the equation in Table B-4-1. It recommends using a deposition term, Ds, and COPC-specific Fv values (fraction of COPC air concentration in vapor
phase) in the Cs equation.

This document is a reference for the equation in Table B-4-1; it recommends that the following be used in the Cs equation: (1) a deposition term, Ds, and (2) a default soil bulk density
value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).

U.S. EPA. 1994b. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-Specific Assessment Procedures. External Review Draft. Office of Research and Development
Washington, D.C. June. EPA/600/6-88/005Cc.

This document recommends values for length of exposure duration, T2, for the subsistence farmer.

The value for dry deposition velocity is based on median dry deposition velocity for HNO3 from a U.S. EPA database of dry deposition velocities for HN03 ozone, and S02. HMO, was
considered me most similar to the constituents covered and the value should be applicable to any organic compound having a low Henry's Law Constant. The reference document for this
recommendation was not cited. This document recommends the following:

• Values for the length of exposure duration, T2
• Value of 0 for the time period of the beginning of combustion, T,
• Fv values (fraction of COPC air concentration in vapor phase) that range from 0.27 to 1 for organic COPCs
• Vdv value (dry deposition velocity) of 3 cm/s (however, no reference is provided for this recommendation)
B-205
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TABLE B-4-1

WATERSHED SOIL CONCENTRATION DUE TO DEPOSITION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 11 of 11)

• Default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
• Vdv value of 3 cm/s, based on median dry deposition velocity for HN03 from an unspecified U.S. EPA database of dry deposition velocities for HN03, ozone, and S02. HN03
was considered the most similar to the COPCs recommended for consideration in the HHRAP.

COPC SOIL LOSS CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the COPC soil loss constant, which accounts for the loss of COPCs from soil by several mechanisms.

Uncertainties associated with this equation include the following:

(1) COPC-specific values for fog are empirically determined from field studies; no information is available regarding the application of these values to the site-specific conditions
associated with affected facilities.
(2)
The source of the equations in Tables B-4-3 through B-4-6 have not been identified.
Equation

ks = ksg + kse + ksr + ksl + ksv
Variable
Description
Units
ks
COPC soil loss constant due to all
processes
yr'
ksg
COPC loss constant due to biotic
and abiotic degradation
yr'
Varies
This variable is COPC-specific and should be determined from the COPC tables in Appendix A-3.

"Degradation rate" values are also presented in NC DEHNR (1997), however, no reference or source is provided for the values.
U.S. EPA (I994a) and U.S. EPA (I994b) state that ksg values are COPC-specific; however, all ksg values are presented as zero
(U.S. EPA I994a) or as "NA" (U.S. EPA I994b); the basis of these assumptions is not addressed.

The following uncertainty is associated with this variable:

COPC-specific values for ksg are empirically determined from field studies; no information is available regarding the
application of these values to the site-specific conditions associated with affected facilities.
B-207
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TABLE B-4-2
COPC SOIL LOSS CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 4)
Variable
Descrintkin
Units
Valnc
kse
COPC loss constant due to soil
erosion
yr'
This variable is COPC- and site-specific, and is further discussed in Table B-4-3. Consistent with U.S. EPA (1994a), U.S. EPA
(1994b) andNC DEHNR (1997), U.S. EPA OSW recommends that the default value assumed for kse is zero because of
contaminated soil eroding onto the site and away from the site.

Uncertainties associated with this variable include the following:

(1) The source of the equation in Table B-4-3 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting a greater mixing
depth. This uncertainty may overestimate kse.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in
situ materials) in comparison to that of other residues. This uncertainty may underestimate kse.
ksr
COPC loss constant due to surface
runoff
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-4. No reference document is cited for
this equation; the use of this equation is consistent with U.S. EPA (1994b) and NC DEHNR (1997). U.S. EPA (1994a) states that
all ksr values are zero but does not explain the basis of this assumption.

Uncertainties associated with this variable (calculated by using Table B-4-4) include the following:

(1) The source of Table B-4-4 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing
depth. This uncertainty may overestimate ksr.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in
situ materials) in comparison to that of other residues. This uncertainty may underestimate ksr.
ksl
COPC loss constant due to leaching
yr-'
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-5. The use of this equation is
consistent with U.S. EPA (1993), U.S. EPA(1994b), and NC DEHNR (1997). U.S. EPA (1994a) states that all ksl values are zero
but does not explain the basis of this assumption.

Uncertainties associated with this variable (calculated by using Table B-4-5) include the following:

(1) The source of Table B-4-5 has not been identified.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in-situ materials) in comparison to that of other residues. This uncertainly may underestimate ksl.
B-208
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TABLE B-4-2
COPC SOIL LOSS CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 4)
Variable
Description
Value
ksv
COPC loss constant due to
volatilization
yr1
V
This variable is COPC- and site-specific, and is further discussed in Table B-4-6. Consistent with U.S. EPA guidance (1994a) and
based on the need for additional research to be conducted to determine the magnitude of the uncertainty introduced for modeling
volatile COPCs from soil, U.S. EPA OSW recommends that, until identification and validation of more applicable models, the
constant for the loss of soil resulting from volatilization (ksv) should be set equal to zero.

Uncertainties associated with this variable include the following:

(1) The source of the equation in Table B-4-6 has not been identified.
(2) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting a greater mixing
depth. This uncertainty may overestimate ksv.
(3) Deposition to hard surfaces may result in dust residues that have negligible dilution, (as a result of potential mixing with
in-situ materials) in comparison to that of other residues. This uncertainty mav underestimate ksv
B-209
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TABLE B-4-2

COPC SOIL LOSS CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. NCDEHNR Protocol far Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the reference documents for Tables B-4-4, B-4-5, and B-4-6. This document is also cited as (1) the source for a range of COPC-specific degradation rates (fag),
and (2) one of the sources that recommend using the assumption that the loss resulting from erosion (foe) is zero because of contaminated soil eroding onto the site and away from the site.

This document is one of the reference documents for Tables B-4-3 and B-4-5.

This document is cited as a source for the assumptions that losses resulting from erosion (foe), surface runoff (for), degradation (fog), leaching (ksl), and volatilization (fav) are all zero.

This document is one of the reference documents for Tables B-4-4, B-4-5, and B-4-6. This document is also cited as one of the sources that recommend using the assumption that the loss
resulting from erosion (foe) is zero and the loss resulting from degradation (fog) is "NA" or zero for all compounds.
B-210
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TABLE B-4-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 1 of 5)
Description
This equation calculates the constant for COPC loss resulting from erosion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997) U S EPA OSW recommends
that the default value assumed for kse is zero because of contaminated soil eroding onto the site and away from the site. In site-specific cases where the permitting authority considers it
appropriate to calculate a kse, the following equation presented in this table should be considered along with associated uncertainties. Additional discussion on the determination of kse can be
obtained fiom review of the methodologies described in U.S. EPA NCEA document, Methodology for Assessing Health Risks Associated with Multiple Exposure Pathways to Combustor
Emissions (In Press). Uncertainties associated with this equation include:
(1)
(2)
For soluble COPCs, leaching might lead to movement below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate kse
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other residues This
uncertainty may underestimate kse.
Equation
kse =
0.1-X-SD-ER
Kd-BD
Variable
kse
Description '
COPC loss constant due to soil
erosion
Units
yr'
Value
Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), U.S. EPA OSW recommends that the default
value assumed for kse is zero because of contaminated soil eroding onto the site and away from the site.
uncertainty may overestimate kse.
Xe
Unit soil loss
kg/m2-yr
Varies
This variable is site-specific and is calculated by using the equation in Table B-4-13.

The following uncertainty is associated with this variable:

COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 5)
Value
SD
Sediment delivery ratio
unitless
Varies
This value is site-specific and is calculated by using the equation in Table B-4-14.

Uncertainties associated with this variable include the following:

(1) The recommended default values for the empirical intercept coefficient, a, are average values that are based on
studies of sediment yields from various watersheds. Therefore, those default values may not accurately represent
site-specific watershed conditions. As a result, use of these default values may under- or overestimate SD.
(2) The recommended default value for the empirical slope coefficient, b, is based on a review of sediment yields from
various watersheds. This single default value may not accurately represent site-specific watershed conditions. As a
result, use of this default value may under- or overestimate SD.
ER
Soil enrichment ratio
unitless
Inorganics: 1
Organics: 3
COPC enrichment occurs because (1) lighter soil particles erode more than heavier soil particles, and (2) concentration of
organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded material
than in in situ soil (U.S. EPA 1993). In the absence of site-specific data, U.S. EPA OSW recommends a default value of 3 for
organic COPCs and 1 for inorganic COPCs. This is consistent with other U.S. EPA guidance (1993), which recommends a
range of 1 to 5 and a value of 3 as a "reasonable first estimate." This range has been used for organic matter, phosphorus, and
other soil-bound COPCs (U.S. EPA 1993); however, no sources or references were provided for this range. ER is generally
higher in sandy soils than in silty or loamy soils (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The default ER value may not accurately reflect site-specific conditions; therefore, kse may be over- or
underestimated to an unknown extent. The extent of any uncertainties will be reduced by using county-specific ER
values.
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffinan
and Baes (1979). U.S. EPA (1994b) recommended a default BD value of 1.5 g/cm3, based on a mean value for loam soil that
was taken from Carsel, Parrish, JonelffHansen, and Lamb (1988). The value of 1.5 g/cm3 also represents the midpoint of the
"relatively narrow range" for BD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-212
-------
TABLE B-4-3
COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 5)
Variable
... Description
tfatet
; Value,
Soil mixing zone depth
cm
Ito20
U.S. EPA recommends the following values for this variable:
Soil
Unfilled
Tilled
Reference
U.S.EPA(1990a)andU.S.EPA(1993a)
U.S.EPA(1990a)andU.S.EPA(1993a)
Depth (cm)

U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate ksr.
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in situ materials) in comparison to that of other residues. This uncertainty may underestimate kse.
Kd.
Soil-water partition coefficient
mL water/g
soil
(or cm3
water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Rvalues are calculated as described in
Appendix A-3.
Soil volumetric water content
mL
water/crn3
soil
0.2
This variable is site-specific, and depends on the available water and on soil structure; 0^ can be estimated as the midpoint.
between a soil's field capacity and wilting point, if a representative watershed soil can be identified. However, U.S. EPA
OSW recommends the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to
0.3 (heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and is
consistent with U.S. EPA (1994b).

The following uncertainty is associated with this variable:

The default 0W value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
B-213
-------
TABLE B-4-3

COPC LOSS CONSTANT DUE TO SOIL EROSION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 5)
REFERENCES AND DISCUSSION

Carsel, R.F., R.S. Parish, RX. Jones, JX. Hansen, and RX. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology. Vol. 2,
Pages 11-24.

This document is cited by U.S. EPA (1994b) as the source for a mean soil bulk density, BD, value of 1.5 (g soil/cm3 soil) for loam soil.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

Hoffman, F.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

This document presents a range of values for soil mixing zone depth, Za for tilled and unfilled soil. The basis or source of these values is not identified.

This document is also a source of the following:

• A "relatively narrow range" for soil bulk density, BD, of 12 to 1.7 (g soil/cm3 water)
• COPC-specific (inorganic COPCs only) Kd, values used to develop a proposed range (2 to 280,000 [mL water/g soil]) of Kd, values
• A range of soil volumetric water content (0^,) values of 0.1 (mL water/cm3 soil) (very sandy soils) to 0.3 (mL water/cm3 soil) (heavy loam/clay soils) (however, no source or
reference is provided for this range)
• A range of values for soil mixing zone depth, Zn for tilled and unfilled soil

B-214
-------
TABLE B-4-3

COPC LOSS CONSTANT DUE TO SOIL EROSION

(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of 5)

This document is the source of values for soil mixing zone depth, Zs, for tilled and unfilled soil, as cited in U.S. EPA (1993).

U.S. EPA. 1994b. RevisedDrqft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends (1) a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen and Lamb
(1988), and (2) a default soil volumetric water content, Q^ value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993).
B-215
-------
TABLE B-4-4

core LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the COPC loss constant due to runoff of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater mixing depth. This uncertainty may overestimate far.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution, in comparison to that of other residues. This uneertainty may underestimate far.
Equation
far =
RO
Variable
COPC loss constant due to runoff
RO
Description
Average annual surface runoff from
pervious areas
Units
cm/yr
Value
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994a), andNC DEHNR (1997), average annual
surface runoff, RO, can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and
Troise 1973). According to NC DEHNR (1997), estimates can also be made by using more detailed, site-specific procedures
for estimating the amount of surface runoff, such as those based on the U.S. Soil Conservation Service curve number equation
(CNE). U.S. EPA (1985) is cited as an example of such a procedure.

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual surface runoff information is not available, default or
estimated values may not accurately represent site-specific or local conditions. As a result, fa/ may be under- or
overestimated to an unknown degree. ^^^^
B-216
-------
TABLE B-4-4
COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 5)
Variable
Description
Soil volumetric water content
mL
water/cm3
soil
0.2
This variable depends on the available water and soil structure; if a representative watershed soil can be identified, 0W can be
estimated as the midpoint between a soil's field capacity and wilting point. U.S. EPA OSW recommends the use of 0.2
mL/cm3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils), which
is recommended by U.S. EPA (1993) (no source or reference is provided for this range), and is consistent with U S EPA
(1994a) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The default &„, value may not accurately reflect site-specific or local conditions; therefore, kse may be under- or
overestimated to a small extent, based on the limited range of values.
Soil mixing zone depth
cm
I to 20
U.S. EPA OSW recommends the following values for this variable:
Soil
Unfilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993) cites U.S. EPA (1994b).

Uncertainties associated with this variable include the following:

(1)

(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate far.
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in-situ materials) in comparison to that of other residues. This uncertainty may underestimate far.
Kd,
Soil-water partition coefficient
mL water/g
soil
(or cm3
water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Rvalues are calculated as described in
Appendix A-3.
B-217
-------
TABLE B-4-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 5)
Variable
Description
Units
Value
BD
Soil bulk density
g soil/cm3
soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffman
and Baes (1979). U.S. EPA (1994a) recommended a default soil bulk density value of 1.5 g/cm3, based on a mean value for
loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also represents the
midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-218
-------
TABLE B-4-4

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

This document is cited by U.S. EPA (1994a) as the source of a mean soil bulk density, BD, value of 1.5 (g soil/cm3 soil) for loam soil.

Geraghty, J.J., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center, Port Washington, New York.

This document is cited by U.S. EPA (1993), U.S. EPA (1994), and NC DEHNR (1997) as a reference to calculate average annual runoff, RO. This reference provides maps with isolines
of annual average surface water runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because
these values are total contributions and not only surface runoff, U.S. EPA (1994) recommends that the volumes be reduced by 50 percent in order to estimate surface runoff.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York.

This document is cited by U.S. EPA (1990) for the statement that dry soil bulk density, BD, is affected by the soil structure, such as looseness or compaction of the soil, depending on the
water and clay content of the soil.

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose of Radionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of Table B-4-4; however, this document is not the original source of this equation (this source is unknown). This document
also recommends the following:

Estimation of annual current runoff, RO (cm/yr), by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) or site-specific procedures,
such as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.
• Default value of 0.2 (mL water/cm3 soil) for soil volumetric water content (8^,)

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate site-specific surface runoff.

COPC LOSS CONSTANT DUE TO RUNOFF
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of5)

This document presents a range of values for soil mixing zone depth, Zn for tilled and unfilled soil; the basis for, or sources of, these values is not identified.

U.S. EPA. 1993. Addendum to the Methodologyfor Assessing Health Risks Associated'with Indirect Exposure to Combuslor Emissions. External Review Draft. Office of Research and
Development Washington, D.C. November.

This document recommends the following:

A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)
A range of soil volumetric water content, &,„, values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) (the original source of, or reference for, these values is not identified)
A range of values for soil mixing depth, Zn for tilled and unfilled soil (the original source of, or reference for, these values is not identified)
A range (2 to 280,000 [mL water/g soil]) of Kd, values for inorganic COPCs
Use of the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) to calculate average annual runoff, RO.

U.S. EPA. 1994b. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development. Washington,
D.C. EPA/600/6-88/005CC. June.

This document presents a range of values for soil mixing zone depth, Zn for tilled and unfilled soil as cited in U.S. EPA (1993).

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Offices of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the following:

• Estimation of average annual runoff, RO, by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973)
• Default soil dry bulk density, BD, value of 1.5 (g soil/cm3 soil), based on the mean for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb (1988)
• Default soil volumetric water content, 6^ value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993)
B-220
-------
TABLE B-4-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page! of6)
Description
This equation calculates the COPC loss constant due to leaching of soil. Uncertainties associated with this equation include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate ksl.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with insitu materials) in comparison to that of other residues. This
uncertainty may underestimate ksl.
(3) The original source of this equation has not been identified. U.S. EPA (1993) presents the equation as shown here. U.S. EPA (1994a) and NC DEHNR (1997) replaced the numerator
as shown with "q", defined as average annual recharge (cm/yr).
ksl =
Equation
P + / - RO - E..
Variable
Description , /
Units
Value
ksl
COPC loss constant due to leaching
yr-1
Average annual precipitation
cm/yr
18.06 to 164.19
This variable is site-specific. This range is based on information presented in U.S. EPA (1990), representing data for 69
selected cities (U.S. Bureau of Census 1987; Baes, Sharp, Sjoreen and Shor 1984). The 69 selected cities are not identified;
however, they appear to be located throughout the continental United States. U.S. EPA OSW recommends that site-specific
data be used.

The following uncertainty is associated with this variable:

To the extent that a site is not located near an established meteorological data station, and site-specific data are not
available, default average annual precipitation data may not accurately reflect site-specific conditions. As a result,
ksl may be under- or overestimated. However, average annual precipitation data are reasonably available; therefore,
uncertainty introduced by this variable is expected to be minimal.
B-221
-------
TABLE B-4-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual irrigation information is not available, default values
(generally based on the closest comparable location) may not accurately reflect site-specific conditions. As a result,
ksl may be under- or overestimated to an unknown degree.
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994a), and NC DEHNR (1997), average annual
surface runoff can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise
1973). According to NC DEHNR (1997), this estimate can also be made by using more detailed, site-specific procedures, such
as those based on the U.S. Soil Conservation Service CNE. U.S. EPA (1985) is cited as an example of such a procedure.

The following uncertainty is associated with this variable:

To the extent that site-specific or local average annual evapotranspiration information is not available, default values
may not accurately reflect site-specific conditions. As a result, ksl may be under- or overestimated to an unknown
degree.
B-222
-------
TABLE B-4-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 3 of 6)
Variable
BD
Description
Soil volumetric water content
Soil depth mixing zone
Soil bulk density
Units
mL
water/cm3
soil
cm
g soil/cm3
soil
Value
0.2
This variable is site-specific, and depends on the available water and on soil structure; if a representative watershed soil can be
identified 6OT can be estimated as the midpoint between a soil's field capacity and wilting point. U.S. EPA OSW recommends
the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the range of 0.1 (very sandy soils) to 0 3 (heavy
loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and is consistent with
other U.S. EPA (1994a) and NC DEHNR (1997).

The following uncertainty is associated with this variable:
The default 0m value may not accurately reflect site-specific or local conditions; therefore, ksl may be under-
overestimated to a small extent, based on the limited range of values.
or
Ito20
U.S. EPA OSW recommends the following values for this variable:
ioil
Unfilled
Tilled
Depth (cm)
1
20
Reference
U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994b).

Uncertainties associated with this variable include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting in a greater
mixing depth. This uncertainty may overestimate ksr.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing
with in-situ materials) in comparison to that of other residues. This uncertainty may underestimate ksl.
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally cited in Hoffinan
and Baes (1979). U.S. EPA (1994) recommended a default soil bulk density value of 1.5 g/cm3, based on a mean value for
loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3 also represents the midpoint of the
"relatively narrow range" for BD of 1.2 to 1.7 g/cm3 (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions.
B-223
-------
TABLE B-4-5
COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of6)
Variable
Kd,

Description
Soil-water partition coefficient

Units
cm3
water/g soil

Value
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.
The following uncertainty is associated with this variable:
Uncertainties associated with this parameter will be limited if &f, values are calculated as described in
Appendix A-3.
B-224
-------
TABLE B-4-5

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of 6)

REFERENCES AND DISCUSSION

For the continental United States, as cited in U.S. EPA (1990), this document is the source of a series of maps showing: (1) average annual precipitation (P), (2) average annual irrigation
(7), and (3) average annual evapotranspiration isolines.

This document is cited by U.S. EPA (1994a) as the source for a mean soil bulk density value, BD, of 1.5 (g soil/cm3 soil) for loam soil.

Geraghty, J.J., D.W. Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center, Port Washington, New York.

This document is cited by U.S. EPA (1993), U.S. EPA (1994a), and NC DEHNR (1997) as a reference for calculating average annual runoff, RO. This document provides maps with
isolines of annual average surface runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because
these volumes are total contributions and not only surface runoff, U.S. EPA (1994a) recommends that the volumes be reduced by 50 percent in order to estimate average annual surface
runoff.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, F.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose of Radionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of the equation in Table B-4-5. However, the document is not the original source of this equation. This document also
recommends the following:

COPC LOSS CONSTANT DUE TO LEACHING
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 6 of 6)

U.S. Bureau of the Census. 1987. Statistical Abstract of'the UnitedStates: 1987. 107th edition. Washington, D.C.

This document is a source of average annual precipitation (F) information for 69 selected cities, as cited in U.S. EPA (1990); these 69 cities are not identified.

This document is cited by NC DEHNR (1997) as an example of the use of the U.S. Soil Conservation Service CNE to estimate RO.

This document presents ranges of (1) average annual precipitation, (2) average annual irrigation, and (3) average annual evapotranspiration. This document cites Baes, Sharp, Sjoreen, and
Shor (1984) and U.S. Bureau of the Census (1987) as the original sources of this information.

This document is one of the reference sources for the equation in Table B-4-5; this document also recommends the following:

• A range of soil volumetric water content, &„, values of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils); the original source or reference for these values is not identified.
• A range of values for soil mixing depth, Za for tilled and unfilled soil; the original source reference for these values is not identified.
A range (2 to 280,000 [mL water/g soil]) of Kd, values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1.2 to 1.7 (g soil/cm3 soil)

This document is one of the reference source documents for the equation in Table B-4-5. The original source of this equation is not identified. This document also presents a range of
values for soil mixing depth, Z, for tilled and untilled soil; the original source of these values is not identified. Finally, this document presents several COPC-specific&i values that were
used to establish a range (2 to 280,000 mL/g) of Kds values.

U.S. EPA. 1994a. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

U.S. EPA. 1994b. Estimating Exposure to Dioxin-Like Compounds. Volulme III: Site-specific Assessment Procedures. External Review Draft. Office of Research and Development. Washington,
D.C. EPA/600/6-88/005CC. June.

This document presents values for soil mixing depth, Za for tilled and untilled soil, as cited in U.S. EPA (1993).

This document recommends (1) a default soil volumetric water content, 6^, value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993), and (2) a default soil bulk density, BD, value of
1.5 (g soil/cm3 soil), based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988).
B-226
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TABLE B-4-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 1 of 6)
Description
This equation calculates the COPC loss constant from soil due to volatilization. Consistent with U.S. EPA guidance (1994) and based on the need for additional research to be conducted to
fhfrr^rri ? ? mc^^ mtr°?cfd for m°de!in8 v°latile COPCs fr°m «®. U-S-EPA OSW recommends that, until identification and validation of more applicable models,
the constant for the loss of soil resulting from volatilization (ksv) should be set equal to zero. In cases where high concentrations of volatile organic compounds are expected to be present in the
soil and toe permitting authority considers calculation of fev to be appropriate, the equation presented in this table should be considered. U.S. EPA OSW also recommends consulting the

a^^
(1)
(2)
For soluble COPCs, leaching might lead to movement to below 1 centimeter in unfilled soils, resulting in a greater mixing depth. This uncertainty may overestimate ksv
Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of potential mixing with in situ materials) in comparison to that of other resi
uncertainty may underestimate ksv.
Variable
ksv
0.482
0.78
-0.67
-0.11
3.1536x10+°'
Definition
Constant for COPC loss due to
volatilization
Empirical constant
Empirical constant
Empirical constant
Empirical constant
Units conversion factor
Equation
ksv =
3.1536 • 107-#
Z-Kd-R-T -BD
0.482-
-0.11
Units
yr'
unitless
unitless
unitless
unitless
s/yr
Value
Consistent with U.S. EPA guidance (1994) and based on the need for additional research to be conducted to
determine the magnitude of the uncertainty introduced for modeling volatile COPCs from soil, U.S. EPA OSW
recommends that, until identification and validation of more applicable models, the constant for the loss of soil
resulting from volatilization (ksv) should be set equal to zero.
This is an empirical constant calculated during the development of this equation.
This is an empirical constant calculated during the development of this equation.
This is an empirical constant,calculated during the development of this equation.
This is an empirical constant calculated during the development of this equation.
B-227
-------
TABLE B-4-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 6)
Variable
Definition
Units
Value
Henry's Law constant
atm-mVmol
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Values for this variable, estimated by using the parameters and algorithms in Appendix A-3, may
under- or overestimate the actual COPC-specific values. As a result, ksv may be under- or
overestimated.
Soil mixing zone depth
cm
Ito20
U.S. EPA OSW recommends the following values for this variable:
Soil
Untilled
Tilled
Depth (cm) Reference
1 U.S. EPA (1990a) and U.S. EPA (1993a)
20 U.S. EPA (1990a) and U.S. EPA (1993a)
U.S. EPA (1990) does not provide a reference for these values. U.S. EPA (1993a) cites U.S. EPA (1994a).

Uncertainties associated with this variable include the following:

(1) For soluble COPCs, leaching might lead to movement to below 1 centimeter in untilled soils, resulting
in a greater mixing depth. This uncertainty may overestimate Asr.
(2) Deposition to hard surfaces may result in dust residues that have negligible dilution (as a result of
potential mixing with in situ materials) in comparison to that of other residues. This uncertainty may
underestimate fcsv.
Kd,
Soil-water partition coefficient
cm3 water/g soil
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kd, values are calculated as described in
Appendix A-3.
Universal gas constant
atm-m3/mol-K
8.205 x JO'5
There are no uncertainties associated with this parameter.
B-228
-------
TABLE B-4-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 6)
Variable
Units
Value
Ambient air temperature
K
298
This variable is site-specific. U.S. EPA (1990) also recommends an ambient air temperature of 298 K.

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for the variable are not available, default values may not
accurately represent site-specific conditions. The uncertainty associated with the selection of a single
value from within the temperature range at a single location is expected to be more significant than the
uncertainty associated with choosing a single ambient temperature to represent all localities. In other
words, the range of average ambient temperatures across the country is generally less than the
temperature range at an individual site.
BD
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water
and clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A rangeof 0.83 to 1.84 was
originally cited in Hoflman and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value
of 1.5 g/cm3, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The
value of 1.5 g/cm3 also represents the midpoint of the "relatively narrow range" forBD of 1.2 to 1.7 g/cm3 (U.S.
EPA 1993).

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for this variable are not available, default values may not
accurately represent site-specific conditions. The uncertainty associated with the selection of a single
value from within the range of windspeeds at a single location may be more significant than the
uncertainty associated with choosing a single windspeed to represent all locations.
B-229
-------
TABLE B-4-6
COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 6)
Variable
P.
Pa
Da
A
Definition
Viscosity of air
Density of air
Diflusivity of COPC in air
Surface area of contaminated area.
Units
g/cm-s
g/cm3
cm2/s
m2
Value
1.81 x 10*
U.S. EPA OSW recommends the use of this value, based on Weast (1980). This value applies at standard
conditions (25 °C or 298 K and 1 atm or 760 mm Hg).
The viscosity of air may vary slightly with temperature.
0.0012
U.S. EPA OSW recommends the use of this value, based on Weast (1980). This value applies at standard
conditions (25°C or 298 K and 1 atm or 760 mm Hg).
The density of air will vary with temperature.
Varies
This value is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.
The following uncertainty is associated with this variable:
The default £>„ values may not accurately represent the behavior of COPCs under site-specific
conditions. However, the degree of uncertainty is expected to be minimal.
1.0
See Chapter 5 of the HHRAP for guidance regarding the calculation of this value.
B-230
-------
TABLE B-4-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of 6)
REFERENCES AND DISCUSSION

Carsel,RF RS,Parrish,R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology. Vol.
Z. ragCS 1 \~2A.

This document is cited by U.S. EPA (1994b) as the source of a mean soil bulk density value, BD, of 1 .5 (g soil/cm3 soil) for loam soil.

Hillel.D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York, New York.

Hoffman, F.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1 .84.

NCDEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documents that cites the use of the equation in Table B-4-6; however, the original source of this equation is not identified.

U. S. EPA. 1 990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office Office of
Research and Development. EPA 600-90-003. January.

This document recommends the following:

• A range of values for soil mixing zone depth, Zs, for tilled and unfilled soil; however, the source or basis for these values is not identified
• A default ambient air temperature of 298 K
• An average annual wind speed of 3.9 m/s; however, no source or reference for this value is identified.

U.S. EPA. 1 993. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft Office of Research and
Development. Washington, D.C. November.

This document is one of the reference source documents for the equation in Table B-4-6; however, the original reference for this equation is not identified.

This document also presents the following:

A range of values for soil mixing depth, Zn for tilled and untilled soil; however, the original source of these values is not identified.
• COPC-specific Kd, values that were used to establish a range (2 to 280,000 [mL water/g soil]) of Kd, values for inorganic COPCs
• A "relatively narrow range" for soil bulk density, BD, of 1 .2 to 1 .7 (g soil/cm3 soil)

U.S. EPA. 1994 Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. April 15.

B-231
-------
TABLE B-4-6

COPC LOSS CONSTANT DUE TO VOLATILIZATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 6 of 6)

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Lite Compounds. Volume III: Site-specific Assessment Procedures, External Review Draft. Office of Research and Development Washington,
D.C. EPA/600/6-88/005CC. June.

This document presents value for soil, mixing depth, Zn for tilled and unfilled soil as cited in U.S. EPA (1993).

U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste. Attachment C, Draft Exposure Assessment Guidance
for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends a default soil density, BD, value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil that is taken from Carsel, Parrish, Jones, Hansen, and Lamb
(1988).

Weast,R.C. 1980. Handbook of Chemistry and Physics. 61stEdition. CRC Press, Inc. Cleveland, Ohio.

This document is cited by NC DEHNR (1997) as the source recommended values for viscosity of air, /UM and density of air, pa.
B-232
-------
TABLE B-4-7
TOTAL WATER BODY LOAD
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 3)
Description
This equation calculates the total average water body load from wet and dry vapor and particle deposition, runoff, and erosion loads. The limitations and uncertainties incorporated by using this
equation include the following:

(1) Uncertainties associated with variables in equations presented in Tables B-4-8, B-4-9, B-4-10, B-4-11, and B-4-12 that are site-specific. These variables includeg, Dywwv, Dytwp, Aw
Cywv, A,, Ai, Cs, and Xe. Values for many of these variables are estimated through the use of mathematical models and the uncertainties associated with values for these variables may
be significant in some cases (Bidleman 1988).
(2) Uncertainties associated with the remaining variables in equations presented in Tables B-4-8, B-4-9, B-4-10, B-4-11, and B-4-12 are expected to be less significant, primarily because
of the narrow ranges of probable values for these variables or because values for these variables (such asKds) were estimated by using well-established estimation methods.
Equation
Ldif + Lm + LR + LE
Variable
Description
Units
Value
Total COPC load to the water body
Total (wet and dry) particle phase
and wet vapor phase COPC direct
deposition load to water body
Varies
This variable is COPC- and site-specific, and is calculated by using equation presented in Table B-4-8.

Uncertainty associated with this variable include the following:

Most of the uncertainty associated with the variables in the equation in Table B-4-8, specifically those associated with
Q Dywwv, Dytwp, and Am are site-specific and may be significant in some cases.
'-at
Vapor phase COPC diffusion (dry
deposition) load to water body
Varies
This variable is calculated by using equation presented in Table B-4-12.

Uncertainty associated with this variable include the following:

Most of the uncertainty associated with the variables in the equation in Table B-4-12, specifically those associated
with Q Cywv, and AM are site-specific.
B-233
-------
TABLE 3-4-7
TOTAL WATER BODY LOAD
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of3)
Variable
Description
Units
Value
Runoffload from impervious
surfaces
g/yr
Varies
This variable is calculated by using the equation presented in Table B-4-9.

Uncertainty associated with this variable include the following:

Most of the uncertainty associated with the variables in this equation, specifically those associated with g,
Dywwv, Dytwp, and A,, are site-specific.
Runoffload from pervious surfaces
g/yr
Varies
This variable is calculated by using equation presented in Table B-4-10.

Uncertainties associated with this variable include the following:

(1) Most of the uncertainties associated with the variables in the equation in Table B-4-10, specifically those for^ A,,
and Cs, are site-specific.
(2) Uncertainties associated with the remaining variable in the equation in Table B-4-10 are not expected to be significant,
primarily because of the narrow ranges of probable values for these variables or the use of well-established
estimation procedures (Kd,).
Soil erosion load
g/yr
Varies
This variable is calculated by using equation presented in Table B-4-11.

Uncertainties associated with this variable include the following:

(1) Most of the uncertainties associated with the variables in the equation in Table B-4-11, specifically those fGtXD, A^
A,, and Cs, are site-specific.
(2) Uncertainties associated with the remaining variables in the equation in Table B-4-11 are not expected to be
significant, primarily because of the narrow range of probable values for these variables or the use of well-established
estimation procedures (Kd,).
B-234
-------
TABLE B-4-7

TOTAL WATER BODY LOAD
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 3)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

For discussion, see References and Discussion in Table B-l-1.
B-235
-------
TABLE B-4-8
DEPOSITION TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 3)
Description
This equation calculates the average load to the water body from direct deposition of wet and dry particles and wet vapors onto the surface of the water body. Uncertainties associated with this
equation include the following:

(1) Most of the uncertainties associated with the variables in this equation, specifically those associated with Q, Dyvnw, Dytwp, and Am are site-specific.
(2) It is calculated on the basis of the assumption of a default ST value for background plus local sources, rather than an ST value for urban sources. If a specific site is located in an urban
area, the use of the latter ST value may be more appropriate. Specifically, the iSr value for urban sources is about one order of magnitude greater than that for background plus local
sources and would result in a lower calculated .Fv value; however, the Fv value is likely to be only a few percent lower.
Equation
LDEP = Q ' [ Fv - Dywwv + (1 - Fv) • Dytwp] • Av
For mercury modeling
LDEP = 0.48g -[F- Dywwv + (1 - F) • Dytwp] • Av
Deposition to water body is calculated using 0.48Q and Fv = 0.85 for divalent mercury. Use Fv = 0.85 for the mercury modeling to calculate LDEP. The calculated LDEP value is split into the
divalent and methyl mercury forms based on the 85% divalent mercury (Hg2*) and 15% methyl mercury (MHg) speciation split

r /TJrt2+\ — n C< T
*-'DEl^r*o ) *"* U.OJ *-*DEP
LDBP(MKg) = 0.15 LDEP
Variable
Description
Units
g/yr
COPC-specific emission rate
Total (wet and dry) particle phase
and wet vapor phase direct
deposition load to water body
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 for guidance regarding the calculation of this
variable. Uncertainties associated with this variable are site-specific.
B-236
-------
TABLE B-4-8
DEPOSITION TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 3)
Variable
Descrintion
Unite
Value
Fraction of COPC air concentration
in vapor phase
unitless
Otol
This variable is COPC-specific. Discussion of this variable and COPC-specific values is presented in Appendix A-3.
This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA (1994b) and NC
DEHNR(1997).

Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs.
U.S. EPA (1994c) states that Fv = 0 for all metals (except mercury).

The following uncertainties are associated with this variable:

(1) It is based on the assumption of a default ST value for background plus local sources, rather than an ST
value for urban sources. If a specific site is located in an urban area, the use of the latter ST value may be
more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than
that for background plus local sources, and it would result in a lower calculated Fv value; however, the Fv
value is likely to be only a few percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge
constant) is constant for all chemicals; however, the value of c depends on the chemical (sorbate)
molecular weight, the surface concentration for monolayer coverage, and the difference between the heat of
desorption from the particle surface and the heat of vaporization of the liquid-phase sorbate. To the extent
that site- or COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a
constant value of c is used to calculate Fv.
Dywwv
Unitized yearly (water body or
watershed) average wet deposition
from particle phase
s/mj-yr
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3).
Uncertainties associated with this variable are site-specific.
Dytwp
Unitized yearly (water body or
watershed) average total (wet and
dry) deposition from vapor phase
s/m2-yr
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3).
Uncertainties associated with this variable are site-specific.
Water body surface area
m2
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3).
Uncertainties associated with this variable are site-specific.
B-237
-------
TABLE B-4-8

DEPOSITION TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 3)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volurae22. Number4. Pages 361-367.

For discussion, see References and Discussion in Table B-l-1.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Buffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is a reference source for the equation in Table B-4-8. This document also recommends by using the equations in Bidleman (1988) to calculate Fv values for all organics
other than dioxins (PCDD/PCDFs). However, the document does not present a recommendation for dioxins. Finally, this document states that metals are generally entirely in the
paniculate phase (Fv= 0) except for mercury, which is assumed to be entirely in the vapor phase. The document does not state whether Fv for mercury should be calculated by using the
equations in Bidleman (1988).

U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance
for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document is a reference source for Equation B-4-8. This document also presents values for organic COPCs that range from 0.27 to 1. Fv values for organics other than PCDD/PCDFs
are calculated by using the equations presented in Bidleman (1988). The Fv value for PCDD/PCDFs is assumed to be 0.27, based on U.S. EPA (no date). Finally, this document presents
Fv values for inorganic COPCs equal to 0, based on the assumption that these COPCs are nonvolatile and assumed to be 100 percent in the particulate phase and 0 percent in the vapor
phase.

IMPERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 1 of 3)
Description
This equation calculates the average runoff load to the water body from impervious surfaces in the watershed from which runoff is conveyed directly to the water body.

Uncertainties associated with this equation include the following:

(1) Most of the uncertainties associated with the variables in this equation, specifically those associated with Q, Dywwv, Dytwp, and A,, are site-specific.
(2) The equation assumes a default ST value for background plus local sources, rather than an ST value for urban sources. If a specific site is located in an urban area, the use of
the latter ST value may be more appropriate. Specifically, the Sr value for urban sources is about one order of magnitude greater than that for background plus local sources and would
result in a lower calculated Fv value; however, the Fv value is likely to be only a few percent lower.
Equation
Lsi = Q ' F
For mercury modeling
(1.0 - Fv) • Dytwp
Lm = 0.480 • [ Fv - Dywwv + (1.0 - Fv) • Dytwp ] • At
Impervious runoff load to water body is calculated using 0.48g and Fv = 0.85 for divalent mercury. Use F, = 0.85 for the mercury modeling to calculate LKI. The calculated LK, value is split into
the divalent and methyl mercury forms based on the 85% divalent mercury (Hg2+) and 15% methyl mercury (MHg) speciation split.
0.85 Lg
0.15 L
Variable
Description
Unite
Runoff load from impervious
surfaces
COPC-specific emission rate
Varies
This variable is COPC- and site-specific (see Chapters 2 and 3). Uncertainties associated with this variable are site-specific.
B-239
-------
TABLE B-4-9
IMPERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 3)
Variable
F*
Dywwv
Dytwp
A,
Description
Fraction of COPC air
concentration in vapor phase
Unitized yearly (water body or
watershed) average wet
deposition from vapor phase
Unitized yearly (water body or
watershed) average total (wet and
dry) deposition from particle
phase
Impervious watershed area
receiving COPC deposition
Units
unitless
s/m2-yr
s/tn2-yr
m2
Value
Otol
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values is presented in Appendix A-3.
This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA (1994b) and NC DEHNR
(1997).
Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs. U.S. EPA
(1994c) states that Fr = 0 for all metals (except mercury).
The following uncertainties are associated with this variable:
(1) It is based on the assumption of a default ST value for background plus local sources, rather than an ST value for urban
sources. If a specific site is located in an urban area, the use of the latter Sr value may be more appropriate.
Specifically, the 5V value for urban sources is about one order of magnitude greater than that for background plus local
sources, and it would result in a lower calculated Fv value; however, the Fv value is likely to be only a few percent
lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant) is
constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from the particle
surface and the heat of vaporization of the liquid-phase sorbate. To the extent that site- or COPC-specific conditions
may cause the value of c to vary, uncertainty is introduced if a constant value of c is used to calculate Fv.
Varies
This variable is COPC- and site-specific, and is determined by ah- dispersion modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated
with this variable are site-specific.
Varies
This variable is site-specific. Uncertainties associated with this variable are site-specific.
B-240
-------
TABLE B-4-9

IMPERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 3)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume22 ••' -rnber4. Pages361-367.

For discussion see References and Discussion in Table B-l-1. .

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR. 1997. FinalNCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is a reference source for the equation in Table B-4-9. This document also recommends using the equations in Bidleman (1988) to calculate Fv values for all organics other
than dioxins (PCDD/PCDFs). However, the document does not present a recommendation for dioxins. Finally, this document states that metals are generally entirely in the paniculate
phase (Fv= 0) except for mercury, which is assumed to be entirely in the vapor phase. The document does not state whether Fv for mercury should be calculated by using the equations in
Bidleman (1988).

This document is a reference source for the equation in Table B-4-9. This document also presents values for organic COPCs that range form 0.27 to 1. Fv values for organics other than
PCDD/PCDFs are calculated by using the equations presented in Bidleman (1988). The Fv value for PCDD/PCDFs is assumed to be 0.27, based on Lorber (no date). Finally, this
document presents Fv values for inorganic COPCs equal to 0, based on the assumption that these COPCs are nonvolatile and assumed to be 100 percent in the particle phase and 0 percent
in the vapor phase.

U.S. EPA. 1997. Mercury Study Report to Congress. Volume III: Fate and Transport of 'Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-241
-------
TABLE B-4-10
PERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the average runoff load to the water body from pervious soil surfaces in the watershed. Uncertainty associated with this equation includes the following:

To the extent that site-specific or local average annual surface runoff information is not available, default or estimated values may not accurately represent site-specific or local
conditions. As a result, LK may be under- or overestimated to an unknown degree.
Equation
CS'ED
- Kds • BD
0.01
For mercury modeling, the runoff load to water body from pervious surfaces is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective Cs values and Kd, values.
Variable
Description
Units
Value
Runoff load from pervious surfaces
RO
Average annual surface runoff from
pervious areas
cm/yr
Varies
This variable is site-specific. According to U.S. EPA (1993), U.S. EPA (1994), andNC DEHNR (1997), average
annual surface runoff, RO, can be estimated by using the Water Atlas of the United States (Geraghty, Miller, Van der
Leeden, and Troise 1973). According to NC DEHNR (1997), more detailed, site-specific procedures for estimating
the amount of surface runoff, such as those based on the U.S. Soil Conservation Service CNE may also be used. U.S.
EPA (1985) is cited as an example of such a procedure.

The following uncertainty is associated with this variable:

PERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 5)
Variable
Description
Units
Value
A,
Impervious watershed area
receiving COPC deposition
Varies
This variable is site-specific. See Chapter 4 for procedures to calculate this variable. Uncertainties associated with
this variable are site-specific.
Cs
Average soil concentration over
exposure duration
mg COPC/kg soil
Varies
This variable is COPC- and site-specific, and is calculated by using the equation presented in Table B-4-1.
Uncertaintiesassociated with this variable are site-specific.
BD
Soil bulk density
g soil/cm3 soil
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water
and clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was
originally cited in Hoffman and Baes (1979). U.S. EPA (1994b) recommended a default soil bulk density value of
1.5 g/cm3, based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value
of 1.5 g/cm3 also represents the midpoint of the "relatively narrow range" for BD of 1.2 to 1.7 g/cm3.

The following uncertainty is associated with this variable:

The recommended range of soil bulk density values may not accurately represent site-specific soil
conditions.
Soil volumetric water content
mL water/cm3 soil
0.2
This variable depends on the available water and on soil structure; 0SW can be estimated as the midpoint between a
soil's field capacity and wilting point, if a representative watershed soil can be identified. However, U.S. EPA OSW
recommends the use of 0.2 mL/cm3 as a default value; this value is the midpoint of the range 0.1 (very sandy soils) to
0.3 (heavy loam/clay soils) recommended by U.S. EPA (1993) (no source or reference is provided for this range) and
is consistent with other U.S. EPA (1994b) and NC DEHNR (1997) guidance.

The following uncertainty is associated with this variable:

The default 0^ value may not accurately reflect site-specific or local conditions; therefore, KK may be
under- or overestimated to a limited extent.
B-243
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TABLE B-4-10
PERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 5)
Variable
Kd,
0.01
Description
Soil-water partition coefficient
Units conversion factor
Unite
cm3 water/g soil
kg-cm2/mg-m2
Value
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.
The following uncertainty is associated with this variable:
Uncertainties associated with this parameter will be limited if £4 values are calculated as described in
Appendix A-3.

B-244
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TABLE B-4-10

PERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

Geraghty, J.J., D.W Miller, F. Van der Leeden, and F.L. Troise. 1973. Water Atlas of the United States. Water Information Center. Port Washington, New York.

This document is cited by U.S. EPA (1993), U.S. EPA (1994c), and NC DEHNR (1997) as a reference for calculating average annual runoff, RO. Specifically, this reference provides
maps with isolines of annual average surface water runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water
recharge. Because these volumes are total contributions and not only surface runoff, U.S. EPA (1994c) notes that they need to be reduced to estimate surface runoff. U.S. EPA (1994c)
recommends a reduction of 50 percent.

Hillel, D. 1980. Fundamentals of Soil Physics. Academic Pres, Inc. New York.

This document is cited by U.S. EPA (1990) for the statement that soil bulk density, BD, is affected by soil structure, such as looseness or compaction of the soil, depending on the water
and clay content of the soil.

Hoffinan, F.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose of Radionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84 (g soil/cm3 soil).

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the source documented that cites the use of the equation in Table B-4-10; however, the document is not the original source of this equation. This document also
recommends the following:

• Estimation of average annual runoff, RO (cm/yr), by using the Water Atlas of the United States (Geraghty, Miller, Van der Leeden, and Troise 1973) or site-specific procedures,
such as the U.S. Soil Conservation Service CNE; U.S. EPA (1985) is cited as an example of the use of the CNE
• A default value of 0.2 (mL water/cm3 soil) for soil volumetric content (Qm)

U.S. EPA. 1985. Water Quality Assessment: A Screening Procedures for Toxic and Conventional Pollutants in Surface and Ground Water - Part I (Revised - 1985). Environmental Research
Laboratory. Athens, Georgia. EPA/600/6-85/002a. September.

This document cites Hillel (1980) for the statement that only soil bulk density, BD, is affected by the soil structure, such as loosened or compaction of the soil, depending on the water and
clay content of the soil.
B-245
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TABLE B-4-10

PERVIOUS RUNOFF LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of 5)

U.S. EPA. 1"993. Addendum; Methodology for Assessing Health Risks Associated with Indirect Exposure to Combtistor Emissions. Working Group Recommendations. Office of Solid Waste and
Office of Research and Development Washington, D.C. September 24.

This document is a source of COPC-specific (inorganics only) Kd, values used to develop a range (2 to 280,000 [mL water/g soil]) of Kd, values. This document also recommends a range
of soil volumetric water content (&„) of 0.1 (mL water/cm3 soil) (very sandy soils) to 0.3 mL water/cm3 soil)(heavy loam/clay soils); however, no source or reference is provided for this
range.

U.S. EPA. 1994. Revised Draft Guidance of Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance
for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends (1) a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988), and
(2) a default soil volumetric water content, 0^, value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993).

EROSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the load to the water body from soil erosion. Uncertainties associated with this equation include the following:

(1) Most of the uncertainties associated with the variables in the equation in Table B-4-11, specifically those forA^ A& A,, and Cs, are site-specific and may be significant in some cases.
(2) Uncertainties associated with the remaining variables in the equation in Table B-4-11 are not expected to be significant, primarily because of the narrow ranges of probable values for
these variables or the use of well-established estimation procedures (Kds).
Equation
Cs • Kd • BD
LF = X - (A, - A,) • SD • ER • - • 0.001
E e L l • BD
Variable
Description
Units
Soil erosion load

Unit soil loss
kg/m2-yr
Varies
This variable is site-specific, and is calculated by using the equation presented in Table B-4-13.

The following uncertainty is associated with this variable:

All of the equation variables are site-specific. Use of default values rather than site-specific values, for any
or all or these variables, will result in estimates of unit soil loss, Xa that are under- or overestimated to
some degree. The range of Xe calculated on the basis of default values spans slightly more than one order
of magnitude (0.6 to 36.3 kg/m2-yr).
Total watershed area receiving
deposition
Varies
This variable is site-specific (see Chapter 4): Uncertainties associated with this variable are site-specific.
A,
Area of impervious watershed
receiving deposition
Varies
This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific.
B-247
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TABLE B-4-11
EROSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 5)
Variable
Description
Units
Value
SD
Watershed sediment delivery ratio
unitless
Varies
This value is site-specific and is calculated by using equation in Table B-4-14.

The following uncertainly is associated with this variable:

The recommended default values for the variables a and b (empirical intercept coefficient and empirical
slope coefficient, respectively) are average values, based on a review of sediment yields from various
watersheds. These default values may not accurately represent site-specific watershed conditions and,
therefore, may contribute to the under- or over estimation of LE.
ER
Soil enrichment ratio
unitless
lor 3
COPC enrichment occurs because (1) lighter soil particles erode more than heavier soil particles and (2)
concentrations of organic COPCs—which is a function of organic carbon content of sorbing media—are expected to
be higher in eroded material than in situ soil (U.S. EPA 1993). In the absence of site-specific data, U.S. EPA OSW
recommends a default value of 3 for organic COPCs and 1 for inorganic COPCs. This is consistent with other U.S.
EPA guidance (1993), which recommends a range of 1 to 5 and a value of 3 as a "reasonable first estimate". This
range has been used for organic matter, phosphorus, and other soil-bound COPCs (U.S. EPA 1993); however,
no sources or references were provided for this range. ER is generally higher in sandy soils than in silty or
loamy soils (U.S. EPA 1993).

The following uncertainty is associated with this variable:

The default ER value may not accurately reflect site-specific conditions; therefore, LE may be over- or
underestimated to an unknown, but relatively small, extent. The extent of any uncertainties will be reduced
by using county-specific ER values.
Cs
Average soil concentration over
exposure duration
mg COPC/kg soil
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-1. Uncertainties are
site-specific.
Soil-water partition coefficient
mL water/g soil
(or cm3 water/g
soil)
Varies
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values are presented in
Appendix A-3.

The following uncertainty is associated with this variable:

Uncertainties associated with this parameter will be limited if Kds values are calculated as described in
Appendix A-3.
B-248
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TABLE B-4-11
EROSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 5)
Variable
. Description
Units
Vain*
BD
Soil bulk density
g/cm3
1.5
This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and
clay content of the soil (Hillel 1980), as summarized in U.S. EPA (1990). A range of 0.83 to 1.84 was originally
cited in Hoffman and Baes (1979). U.S. EPA (1994a) recommended a default soil bulk density value of 1.5 g/cm3,
based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988). The value of 1.5 g/cm3
also represents the midpoint of the "relatively narrow range" fbr5D of 1.2 to 1.7 g/cm3. The following uncertainty is
associated with this variable:

The recommended soil bulk density value may not accurately represent site-specific soil conditions; and
may under- or overestimate site-specific soil conditions to an unknown degree.
Soil volumetric water content
mL water/cm3 soil
0.2
This variable is site-specific, and depends on the available water and on soil structure. 6^ can be estimated as the
midpoint between a soil's field capacity and wilting point, if a representative watershed soil can be identified.
However, U.S. EPA OSW recommends the use of 0.2 mL/cm3 as a default value. This value is the midpoint of the
range of 0.1 (very sandy soils), to 0.3 (heavy loam/clay soils), recommended by U.S. EPA (1993) (no source or
reference is provided for this range) and is consistent with U.S. EPA (1994) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The default 0^, value may not accurately reflect site-specific or local conditions; therefore, LE may be
under- or overestimated to a small extent, based on the limited range of values.
0.001
Units conversion factor
kg-cm2/mg-m2
B-249
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TABLE B-4-11

EROSION LOAD TO WATER BODY

(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

Carsel, R.F., R.S. Parrish, R.L. Jones, JX. Hansen, and R.L. Lamb. 1988. "Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils." Journal of Contaminant Hydrology
Volume 2. Pages 11-24. **'

This document is the source for a mean soil bulk density, BD, of 1.5 (g soil/cm3 soil) for loam soil.

Hillel.D. 1980. Fundamentals of Soil Physics. Academic Press, Inc. New York,

Hoffman, P.O., and C.F. Baes. 1979. A Statistical Analysis of Selected Parameters for Predicting Food Chain Transport and Internal Dose ofRadionuclides. ORNL/NUREG/TM-882.

This document presents a soil bulk density, BD, range of 0.83 to 1.84 (g soil/cm3 soil).

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the sources for the range of BD values, and the default value for the volumetric soil water content.

U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office Office of
Research and Development. EPA 600-90-003. January.

This document cites Hillel (1980) for the statement that soil bulk density, BD, is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay
content of the soil.

This document is the source of the recommended range of COPC enrichment ratio, ER, values. This range, 1 to 5, has been used for organic matter, phosphorous, and other soil-based
COPCs. This document recommends a value of 3 as a "reasonable first estimate," and states that COPC enrichment occurs because lighter soil particles erode more than heavier soil
particles. Lighter soil particles have higher surface-area-to-volume ratios and are higher in organic matter content. Therefore, concentrations of organic COPCs, which are a function of
the organic carbon content of sorbing media, are expected to be higher in eroded material than in in situ soil.

This document is also the source of the following:

• COPC-specific (inorganics only) Kd, values used to develop a proposed range (0 to 280,000 [mL water/g soil]) of Kd, values
A range of soil volumetric water content (0J values of 0.1 (mL water/cm3 soil) (very gravelly soils) to 0.3 (mL water/cm3 soil) (heavy loam/clay soils); however, no source or
reference is provided for this range.
B-250
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TABLE B-4-11

EROSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(PageS of S)

This document recommends (1) a default soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil from Carsel, Parrish, Jones, Hansen, and Lamb (1988), and (2)
a default soil volumetric water content, 0^, value of 0.2 (mL water/cm3 soil), based on U.S. EPA (1993).

U.S. EPA. 1997. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-251
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TABLE B-4-12
DIFFUSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 1 of 4)
Description
This equation calculates the load to the water body due to dry vapor phase diffusion. Uncertainties associated with this equation include the following:

(1) Most of the uncertainties associated with the variables in this equation, specifically those associated with*, Q Cywv, and Am are site-specific.
(2) This equation assumes a default ST value for background plus local sources, rather than an ST value for urban sources. If a specific site is located in an urban area, the use of the latter
ST value may be more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources and would result in a
lower calculated Fv value; however, the Fv value is likely to be only a few percent lower.
Ldif -
Equation
Q • Fv • Cywv • A
H
R • T
wk
For mercury modeling

L - KV ' °'48g ' FV ' CyWV ' AW

R • T

Diffusion load to water body is calculated using 0.48Q and Fv = 0.85 for divalent mercury. Use Fv = 0.85 and HH^ for the mercury modeling to calculate Iw. The calculated LR, value is split
into the divalent and methyl mercury (MHg) forms based on me 85% Hg2* and 15% MHg speciation split

0.85V
Variable
Value
Dry vapor phase diffusion load to
water body
g/yr
,,-** * ^v*».
Overall transfer rate coefficient
m/yr
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-19. Uncertainties associated
with this variable are site-specific.
B-252
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TABLE B-4-12
DIFFUSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 2 of 4)
Variable
Q
Fv
Cywv
A.
Idr6
- Description
COPC-specific emission rate
Fraction of COPC air concentration
in vapor phase
Unitized yearly watershed air
concentration from vapor phase
Water body surface area
Units conversion factor
Unite
g/S
unitless
ug-s/g-m3
m2
g/Mg
Value
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 for guidance on the calculation of this variable.
Uncertainties associated with this variable are site-specific.
Otol
This variable is COPC-specific and should be determined from the COPC tables in Appendix A-3. Values are also
presented in U.S. EPA (1994), RTI (1992), and NC DEHNR (1997). Values are based on the work of Bidleman (1998), as
cited in U.S. EPA (1994) and NC DEHNR (1997). U.S. EPA (1994) presents values for organic COPCs that range from
0.27 to 1. AH values presented by U.S. EPA (1994) for inorganic COPCs are given as 0.
Uncertainties associated with this variable include the following:
(1) This equation assumes a default ST value for background plus local sources, rather than an ST value for urban
sources. If a specific site is located in an urban area, the use of the latter ST value may be more appropriate.
Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus
local sources and would result in a lower calculated Fv value; however, the Fv value is likely to be only a few
percent lower. -
(2) According to Bidleman (1988), the equation used to calculate F, assumes that the variable c is
constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight,
the surface concentration for monolayer coverage, and the difference between the heat of desorption from
the particle surface and the heat of vaporization of the liquid phase sorbate. To the extent that site- or
COPC-specific conditions may cause the value of c to vary, uncertainty is introduced if a constant value of
c issued to calculate Fv.
Varies
This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are site-specific.
Varies
This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific. However, it is
expected that the uncertainty associated with this variable will be limited, because maps, aerial photographs, and other
resources from which water body surface areas can be measured, are readily available.

B-253
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TABLE B-4-12
DIFFUSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 4)
Variable
H
R
T^
"""• " "•" ••"• • • 1 1 in .«' ••• irn
Description
Henry's Law constant
Universal gas constant
Water body temperature
Units
atm-mVmol
atm-m3/mol-K
K
Valnc
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.
The following uncertainty is associated with this variable:
Values for this variable, estimated by using the parameters and algorithms in Appendix A-3, may under- or
overestimate the actual COPC-specific values. As a result, LDlfmay be under- or overestimated to a limited
degree.
8.205 x 10'5
298
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of site-specific
information, consistent with U.S. EPA (1993) and U.S. EPA (1994).
The following uncertainty is associated with this variable:
To the extent that the default water body temperature value does not accurately represent site-specific or local
conditions, LM will be under- or overestimated.
B-254
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TABLE B-4-12

DIFFUSION LOAD TO WATER BODY
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

For discussion, see References and Discussion in Table B-l-1.

NC DEHNR. 1997. NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is a reference source for the equation in Table B-4-12. This document also recommends using the equations in Bidleman (1988) to calculate Fv values for all organics other
than dioxins (PCDD/PCDFs). However, the document does not present a recommendation for dioxins. This document also states that metals are generally entirely in the particulate phase
(Fv = 0), except for mercury, which is assumed to be entirely in the vapor phase. The document does not state whether Fy for mercury should be calculated by using the equations in
Bidleman (1988); U.S. EPA assumes that this is the case.

U.S.EPA. 1993. Addendum to Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Ofliceof Solid Waste and Office
Research and Development. Washington, D.C. November 10.

This document recommends a range (10°C to 30°C. 283 K to 303 K) for water body temperature, T^. No source was identified for this range.

U.S. EPA 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance
for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document is cited as the reference source for Twk water body temperature (298 K); however, no references or sources are identified for this value. This document is a reference source
for the equation in Table B-4-8. This document also presents values for organic COPCs that range from 0.27 to 1. Fv values for organics other than PCDD/PCDFs are calculated by using
the equations presented in Bidleman (1988). The Fv value for PCDD/PCDFs is assumed to be 0.27, based on Lorber (no date). Finally, this document presents Fv values for inorganic
COPCs equal to 0, based on the assumption that these COPCs are nonvolatile and 100 percent in the particulate phase and 0 percent in the vapor phase.

U.S.EPA. 1997. Mercury Study Report to Congress. Volumettl: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-255
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TABLE B-4-13
UNIVERSAL SOIL LOSS EQUATION (USLE)
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 5)
Description
This equation calculates the soil loss rate from the watershed by using the Universal Soil Loss Equation (USLE); the result is used in the soil erosion load equation hi Table B-4-11. Estimates of
unit soil loss,Xa should be determined specific to each watershed evaluated. Information on determining site- and watershed-specific values for variables used in calculating.*", is provided in
U.S. Department of Agriculture (U.S. Department of Agriculture 1997) and U.S. EPA guidance (U.S. EPA 1985). Uncertainties associated with this equation include the following:

(1) All of the equation variables are site-specific. Use of site-specific values will result in estimates of unit soil \oss,XB that are under- or overestimated to some unknown degree.
Equation
X = RF • K • LS • C - PF •
4047
Variable
Description
Unite
Value
Unit soil loss
kg/m2-yr
4.
, "^=5 «5*3*- sESSif'^^^fi
RF
USLE rainfall (or erosiyity) factor
yr'
50 to 300
This value is site-specific and is derived on a storm-by-storm basis. As cited in U.S. EPA (1993b), average annual
values have been compiled regionally by Wischmeier and Smith (1978); the recommended range reflects these
compiled values.

The following uncertainty is associated with this variable:

The range of average annual rainfall factors (50 to 300) from Wischmeier and Smith (1978) may not accurately
reflect site-specific conditions. Therefore, unit soil loss.A'j, may be under- or overestimated.
B-256
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TABLE B-4-13
UNIVERSAL SOIL LOSS EQUATION (USLE)
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 5)
Variable
Description
Value
K
USLE credibility factor
ton/acre
Varies
This value is site-specific. U.S. EPA OSW recommends the use of current guidance (U.S. Department of Agriculture 1997;
U.S. EPA 1985) in determining watershed-specific values for this variable based on ite-specific information. A default
value of 0.39, as cited in NC DEHNR (1997) and U.S. EPA (1994), was based on a soil organic matter content of 1 percent
(Droppo, Strenge, Buck, Hoopes, Brockhaus, Walter, and Whelan 1989), and chosen to be representative of a whole
watershed, not just an agricultural field.

The following uncertainty is associated with this variable:

The use of a site-specific USLE soil erodibility factor, K, may cause unit soil loss, Xe, to be under- or
overestimated to some unknown degree.
LS
USLE length-slope factor
unitless
Varies
This value is site-specific. U.S. EPA OSW recommends the use of current guidance (U.S. Department of Agriculture 1997;
U.S. EPA 1985) in determining watershed-specific values for this variable based on ite-specific information. A value of 1.5
as cited in NC DEHNR (1997) and U.S. EPA (1994), reflects a variety of possible distance and slope conditions (U.S. EPA
1988), and was chosen to be representative of a whole watershed, not just an agricultural field.

The following uncertainty is associated with this variable:

A site-specific USLE length-slope factor, LS, may not accurately represent site-specific conditions. Therefore,
unit soil loss, Xa may be under- or overestimated to some unknown degree.
USLE cover management factor
unitless
Varies
This value is site-specific. U.S. EPA OSW recommends the use of current guidance (U.S. Department of Agriculture 1997;
U.S. EPA 1985) in determining watershed-specific values for this variable based on ite-specific information. The range of
values up to 0.1 reflect dense vegetative cover, such as pasture grass; values from 0.1 to 0.7 reflect agricultural row crops;
and a value of 1.0 reflects bare soil (U.S. EPA 1993b). U.S. EPA (1993a) recommended a value of 0.1 for both grass and
agricultural crops. This range of values was also cited in NC DEHNR (1997). However, U.S. EPA (1994) and NC DEHNR
(1997) both recommend a default value of 0.1 to be representative of a whole watershed, not just an agricultural field.

The following uncertainty is associated with this variable:

The USLE cover management factor, C, value determined may not accurately represent site-specific conditions.
Therefore, the value for C may result in the under- or overestimation of unit soil loss, Xe.
B-257
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I
TABLE B-4-13

UNIVERSAL SOIL LOSS EQUATION (USLE)
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 5)
Variable
PF
Description
USLE supporting practice factor
Units
unitless
Value
Varies
This value is site-specific. U.S. EPA OSW recommends the use of current guidance (U.S. Department of Agriculture 1997;
U.S. EPA 1985) in determining watershed-specific values for this variable based on ite-specific information. A default
value of 1.0, which conservatively represents the absence of any erosion or runoff control measures, was cited in NC
DEHNR (1997) and U.S. EPA (1993; 1994).

The following uncertainty is associated with this variable:

Use of a site-specific USLE supporting practice factor, PF, may result in the under- or overestimation of unit soil
loss, Xe, depending on the actual extent that there are erosion or runoff control measures in the vicinity of the
watershed evaluated.
B-258
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TABLE B-4-13

UNIVERSAL SOIL LOSS EQUATION (USLE)
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 5)

REFERENCES AND DISCUSSION

Droppo, J.G. Jr., D.L. Strenge, J.W. Buck, B.L. Hoopes, R.D. Brockhaus, M.B. Walter, and G. Whelan. 1989. Multimedia Environmental Pollutant Assessment System (MEPAS) Application
Guidance: Volume 2-Guidelines for Evaluating MEPAS Input Parameters. Pacific Northwest Laboratory. Richland, Washington. December.

This document is cited by U.S. EPA 1994 and NC DEHNR1997 as the reference source for a USLE credibility factor value of 0.36, based on a soil organic matter content of 1 percent.

NCDEHNR. 1997. Final NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document recommended the following:

• A USLE credibility factor, K, value of 0.36 ton/acre
• A USLE length-slope factor, 15, value of 1.5 (unitless)
• A range of USLE cover management factor, C, values of 0.1 to 1.0; it also recommended a value of 0.1 to be representative of a whole watershed, not just an agricultural field.
« A USLE supporting practice factor, PF, value of 1.0

U.S. Department of Agriculture. 1997. Predicting Soil Erosion by Water: A Guide to Conservation Planning With the Revised Universal Soil Loss Equation (RUSLE). Agricultural Research
Service, Agriculture Handbook Number 703. January.

U.S. EPA. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventional Pollutants in Surface and Ground Water-—Parti (Revised). ORD. Athens, Georgia.
EPA/600/6-85/002a.

U.S. EPA. 1988. Superfund Exposure Assessment Manual. Office of Solid Waste. Washington, D.C. April.

This document is cited by U.S. EPA 1994 and NC DEHNR 1997 as the reference source for the USLE length-slope factor, LS, value of 1.5. This value reflects a variety of possible
distance and slope conditions and was chosen to be representative of a whole watershed, not just an agricultural field.

U.S. EPA. 1993a. Addendum: Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid Waste and
Office of Research and Development. Washington, D.C. September 24.

This document cites Wischmeier and Smith (1978) as the source of average annual USLE rainfall factors, RF, and states that annual values range from less than 50 for the arid western
United States to greater than 300 for the southeast.

This document also recommends the following:

• A USLE cover management factor, C, of 0.1 for both grass and agricultural crops
• A USLE supporting practice factor, PF, of 1.0, based on the assumed absence of any erosion or runoff control measures
B-259
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TABLE B-4-13

UNIVERSAL SOIL LOSS EQUATION (USLE)
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of 5)

U.S. EPA. 1993b. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustion Emissions. Office of Health and Environmental
Assessment. Office of Research and Development EPA-600-AP-93-003. November 10.

This document discusses the USLE cover management factor. This factor, C, primarily reflects how erosion is influenced by vegetative cover and cropping practices, such as planting
across slope rather than up and down slope. This document discusses a range of C values for 0.1 to 1.0; values greater than 0.1 but less than 0.2 are appropriate for agricultural row crops,
and a value of 1.0 is appropriate for sites mostly devoid of vegetation.

U.S. EPA. 1994. Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Office of Emergency and Remedial Response. Office of Solid
Waste. December 14.

This document recommends the following:

• A USLE credibility fector, K, value of 0.36 ton/acre •
• A USLE length-slope factor, LS, value of 1.5 (unitless)
• A range of USLE cover management factor, C, values of 0.1 to 1.0; it recommends a default value of 0.1 to be representative of a whole watershed, not just an agricultural field.
• A USLE supporting practice factor, PF, value of 1.0

Wischmeire, W.H., and D.D. Smith. 1978. Predicting Rainfall Erosion Losses—A Guide to Conservation Planning. Agricultural Handbook No. 537. U.S. Department of Agriculture Washington,
D.C.

This document is cited by U.S. EPA (1993) as the source of average annual USLE rainfall factors, RF, compiled regionally. According to U.S. EPA (1993), annual values range from less
than 50 for the arid western United States to greater than 300 for the southeast
B-260
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TABLE B-4-14

SEDIMENT DELIVERY RATIO
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 3)
Description
This equation calculates the sediment delivery ratio for the watershed; the result is used in the soil erosion load equation in Table B-4-11.

Uncertainties associated with this equation include the following:

(1) The recommended default empirical intercept coefficient, a, values are average values based on various studies of sediment yields from various watersheds. Therefore, these default
values may not accurately represent site-specific watershed conditions. As a result, use of these default values may under- or overestimate the watershed sediment delivery ratio, SD.
(2) The recommended default empirical slope coefficient, b, value is based on a review of sediment yields from various watersheds. This single default value may not accurately represent
site-specific watershed conditions. As a result, use of this default value may under- or overestimate the watershed sediment delivery ratio, SD.
Equation
Variable
Description >'- -y '.]'••• Pnte'. '•'• I-'-'-
Value
Watershed sediment delivery ratio
unitless
B-261
-------
f
TABLE B-4-14

SEDIMENT DELIVERY RATIO
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 3)
Variable
Description
Units
Value
Empirical intercept coefficient
unitless
0.6 to 2.1
This variable is site-specific and is determined on the basis of the watershed area (Vanoni 1975), as cited in U.S. EPA
(1993):
Watershed
"a" Coefficient
Area (so. miles') (unitless)
0.1
1
10
100
1,000
2.1
1.9
1.4
1.2
0.6
Note: 1 sq. mile = 2.59 x 106 m2

The use of these values is consistent with U.S. EPA (1994a), U.S. EPA (1994b), andNC DEHNR (1997).

The following uncertainty is associated with this variable:

The recommended default empirical intercept coefficient, a, values are average values based on various studies of
sediment yields from various watersheds. Therefore, these default values may not accurately represent site-specific
watershed conditions. As a result, use of these default values may under- or overestimate the watershed sediment
delivery ratio, SD.
Total watershed area receiving
deposition
m2
Varies
This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific.
Empirical slope coefficient
unitless
0.125
As cited in U.S. EPA (1993), this variable is an empirical constant based on the research of Vanoni (1975), which concludes
that sediment delivery ratios vary approximately with negative one-eighth (~l/8) power of the drainage area. The use of this
value is consistent with U.S. EPA (1994a), U.S. EPA (1994b), and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The recommended default empirical slope coefficient, b, value is based on a review of sediment yields from various
watersheds. This single default value may not accurately represent site-specific watershed conditions. As a result,
use of this default value may under- or overestimate the watershed sediment delivery ratio, SD.
B-262
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TABLE B-4-14

SEDIMENT DELIVERY RATIO
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 3)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. Final NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the reference source documents for the empirical intercept coefficient, a, and empirical slope coefficient, b, values. This document cites U.S. EPA (1993)
as the source of its information.

This document is cited as one of the reference source documents for the empirical intercept coefficient, a, and empirical slope coefficient, b, values. This document cites Vanoni (1975) as
its source of information.

U.S. EPA. 1994a. Draft Guidance for Performing Screening Level Risk Analysis at Combustor Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. April 15.

This document is cited as one of the reference source documents for the empirical intercept coefficient, a, and empirical slope coefficient, b, values. This document does not identify
Vanoni (1975) as the source of its information.

This document is cited as one of the reference source documents for the empirical intercept coefficient, a, and the empirical slope coefficient, b, values. This document cites U.S. EPA
(1993) as the source of its information.

Vanoni, V. A. 1975. Sedimentation Engineering. American Society of Civil Engineers. New York, New York. Pages 460-463.

This document is cited by U.S. EPA (1993) as the source of the equation inTable B-4-14 and the empirical intercept coefficient, a, and empirical slope coefficient, b, values. Based on
various studies of sediment yields from watersheds, this document concludes that the sediment delivery ratios vary approximately with negative one-eighth (~l/8) power of the drainage
ratio. U.S. EPA has not completed a review of this document.
B-263
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TABLE B-4-15
TOTAL WATER BODY CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the total water body concentration, including the water column and the bed sediment

Uncertainties associated with this equation include the following:

(1) The default variable values recommended for use in the equation in Table B-4-15 may not accurately represent site-specific water body conditions. The degree of uncertainty associated
with the variables Vf^Awdwa anddi, is expected to be limited either because the probable ranges for these variables are narrow or information allowing accurate estimates is generally
available.
(2) Uncertainty associated with/^. is largely the result of uncertainty associated with default organic carbon (OC) content values and may be significant in specific instances. Uncertainties
associated with the total core load into water body (Lj) and overall total water body core dissipation rate constant (fcj may also be significant in some instances because of the
summation of many variable-specific uncertainties.
Equation
'wtot
For mercury modeling, the total water body concentration is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective LT values,/,,, values, and Rvalues.
Variable
Description
Units
ValBfe
Total water body COPC
concentration, including water
column and bed sediment
gCOPC/m3
water body
(equivalent
tomg
COPC/L
water body)
Total COPC load to the water body,
including deposition, runoff, and
e/yr
erosion
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-7. Uncertainties associated
with LDEP, LDf Lg,, Lg, and LE, as presented in the equation in Table B-4-7, are also associated withlr.
B-264
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TABLE B-4-15

TOTAL WATER BODY CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 4)
Units
Value
Average volumetric flow rate
through water body
m'/yr
Varies
This variable is site-specific. The following uncertainty is associated with this variable:

Use of default average volumetric flow rate (PjQ information may not accurately represent site-specific conditions,
especially for those water bodies for which flow rate information is not readily available. Therefore, use of default
Vfx values may contribute to the under- or overestimation of total water body COPC concentration, C^,.
Fraction of total water body COPC
concentration in the water column
unitless
Otol
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-16.

The following uncertainty is associated with this variable:

The default values for the variables in the equation in Table B-4-16 may not accurately represent site- and water
body - specific conditions. However, the range of several variables—including dbs,CBS> and 6j,s—is relatively
narrow. Other variables, such as dwc and <4 can be reasonably estimated on the basis of generally available
information. The largest degree of uncertainty may be introduced by the default medium-specific organic carbon
(OC) content values. Because OC content values may vary widely in different locations in the same medium, by
using default values may result in insignificant uncertainty in specific cases.
Overall total water body dissipation
rate constant
yr'
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-17.

The following uncertainty is associated with this variable:

All of the variables in the equation in Table B-4-17 are site-specific; therefore, the use of default values for any or
all of these variables will contribute to the under- or overestimation of C^ The degree of uncertainty associated
with the variable Kb is expected to be under one order of magnitude and is associated largely with the estimation of
the unit soil loss, Xa values for the variables/^, K^, wAfbs are dependent on medium-specific estimates of OC
content. Because OC content can vary widely for different locations in the same medium, uncertainty associated
with these three may be significant in specific instances.
Water body surface area
Varies
This variable is site-specific. The value selected is assumed to represent an average value for the entire year. See Chapter 4
for procedures to determine this variable.

Uncertainties associated with this variable are site-specific. However, it is expected that the uncertainty associated with this
variable will be limited because maps, aerial photographs, and other resources from which water body surface,areas can be
measured, are readily available. ^^^^^
B-265
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I
TABLE B-4-15

TOTAL WATER BODY CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 4)
Variable
Description
Units
Value
Depth of water column
m
Varies
This variable is site-specific. The value selected is assumed to represent an average value for the entire year.

The following uncertainty is associated with this variable:

Use of depth of water column, 4,CT values may not accurately reflect site-specific conditions, especially for those
water bodies for which depth of water column information is unavailable or outdated. Therefore, use of d^ values
may contribute to the under-or overestimation of total water body COPC concentration, Cm,.
Depth of upper benthic sediment
layer
m
0.03
This variable is site-specific. The value selected is assumed to represent an average value for the entire year. U.S. EPA
OSW recommends a default upper benthic sediment depth of 0.03 meter, which is consistent with U.S. EPA (1994) and NC
DEHNR (1997) guidance. This value was cited by U.S. EPA (1993); however, no reference was presented.

The following uncertainty is associated with this variable:

Use of default depth of upper benthic sediment layer, dta values may not accurately represent site-specific water
body conditions. However, based on the narrow recommended range, any uncertainty introduced is believed to be
limited.
B-266
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TABLE B-4-15

TOTAL WATER BODY CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is also cited as one of the reference source documents for the default depth of upper benthic layer value. The default value is the midpoint of an acceptable range. This
document cites U.S. EPA (1993) as its source of information for the range of values for the depth of the upper benthic layer.

U.S. EPA. 1993. Addendum: Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid Waste and
Office of Research and Development. Washington, D.C. September 24.

This document is cited by NC DEHNR (1997) and U.S. EPA (1994) as the source of the range and default value for the depth of the upper benthic layer (dts).

U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combustor Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. April 15.

This document is cited as one of the reference source documents for the default depth of the upper benthic layer value. The default value is the midpoint of an acceptable range. This
document cites U.S. EPA (1993) as its source of information for the range of values for the depth of the upper benthic layer.

(Page 1 of 5)
Description
This equation calculates the fraction of total water body concentration occurring in the water column and the bed sediments.

Uncertainties associated with this equation include the following:

(1) The default variable values may not accurately represent site-specific water body conditions. However, the range of several variables—including d^ CM, and 84,—is relatively narrow.
Other variables, such as d^ and dlt can be reasonably estimated on the basis of generally available information. The largest degree of uncertainty may be introduced by the default
medium-specific OC content values. OC content values can vary widely for different locations in the same medium. Therefore, the use of default values may introduce
significant uncertainty in some cases.
Equations
Jv/c
TSS
djdz
Kd
bs
*J*.
For mercury modeling, the fraction in water column (/^.) is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective Kd^, values and Kdbs values; the fraction in
benthic sediment (/J,) is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective/,,, values.
Fraction of total water body COPC
concentration in the water column
Fraction of total water body COPC
concentration in benthic sediment
B-268
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TABLE B-4-16

FRACTION IN WATER COLUMN AND BENTHIC SEDIMENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 5)
Varinhle
Descrintinti
Units
Value
Suspended sediments/surface water
partition coefficient
L water/kg
suspended
sediment
(or cm3
water/kg
suspended
sediment)
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

KdM values in Appendix A-3 are based on default OC contents for surface water and soil. KdM values based on
default values may not accurately reflect site- and water body-specific conditions and may under- or overestimate
actual Kdm values. Uncertainty associated with this variable will be reduced if site-specific and medium-specific
OC estimates are used to calculate Kd^
TSS
Total suspended solids
concentration
Depth of water column
mg/L
2 to 300
This variable is site-specific. U.S. EPA recommends the use of site- and waterbody specific measured values, representative
of long-term average annual values for the water body of concern (see Chapter S). A value of 10 mg/L was cited by NC
DEHNR (1997), U.S. EPA (1993a), and U.S. EPA (1993b) in the absense of site-specific measured data.

The following uncertainty is associated with this variable:

Limitation on measured data used for determining a water body specific total suspended solids (755) value may
not accurately reflect site- and water body-specific conditions long term. Therefore, the TSS value may contribute
to the under-or overestimatio
m
Varies
This variable is site-specific. The value selected is assumed to represent an average value for the entire year.

The following uncertainty is associated with this variable:

Use of depth of water column, d^ values may not accurately reflect site-specific conditions, especially for those
water bodies for which depth of water column information is unavailable or outdated. Therefore, use of d^. values
may contribute to the under- or overestimation of total water body COPC concentration, C^,.
B-269
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I
TABLE B-4-I6
FRACTION IN WATER COLUMN AND BENTHIC SEDIMENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 5)
Variable
Description
Units
V«Iuc
Depth of upper benthic sediment
layer
m
0.03
This variable is site-specific. U.S. EPA OSW recommends a default upper benthic sediment depth of 0.03 meter, which is
consistent with U.S. EPA (1994) and NC DEHNR (1997) guidance. This value was cited by U.S. EPA (1993b); however,
no reference was presented.

The following uncertainty is associated with this variable:

Use of default depth of upper benthic sediment layer, <4n values may not accurately represent site-specific water
body conditions. However, any uncertainly introduced is expected to be limited on the basis of the narrow
recommended range.
Total water body depth
m
Varies
This variable is site-specific. U.S. EPA OSW recommends that the following equation be used to calculate total water body
depth, consistent with NC DEHNR (1997):
+ 4,
The following uncertainty is associated with this variable:
Calculation of this variable combines the concentrations associated with the two variables summed, dm and dbs.
Because most of the total water body depth (d,) is made up of the depth of the water column (dm), and the
uncertainties associated with dm are not expected to be significant, the total uncertainties associated with this
variable, 4. are also not expected to be significant.
Bed sediment concentration (or bed
sediment bulk density)
g/cm3
(equivalent to
kg/L)
1.0
This variable is site-specific. U.S. EPA OSW recommends a default value of 1.0, consistent with U.S. EPA (1993a), which
states that this value should be reasonable for most applications. The recommended default value is also consistent with
other U.S. EPA (1993b), U.S. EPA (1994), and NC DEHNR (1997) guidance.

The following uncertainty is associated with this variable:

The recommended default value may not accurately represent site- and water body-specific conditions. Therefore,
the variable/,,, may be under- or overestimated; the assumption that under- or overestimation will be limited is
based on the narrow recommended range.
B-270
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TABLE B-4-16
FRACTION IN WATER COLUMN AND BENTHIC SEDIMENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 5)
Variable
-..' ' Description
Unte
Value
Bed sediment porosity
0.6
This variable is site-specific. U.S. EPA OSW recommends a default bed sediment porosity of 0.6 (by using a C^ value of
1 g/cm3 and a solid density (p,) value of 2.65 kg/L) calculated by using the following equation (U.S. EPA 1993a):

64j = 7 - CBs/p,

This is consistent with other U.S. EPA (1993b), U.S. EPA (1994), and NC DEHNR (1997) guidance.

The following uncertainty is associated with this variable:

Calculation of this variable combines the uncertainties associated with the two variables, CBS and p,, used in the
calculation. To the extent that the recommended default values of CBS and ps do not accurately represent site- and
water body-specific conditions, 0fa will be under- or overestimated.
Kdb,
Bed sediment/sediment pore water
partition coefficient
L water/kg
bottom
sediment
(or
cmVater/g
bottom
sediment)
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

The Kdbs values in Appendix A-3 are based on default OC contents for sediment and soil. Kdbs values based on"
default OC values may not accurately represent site- and water body-specific conditions and may under- or
overestimate actual Kdb, values. Uncertainty associated with this variable will be reduced if site- and water
body-specific OC estimates are used to calculate Kdbs.
B-271
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I
TABLE B-4-16

FRACTION IN WATER COLUMN AND BENTfflC SEDIMENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of 5)

REFERENCES AND DISCUSSION

NC DEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessmentsfor Hazardous Waste Combustion Units. January.

This document is cited as one of the sources of the range ofKd, values and assumed OC values of 0.075 and 0.04 for surface water and sediment, respectively. This document is also cited
as one of the sources of TSS. This document cites U.S. EPA (1993b) as its source of information. This document is also cited as the source of the equation for calculating total water body
depth. No source of this equation was identified. This document is also cited as one of the reference source documents for the default value for bed sediment porosity. This document
cites U.S. EPA (1993b) as its source of information. This document is also cited as one of the reference source documents for the default value for depth of the upper benthic layer. The
default value is the midpoint of an acceptable range. This document cites U.S. EPA (1993b) as its source of information for the range of values for the depth of the upper benthic layer.
This document is also cited as one of the reference source documents for the default bed sediment concentration. This document cites U.S. EPA (1993b) as its source of information.

This document is cited as one of the sources of the range of Kd, values and assumed OC values of 0.075 and 0.04 for surface water and sediment, respectively. The generic equation for
calculating partition coefficients (soil, surface water, and bed sediments) is Kdg = (Koc • OC,). Koc is a chemical-specific value; however, OC is medium-specific. The range of Kd,
values was based on an assumed OC value of 0.01 for soil. Kdm and Kdb, values were estimated by multiplying the Kd, values by 7.5 and 4, because the OC values for surface water and
sediment are 7.5 and 4 times greater than the OC value for soil. This document also presents the equation for calculating bed sediment porosity (6tl); no source of this equation was
identified. This document was also cited as the source for the range of the bed sediment concentration (CBS); no original source of this range was identified. Finally, this document
recommends that, in the absence of site-specific information, a TSS value of 1 to 10 be specified for parks and lakes, and a TSS value of 10 to 20 be specified in streams and rivers.

U.S. EPA. 1993b. Addendum: Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid Waste and
Office of Research and Development. Washington, D.C. September 24.

This document is cited by NC DEHNR (1997) as the source of the TSS value. This document is also cited by NC DEHNR (1997) and U.S. EPA (1994) as the source of the default bed
sediment porosity value and the equation used to calculate the variable, the default bed sediment concentration value, and the range for the depth of the upper benthic layer values.

This document is cited as one of the reference source documents for the default value for bed sediment porosity. This document cites U.S. EPA (1993b) as its source of information. This
document is also cited as one of the reference source documents for the default value for depth of the upper benthic layer. The default value is the midpoint of an acceptable range. This
document cites U.S. EPA (1993b) as its source of information for the range of values for the depth of the upper benthic layer. This document is also cited as one of the reference source
documents for the default bed sediment concentration. This document cites U.S. EPA (1993b) as its source of information.

OVERALL TOTAL WATER BODY DISSIPATION RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 2)
Description
This equation calculates the overall COPC dissipation rate in surface water due to volatilization and benthic burial.

Uncertainties associated with this equation include the following:

(1) All of the variables in the equation in Table B-4-17 are site-specific. Therefore, the use of default values for any or all of these variables will contribute to the under- or overestimation
of kw- The degree of uncertainty associated with the variable kb is expected to be one order of magnitude at most and is associated with the estimation of the unit soil loss,^Te. Values
for the variables./^., Ay, and./^ are dependent on medium-specific estimates of medium-specific OC content. Because OC content can vary widely for different locations in the same
medium, uncertainty associated with these three variables may be significant in specific instances.
Equation
Variable
Overall total water body dissipation
rate constant
yr'1
Fraction of total water body COPC
concentration in the water column
unitless
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-16.

Uncertainties associated with this variable include the following:

(1) The default variable values recommended for use in the equation in Table B-4-16 may not accurately represent
site-specific water body conditions. However, the range of several variables—including dbs, CBS, and 6OT—is
moderate (factors of 5,3, and 2, respectively); therefore, the degree of uncertainty associated with these variables
is expected to be moderate. Other variables, such as d^. and da can be reasonably estimated on the basis of
generally available information; therefore, the degree of uncertainty associated with these variables is expected to
be relatively small.
(2) The largest degree of uncertainty may be introduced by the default medium-specific OC content values. OC
content values are often not readily available and can vary widely for different locations in the same medium.
Therefore, the degree of uncertainty may be significant in specific instances.
B-273
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TABLE B-4-17
OVERALL TOTAL WATER BODY DISSIPATION RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 2)
Variable
Description
Units
Value
Water column volatilization rate
constant
yr'
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-18.

Uncertainties associated with this variable include the following:

(1) All of the variables in the equation in Table B-4-18 are site-specific. Therefore, the use of default values for any
or all of these variables could contribute to the under- or overestimation of/^
(2) The degree of uncertainty associated with the variables 4 and TSS is expected to be minimal either because
information necessary to estimate these variables is generally available or because the range of probable values is
narrow.
(3) Values for the variable k, and Kdm are dependent on medium-specific estimates of OC content Because OC
content can vary widely for different locations in the same medium, uncertainty associated with these two
variables may be significant in specific instances.
Fraction of total water body COPC
concentration in benthic sediment
unitless
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-16.

Uncertainties associated with this variable include the following:

(1) The default variable values recommended for use in the equation in Table B-4-16 may not accurately represent
site-specific water body conditions. However, the range of several variables—including dtn CM, and 0W—is
relatively narrow; therefore, the degree of uncertainty associated with these variables is expected to be relatively
small. Other variables, such as d^ and d2, can be reasonably estimated on the basis of generally available
information.
The largest degree of uncertainty may be introduced by the default medium-specific OC contact values. OC
content values are often not readily available and can vary widely for different locations in the same medium.
Therefore, the degree of uncertainty may be significant in specific instances.
(2)
Benthic burial rate constant
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-22.

Uncertainties associated with this variable include the following:

(1) All of the variables in the equation in Table B-4-22 are site-specific. Therefore, the use of default values rather
than site-specific values, for any or all of these variables, will contribute to the under- or overestimation of Kb.
(2) The degree of uncertainty associated with each of these variables is as follows: (\)Xe—about one order of
magnitude at most, (2) CBS d^, Vfv TSS, and Aw—limited because of the narrow recommended ranges for these
variables or because resources to estimate variable values are generally available, and (S)AL and SD—very
site-specific, degree of uncertainty unknown.
B-274
-------
TABLE B-4-18
WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the water column COPC loss rate constant due to volatilization. Uncertainty associated with this equation includes the following:

All of the variables in the equation in Table B-4-18 are site-specific. Therefore, the use of default values for any or all of these variables will contribute to the under- or over estimation
of k,. The degree of uncertainty associated with the variables d^., d^, and d^ are expected to be minimal either because information necessary to estimate these variables is generally
available or because the range of probable values is narrow. Values for the variables K, and Kd^, are dependent on medium-specific estimates of OC content. Because OC content can
vary widely for different locations in the same medium, uncertainty associated with these two variables may be significant in specific instances.
*v =
Equation
K.
0
TSS • 10'6)
For mercury modeling, the water column volatilization loss rate constant is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective fate and transport parameters.
Variable
Description
Units
Value,
Water column volatilization rate
constant
Overall COPC transfer rate
coefficient
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-19.

Uncertainties associated with this variable include the following:

(1) All of the variables in the equation in Table B-4-19—except R, the universal gas constant, which is
well-established—are site-specific. Therefore, the use of default values, for any or all these variables, could
contribute to the under- or overestimation of A,.
(2) The degree of uncertainty associated with the variables H and Twt is expected to be minimal; values for H are
well-established, and average water body temperature, T^, will likely vary less than 10 percent of the default value.
(3) The uncertainty associated with the variables KL and KG is attributable largely to medium-specific estimates of
organic carbon, OC, content. Because OC content values can vary widely for different locations in the same medium,
the use of default values may generate significant uncertainty in specific instances. Finally, the origin of the
recommended temperature correction factor, 0, value is unknown; therefore, the degree of associated uncertainty is
also unknown.
B-275
-------
I
TABLE B-4-18
WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 4)
Variable
DwcriDtion
Units
Value
Total water body depth
m
Varies
This variable is site-specific. U.S. EPA OSW recommends that the following equation be used to calculate total water body
depth, consistent withNC DEHNR (1997):
The following uncertainty is associated with this variable:

Calculation of this variable combines the concentrations associated with the two variables summed, d^. and dbs.
Because most of the total water body depth (4) is made up of the depth of the water column (d^), and the
uncertainties associated with 4* are not expected to be significant, the total uncertainties associated with this
variable, da are also not expected to be significant.
Depth of water column
m
Varies
This variable is site-specific.

The following uncertainty is associated with this variable:

Use of default values for depth of water column, d^ may not accurately reflect site-specific conditions, especially for
water bodies for which depth of water column information is unavailable or outdated. Therefore, use of default d^
values may contribute to the under- or overestimation of total water body COPC concentration, Cwlat. However, the
. degree of under- or overestimation is not expected to be significant.
Depth of upper benthic sediment
layer
m
0.03
This variable is site-specific. U.S. EPA OSW recommends a default upper-benthic sediment depth of 0.03 meters, which is
based on the center of a range cited by U.S. EPA (1993b). This is consistent with U.S. EPA (1994) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

Use of default values for depth of upper benthic sediment layer, dta may not accurately represent site-specific water
body conditions. However, any uncertainty introduced is expected to be limited, based on the narrow recommended
range.
B-276
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TABLE B-4-18
WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 4)
Variable
Description
Value
Suspended sediments/surface water
partition coefficient
L water/kg
suspended
sediments
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

The Kdm values presented in Appendix A-3 are calculated on the basis of default OC contents for surface water and
soil. Kd^ values based on default values may not accurately reflect site-and water body-specific conditions and may
under- or overestimate actual Kdm values. Uncertainty associated with this variable will be reduced if site-specific
and medium-specific OC estimates are used to calculate Kd^.
TSS
Total suspended solids
concentration
mg/L
2 to 300
This variable is site-specific. U.S. EPA recommends the use of site- and waterbody specific measured values, representative of
long-term average annual values for the water body of concern (see Chapter 5). A value of 10 mg/L was cited by NC DEHNR
(1997), U.S. EPA (1993a), and U.S. EPA (1993b) in the absense of site-specific measured data.

The following uncertainty is associated with this variable:

Limitation on measured data used for determining a water body specific total suspended solids (TSS) value may not
accurately reflect site- and water body-specific conditions long term. Therefore, the TSS value may contribute to the
under-or overestimation offm.
Units conversion factor
kg/mg
B-277
-------
TABLE B-4-18

WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessmentsfor Hazardous Waste Combustion Units. January.

This document is cited as the source of the equation for calculating total water body depth. No source of this equation was identified. This document is also cited as one of the sources of
the range of Kd, values and an assumed OC value of 0.075 for surface water. This document is also cited as one of the sources of TSS. This document cites U.S. EPA (1993b) as its source
of information.

This document is cited as one of the sources of the range of Ay, values and assumed OC content value of 0.075 for surface water. The generic equation for calculating partition coefficients
(soil, surface water, and bed sediments) is as follows: Kd9 - K^ OCt K^. is a chemical-specific value; however, OC is medium-specific. The range of Kd, values was based on an
assumed OC value of 0.01 for soil. This document is one of the sources cited that assumes an OC value of 0.075 for surface water. Therefore, the Kdm value was estimated by
multiplying the Kd, values by 7.5, because the OC value for surface water is 7.5 times greater than the OC value for soil.

U.S. EPA. 1993b. Addendum: Methodologyfor Assessing Health Risks Associated'with IndirectExposure to Combustor Emissions. Working Group Recommendations. Office of Solid Waste and
Office of Research and Development. Washington, D.C. September 24.

This document is cited by U.S. EPA (1994) and NC DEHNR (1997) as the source of the range and default value for the depth of the upper benthic layer (rfj,). This document is also cited
by NC DEHNR (1997) as the source of the TSS value.

U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facility Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA
Hazardous Waste Combustion Facility. April 15.

This document is cited as one of the reference source documents for the default value of the depth of the upper benthic layer. The default value is the midpoint of an acceptable range.
This document cites U.S. EPA (1993b) as its source of information.

U.S. EPA. 1997. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. Ofiiceof Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-278
-------
TABLE B-4-19
OVERALL COPC TRANSFER RATE COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the overall transfer rate of contaminants from the liquid and gas phases in surface water.

Uncertainties associated with this equation include the following:

(1) All of the variables in the equation in Table B-4-19 — except/?, the universal gas constant, which is well-established — are site-specific. Therefore, the use of any or all of these
variables will contribute to the under- or overestimation of K,.
(2) The degree of uncertainty associated with the variables/? and 7^ is believed to be minimal. Values for Hare well-established, and average water body temperature will likely vary less
than 1 0 percent of the default value.
(3) The uncertainty associated with the variables Kv and Kg is attributable largely to medium-specific estimates of OC content. Because OC content values can vary widely for different
locations in the same medium, the use of default values may generate significant uncertainty in specific instances. Finally, the origin of the recommended value is unknown; therefore,
the degree of associated uncertainty is also unknown.
Equation
rr _
-\
+ *
H

*
- 293)
For mercury modeling, the overall COPC transfer rate coefficient is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective fate and transport parameters.
Variable
Description
llnits
Kv
Overall COPC transfer rate
coefficient
m/yr
B-279
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TABLE B-4-I9
OVERALL COPC TRANSFER RATE COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 4)
Variable
Description
Units
Value
Liquid phase transfer coefficient
m/yr
Varies
This variable is COPC- and site-specific, and is calculated by using the equation hi Table B-4-20.

Uncertainties associated with this variable include the following:

All of the variables in the equation in Table B-4-20 are site-specific. Therefore, the use of default values rather
than site-specific values, for any or all of these variables, will contribute to the under- or overestimation ofKy. The
degree of uncertainty associated with these variables is as follows:

a) Minimal or insignificant uncertainty is assumed to be associated with six variables—Dm u, 4, pa, pm and
^w—either because of narrow recommended ranges for these variables or because information to estimate
variable values is generally available.
b) No original sources were identified for the equations used to derive recommended values or specific
recommended values for variables C& k, and A^ Therefore, the degree and direction of any uncertainties
associated with these variables are unknown.
c) Uncertainties associated with the variable Waie site-specific.
Gas phase transfer coefficient
m/yr
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-21.

Uncertainties associated with this variable include the following:

All of the variables in the equation in Table B-4-21, with the exception of A:, are site-specific. Therefore, the use of
default values rather than site-specific values, for any or all of these variables, will contribute to the under- or
overestimation ofKG. The degree of uncertainty associated with each of these variables is as follows:

a) Minimal or insignificant uncertainty is assumed to be associated with the variables Da, /*„ and pu
because these variables have been extensively studied, and equation procedures are well-established.
b) No original sources were identified for equations used to derive recommended values or specific
recommended values for variables C# k, and 4- Therefore, the degree and direction of any uncertainties
are unknown.
c) Uncertainties associated with the variable Ware site-specific and cannot be readily estimated.
B-280
-------
TABLE B-4-19
OVERALL COPC TRANSFER RATE COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 4)
Variable
Description
Units
Value
H
Henry's Law constant
atm-m3/mol
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

Values for this variable, estimated by using the parameters and algorithms in Appendix A-3, may under- or
overestimate the actual COPC-specific values. As a result, K, may be under- or overestimated to a limited degree.
R
Universal gas constant
atm-mVmol-K
8.205x10"
There are no uncertainties associated with this constant.
Water body temperature
K
298
This variable is site-specific. U.S. EPA OSW recommends the use of this default value when site-specific information is not
available; this is consistent with U.S. EPA (1993a), U.S. EPA (1993b), and U.S. EPA (1994).

The following uncertainty is associated with this variable:

To the extent that the default water body temperature value does not accurately represent site- and water
body-specific conditions, K^, will be under- or overestimated to a limited degree.
Temperature correction factor
unitless
1.026
This variable is site-specific. U.S. EPA OSW recommends the use of this default value when site-specific information is not
available; this is consistent with U.S. EPA (1993a), U.S. EPA (1993b), and U.S. EPA (1994).

The following uncertainty is associated with this variable:

The purpose and sources of this variable and the recommended value are unknown.
B-281
-------
TABLE B-4-19

OVERALL COPC TRANSFER RATE COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

This document is the reference source for the equation in Table B-4-19, including the use of the temperature correction fraction (0).

This document is also cited by U.S. EPA (1994) andNC DEHNR (1997) as the source of the T^ value of 298 K (298 K = 25°C) and the default temperature correction fraction, 0, value of
1.026.

U.S. EPA. 1993b. Addendum to Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Solid Waste and Office of
Research and Development. Washington, D.C. November 10.

This document recommends the 7"^ value of 298 K (298 K = 25°C) and the temperature correction fraction value, 0, of 1.026. No source was identified for these values.

U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. AttachmentC, Draft Exposure Assessment Guidance
for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document is cited as the reference source for water body temperature (Twt) and temperature correction factor (0). This document apparently cites U.S. EPA (1993a) as its source of
information.

U.S. EPA. 1997. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-282
-------
TABLE B-4-20
LIQUID PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 1 of 5)
Description

This equation calculates the rate of COPC transfer from the liquid phase for a flowing or quiescent water body.

Uncertainties associated with this equation include the following:

(1) Minimal or insignificant uncertainly is assumed to be associated with the following six variables: Dw u, da $„ pwand(j.^ jj-n.fi.
(2) No original sources were identified for equations used to derive recommended values or specific recommended values for the following three variables: C* k, and d,. Therefore, the

degree and duration of any uncertainties associated with these variables is unknown.
(3) Uncertainties associated with the variable Ware site-specific.
Equation
For flowing streams or rivers
KL =
\
For quiescent lakes or ponds
V - /T"0-5 . W\ ' f " ~>°-s •
&i ~ {^d "' { '
,0.33

• 3.1536 xlO7
For mercury modeling, the liquid phase transfer coefficient is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective fate and transport parameters.
Variable
Description
Units
Value ,
Liquid phase transfer
coefficient
m/yr
B-283
-------
TABLE B-4-20
LIQUID PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 2 of 5)
Variable
Units
Value
Diffusivity of COPC in water
cm2/s
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

The default Dw values may not accurately represent the behavior of COPCs under water body-specific conditions.
However, the degree of uncertainty is expected to be minimal.
Current velocity
m/s
Varies
This variable is site-specific, and should relate to the volumetric flow rate of the waterbody evaluated.

The following uncertainty is associated with this variable:

Sources of values for this variable are reasonably available for most large surface water bodies. Estimated values
for this variable be necessary for smaller water bodies; uncertainty will be associated with these estimates. The
degree of uncertainty associated with this variable is not expected to be significant
Total water body depth
m
Varies
This variable is site-specific, and, in most cases, should represent the average mean across the waterbody evaluated. U.S.
EPA OSW recommends that this value be calculated by using the following equation, consistent with U S EPA (1994) and
NCDEHNR(1997):
No reference was cited for this recommendation.

The following uncertainty is associated with this variable:

Calculation of this variable combines the concentrations associated with the two variables summed, d^ and dts.
Because most of the total water body depth (dz) is made up of the depth of the water column (d^, and
the uncertainties associated with d^. are not expected to be significant, the total uncertainties associated with mis
variable 4 are also not expected to be significant.
B-284
-------
TABLE B-4-20
LIQUID PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 5)
VaBabte
Description
Drag coefficient
Unite
unitless
Vain*
0.0011
This variable is site-specific. U.S. EPA OSW recommends a default value of 0.0011, consistent with U.S. EPA (1993a),
U.S. EPA (1993b), U.S. EPA (1994), andNC DEHNR (1997).

The following uncertainty is associated with this variable:

The original source of this variable value is unknown. Therefore, any uncertainties associated with its use are also
unknown.
W
Average annual wind speed
m/s
3.9
Consistent with U.S. EPA (1990), U.S. EPA OSW recommends a defeult value of 3.9 m/s. See Chapter 3 for guidance
regarding the references and methods used to determine a site-specific value that isconsistent with air dispersion modeling.

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for this variable are not available, default values may not accurately
represent site-specific conditions. The uncertainty associated with the selection of a single value from within the
range of windspeeds at a single location may be more significant than the uncertainty associated with choosing a
single windspeed to represent all locations.
Density of air
g/cm3
0.0012
U.S. EPA OSW recommends this defeult value when site-specific information is not available. This is consistent with U.S.
EPA (1994) and NC DEHNR (1997), both of which cite Weast (1979) as the source of this value. This value applies at
standard conditions (25°C or 298 K and 1 atm or 750 mm Hg).

The density of air will vary with temperature.
Density of water
g/cm3
1
U.S. EPA recommends this default value, consistent with U.S. EPA (1994) and NC DEHNR (1997), both of which cite Weast
(1979) as the source of this value. This value applies at standard conditions (25°C or 298 K and 1 atm or 750 mm Hg).
There is no significant uncertainty associated with this variable.
B-285
-------
TABLE B-4-20
LIQUID PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 5)
Variable
Pgcripttom
Units
Value
von Karman's constant
unitless
0.4
This value is a constant. U.S. EPA OSW recommends the use of this value, consistent with U.S. EPA (1994) and NC
DEHNR (1997).

The following uncertainty is associated with this variable:

The original source of this variable value is unknown. Therefore, any uncertainties associated with its use are also
unknown.
Dimensionless viscous
sublayer thickness
unitless
4
This value is site-specific. U.S. EPA OSW recommends the use of this default value when site-specific information is not
available; consistent with U.S. EPA (1994) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The source of the value for this variable is unknown. Therefore, any uncertainties associated with its use cannot be
quantified.
Viscosity of water
corresponding to water
temperature
g/cm-s
1.69 x lO'02
U.S. EPA OSW recommends this defcult value, consistent with U.S. EPA (1994) and NC DEHNR (1997), which both cite
Weast (1979) as the source of this value. This value applies at standard conditions (25°C or 298 K and 1 atm or 760 mm Hg).
There is no significant uncertainty associated with this variable
B-286
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TABLE B-4-20

LIQUID PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 5 of 5)

REFERENCES AND DISCUSSION

NC DEHNR. 1997. Final NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the sources of the range ofDw values and assumed C* pa pw A; o^, and fiv values of 0.0011,1.2 x 10'3,1,0.4,4, and 1.69 x 10'2, respectively. This
document cites (1) Weast (1979) as its source of information regarding pa, pm and /^; and (2) U.S. EPA (1993a) as its source of information regarding Q k, and d2.

U.S. EPA. 1993a. Addendum: Methodology for Assessing Health Risks Associatedwith Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid Waste and
Office of Research and Development. Washington, D.C. September 24.

This document is cited by U.S. EPA (1994) and NC DEHNR (1997) as the source of the recommended drag coefficient (Crf) value of 0.0011 and the recommended von Karman's constant
(K) value of 0.4. The original sources of variable values are not identified.

This document recommends a value of 0.0011 for the drag coefficient (Crf) variable or a value of 0.4 for von Karman's constant (k). No sources are cited for these values.

This document is cited as one of the sources of the range of Dw values and assumed Q, p,,, p^ k, XB and fiw values of 0.0011,1.2x 10'3, l,0.4,4,and 1.69x 10"2, respectively. This
document cites (1) Weast (1979) as its source of information regarding pa, pm and f^; and (2) U.S. EPA (1993a) as its source of information regarding Cd k, and dr

Weast, R. C. 1979. CRC Handbook of Chemistry and Physics. 60th ed. CRC Press, Inc. Cleveland, Ohio.

This document is cited as the source of p,,, pm and ^variables of 1.2 x 10'3, l,and 1.69 x 10'2, respectively.
B-287
-------
TABLE B-4-2I
GAS PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the rate of COPC transfer from the gas phase for a flowing or quiescent water body. Uncertainties associated with this equation include the following:

(1) Minimal or insignificant uncertainty is assumed to be associated with the variables Dm i*m and pa.
(2) No original sources were identified for equations used to derive recommended values or specific recommended values for variables C& k, and A». Therefore, the degree and direction of
any uncertainties associated with these variables are unknown.
(3) Uncertainties associated with the remaining variables are site-specific.
Flowing streams or rivers
Equation
Kg = 36500 mlyr
Quiescent lakes or ponds
W)
j.0.33
"a fl
3.1536xl07
For mercury modeling, the gas phase transfer coefficient is calculated for divalent mercury (Hg24) and methyl mercury (MHg) using their respective fate and transport parameters.
Variable
Description
Cnifat
Gas phase transfer coefficient
Drag coefficeint
unitless
0.0011
This variable is site-specific. U.S. EPA recommends the use of this default value when site-specific information is not
available, consistent with U.S. EPA (1993a), U.S. EPA (1993b), U.S. EPA (1994), and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The original source of this variable is unknown. Therefore, any uncertainties associated with its use are also
unknown.
B-288
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TABLE B-4-21
GAS PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 4)
Variable
Valoe
Average annual wind velocity
m/s
3.9
Consistent with U.S. EPA (1990), U.S. EPA OSW recommends a default value of 3.9 m/s. See Chapter 3 for guidance
regarding the references and methods used to determine a site-specific value that isconsistent with air dispersion modeling.

The following uncertainty is associated with this variable:

To the extent that site-specific or local values for this variable are not available, default values may not accurately
represent site-specific conditions. The uncertainty associated with the selection of a single value from within the
range of windspeeds at a single location may be more significant than the uncertainty associated with choosing a
single windspeed to represent all locations.
von Karman's constant
unitless
0.4
This value is a constant. U.S. EPA OSW recommends the use of this value, consistent with U.S. EPA (1994) and NC
DEHNR(1997).

The following uncertainty is associated with this variable:

The original source of this variable is unknown. Therefore, any uncertainties associated with its use are also
unknown.
Dimensionless viscous
sublayer thickness
unitless
This value is site-specific. U.S. EPA OSW recommends the use of this default value when site-specific information is not
available, consistent with U.S. EPA (1994) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The original source of this variable is unknown. Therefore, any uncertainties associated with its use are also
unknown.
Viscosity of air
g/cm-s
LSI x i
-------
TABLE B-4-21
GAS PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 4)
Variable
Description
Units
Value
Density of air
g/cm1
0.0012
U.S. EPA OSW recommends the use of this default value when site-specific information is not available, consistent with U.S.
EPA (1994) andNC DEHNR (1997), both of which cite Weast (1979) as the source of this value. This value applies at
standard conditions (25°C or 298 K and 1 atm or 760 mm HgJ.

The density of air will vary with temperature.
Difiusivity of COPC hi air
cmVs
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

The recommended Da values may not accurately represent the behavior of COPCs under water body-specific
conditions. However, the degree of uncertainty is expected to be minimal.
B-290
-------
TABLE B-4-21

GAS PHASE TRANSFER COEFFICIENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. Final NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the sources of the variables p^k,^, and^a values of 1.2 x 10"3,0.4,4, and 1.81 x 10"04, respectively. This document cites (1) Weast (1979) as its source
of information for pa and tta and (2) U.S. EPA (1993a) as its source of information for k and A^.

U.S. EPA. 1993a. Addendum: Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustion Emissions. Working Group Recommendations. Office of Solid Waste,
and Office of Research and Development. Washington, B.C. September 24.

This document is cited by U.S. EPA (1994) andNC DEHNR (1997) as the source of (1) the recommended drag coefficient (Cd) value of 0.0011, (2) the recommended von Karman's
constant (k) value of 0.4, and (3) the recommended dimensionless viscous sublayer thickness (A,z) value of 4. The original sources of these variable values are not identified.

U.S. EPA. 1993b. Addendum to Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Solid Waste, and Office of
Research and Development Washington, D.C. November 10.

This document recommends (1) a value of 0.0011 for the drag coefficient (Cd) variable, (2) a value of 0.4 for von Karman's constant (K), and (3) a value of 4 for the dimensionless viscous
sublayer thickness (AJ variable. The original sources of the variable values are not identified.

This document is cited as one of the sources of the variables p,,, k, A2, and na values of 1.2 x 10'3,0.4,4, and 1.81 x 10"04, respectively. This document cites (1) Weast (1979) as its source
of information for pa and fj.a, and (2) U.S. EPA (1993a) as its source of information for k and Ar

Weast, R.C. 1979. CRC Handbook of Chemistry and Physics. 60th ed. CRCPres.Inc. Cleveland, Ohio.

This document is cited as the source of pp pm and ua variables of 1.2 x 10'3,1, and 1.69 x 10"2, respectively.
B-291
-------
TABLE B-4-22
BENTHIC BURIAL RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates the water column loss constant due to burial in benthic sediment.
Uncertainties associated with this equation include the following:
(1) All of the variables in the equation in Table B-4-22 are site-specific. Therefore, the use of default values rather than site-specific values, for any or all of these variables, will contribute
to the under- or overestimation of kt. The degree of uncertainty associated with each of these variables is as follows: (a)JT(— -about one order of magnitude at the most, (b) Cj» d^ Vp,
TSS, and A^— limited because of the narrow recommended ranges for these variables or because resources to estimate variable values are generally available, (c)^ and SD— very
site-specific, degree of uncertainty unknown.
Based on the possible ranges for the input variables to this equation, values ofkb can range over about one order of magnitude.

Variable
*»
X.
AL

Description
Benthic burial rate constant
Unit soil loss
Total watershed area receiving
deposition
Equation
] (xe-AL-SD- IxlO3 - Vfx-TSS\ (TSS-lxlO-M
C" ( ^-TSS j ( CBS-dbs J
Units
yr-'
kg/m2-yr
m2
Value
?* .„"- i,3^ £ tt?^, V ^ * 4 *" V>° \ } ^ * ^ **~"i *^*^ ^.^
Varies
This variable is site-specific and is calculated by using the equation in Table B-4-13.
The following uncertainty is associated with this variable:
All of the variables in the equation used to calculate unit soil loss.A'j, are site-specific. Use of default values rather
than site-specific values, for any or all of the equation variables, will result in estimates ofXe that under- or
overestimate the actual value. The degree or magnitude of any under- or overestimation is expected to be about
one order of magnitude or less.
Varies
This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific.
B-292
-------
TABLE B-4-22
BENTHIC BURIAL RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 4)
Variable
• Description
Value,
SD
Watershed sediment delivery ratio
unitless
Varies
This value is site-specific and is calculated by using the equation in Table B-4-14.

Uncertainties associated with this variable include the following:

(1) The default values for empirical intercept coefficient, a, recommended for use in the equation in Table B-4-14, are
average values based on various studies of sediment yields from various watersheds. Therefore, these default
values may not accurately represent site-specific watershed conditions. As a result, use of these default values may
contribute to under- or overestimation of the benthic burial rate constant, kb.
(2) The default value for empirical slope coefficient, b, recommended for use in the equation in Table B-4-14 is based
on a review of sediment yields from various watersheds. This single default value may not accurately represent
site-specific watershed conditions. As a result, use of this default value may contribute to under-or overestimation
of**.
Vf,
Average volumetric flow rate
through water body
mVyr
Varies
This variable is site-specific. U.S. EPA recommends the use of site- and waterbody specific measured values, representative
of long-term average annual values for the water body of concern.

The following uncertainty is associated with this variable:

Use of default average volumetric flow rate, Vfn values may not accurately represent site-specific water body
conditions. Therefore, the use of such default values may contribute to the under- or overestimation of kb.
However, it is expected that the uncertainty associated with this variable will be limited, because resources such as
maps, aerial photographs, and gauging station measurements—from which average volumetric flow rate through
water body, Vfa can be estimated—are generally available.
TSS
Total suspended solids
concentration
mg/L
2to300
This variable is site-specific. U.S. EPA recommends the use of site- and waterbody specific measured values, representative
of long-term average annual values for the water body of concern (see Chapter 5). A value of 10 mg/L was cited by NC
DEHNR (1997), U.S. EPA (1993a), and U.S. EPA (1993b) in the absense of site-specific measured data.

The following uncertainty is associated with this variable:

Limitation on measured data used for determining a water body specific total suspended solids (TSS) value may not
accurately reflect site- and water body-specific conditions long term. Therefore, the TSS value may contribute to
the under-or overestimation of/,,,.
B-293
-------
TABLE 3-4-22
BENTfflC BURIAL RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 4)
Variable
Description
Units
Valve
Water body surface area
Varies
This variable is she-specific. The value selected is assumed to represent an average value for the entire year. See Chapter 4
for guidance regarding the references and methods used to determine this value. Uncertainties associated with this variable
are site-specific. However, it is expected that the uncertainty associated with this variable will be limited, because maps,
aerial photographs—and other resources from which water body surface area, Am can be measured—are readily available.
lxlO'e
Units conversion factor
kg/mg
Bed sediment concentration
g/cm3
This variable is site-specific. U.S. EPA OSW recommends a default value of 1.0, consistent with U.S. EPA (1993b), which
states that this value should be reasonable for most applications. No reference is cited for this recommendation. The
recommended default value is also consistent with U.S. EPA (1993a), U.S. EPA (1993b), U.S. EPA (1994), and NC DEHNR
(1997).

The following uncertainty is associated with this variable:

The recommended value may not accurately represent site-specific water body conditions.
Depth of upper benthic sediment
layer
m
0.03
This variable is site-specific. The value selected is allowed to represent an average value for the entire year. U.S. EPA
OSW recommends a default upper-benthic sediment depth of 0.03 meters, which is based on the center of the range cited by
U.S. EPA (1993a) and U.S. EPA (1993b). This value is also consistent with U.S. EPA (1994) and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The recommended default value for depth of upper benthic sediment layer, dbs, may not accurately represent
site-specific water body conditions. Therefore, use of this default value may contribute to the under- or
overestimation of kt. However, the degree of uncertainty associated with this variable is expected to be limited
because of the narrow recommended range.
B-294
-------
TABLE B-4-22

BENTfflC BUMAL RATE CONSTANT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. FinalNCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the sources of the range of all recommended specific CBS and dt, values. This document cites U.S. EPA (1993a) as its source.

U.S. EPA. 1993a. Addendum: Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid Waste, and
Office of Research and Development. Washington, D.C. September 24.

This document is cited by U.S. EPA (1994) and NC DEHNR (1997) as the source of (1) the TSS value, (2) the range and recommended CBS value, and (3) the range and recommended
depth of upper benthic layer (dbs) value.

U.S. EPA 1993b. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November.

This document states that the upper benthic sediment depth, dbs> representing the portion of the bed in equilibrium with the water column, cannot be precisely specified. However, the
document states that values from 0.01 to 0.05 meters would be appropriate. This document also recommends a TSS value of 10 mg/L and a specific bed sediment concentration (CBS)
value.

U.S. EPA 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combustor Facilities Burning Hazardous Waste. Attachment C, Draft Exposure Assessment Guidance for RCRA
Hazardous Waste Combustion Facilities. April 15.

This document is cited as one of the reference sources for the dbs value. The recommended value is the midpoint of an acceptable range. This document is also cited as one of the
reference source documents for the default CBS value. This document cites U.S. EPA (1993a) as its source.
B-295
-------
TABLE B-4-23
TOTAL WATER COLUMN CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 1 of 3)
Description
This equation calculates the total water column concentration of COPCs including (1) both dissolved COPCs and (2) COPCs sorbed to suspended solids. Uncertainties associated with this
equation include the following:

(1) All of the variables in the equation in Table B-4-23 are COPC- and site-specific. Therefore, the use of default values rather than site-specific values, for any or all of these variables,
will contribute to the under- or overestimation of €„,#.

The degree of uncertainly associated with the variables d^ and rfj, is expected to be minimal either because information for estimating a variable (#J is generally available or because the
probable range for a variable (dt!) is narrow. The uncertainty associated with the variables/,,, and CMO, is associated with estimates of OC content. Because OC content values can vary widely
for different locations in the same medium, the uncertainty associated with using default OC values may be significant in specific cases.
Equation
'wctot
= f
J \O
wtot
For mercury modeling, the total water column concentration is calculated for divalent mercury (Hg2*) and methyl mercury (MHg) using their respective CMa values andj^. values.
Variable
Description
Units
Value
Total COPC concentration in water
column
mg
COPC/L
water
column
Fraction of total water body COPC
concentration in the water column
unitless
Otol
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-16.

The following uncertainty is associated with this variable:

The default variable values recommended for use in the equation in Table B-4-16 may not accurately represent
site-specific water body conditions. However, the ranges of several variables—including dbo CK, and Qm—is
relatively narrow. Therefore, the uncertainty is expected to be relatively small. Other variables, such as d^. and dn
can be reasonably estimated on the basis of generally available information. The largest degree of uncertainty may
be introduced by the default medium specific OC content values. OC content values are often not readily available
and can vary widely for different locations in the same medium. Therefore, default values may not adequately
represent site-specific conditions.
B-296
-------
TABLE B-4-23

TOTAL WATER COLUMN CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 3)
Vrtrffttife
Units
Value
Total waterbody COPC
concentration including water
column and bed sediment
mg
COPC/L
water body
(org
COPC/m3
water body)
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-15.

The following uncertainty is associated with this variable:

The default variable values recommended for use in the equation in Table B-4-15 may not accurately represent site-
-specific water body conditions. The degree of uncertainty associated with variables Vfx Am dw and d^ is expected
to be limited either because the probable ranges for variables are narrow or information allowing accurate estimates
is generally available. Uncertainty associated with/^ is largely the result of water body associated with default OC
content values, and may be significant in specific instances. Uncertainties associated with the total COPC load into
water body (L,) and overall total water body COPC dissipation rate constant (k^) may also be significant in some
instances because of the summation of many variable-specific uncertainties.
Depth of water column
m
Varies
This variable is site-specific. The following uncertainty is associated with this variable:

Use of default values for depth of water column,
-------
TABLE B-4-23

TOTAL WATER COLUMN CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 3)

REFERENCES AND DISCUSSION

NC DEHNR. 1997. Final NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the sources of the range of dt, values. This document cites U.S. EPA (1993a) as its source.

This document is cited by U.S. EPA (1994) and NC DEHNR (1997) as one of the sources of the ranges of dt, values. No original source of this range was identified.

U.S. EPA. 1993b. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and
Development. Washington, D.C. November.

This document states that the upper benthic sediment depth, d^ representing the portion of the bed in equilibrium with the water column, cannot be precisely specified. However, the
document states that values from 0.01 to 0.05 meters would be appropriate.

U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combustor Facilities Burning Hazardous Waste. Attachment C, Draft Exposure Assessment Guidance for RCRA
Hazardous Waste Combustion Facility. April 15.

This document is cited as one of the reference sources for the default value for depth of upper benthic layer (dbs). The recommended value is the midpoint of an acceptable range. This
document cites U.S. EPA (1993a) as the source of its information. The degree of uncertainty associated with the variables dm and dbs is expected to be minimal either because information
for estimating these variables is generally available (d^) or the probable range for a variable (db,) is narrow. Uncertainty associated with the variables/,,, and Cwut is largely associated
with the use of default OC content values. Because OC content is known to vary widely in different locations in the same medium, use of default medium-specific values can result in
significant uncertainty in some instances.

U.S. EPA. 1997. Mercury Study Report to Congress. Volume III: Fate and Transport oj'Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-298
-------
TABLE B-4-24
DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 1 of 3)
Description
This equation calculates the concentration of COPC dissolved in the water column. Uncertainties associated with this equation include the following:

The following uncertainty is associated with this variable:

All of the variables in the equation in Table B-4-23 are COPC- and site-specific. Therefore, the use of default values
rather than site-specific values, for any or all of these variables, will contribute to the under- or overestimation of
The degree of uncertainty associated with the variables d^. and dbs is expected to be minimal either because
information for estimating a variable (4J is generally available or because the probable range for a variable (dbl) is
narrow. The uncertainty associated with the variables/^, and C^, is associated with estimates of Organic Carbon,
OC, content. Because OC content values can vary widely for different locations in the same medium, using default
OC values may result in significant uncertainty in specific cases. _ ______^_^
B-299
-------
TABLE B-4-24
DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)
(Page 2 of 3)
Description
Suspended sediments/surface water
partition coefficient
Units
L water/kg
suspended
sediment
Value
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

Values contained in Appendix A-3 for KdM are based on defeult OC content values for surface water and soil.
Because OC content can vary widely for different locations in the same medium, the uncertainty associated with
estimated Kdm values based on default OC content values may be significant in specific cases.
TSS
Total suspended solids
concentration
mg/L
2 to 300
This variable is site-specific. U.S. EPA recommends the use of site- and waterbody specific measured values, representative of
long-term average annual values for the water body of concern (see Chapter 5). A value of 10 mg/L was cited by NC DEHNR
(1997), U.S. EPA (1993a), and U.S. EPA (1993b) in the absense of site-specific measured data.

The following uncertainty is associated with this variable:

Limitation on measured data used for determining a water body specific totaTsuspended solids (TSS) value may not
accurately reflect site- and water body-specific conditions long term. Therefore, the TSS value may contribute to the
under-or overestimation offm
B-300
-------
TABLE B-4-24

DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of 3)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. Final NCDEHNR Protocol for Performing Indirect Exposure Risk Assessmentsfor Hazardous Waste Combustion Units. January.

This document is cited as one of the sources of the range of Kds values and the TSS value of 10. This document cites (1) U.S. EPA (1993a) and U.S. EPA (1993b) as its sources of
information regarding TSS, and (2) RTI (1992) as its source regarding Kds.

U.S. EPA. 1993a. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Working Group Recommendations. Office of Solid
Waste and Office of Research and Development. Washington, D.C. September 24.

This document is cited by U.S. EPA (1994) and NC DEHNR (1997) as one of the sources of the range of Kds value and the assumed OC value of 0.075 for surface water. The generic
equation for calculating partition coefficients (soil, surface water, and bed sediments) is as follows: Kd9 = K^ * OC,. Kx is a chemical-specific value; however, OC is medium-specific.
The range of Kds values was based on an assumed OC value of 0.01 for soil. Therefore, the Kdm values were estimated by multiplying the £4 values by 7.5, because the OC value for
surface water is 7.5 times greater than the OC value for soil. This document is also cited by U.S. EPA (1994) and NC DEHNR (1997) as the source of the recommended TSS value.

U.S. EPA. 1993b. Addendum: Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft. Office of Research and Development.
November.

This document is cited by U.S. EPA (1994) and NC DEHNR (1997) as one of the sources of the range of Kds value and the assumed OC value of 0.075 for surface water. The generic
equation for calculating partition coefficients is as follows: Kds = K^ • OC,. K^. is a chemical-specific value; however, OC is medium-specific. The range of Kd, values was based on
an assumed OC value of 0.01 for soil. Therefore, the Kd^ values were estimated by multiplying the Kd, values by 7.5, because the OC value for surface water is 7.5 times greater than the
OC value for soil. This document is also cited by U.S. EPA (1994) andNC DEHNR (1997) as the source of revalues.

U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Waste. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. April 15.

This document is cited as one of the sources of the range of Kds values, citing RTI (1992) as its source of information.

(Page 1 of 4)
This equation calculates the concentration of COPCs sorbed to bed sediments.

Uncertainties associated with this equation include the following:
Description
(1) The default variable values recommended for use in the equation in Table B-4-25 may not accurately represent site-specific water body conditions. The degree of uncertainty associated
with variables 0to C^ d^, and du is expected to be limited either because the probable ranges for these variables are narrow or because information allowing reasonable estimates is
generally available.
Uncertainties associated with variables^, C^ and Kd^, are largely associated with the use of default OC content values in their calculation. The uncertainty may be significant in
specific instances, because OC content is known to vary widely in different locations in the same medium.
(2)
Equation
Kd,
bs
•'wtot
Qbs+Kdb,'CBS dbs
For mercury modeling, the COPC concentration sorbed to bed sediment is calculated for divalent mercury (Hg*1) and methyl mercury (MHg) using their respective
Kdt, values.
ues;^, values; and
Variable
Concentration sorbed to bed
sediment
Description
Fraction of total water body COPC
concentration that occurs in the
benthic sediment
Units
unitless
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-16.

The following uncertainty is associated with this variable:

The default values for the variables in the equation in Table B-4-16 may not accurately represent site- and water
body-specific conditions. However, the range of several variables—including dbs> CK, and Qt,—is relatively
narrow. Other variables, such as d^. and 4, can be reasonably estimated on the basis of generally available
information. The largest degree of uncertainty may be introduced by the default medium-specific OC content
values. Because OC content values may vary widely in different locations in the same medium, by using default
values may result in significant uncertainty in specific cases.
B-302
-------
TABLE B-4-25
COPC CONCENTRATION SORBED TO BED SEDIMENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 2 of 4)
Variable
$.-..' Description r.
. Vaitr
Value
Total water body concentration
including water column and bed
sediment
mg COPC/L
water body
(org
COPC/cm3
water body)
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-15.

The following uncertainty is associated with this variable:

(1) The default variable values recommended for use in the equation in Table B-4-15 may not accurately represent site-
-specific water body conditions. The degree of uncertainty associated with variables Vfv Aw d^ and dbs is expected
to be limited either because the probable ranges for these variables are narrow or information allowing reasonable
estimates is generally available.
(2) Uncertainty associated with/«. is largely the result of uncertainty associated with default OC content values and
may be significant in specific instances. Uncertainties associated with the variable LT and Kni may also be
significant because of the summation of many variable-specific uncertainties.
Bed sediment/sediment pore water
partition coefficient
L water/kg
bed
sediment
(or cm3
water/g bed
sediment)
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

The following uncertainty is associated with this variable:

The default Kdb, values in Appendix A-3 are based on default OC content values for sediment and soil. Because
medium-specific OC content may vary widely at different locations in the same medium, the uncertainty associated
with Kdbs values calculated by using default OC content values may be significant in specific instances.
Bed sediment porosity
unitless
rolume'J-'sediment/
0.6
This variable is site-specific. U.S. EPA OSW recommends a default bed sediment porosity of 0.6 (by using a CBS value of
1 g/cm3 and a solids density (ps) value of 2.65 kg/L), calculated by using the following equation (U.S. EPA 1993a):

66j = 7 - CBS/P,

This also is consistent with U.S. EPA (1993b), U.S. EPA (1994), and NC DEHNR (1997).

The following uncertainty is associated with this variable:

To the extent that the recommended default values ofCss and ps do not accurately represent site- and water
body-specific conditions, 6is will be under- or overestimated to some degree. However, the degree of uncertainty is
expected to be minimal, based on the narrow range of recommended values.
B-303
-------
r
TABLE B-4-25
COPC CONCENTRATION SORBED TO BED SEDIMENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 3 of4)
Variable
Description
Unite
Value
Bed sediment concentration (or bed
sediment bulk density)
g/cm3
1.0
This variable is site-specific. U.S. EPA OSW recommends a default value of 1.0, consistent with U.S. EPA (1993a), which
states that this value should be reasonable for most applications. No reference is cited for this recommendation. This is also
consistent with U.S. EPA (1993b), U.S. EPA (1994), and NC DEHNR (1997).

The following uncertainty is associated with this variable:

The recommended default value for 0t, may not accurately represent site- and water body-specific conditions.
Therefore, the variable C,b may be under- or overestimated to a limited degree, as indicated by the narrow range of
recommended values.
Depth of water column
m
Varies
This variable is site-specific.

The following uncertainty is associated with this variable:

Use of d^. values may not accurately reflect site-specific conditions. Therefore, use of these values may contribute
to the under- or overestimation of the variable Csb, However, the degree of uncertainty is expected to be minimal,
because resources allowing reasonable water body-specific estimates of d^ are generally available.
Depth of upper benthic sediment
layer
m
0.03
This variable is site-specific. U.S. EPA OSW recommends a default upper-benthic sediment depth of 0.03 meters, which is
based on the center of a range cited by U.S. EPA (1993b). This value is consistent with U.S. EPA (1994) andNC DEHNR
(1997).

The following uncertainty is associated with this variable:

Use of default dts values may not accurately reflect site-specific conditions. Therefore, use of these values may
contribute to the under- or overestimation of the variable Csb. However, the degree of uncertainty is expected to be
small, based on the narrow recommended range of default values.
B-304
-------
TABLE B-4-25

COPC CONCENTRATION SORBED TO BED SEDIMENT
(CONSUMPTION OF DRINKING WATER AND FISH EQUATIONS)

(Page 4 of 4)

REFERENCES AND DISCUSSION

NC DEHNR. 1997. Final NC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the sources of the range of Kds values and an assumed OC value of 0.04 for sediment. This document cites RTI (1992) as its source of information
regarding Kds values. This document is also cited as one of the reference source documents for the default value for bed sediment porosity^). This document cites U.S. EPA (1993a;
1993b) as its source of information. This document is also cited as one of the reference source documents for the default value for depth of the upper benthic layer. The default value is
the midpoint of an acceptable range. This document cites U.S. EPA (1993a) and U.S. EPA (1993b) as its source of information for the range of values for the depth of the upper benthic
layer. This document is also cited as one of the reference source documents for the default bed sediment concentration (CBS). This document cites U.S. EPA (1993a; 1993b) as its source.

This document is cited by U.S. EPA (1994) and NC DEHNR (1997) as one of the sources of the range of Kds values and an assumed OC value of 0.04 for sediment. The generic equation
for calculating partition coefficients (soil, surface water, and bed sediments) is as follows: Kdt = Koc • OCt Koc is a chemical-specific value; however, OC is medium-specific. The range
of Kds values was based on an assumed OC value of 0.01 for soil. Therefore, the Kdbs value was estimated by multiplying the Kds values by 4, because the OC value for sediment is four
times greater than the OC value for soil. This document is also cited as the source of the equation for calculating bed sediment porosity (0^). No source of this equation was identified.
This document was also cited as the source for the range of the bed sediment concentration (Ces). No source of this range was identified.

This document is cited by NC DEHNR (1997) and U.S. EPA (1994) as the source of the default bed sediment porosity value (0TO), the default bed sediment concentration value (CM), and
the range for depth of upper benthic layer (dbs) values.

This document is cited as one of the sources of the range of Kd, values and an assumed OC value of 0.04 for sediment. This document cites RTI (1992) as its source of information
regarding Kd, values. This document is cited as one of the reference source documents for the default value for bed sediment porosity (0^,). This document cites U.S. EPA (1993a; 1993b)
as its source. This document is also cited as one of the reference source documents for the default value for depth of upper benthic layer (dbs). The default value is the midpoint of an
acceptable range. This document cites U.S. EPA (1993a) and U.S. EPA (1993b) as its source of information for the range of values for the depth of the upper benthic layer. This
document is also cited as one of the reference source documents for the default bed sediment concentration (CBS). This document cites U.S. EPA (1993b) as its source.

U.S. EPA. 1997. Mercury Study Report to Congress. Volume III: Fate and Transport of'Mercury in the Environment. Office of Air Quality and Planning and Standards and Office of Research
and Development. EPA 452/R-97-005. December.
B-305
-------
TABLE B-4-26
FISH CONCENTRATION FROM BIOCONCENTRATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates fish concentration, from Dissolved COPCs, by using a bioconcentration factor. Uncertainty associated with this equation include the following:

The calculation of C&, is dependent on default values for two variables C^,a and Kd^. Values for these two variables are, in turn, dependent on default medium-specific OC content
values. Because OC content can vary widely at different locations in the same medium, significant uncertainty may be associated with C^ and Kdn and, in turn, Q, in specific
instances.
Equation
- C
dw
Variable
Description
Units
Value
Concentration of COPC in fish
mg
COPC/kg
FW tissue
Dissolved phase water
concentration
mg
COPC/L
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-24.

Uncertainties associated with this variable include the following:

FISH CONCENTRATION FROM BIOCONCENTRATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 2 of 4)
lliiit*
Value
BCF,
fish
Bioconcentration factor for COPC
in fish
unitless

([mg
COPC/kg
FW
tissue]/[mg
COPC/kg
feed])
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3. Values

As explained in Appendix A-3, U.S. EPA OSW recommends using BCFs for organic COPCs with log Km less than 4.0 and
BAFs (rather than BCFs) for organic COPCs with log Km of 4.0 or greater. For organics with a log Km value of less than 4.0
and all metals (except lead and mercury), values were obtained from U.S. EPA (1998) or, when measured values were not
available, derived from the correlation equation presented by Lyman, Reehl, and Rosenblatt (1982).

The following uncertainty is associated with this variable:

The COPC-specific BCF values may not accurately represent site-specific water body conditions, because estimates
of BCFs and BAFs can vary, based on experimental conditions. _^^___^^_
B-307
-------
TABLE B-4-26

FISH CONCENTRATION FROM BIOCONCENTRATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 3 of 4)

REFERENCES AND DISCUSSION

Ellgenhausen, H. J., A, Guth, and H,0. Esser. 1980. "Factors Determining the Bioaccunmlan'on Potential of Pesticides in the Individual Compartments of Aquatic Food Chains." EcotoxlcoJogy
Environmental Safety. Vol.4. P. 134.

BCFs for pesticides and polycyclic aromatic hydrocarbons (PAHs) with log K^ less than 5.5 were apparently calculated by using the following equation derived for pesticides from this
document:
logfiCF = 0.83 • logKw-1.71
where
BCF = Bioconcentration factor for COPC in fish(unitless)
Km = Octanol-water partition coefficient (unitless)

Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt. 1982. Handbook of Chemical Property Estimation Methods: Environmental Behavior of Organic Compounds. McGraw-Hill Book Company New
York, New York.

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document cites the following documents as its sources of the equations used to calculate BCFs fish:

Ogata, M.K., Y. Ogino Fijusaw, and E. Mano. 1984. "Partition Coefficients as a Measure of Bioconcentration Potential of Crude Oil Compounds in Fish and Shellfish." Bulletin of Environmental
Contaminant Toxicology. Vol. 33. P. 561.

BCFs for compounds with log Km less than 5.5 were calculated by using the following equation derived for aromatic compounds from this document:

log BCF = 0.71 • logKm- 0.92

where

BCF = Bioconcentration factor for COPC in fish (unitless)
Km = Octanol-water partition coefficient (unitless)

U.S. EPA. 1994. RevisedDrqft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance
for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

See the note for NC DEHNR (1997).
B-308
-------
TABLE B-4-26

FISH CONCENTRATION FROM BIOCONCENTRATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 4 of 4)

U.S. EPA. 1995. Review Draft Development of Human-Health Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and II. OfflceofSolid
Waste. March 3.

This document recommends that the following references be used:

• BCFs for organic COPCs with log Km less than 4.0 should be based on equations presented in Thomann, R.V. 1989. "Bioaccumulation Model of Organic Chemical Distribution
in Aquatic Food Chains." Environmental Science and Technology-ttQ*): 699-707.
• BAFs for organic COPCs with log Km greater than or equal to 4.0 and less than 6.5 are estimated on the basis of models presented in Thomann (1989) - see above - for the
limnetic ecosystem, or for the littoral ecosystem, based on the following document:

- Thomann, R.V., J.P. Connolly, and T.F. Parkerton. 1992. "An Equilibrium Model of Organic Chemical Accumulation in Aquatic Food Webs with Sediment
Interaction." Environmental Toxicology and Chemistry. 11:615-629.

• For organics with log Km greater than or equal to 6.5, a default BAF of 1,000 was assumed on the basis of an analysis of available data on polycyclic aromatic hydrocarbons
(PAH), and the following document:

- Stephan, C.E. et al. 1993. "Derivation of Proposed Human Health and Wildlife Bioaccumulation Factors for the Great Lake Initiative? Office of Research and
Development. U.S. EPA Research Laboratory. PB93-154672. Springfield, Virginia.

• BCFs for inorganics were obtained from various literature sources and the AQUIRE electronic database.

All BCFs and BAFs were corrected to 5 percent lipid, reflecting a typical value for a fish fillet.

U.S. EPA. 1998. Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities. Interim Final. Office of Solid Waste. February.
B-309
-------
TABLE B-4-27
FISH CONCENTRATION FROM BIOACCUMULATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 1 of 4)
Description
This equation calculates fish concentration from dissolved COPC concentration by using a bioaccumulation factor. Uncertainty associated with this equation include the following:

The calculation of Q, is dependent on default values for variables FMa. and C^. Values for these two variables are, in turn, dependent on default medium-specific OC content values.
Because OC content can vary widely at different locations in the same medium, significant uncertainty may be associated with F^ and C^, and, in turn, CM in specific instances.
Equation
For mercury modeling, the concentration of COPC in fish from total water column concentration is calculated for methyl mercury (MHg) by applying the concentration of Hg2* and MHg as shown
in the following equation:
_ /-r
Concentration of COPC in fish
B-310
-------
TABLE B-4-27

FISH CONCENTRATION FROM BIOACCUMULATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 2 of 4)
Variable
" Descrintioii
Units
Value
Dissolved phase water
concentration
mg
COPC/L
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-24.

Uncertainties associated with this variable include the following:

(1) The variables in the equation in Table B-4-24 are site-specific. Therefore, the use of default values rather than site-
specific values, for any or all of these variables, will contribute to the under- or overestimation of C^,. The degree of
uncertainty associated with TSS is expected to be relatively small, because information regarding reasonable
site-specific values for this variable is generally available or can be easily measured.
(2) The uncertainty associated with the variables Cvaot and Kdm is dependent on estimates of OC content. Because OC
content values can vary widely for different locations in the same medium, the uncertainty associated with using
different OC content values may be significant in specific cases.
BAFfi,
Bioaccumulation factor for COPC
in fish
L/kgFW
tissue
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3. As
discussed in Appendix A-3, BAFj^ values were adjusted for dissolved water concentrations. ,
For all organics with a log Km greater than or equal to 4.0, BAFs were obtained from U.S. EPA (1998), which cites U.S. EPA
(1995a), U.S. EPA (1995b), and U.S. EPA (1994b). EAFfKh value for lead was obtained as a geometric mean from various
literature sources described in U.S. EPA (1998). Elemental mercury is not expected to deposit significantly onto soils and
surface water; therefore, it is assumed that no transfer of elemental mercury to fish. All mercury in fish is assumed to exist or
be converted to methyl mercury (organic) form after uptake into the fish tissue. For this HHRAP, the BAF^ value for methyl
mercury was obtained from U.S. EPA (1997) for a trophic level 4 fish.

The following uncertainty is associated with this variable:

The COPC-specific BAF values may not accurately represent site-specific water body conditions, because estimates
of BAFs can vary, based on experimental conditions. _
B-311
-------
TABLE B-4-27

FISH CONCENTRATION FROM BIOACCUMULATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 3 of4)

REFERENCES AND DISCUSSION

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessmentsfor Hazardous Waste Combustion Units. January.

This document cites the following documents as its sources of information regarding BAFs:

U.S. EPA, 1993. "Derivation of Proposed Human Health and Wildlife Bioaccumulation Factors for the Great Lakes Initiative." Office of Research and Development, U.S. Environmental
Research Laboratory. Duluth, Minnesota. March.

This study presents three methods for estimating BAFs, in the following order of preference (first to last): (1) measured BAF; (2) measured BCF multiplied by a food-chain multiplier
estimated from log K^ and (3) BAF estimated from log KM

U.S. EPA 57 Federal Register 20802. 1993. "Proposed Water Quality Guidance for the Great Lakes System." April 16.

This document recommends that BAFs be used for compounds with a log Km greater than 5.5.

U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes Attachment C, Draft Exposure
Assessment Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

See the note forNC DEHNR (1997).

U.S. EPA. 1995a. Review Draft Development of Human Health-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and II. Office of Solid
Waste. March 3.

This document recommends that the following references be used.

• BAFs for organic COPCs with log A^ should be calculated from the following references
• BAFs for organic COPCs with log K^ greater than 4.0 but less than 6.5 should be calculated from the following references for the limetic ecosystem and the litteral ecosystem,
respectively.

- Thomann.R.V. 1989. "Bioaccumulation Model of Organic Chemical Distribution in Aquatic Food Chains." Environmental Science and Technology. 23(6):699-
707.
- Thomarm, R.V., J.P. Connolly, and T.F. Parkerton. 1992. "An Equilibrium Model of Organic Chemical Accumulation in Aquatic Food Webs with Sediment
Interaction." Environmental Toxicology and Chemistry. 11:6115-629.

• BAFs for compounds with log Km greater than 6.5 were allowed to equal 1,000, based on an analysis of available data on PAHs and the following document:

- Stephan, C.E. et al. 1993. "Derivation of Proposed Human Health and Wildlife Bioaccumulation Factors for the Great Lakes Initiative." Office of
Research and Development, U.S. Environmental Research Laboratory. PB93-154672. Springfield, Virigina.

All BAFs were corrected to 5 percent lipid, reflecting a typical value for a fish fillet

B-312
-------
TABLE B-4-27

FISH CONCENTRATION FROM BIOACCUMULATION FACTORS USING DISSOLVED PHASE WATER CONCENTRATION
(CONSUMPTION OF FISH EQUATIONS)

(Page 4 of4)

U.S. EPA. 1995b. Great Lakes Water Quality Initiative. Technical Support Document for the Procedure to Determine Bioaccumulation Factors. Office of Water. EPA-820-B-95-005. March.

U.S. EPA. 1998. Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities. Draft Interim Final. Office of Solid Waste. February.
B-313
-------
TABLE B-4-28
FISH CONCENTRATION FROM BIOTA-TO-SEDIMENT ACCUMULATION FACTORS USING COPC SORBED TO BED SEDIMENT
(CONSUMPTION OF FISH EQUATIONS)

(Page 1 of 3)
Description
This equation calculates fish concentration from bed sediment concentration, by using a biota-to-sediment accumulation factor (BSAF). Uncertainties associated with this equation include the
following:

(1) Calculation of C,t is largely dependent on default medium-specific OC content values. Because OC content can vary widely within a medium, significant uncertainty may be associated
with estimates of Crt in specific instances.
(2) Lipid content varies between different species offish. Therefore, use of a default^ value results in a moderate degree of uncertainty.
(3) Some species offish have limited, if any, contact with water body sediments. Therefore, use ofBSAFs to estimate the accumulation of COPCs in these species may be signficantly
uncertain.
Equation
Csb'flipid'BSAF
'lipid
OC
sed
Variable
Description
Unite
VaM
-/Zrt
Concentration of COPC in fish
mg
COPC/kg
FW tissue
Concentration of COPC sorbed to
bed sediment
mg
COPC/kg
bed
sediment
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-4-25.

Uncertainties associated with this variable include the following:

(1) The default variable values recommended for use in the equation in Table B-4-25 may not accurately represent site-
specific water body conditions. The degree of uncertainty associated with variables 6^, TSS, d^, and d^ is expected
to be limited either because the probable ranges for these variables are narrow or information allowing reasonable
estimates is generally available.
(2) Uncertainty associated with variables^ CWo(, and Kdt, is largely associated with the use of default OC content
values. Because OC content is known to vary widely in different locations in the same medium, use of default
medium-specific values can result in significant uncertainty in some instances.
B-314
-------
TABLE B-4-28

FISH CONCENTRATION FROM BIOTA-TO-SEDIMENT ACCUMULATION FACTORS USING COPC SORBED TO BED SEDIMENT
(CONSUMPTION OF FISH EQUATIONS)

(Page 2 of 3)
Value
Fish lipid content
unitless
0.07
U.S. EPA OSW recommends this default value, consistent with U.S. EPA (1994a), U.S. EPA (1993), and U.S. EPA (1994b).
This value was originally cited by Cook, Duehl, Walker, and Peterson (1991).

The following uncertainty is associated with this variable:

(1) Lipid content may vary between different species offish. Therefore, the use of a default^ value may result in
under- or overestimation of C^. ____^^__
BSAF
Biota-to-sediment accumulation
factor
unitless

([mg
COPC/kg
lipid
tissue]/[m
g
COPC/kg
sediment])
Varies
This variable is COPC-specific. Discussion of this variable and COPC-specific values are presented in Appendix A-3.

These factors are applied only to PCDDs, PCDFs, and polychlorinated biphenyls (PCBs), consistent with NC DEHNR (1997);
U.S. EPA (1992), U.S. EPA (1993), U.S. EPA (1994), and U.S. EPA (1995).

Uncertainty is associated with this variable:

The greatest uncertainty associated with using BSAFs is that some species offish have limited, if any, contact with
water body sediments. Any accumulation of compounds into the tissue of these fishes is almost entirely the result of
contact with surface water. Therefore, use of BSAFs to estimate COPC accumulation in these species may be
uncertain.
oc,e
Fraction of organic carbon in
bottom sediment
unitless
0.04
This variable is site-specific. U.S. EPA OSW recommends a default value of 0.04, the midpoint of the range (0.03 to 0.05), if
site-specific information is not available. This is consistent with other U.S. EPA (1993 and 1994b) and NC DEHNR (1997)
guidance.

The following uncertainty is associated with this variable::

The recommended OCsed value may not accurately represent site-specific water body conditions. However, as ^
indicated bv the probable range of values for this parameter, any uncertainty is expected to be limited in most cases.
B-315
-------
TABLE B-4-28

FISH CONCENTRATION FROM BIOTA-TO-SEDIMENT ACCUMULATION FACTORS USING COPC SOBBED TO BED SEDIMENT
(CONSUMPTION OF FISH EQUATIONS)

(Page 3 of3)

REFERENCES AND DISCUSSION

Cook, PJvL, D.W. DeehUOC. Walker, and R.E. Peterson. 1991. Bioaccumulation and Toxicity ofTCDD and Related Compounds in Aquatic Ecosystem. In Gallo, MA., RJ. Scheuplein, and
KA. Van Der Heijden (eds). Banbury Report 35: Biological Basis for Risk Assessment ofDioxins and Related Compounds. Cold Spring Harbor Laboratory Press. 0-87969-235-9/91.

This document is cited by U.S. EPA (1992), U.S. EPA (1993), and U.S. EPA (1994) as the source of the fish lipid content value.

NC DEHNR. 1997. NCDEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is cited as one of the reference source documents for biota-to-sediment factors for PCBs and dioxins. This document cites U.S. EPA (1992) as its source This document is
also cited as one of the reference documents for the default value for fraction OC in bottom sediment The default value is the midpoint of the range obtained from U S EPA (1993) No
source of this recommendation was identified.

This document is cited as one of the reference source documents for the fish lipid content value. The document cites Cook, Duehl, Walker, and Peterson (1991) as its original source of
information. This document is also cited by U.S. EPA (1994) and NC DEHNR (1997) as the source of the BSAFs. BSAF values from this document were either measured values or
estimates based on a whole fish lipid content of 7 percent. Specifically, BSAF values from this document must be evaluated because of the difficult experimental methods used to derive
them.

U.S. EPA. 1993. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. External Review Draft Office of Research and
Development. Washington, D.C. November.

This document is cited as one of the reference source documents for the fish lipid content value. The document cites Cook, Duehl, Walker, and Peterson (1991) as its original source of
information. This document is also cited for the range for fraction OC in bottom sediment No reference document was cited for this range. Finally, this document recommends using
biota-sediment accumulation factors (BSAF) for dioxin-like, compounds, including PCBs, because of their lipophilic nature.

U.S. EPA. 1994b. Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for
RCRA Hazardous Waste Combustion Facilities. April 15.

This document is cited as one of the reference source documents for the fish lipid content value. The document cites Cook, Duehl, Walker, and Peterson (1991) as its original source of
information. This document is also cited as one of the reference source documents for biota-to-sediment factors for PCBs and dioxins. This document cites U.S. EPA (1992) as its source
of information. This document is also cited as one of the reference documents for the default fraction OC in bottom sediment value. The default value is the midpoint of the range
obtained from U.S. EPA (1993). No source of this recommendation was identified.

U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project. Volumes I and II. OfficeofSolid
Waste. March 3.

This document states that a BSAF is a more reliable measure of bioaccumulation potential because of the analytical difficulties in measuring dissolved concentrations in surface water
This document also recommends using BSAFs for 2,3,7,8-TCDD and PCBs..

B-316
-------
TABLE B-5-1

AIR CONCENTRATION
(DIRECT INHALATION EQUATION)

(Page 1 of 3)
Description
This equation calculates the air concentration of a COPC based on the fraction in vapor phase and the fraction in particle phase.

Uncertainties associated with this equation include the following:

(1) Most of the uncertainties associated with the variables in this equation—specifically, those associated with variables Q, Cyv, and Cyp—are site-specific.
(2) In calculation of Fw the equation assumes a default ST value for background plus local sources, rather than an"ST value for urban sources. If a specific site is located in an urban area, the
use of the latter ST value may be more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than the ST value for background plus local
sources and would result in a lower calculated Fv value; however, the Fv value is likely to be only a few percent lower.
Equation
For all GOPCs (except mercury)
Ca = Q • [ Fv • Cyv + (1.0. - Fv ) • Cyp }
Air concentration is calculated using (1) 0.0023 andfv = 1.0 for elemental mercury (Hg°) and (2) 0.48Q and Fv = 0.85 for divalent mercury (Kg2*). Elemental mercury is evaluated only for the
inhalation exposure pathway (see discussion in Chapter 2).
For Hg°: Ca = 0.0026 '[Fv-Cyv+. (1.0 -Fv)-Cyp]

For Hg2+: Ca = 0.480 • [ Fv - Cyv + (1.0 - Fv ) • Cyp ]
Variable
Descrition
Unite
s.
Q
Air concentration
COPC-specific emission rate
g/S
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 for guidance regarding the calculation of this variable.
Uncertainties associated with this variable are COPC- and site-specific.
B-317
-------
TABLE B-5-1
AIR CONCENTRATION
(DIRECT INHALATION EQUATION)

(Page 2 of 3)
Variable
F,
Cyv
Cyp
Description >
Fraction of COPC air concentration
in vapor phase
Unitized yearly air concentration
from vapor phase
Unitized yearly air concentration
from particle phase
Units
witless
ug-s/g-m3
Hg-s/g-m3
Value
Otol
This variable is COPC-specific. A detailed discussion of this variable and COPC-specific values is presented hi Appendix A-
3. This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA (1994b) andNC DEHNR
(1997).
Fv was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs. U.S.
EPA (1994c) states that Fv = 0 for all metals (except mercury).
The following uncertainties are associated with this variable:
(1) It is based on the assumption of a default, ST value for background plus local sources, rather than an ST value for
urban sources. If a specific site is located in an urban area, the use of the latter SV value may be more appropriate.
Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus
local sources, and it would result in a lower calculated Fv value; however, the F, value is likely to be only a few
percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant) is
constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from the particle
surface and the heat of vaporization of the liquid-phase sorbate. To the extent that site- or COPC-specific conditions
may cause the value of c to vary, uncertainty is introduced if a constant value of c is used to calculate Fv.
Varies
This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are COPC- and site-specific.
Varies
This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are COPC- and site-specific.
B-318
-------
TABLE B-5-1

AIR CONCENTRATION
(DIRECT INHALATION EQUATION)

(Page 3 of 3)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

For discussion, see References and Discussion, Table B-l-1.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document recommends using the equations in Bidleman (1988) to calculate Fv values for all organics other than dioxins (PCDD/PCDFs). However, this document does not present a
recommendation for dioxins. This document also states that metals are generally entirely in the particulate phase (Fv = 0), except for mercury, which is assumed to be entirely in the vapor
phase. The document does not state whether Fv for mercury should be calculated by using the equations in Bidleman (1988).

This document presents Fv values for organic COPCs that range from 0.27 to 1. F, values for organics other than PCDD/PCDFs are calculated by using the equations presented in Bidleman
(1988). The Fv value for PCDD/PCDFs is assumed to be 0.27. This value represents dioxin TEQs by weighting data for all dioxin and furan congeners with nonzero TEFs. This document
presents Fv values for most inorganic COPCs equal to 0, based on the assumption that these COPCs are nonvolatile and assumed to be 100 percent in the particulate phase and 0 percent in
the vapor phase.

(Page 1 of 3)
Description
This equation calculates the total air concentration of a COPC (hourly) based on the faction in vapor phase and the faction in particle phase.

Uncertainties associated with this equation include the following:
(1) Most of the uncertainties associated with the variables in this equation—specifically, those associated with variables Q, Chv, and Chp—are site-specific.
(2) In calculation of Fw the equation assumes a default ST value for background plus local sources, rather than an ST value for urban sources. If a specific site is located in an urban area, the
use of the latter ST value may be more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than the ST value for background plus local
sources and would result in a lower calculated Fv value; however, the Fv value is likely to be only a few percent lower.
For all COPCs (except mercury)
Equation
= Q • I Fv ' ^ + (1.0 -
Acute air concentration is calculated using 0.002Q and F, = 1.0 for elemental mercury (Hg°). Elemental mercury is the only species of mercury evaluated for the acute inhalation exposure
pathway (see discussion in Chapter 2).
(1.0 -
Variable
Description
Units
Value
Acute air concentration

COPC-specific emission rate
g/s
Varies
This variable is COPC- and site-specific. See Chapters 2 and 3 for guidance regarding the calculation of this variable.
Uncertainties associated with this variable are COPC- and site-specific.
B-320
-------
TABLE B-6-1
ACUTE AIR CONCENTRATION EQUATION
(ACUTE EQUATION)

(Page 2 of 3)
Variable
^v
Chv
Chp
>.. ' ' Description i
Fraction of COPC air concentration
in vapor phase
Unitized hourly air concentration
from vapor phase
Unitized hourly air concentration
from particle phase
Units ,
unitless
ug-s/g-m3
ug-s/g-m3
"" ' /Value,' - .' v M ' ,
Otol
This variable is COPG-specific. A detailed discussion of this variable and COPC-specific values is presented in Appendix A-
3. This range is based on values presented in Appendix A-3. Values are also presented in U.S. EPA (1994b) and NC DEHNR
(1997).
Fr was calculated using an equation presented in Junge (1977) for all organic COPCs, including PCDDs and PCDFs. U.S.
EPA (1994c) states that Fv = 0 for all metals (except mercury).
The following uncertainties are associated with this variable:
(1) It is based on the assumption of a default, ST value for background plus local sources, rather than an ST value for
urban sources. If a specific site is located in an urban area, the use of the latter ST value may be more appropriate.
Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus
local sources, and it would result in a lower calculated Fv value; however, the Fv value is likely to be only a few
percent lower.
(2) According to Bidleman (1988), the equation used to calculate Fv assumes that the variable c (Junge constant) is
constant for all chemicals; however, the value of c depends on the chemical (sorbate) molecular weight, the
surface concentration for monolayer coverage, and the difference between the heat of desorption from the particle
surface and the heat of vaporization of the liquid-phase sorbate. To the extent that site- or COPC-specific conditions
may cause the value of c to vary, uncertainty is introduced if a constant value of c is used to calculate Fv.
Varies
This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are COPC- and site-specific.
Varies
This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties
associated with this variable are COPC- and site-specific.
B-321
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TABLE B-6-1

ACUTE AIR CONCENTRATION EQUATION
(ACUTE EQUATION)

(Page 3 of 3)

REFERENCES AND DISCUSSION

Bidleman, T.F. 1988. "Atmospheric Processes." Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

For discussion, see References and Discussion, Table B-l-1.

Junge, C.E. 1977. Fate of Pollutants in Air and Water Environments, Part I. Suffet, I.H., Ed. Wiley. New York. Pages 7-26.

NCDEHNR. 1997. Final NCDEHNR Protocolfor Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document recommends using the equations hi Bidleman (1988) to calculate Fv values for all organics other than dioxins (PCDD/PCDFs). However, this document does not present a
recommendation for dioxins. This document also states that metals are generally entirely in the particulate phase (Fv = 0), except for mercury, which is assumed to be entirely in the vapor
phase. The document does not state whether Fv for mercury should be calculated by using the equations in Bidleman (1988).

This document presents Fv values for organic COPCs that range from 0.27 to 1. Fv values for organics other than PCDD/PCDFs are calculated by using the equations presented in Bidleman
(1988). The Fv value for PCDD/PCDFs is assumed to be 0.27. This value represents dioxui TEQs by weighting data for all dioxin and furan congeners with nonzero TEFs. This document
presents Fv values for most inorganic COPCs equal to 0, based on the assumption that these COPCs are nonvolatile and assumed to be 100 percent hi the particulate phase and 0 percent in
the vapor phase.

U.S. EPA. 1997. "Mercury Study Report to Congress." Volume IE. Draft. Office of Air Quality and Planning and Standards and Office of Research and Development. December.
B-322
-------
APPENDIX C

RISK CHARACTERIZATION EQUATIONS

Human Health Risk Assessment Protocol

July 1998
-------
-------
APPENDIX C

RISK CHARACTERIZATION EQUATIONS

TABLE PAGE

C-l-1 COPC INTAKE FROM SOIL C-1

C-l-2 COPC INTAKE FROM PRODUCE C-6

C-l-3 COPC INTAKE FROM BEEF, MILK, PORK, POULTRY, AND EGGS ,. C-11

C-l-4 COPC INTAKE FROM FISH C-16

C-l-5 COPC INTAKE FROM DRINKING WATER C-20

C-l-6 TOTALDAILYINTAKE C-23

C-l-7 INDIVIDUALCANCERRISK: CARCINOGENS C-26

C-l-8 HAZARD QUOTIENT: NONCARCINOGENS C-30

C-l-9 TOTAL CANCERRISK: CARCINOGENS C-33

C-l-10 TOTAL HAZARD INDEX: NONCARCINOGENS C-34

C-l-11 SEGREGATED HAZARD INDEX FOR SPECIFIC ORGAN EFFECTS:
NONCARCINOGENS .^ C-35

C-2-1 INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS .. C-36

C-2-2 INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCINOGENS C-44

C-2-3 TOTAL INHALATION CANCER RISK: CARCINOGENS C-49

C-2-4 HAZARD INDEX FOR INHALATION: NONCARCINOGENS C-50

C-3-1 CONCENTRATION OF DIOXINS IN BREAST MILK C-51

C-3-2 AVERAGE DAILY DOSE TO THE EXPOSED INFANT C-55

C-4-1 ACUTE HAZARD QUOTIENT C-59
C-i
-------
APPENDIX C

LIST OF VARIABLES
ADD
ADI
AHQ
AIEC
A,
AT
BW
Cancer Risfy =
Cancer Riski^fl =
CR
Cs
ED
EF
ET

ft
/7
f3
Average daily dose (mg COPC/kg BW-day)
Average daily dose for infant exposed to contaminated breast milk (pg [or mg]
COPC/kg BW infant/day)
Average daily dose, mother (pg COPC/kg BW mother/day)
Average daily COPC intake via inhalation (mg COPC/kg BW-day)
Acute hazard quotient for inhalation of COPCs (unitless)
COPC acute inhalation exposure criteria (mg/m3)
Concentration of COPC /in animal tissue/ (mg COPC/kg FW tissue)
Averaging time (yr)
Averaging time for infant (yr)

Body weight (kg)
Body weight of infant (kg)

Total COPC air concentration (ug/m3)
Acute air concentration (ug/m3)
Individual lifetime risk through indirect exposure to COPC carcinogen/(unitless)
Individual lifetime cancer risk through direct inhalation of COPC carcinogen/
(unitless)
Dissolved phase water concentration (mg COPC/L water)
Concentration in fish (mg COPC/kg FW tissue)
Concentration in milk fat of breast milk for a specific exposure scenario
(pg [or mg] COPC/kg milk fet)
Consumption rate of aboveground produce (kg DW plant/kg BW-day)
Consumption rate of belowground produce (kg DW plant/kg BW-day)
Consumption rate of drinking water (L water/day)
Consumption rate of fish (kg/kg BW-day)
Consumption rate of animal tissue/ (kg/kg-day FW)
Consumption rate of protected aboveground produce (kg DW plant/kg BW-day)
Consumption rate of soil (kg soil/day)
Average soil concentration over exposure duration (mg COPC/kg soil)

Exposure duration (yr)
Exposure duration of infant to breast milk (yr)
Exposure frequency (days/yr)
Exposure time (hrs/day)

Fraction of ingested dioxin that is stored in fat (unitless)
Fraction of mother's weight that is fat (unitless)
Fraction of mother's breast milk that is fat (unitless)
Fraction of ingested COPC that is absorbed (unitless)
Fraction of produce that is contaminated (unitless)
Fraction of belowground produce that is contaminated (unitless)
C-ii
-------
APPENDIX C

LIST OF VARIABLES
HI,
inhff)
7

/i
*.
Inhalation CSF
IR
LADD

Oral CSF

Pv*

RfC
RJD

Total Cancer
Risk
Fraction of drinking water that is contaminated (unitless)
Fraction of fish that is contaminated (unitless)
Fraction of animal tissue y that is contaminated (unitless)
Fraction of soil that is contaminated (unitless)

Half-life of dioxin in adults (days)
Hazard index for target organ effecty through direct inhalation of all COPCs
(unitless)
Hazard index for exposure pathway./ (unitless)
Hazard quotient for COPC / (unitless)
Hazard quotient for direct inhalation of COPC / (unitless)

Total daily intake of COPC (mg COPC/kg BW-day)
Daily intake of COPC /from animal tissue./ (mg COPC/kg BW-day)
Daily intake of COPC from produce (mg COPC/kg BW-day)
Daily intake of COPC from belowground produce (mg COPC/kg BW-day
Daily intake of COPC from drinking water (mg COPC/kg BW-day)
Daily intake of COPC from fish (mg COPC/kg BW-day)
Daily intake of COPC from soil (mg COPC/kg BW-day)
Inhalation cancer slope factor (mg/kg-day)"1
Inhalation rate (m3/hr)
Ingestion rate of breast milk by the infant (kg/day)

Lifetime average daily dose (mg COPC/kg BW-day)

Average maternal intake of dioxin for each adult exposure scenario (mg COPC/kg
BW-day)

Oral cancer slope factor (mg/kg-day)"1

Aboveground exposed produce concentration due to direct (wet and dry)
deposition onto plant surfaces (mg COPC/kg DW)
Total COPC concentration in plant type / eaten by the animal (mg/kg DW)
Aboveground exposed and protected produce concentration due to root uptake
(mg COPC/kg DW)
Belowground produce concentration due to root uptake (mg COPC/kg DW)
Concentration of COPC in plant due to air-to-plant transfer (mg COPC/kg DW)

Reference concentration (mg/kg)
Reference dose (mg/kg-day)

Individual lifetime cancer risk through indirect exposure to all COPC
carcinogens (unitless)
C-iii
-------
Total Corner
RiskM
URF
APPENDIX C

LIST OF VARIABLES
Total individual lifetime cancer risk through direct inhalation of all COPC
carcinogens (unitless)

Unit risk factor (jog/m3)'1
C-iv
-------
TABLE C-l-1
COPC INTAKE FROM SOIL
(Page 1 of 5)
Description
This equation calculates the daily intake of COPC from soil consumption. The soil concentration will vary with each scenario location, and the soil consumption rate varies for children and
adults. Uncertainties associated with this equation include:

(1) The amount of soil intake is assumed to be constant and representative of the exposed population. This assumption may under- or overestimate /,„„.
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This assumption may under- or overestimate /„„.
Equation
BW
Variable
^Description •
; Units v-
~Valne,
Daily intake of COPC from soil
mg/kg-day
C-l
-------
TABLE C-l-1
COPC INTAKE FROM SOIL
(Page 2 of 5)
Variable
Units
Value
Cs
Average soil concentration over
exposure duration
mg/kg
Varies
This variable is COPC- and site-specific, and is calculated using the equation in Table B-1-1. Cs will vary based on whether
the COPC is carcinogenic or noncarcinogeriic.

For carcinogenic COPCs, this value is equal to the soil concentration averaged over the exposure duration (Table B-1-1) (U.S.
EPA 1994 andNC DEHNR1997). For nonearcinogenic COPCs, this value is equal to the highest annual soil concentration
occurring within the exposure duration. The highest annual soil concentration would occur at the end of the time period of
combustion (Table B-1-1) (U.S. EPA 1994 and NC DEHNR 1997).

Uncertainties associated with this variable include:

(1) The time period over which deposition of COPCs due to hazardous waste combustion is assumed to be conservative,
long-term value. This assumption may overestimate Cs.
(2) Exposure durations are based on historical mobility rates, and may not remain constant. This assumption may
overestimate or underestimate Cs.
(3) Mobility studies indicate that most receptors that move remain in the vicinity of the emission source, however, the
likelihood that these short distances moves will influence exposure based on factors such as atmospheric transport of
pollutants cannot be predicted accurately. This assumption may overestimate or underestimate Cs.
(4) The use of a value of 0 for T, does not account for exposure that may have occurred prior to hazardous waste combustion.
This may underestimate Cs.
(5) For soluble COPCs, leaching may lead to movement below 1 cm in unfilled soils; resulting in a greater mixing depth.
This uncertainty may overestimate Cs.
(6) Deposition to hard surfaces may result in dust residues that have negligible dilution compared to other residues. This
uncertainty may underestimate Cs.
C-2
-------
TABLE C-l-1
COPC INTAKE FROM SOIL
(Page 3 of 5)
Units
Value.,
CR,C
Consumption rate of soil
kg/day
0.00005 to 0.0001
The soil consumption rate varies for the adult and child receptors (U.S. EPA 1997).

Receptor Intake Rate (kg/day)
Adult O.OOOOS
Child 0.0001

U.S. EPA (1997) states that a child intake rate of 0.0002 kg/day for a child receptor may be used as a conservative estimate of
exposure. U.S. EPA (1997) references studies done by Hawley (1985) and Calabrese (1990) as the sources used to derive soil
consumption rates.

Uncertainties associated with this variable include:

(1) Tracer studies have resulted in wide ranging estimates of the amount of soil and dust ingested by young children, making
it difficult to identify a single value which should be used. Additionally it is extremely difficult to separate the
contribution of exposure resulting from exterior soil vs. interior dust. As a result the intake rate is reported as the
combined rate for soils and dusts. This uncertainty may under- or overestimate CR ma.
(2) The recommended intake rates may not accurately represent behavioral characteristics since they are upper estimates.
This uncertainty may overestimate CRMfl.
(3) The intake rates represent normal mouthing tendencies. Some children exhibit abnormal mouthing behavior or "pica"
and would have much higher intake rates. This uncertainty may considerably underestimate CRsott.
Fraction of soil that is contaminated
unitless
1.0
U.S. EPA OSW assumes the fraction of consumed soil contaminated is equal to 1.0. This is consistent with NC DEHNR
(1997) and U.S. EPA (1994), which assumes the fraction of consumed soil contaminated is 1.0 for all exposure scenarios.

Uncertainty associated with this variable include:

U.S. EPA guidance recommends the fraction of consumed soil contaminated is equal to 1.0. However, due to variations
in the proximity of the receptor to the contaminated source, size of the contaminated source, receptors of concern,
mobility of receptors, and nature of exposure, FM(/ may be overestimated or underestimated.
C-3
-------
TABLE C-l-1

COPC INTAKE FROM SOIL

(Page 4 of 5)
Variable
BW
— i .-I. —
Description
Body weight
^^^BSHB^BE*g^^^JgMBB""^*^^^^»ppHi^^^^MMiii^^
Units
kg
„ , Value
15 or 70
U.S. EPA OSW recommends using default values of 70 (adults) and 15 (children). These de&ult values arc consistent with
Uncertainty associated with this variable include:
These body weights represent the average weight of an adult and child. However, depending on the actual receptor
body weights may be higher or lower. These defcult values may overestimate or underestimate actual body weights'.
However, the degree of under- or overestimation is not expected to be significant
C-4
-------
TABLE C-l-1

COPC INTAKE FROM SOIL

(Page 5 of 5)

REFERENCES AND DISCUSSION

Calabrese, E.J., Stanek, E.J., Gilbert, C.E., and Barnes, R.M. 1990. Preliminary adult soil ingestion estimates; results of a pilot study. Regul. Toxicol. Pharmacol. 12:88-95.

This document is cited by U.S. EPA (1997) as a source of information used to derive soil consumption rates.

Hawley, J.K. 1985. Assessment of health risk from exposure to contaminated soil. Risk Analysis 5:289-302.

This document is cited by U.S. EPA (1997) as a source of information used to derive soil consumption rates.

NCDEHNR. 1997. North Carolina Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the sources for the equation in Table C-l-1. This document also states that (1) for carcinogenic COPCs, Cs is equal to the soil concentration averaged over the
exposure duration; however, no reference document is cited and (2) for noncarcinogenic COPCs, Cs is equal to the highest annual soil concentration occurring within the exposure duration;
the highest annual soil concentration would occur at the end of the time period of emissions.

U.S.EPA. 1991. Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. Officeof Solid Waste and Emergency Response. OSWER Directive 9285.6-
03. Washington, D.C. March 21.

This document is cited as the reference source document of the exposure frequency and body weight-variables.

U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

U.S.EPA. 1997. Exposure Factors Handbook. Office of Research and Development. EPA/600/P-95/002F. August.

This document is the source for soil consumption rates.
C-5
-------
TABLE C-l-2
COPC INTAKE FROM PRODUCE
(Page 1 of 5)
Description
This equation calculates the daily intake of COPC from ingestion of exposed aboveground, protected aboveground, and belowground produce. The consumption rate varies for children and
adults, and for the type of produce. The concentration in exposed aboveground, protected aboveground, and belowground produce will also vary with each scenario location.

Consumption rates were derived from the Exposure Factors Handbook (U.S. EPA 1997). U.S. EPA (1997) presents consumption rates based on body weight; therefore, body weight is not
included as a variable in the calculation of/ar

Uncertainties associated with this equation include the following:

(1) The amount of produce intake is assumed to be constant and representative of the exposed population. This assumption may under- or overestimate 7or
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This assumption may under- or overestimate Iag.
Equation-
Iag = [((Pd+Pv+Pr) • CRag) + (fir • CRpp) * (Prbg • CRbg)] • Fag
Variable
Daily intake of COPC from
produce
Description
Aboveground exposed
produce concentration due
to direct (wet and dry)
deposition onto plant
surfaces
Units
mg/kg
Valne
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-2-7.

Uncertainties associated with this variable include the following:

(1) The calculation of lip values does not consider chemical degradation processes. Inclusion of chemical degradation processes
would decrease the amount of time that a chemical remains on plant surfaces (half-time) and thereby may increase kp values.
Pd decreases with increased Jq> values. Reduction of half-time from the assumed 14 days to 2.8 days, for example, would
decrease Pd about five-fold.
(2) The calculation of other parameter values (for example, Fw and Rp) is based directly or indirectly on studies of vegetation other
than aboveground produce (primarily grasses). Uncertainty is introduced to the extent that the calculated parameter values do
not accurately represent aboveground produce-specific values.
C-6
-------
TABLE C-l-2
COPC INTAKE FROM PRODUCE
(Page 2 of 5)
Variable
Units
Value
Pv Aboveground exposed
produce concentration due
to air-to-plant transfer
mg/kg
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-2-8.

Uncertainties associated with this variable include the following:

(1) The range of values for the variable Bv (air-to-plant biotransfer factor) is about 19 orders of magnitude for organic COPCs.
(2) The algorithm used to calculate values for the variable F, assumes a default value for the parameter ST (Whitby's average
surface area of parti culates [aerosols]) of background plus local sources rather than aaST value for urban sources. If a specific
site is located in an urban area, the use of the latter ST value may be more appropriate. The ST value for urban sources is about
one order of magnitude greater than that for background plus local sources and would result in a lower Fv value; however, the fv
value is likely to'be only a few percent lower.
Pr Aboveground exposed and
protected produce
concentration due to root
uptake
mg/kg
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-2-9.

Uncertainty associated with this variable include the following:

Estimated COPC-specific soil-to-plant bioconcentration factors (Br) may not be representative of site-specific conditions.
Prt, Belowground produce
concentration due to root
uptake
mg/kg
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-2-10.

Uncertainty associated with this variable include the following:

Estimated COPC-specific soil-to-plant bioconcentration factors (Br) may not be representative of site-specific conditions.
C-7
-------
TABLE C-l-2
COPC INTAKE FROM PRODUCE
(Page 3 of 5)
Vwiible
CRj
cv
CRt,
Dwcriptkin
Consumption rate of
aboveground, protected
aboveground, and
belowground produce,
respectively
Units
kg/kg-day
DW
vtSm : ' " "-•;-'
This variable is site-specific. The recommended default values represent the total of the following produce-specific ingestion rates:
Ingestion Rate
Plant Tvne Receptor (ke/kK-dayDW)
Exposed Aboveground Produce (Cr^) Adult 0.0003
Child 0.00042
Protected Aboveground Produce (Crpp) Adult 0.00057
Child 0.00077
Belowground Produce (Cr,^) Adult 0.00014
Child 0.00022
Ingestion rates were derived from U.S. EPA (1997), Tables 13-61 and 13-65. The ingestion rates listed in U.S. EPA (1997) are
derived from the 1987-1988 USDA National Food Consumption Survey and may be used to assess exposure to contaminants in foods
grown, raised, or caught at a specific site. The ingestion rates were adjusted for cooking and preparation loss as recommended by
U.S. EPA (1997). The average preparation and cooking loss used for exposed vegetables was 15.8 percent (U.S. EPA 1997).
However, it is assumed that no preparation and cooking loss occurs with exposed fruits because it is further assumed the fruit is eaten
in the raw form. In addition, ingestion rates for the child receptor represent a time-weighted mean from the respective tables.
Uncertainty associated with this variable include the following:
The recommended ingestion rates are based on national average home produced consumption rates. Site-specific ingestion rates
may be higher or lower than those recommended. Therefore, use of the recommended ingestion rates may under- or
overestimate 1^.
C-8
-------
TABLE C-l-2
COPC INTAKE FROM PRODUCE
(Page 4 of 5)
Variable
Description
Units
Value
Fraction of produce that
is contaminated
unitless
Varies
This variable is site-specific. U.S. EPA OSW recommends the following default values in the absence of site-specific information,
consistent with U.S. EPA (1994). The fraction of produce that is contaminated varies for each exposure scenario:

Exposure Scenario £,g
Adult Resident 0.25
Child Resident 0.25
Subsistence Farmer 1.0
Subsistence Farmer Child 1.0
Subsistence Fisher 0.25
Subsistence Fisher Child 0.25

U.S. EPA (1994) cites U.S. EPA (1990) as the reference source for the Fag value for the adult resident, child resident, subsistence
fisher, and subsistence fisher child. U.S. EPA (1994) does not provide a reference for the Fag value for the subsistence farmer and the
subsistence farmer child.

The following uncertainty is associated with this variable:

Fraction of produce that is contaminated will vary from site to site. Use of default values may overestimate or underestimate
Fa,.
C-9
-------
TABLE C-l-3

COPC INTAKE FROM BEEF, MBLK, PORK, POULTRY, AND EGGS

(Page 5 of 5)

REFERENCES AND DISCUSSION

Baes, C.R, R.D. Sharp, AX, Sjoreen, and R.W. Shor. 1984. Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionuclides through Agriculture. Oak
Ridge National Laboratory. Oak Ridge, Tennessee.

This document is cited as a source for Br values.

U.S. EPA 1990. Exposure Factors Handbook. Office of Health and Environmental Assessment, Exposure Assessment Group. Washington, D.C. March.

This is the document cited as the source of the fraction of produce that is contaminated (Fai) the adult resident, child resident, and subsistence fisher. U.S. EPA assumes thatF^ for the
subsistence fisher child is the same as for the subsistence fisher.

U.S. EPA 1992. Technical Support Document for Land Application of Sewage Sludge. Volumes I and II. Office of Water. Washington, D.C. EPA 822/R-93-001a.

This document is cited as a soource for plant uptake response slope factors.

U.S. EPA. 1994. Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste. Office of Emergency and Remedial Response. Office of Solid
Waste.

This document is cited as the source of the fraction of produce that is contaminated (F^) for the subsistence farmer (U.S. EPA assumes that Fag for the subsistence farmer child is the same as
for the subsistence farmer).

U.S. EPA. 1997. Exposure Factors Handbook Office of Research and Development. EPA/600/P-95/002F. August

This document is the source for produce consumption rates.
C-10
-------
TABLE C-l-3
COPC INTAKE FROM BEEF, MILK, PORK, POULTRY, AND EGGS

(Page 1 of 5)
Description
This equation calculates the daily intake of COPCs from the ingestion of animal tissue (where the i in the equation refers to beef, milk, pork, poultry, or eggs). The consumption rate varies
for children and adults and for the type of animal tissue (/). The concentration in the animal tissue will also vary with each scenario location.

Uncertainties associated with this equation include the following:

(1) The amount of animal tissue intake is assumed to be constant and representative of the exposed population. This assumption may under- or overestimate/,.
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This assumption may under- or overestimate /,.
Equation
I, = A, • CRt - Ft
Variable
Description
Units
Daily intake of COPC / from
animal j tissue
C-ll
-------
TABLE C-l-3
COPC INTAKE FROM BEEF, MILK, PORK, POULTRY, AND EGGS

(Page 2 of 5)
V»ri»W«
DescriDrion
Units
Value
Concentration of COPC / in animal
tissue./
mg/kgFW
Varies
This variable is COPC- and site-specific, and is calculated by using the equations in Tables B-3-10, B-3-
11, B-3-12, B-3-13, and B-3-14.

Uncertainties associated with this variable include the following:

(1) Based on the information provided, A^wAAf^ are dependent on the concentrations of COPCs
estimated in plant feeds and soil, and the biotransfer factors estimated for each constituent. To the
extent the estimated concentrations in plants and the biotransfer factors do not reflect site-specific
on local conditions, Abaf may be under- or overestimated.
(2) Uptake of COPCs into chicken and eggs has typically been applied only to PCDDs and PCDFs but
could possibly be used to calculate A^ and Ae^ resulting from other COPCs.
(3) The assumption that 10 percent of a chicken's diet is soil may not represent site-specific or local
conditions of chickens raised on subsistence farms. Stephens, Petreas, and Hayward (1992) and
Stephens, Petreas, and Hayward (1995) suggest the percentage of soil in the diet of chickens raised
under field conditions may be greater than 10 percent. Therefore, the concentration of COPCs in
eggs, Aegg> and the concentration of COPCs in chicken, A^^ may be underestimated.
C-12
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TABLE C-l-3

COPC INTAKE FROM BEEF, MILK, PORK, POULTRY, AND EGGS
(Page 3 of 5)
Variable
tJheserinttoR •
Valne
CR,
Consumption rate of animal tissue 7
kg/kg-day
FW
Varies
This variable is site-specific. U.S. EPA OSW recommends the ingestion rates of animal tissues (see the
equation in Table C-l-4 for fish ingestion). The recommended ingestion rates for homegrown beef, milk,
poultry, eggs, and pork have been derived from U.S. EPA (1997):
Animal Tissue Ingestion Rates (kg/kg-day FW)
Homegrown Beef
Homegrown Milk
Homegrown Poultry
Homegrown Eggs
Homegrown Pork
Adult
0.00114
0.00842
0.00061
0.00062
0.00053
Child
0.00051
0.01857
0.000425
0.000438
0.000398
Ingestion rates were determined from U.S. EPA (1997) Tables 13-28,13-36,13-43,43-54, and 13-55.
The ingestion rates listed in U.S. EPA (1997) were derived from the 1987-1988 USDA National Food
Consumption Survey and may be used to assess exposure to contaminants in foods grown, raised, or
caught at a specific site. Prior to the adjustment for cooking and preparation loss, the mean individual
meat consumption rates were weighted by age group. The ingestion rates were then adjusted for cooking
and preparation loss as recommended in U.S. EPA (1997). The total preparation and cooking loss was in
the range of 45 to 54 percent for beef, pork, and poultry.

In addition, ingestion rates for the child receptor represent a time-weighted mean from the respective
tables. Where data for a specific age group was incomplete, the intake was extrapolated using data from
the general population (Tables 11-11 and 11-13 of U.S. EPA 1997). Specifically, an age-group home
produced item intake was derived by multiplying the total mean intake for that home produced item by
the ratio of the item- and age-group general population intake rate (Tables 11-11 and 11-13 of U.S. EPA
1997) to a total individual general population intake rate for that item (Tables 11-11 and 11-13 of U.S.
EPA 1997). For example:
Child (01-02)
home produced
beef intake rate
= 2.45 e/kg-dav (Table 13-36) x 10 g/day (Table 11-11)
32 g/day (Table 11-11)
U.S. EPA (1997) provides information for total home produced dairy (Table 13-28 of U.S. EPA 1997),
but does not specify intake for fluid milk.
C-13
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TABLE C-l-3
COPC INTAKE FROM BEEF, MILK, PORK, POULTRY, AND EGGS
(Page 4 of 5)
Variable
Description
Uniti
Value
continued
Consumption rate of animal tissue/
kg/kg-day
FW
For the metals mercury, selenium, and cadmium, the concentration in beef, milk, and pork, and the
consumption rate are in kilograms dry weight per day. Wet-weight to dry-weight conversion information
for beef, milk, and pork is presented in U.S. EPA (1997)

The following uncertainty is associated with this variable:

The recommended tissue-specific consumption rates may not accurately reflect site-specific in local
conditions. As a result, tissue-specific intakes may be over- or underestimated.
Fraction of animal tissuey that is
contaminated
unitless
1.0
This variable is site-specific. U.S. EPA OSW recommends an Fj of 1.0 for all animal tissues consumed.
This recommendation is consistent with NC DEHNR (1997).

The following uncertainty is associated with this variable:

The fraction of animal tissue that is contaminated is site-specific; therefore, any of the following may
be under- or overestimated: variations in the proximity of the receptor to the contaminated source,
size of the contaminated source, receptors of concern, mobility of receptors, and nature of exposure.
C-14
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TABLE C-l-3

COPC INTAKE FROM BEEF, MILK, PORK, POULTRY, AND EGGS

(Page 5 of 5)

REFERENCE AND DISCUSSIONS

This document is cited as the source of the assumption that free-range chickens ingest soil as 10 percent of their diet and as the source of the dioxin and furan congeners-specific BCFs
recommended by NC DEHNR (1997). However this document does not clearly reference or document the assumption that soil represents 10 percent of a free-range chicken's diet. The
document appears to cite two other documents as supporting its assumption: (1) Chang, Hayward, Goldman, Harnly, Flattery and Stephens (1989) and (2) Petreas, Goldman, Hayward, Chang,
Flattery, Wiesmuller, Stephens, Fry, and Rappe (1992).

Also, this document presents dioxin and filran congener-specific BCFs (thigh) for the low- exposure group after 80 days of a 178-day total exposure period. The chickens in the low-dose group
were fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 42 ppt I-TEQ. Chickens in the high-dose group were fed a diet containing 10 percent soil with a PCDD/PCDF
concentration of 458 ppt I-TEQ; BCF results were not presented from the high-dose group.

Also, this document presents dioxin and furan congener-specific BCFs (thigh) under two exposure schemes; low exposure and high exposure. The white leghorn (Babcock D 300) chickens in
the low group were fed a diet containing 10 percent soil with a PCDD/PCDF concentrations of 42 ppt I-TEQ. Chickens in the high group were fed a diet containing 10 percent soil with a
PCDD/PCDF concentration of 460 ppt I-TEQ (some congeners were fortified by spiking).

The BCFs presented for low- and high-dose groups both represent averages of results from Day-80 and Day-164 of a total 178-day exposure period.

U.S. EPA. 1997. Exposure Factors Handbook, Office of Research and Development. EPA/600/P-95/002F. August.

This document is the source for home produced beef, milk, pork, poultry, and egg consumption rates.
C-15
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TABLE C-l-4
COPC INTAKE FROM FISH
(Page 1 of 4)
Description
This equation calculates the daily intake of COPCs from the ingestion offish. Consumption rates were derived from the Exposure Factors Handbook (U.S. EPA 1997). U.S. EPA
(1997) presents consumption rates based on body weight; therefore, body weight is not included as a variable in the calculation of^jjfr

The limitations and uncertainty introduced in calculating this value include the following:

(1) The amount offish intake is assumed to be constant and representative of the exposed population. This assumption may under- or overestimate 1^.
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This assumption may under- or overestimate 7^,.
Equation
fish
Variable
lfish
Description
Daily intake of COPC from
fish
Concentration in fish
Unite
mg/kg-day
mg/kg
Value
Varies
This variable is COPC- and site-specific, and is calculated by using the equations hi Tables B-4-26 through B-4-28; the fish
concentration will vary for each water body.

The following uncertainty is associated with this variable:

The methodology does not account for concentration variations across fish species. Different species may accumulate
COPCs to different extents depending, for example, on their feeding habits and fat content. This may cause C^ to
be under- or overestimated.
C-16
-------
TABLE C-l-4
COPC INTAKE FROM FISH
(Page 2 of 4)
Variable
Units
Cfc
lfish
Consumption rate offish
kg/kg-day
FW
Varies
The consumption rate varies for the receptor considered. The following home produced or caught ingestion rates for fish
were derived from U.S. EPA (1997):
Receptor
Adult
Child
Ingestion Rate (kg/kg-dav FW)
0.00117
0.000759
Ingestion rates were determined from U.S. EPA (1997) Table 13-23. The ingestion rates listed in U.S. EPA (1997) were
derived from the 1987-1988 USDA National Food Consumption Survey and may be used to assess exposure to contaminants
in foods grown, raised, or caught at a specific site. Prior to the adjustment for cooking and preparation loss, the mean
individual fish consumption rates were weighted by age group. The ingestion rates were then adjusted for cooking and
preparation loss as recommended in U.S. EPA (1997). The total preparation and cooking loss for fish was 38 percent.

Uncertainties introduced by assumptions made to calculate this value include the following:

(1) The intake rates presented do not take into account the types offish that will be present in the water body. Separate
intake rates are needed for freshwater and estuarine fish and shellfish, depending on the nature of the local surface
water body. This assumption can overestimate or underestimate CR^.
C-17
-------
TABLE C-l-4
COPC INTAKE FROM FISH
(Page 3 of 4)
Variable
Description
Units
Value
continued
Consumption rate offish
kg/kg-day
FW
(2) These intake rates do not represent long behavior patterns, which is the focus of the exposure assessments used to
support chronic health effects. This introduces uncertainty into the estimates of medians and other percentiles. This
assumption can overestimate or underestimate CRjw
(3) The intake rates represent total intake rates of home-caught fish. Where use of site-specific information would reveal
the amount offish consumed from waters within the study area, this information should be used. This assumption can
overestimate or underestimate CRh.
Fraction offish that is
contaminated
unitless
1.0
U.S. EPA OSW recommends that this default value be used if site-specific information is not available. The contaminated
fraction will vary with each exposure scenario; however, NC DEHNR (1997) and U.S. EPA (1994) assume that this value
equals 1.0 for the subsistence fisher.

The following uncertainty is associated with this variable:

Using 1.0 as a default value for fraction offish that is contaminated assumes that receptors consume only
contaminated fish; this assumption may overestimate Frah.
C-18
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TABLE C-l-5

COPC INTAKE FROM DRINKING WATER

(Page 4 of 4)

REFERENCES AND DISCUSSION

NC DEHNR. 1997. JVC DEHNR Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. January.

This document is one of the reference source documents for the equation in Table C-l-4.

U.S. EPA. 1997. Exposure Factors Handbook. Office of Research and Development. EPA/600/P-95/002F. August.

This document is the source for home-caught fish consumption rates.
C-19
-------
TABLE C-l-5

COPC INTAKE FROM DRINKING WATER

(Page 1 of 3)
Description
This equation calculates the daily intake of COPC from drinking water. COPC intake from drinking water is calculated from the concentration of COPC dissolved in the water column of each
surface water body or watershed identified as a drinking water source. The dissolved concentration is used for calculating COPC intake from drinking water because it is assumed the water is
filtered pnor to human consumption. The COPC concentration will vary for each water body. The consumption rate varies for children and adults.

Uncertainties associated with this equation include the following:

(1) The amount of drinking water intake is assumed to be constant and representative of the exposed population. This assumption may under- or overestimate/^.
(2) The standard assumptions regarding periodexposed may not be representative of any actual exposure situation. This assumption may under-or overestimate/^
Equation
*>
BW
Variable
==
/*
Description
Daily intake of COPC from
drinking water
Dissolved phase water
concentration
Units
mg/kg-day
mg/L
Value
Varies
This variable is COPC- and site-specific, and is calculated by using the equation hi Table B-4-24.

Uncertainties associated with this variable include the following:

All of the variables in the equation in Table B-4-24 are COPC- and site-specific. Therefore, the use of default values
rather than site-specific values, for any or all of these variables, will contribute to the under- or overestimation of C^

The degree of uncertainty associated with the variables d^ and dh is expected to be minimal because information for
estimating a variable (4) is generally available and the probable range for a variable (db) is narrow. The uncertainty
associated with the variables F^,^ and CWD( is associated with estimates of OC content. Because OC content values
can vary widely for different locations in the same medium, using default OC values may result in significant
uncertainty in specific cases.
C-20
-------
TABLE C-l-5
COPC INTAKE FROM DRINKING WATER
(Page 2 of 3)
Variable
Describtion
Units
Value
Rate of consumption of drinking
water
L/day
0.67 or 1.4
This variable is site-specific. U.S. EPA OSW recommends default values of 1.4 (adult) and 0.67 (child) in the absence of
site-specific data.

The recommendation for the average adult consumption rate of drinking water is based on information cited in U.S. EPA
(1997). For the child receptor, U.S. EPA (1997) provides recommended drinking water intake rates for various age groups in
Table 3-30. The child default drinking water intake was derived by using a time-weighted average for the age groups 0 to 6
years of age.

The following uncertainty is associated with this variable:

The average consumption rate of drinking water is based on the average intake observed from five studies. The
number of studies conduct may underestimate or underestimate CR^
Fraction of drinking water that is
contaminated
unitless
1.0
This variable is site-specific. U.S. EPA OSW, consistent with U.S. EPA (1994), recommends assuming 1.0 for the fraction
of drinking water that is contaminated.

The following uncertainty is associated with this variable:

Some receptors may consume a fraction of their drinking water from sources unimpacted by facility emissions.
Therefore, this assumption will likely overestimate F^,.
BW
Body weight
15 or 70
This variable is site-specific. U.S. EPA OSW recommends using default values of 70 (adults) and 15 (children) in the
absence of site-specific information. These default values are consistent with U.S. EPA (1991; 1994).

Uncertainties associated with this variable include:

These body weights represent the avearge weight of an adult and child. However, depending on the receptor, the
body weights may be higher or lower. These default values may overestimate or underestimate actual body weights.
However, the degree of under- or overestimation is not expected to be significant.
C-21
-------
TABLE C-l-5
COPC INTAKE FROM DRINKING WATER
(Page 3 of 3)
REFERENCES AND DISCUSSION
U.S. EPA. 1991. Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. Office of Solid Waste and Emergency Response OSWER Directive 9285 6-
03. Washington, D.C. March 21.
This document is cited as the reference source document of the exposure frequency and body weight variables.
U.S. EPA. 1994. Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Office of Emergency and Remedial Response Office of Solid
Waste.
This document was cited as the source of the fraction of drinking water that is contaminated.
U.S.EPA. 1997. Exposure Factors Handbook. Office of Research and Development EPA/600/P-95/002F. August.
This document is the source for the drinking water consumption rates.
C-22
-------
TABLE C-l-6
TOTAL DAILY INTAKE
(Page 1 of 3)
Description
This equation calculates the daily intake of COPC via all indirect exposure pathways. As discussed in Chapter 4 and Table 4-1, the indirect exposure pathways considered in the calculation of
the total daily intake of COPCs are specific to the recommended exposure scenario evaluated and the representative exposure setting. Daily intake values from exposures scenarios which are
not evaluated in a respective exposure scenario may be assumed to be zero when calculating the total daily intake of COPC (I).

Uncertainties associated with this equation include the following:

(1) The uncertainties associated with estimates of total intake are those associated with each of the medium- or tissue-specific intakes.
(2) To the extent that medium- or tissue-specific intakes do not accurately represent site-specific local conditions local conditions, 7 may be under- or overestimated.
Equation
I soil + lag + heef + ^milk + ^flsh + ^pork + 'poultry + *eggs + *dw
Variable
Units
Total daily intake of COPC

Daily intake of COPC from soil
mg/kg-day
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-l-1. The value for this variable
will vary for each receptor and each exposure scenario location.

Uncertainties associated with this variable include the following:

(1) The amount of soil intake is assumed to be constant and representative of the exposed population. This assumption
may under- or overestimate Isott.
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This
assumption may under- or overestimate 4,fl.
C-23
-------
TABLE C-l-6
TOTAL DAILY INTAKE
(Page 2 of 3)
Description
Units
Daily intake of COPC from
aboveground produce
mg/kg-day
DW
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-l-2. The value for this variable
will vary for each receptor and each exposure scenario location.

Uncertainties associated with this variable include the following:

(1) The amount of produce intake is assumed to be constant and representative of the exposed population. This
assumption may under- or overestimate Ias.
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This
assumption may under- or overestimate Ias.
Daily intake of COPC from beef,
milk, pork, poultry, and eggs
mg/kg-day
FW
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-1-3. The value for this variable
will vary for each receptor and each exposure scenario location.

Uncertainties associated with this variable include the following:

(1) The amount of animal tissue intake is assumed to be constant and representative of the exposed population. This
(2)
assumption may under- or overestimate /^ /„,«, /^j, /|WBtoy, and Ie
The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This
assumption may under- or overestimate /j^ Imab 1 and 7
Daily intake of COPC from fish
mg/kg-day
FW
Varies
This variable is COPC- and site-specific, and is calculated by using the equation hi Table C-l-4. The value for this variable
will vary for each water body evaluated.

Uncertainties associated with this variable include the following:

(1) The amount offish intake is assumed to be constant and representative of the exposed population. This assumption
may under- or overestimate 1^.
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This
assumption may under- or overestimate Ifah.
C-24
-------
TABLE C-l-6
TOTAL DAILY INTAKE
(Page 3 of 3)
Variable
Description '
Units
Value
Daily intake of COPC from
drinking water
mg/kg-day
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-1-5. The value for this variable
will vary for each water body evaluated.

Uncertainties associated with this variable include the following:

(1) The amount of drinking water intake is assumed to be constant and representative of the exposed population. This
assumption may under- or overestimate 1^.
(2) The standard assumptions regarding period exposed may not be representative of any actual exposure situation. This
assumption may under- or overestimate /^.
€-25
-------
TABLE C-l-7
INDIVIDUAL CANCER RISK: CARCINOGENS
(Page 1 of 4)
Description
This equation calculates the individual cancer risk from bdirect exposure to carcinogenic COPCs. The exposure duration varies for different scenarios. Uncertainties associated with this
equation include the following:

(1) Default factors for exposure frequency and exposure duration are assumed to represent the highest exposure that is reasonably expected to occur at a site and, hi practice, is
estimated by combining upper-bound (90th to 95th percentile) values for these exposure parameters, but not all parameters. This assumption may over- or underestimate the Cancer
Risk,.
(2) Slope factors are used to estimate an upper-bound lifetime probability of an individual developing cancer as a result of exposure to a particular level of a potential carcinogen, and
are accompanied by the weight of evidence classification to indicate the strength of the evidence that the agent is a human carcinogen. This classification has the potential to over-
or underestimate Cancer Risk,.
(3) Risk at low exposure levels is difficult to measure directly either by animal experiments or by epidemiological studies. The development of a cancer slope factor generally entails
applying a model to the available data set and using the model to extrapolate from the relatively high doses administered to experimental animals (or the exposures noted in
epidemiological studies) to lower exposure levels expected for human contact in the environment This approach may under- or overestimate Oral CSF.
Equation
Cancer Risk, =
I - ED - EF • CSF
AT • 365
Variable
Cancer
Risk,
Description
Individual lifetime cancer
risk through indirect
exposure to COPC
carcinogen i
Units
unitless
Vaine
Daily intake of COPC i from
animal tissue 7
mg COPC/kg
BW-day
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-l-6. The value for this variable will
vary for each exposure pathway and each exposure scenario location.

The following uncertainly is associated with this variable:

This variable is COPC- and site-specific. See the equation in Table C-l-6 regarding the calculation of and uncertainities
associated with this variable.
C-26
-------
TABLE C-l-7
INDIVIDUAL CANCER RISK: CARCINOGENS
(Page 2 of 4)
Variable
Description
Units
Value
ED
Exposure duration
This variable is exposure scenario-specific:

Exposure Scenario ED
6,30, or 40
Subsistence Farmer
Subsistence Farmer Child
Subsistence Fisher
Subsistence Fisher Child
Adult Resident
Child Resident
40 (U.S. EPA 1994)
6 (U.S. EPA 1989)
30 (U.S. EPA 1994)
6 (U.S. EPA 1989)
30 (U.S. EPA 1989)
6 (U.S. EPA 1989)
The following uncertainty is associated with this variable:

This exposure duration is a single value that represents the highest exposure that is reasonably expected to occur at a site.
This assumption may overestimate ED.
EF
Exposure frequency
days/yr
350
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of site-specific
information, consistent with U.S. EPA (1991).

The following uncertainty is associated with this variable:

This exposure frequency is a single value that represents the most frequent exposure that is reasonably expected to occur at
a site, assuming 2 weeks of vacation or travel. This assumption may overestimate EF.
AT.
Averaging time
yr
70
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of site-specific
information, consistent with U.S. EPA (1989).

The following uncertainty is associated with this variable:

The recommendation for averaging time may not accurately represent site-specific time; specifically, this single value may
under- or overestimate the length of time of exposure.
555
Units conversion factor
day/yr
C-27
-------
TABLE C-l-7
INDIVIDUAL CANCER RISK: CARCINOGENS
(Page 3 of 4)
Virkble
Description
Units
Value
Oral
CSF
Oral Cancer Slope Factor
(mg/kg-day)'1
Varies
This variable is COPC-specific, and should be determined from the COPC tables in Appendix A-3.

Uncertainties associated with this variable include the following:

(1) Slope factors are used to estimate an upper-bound lifetime probability of an individual developing cancer as a result of
exposure to a particular level of a potential carcinogen; and are accompanied by the weight of evidence classification to
indicate the strength of the evidence that the agent is a human carcinogen.
(2) Risk at low exposure levels is difficult to measure directly either by animal experiments or by epidemiological studies.
The development of a cancer slope factor generally entails applying a model to the available data set and using the model to
extrapolate from the relatively high doses administered to experimental animals (or the exposures noted in epidemiological
studies) to the lower exposure levels expected for human contact in the environment. This approach may under- or
overestimate Oral CSF.
C-28
-------
TABLE C-l-7

INDIVIDUAL CANCER RISK: CARCINOGENS

(Page 4 of 4)

REFERENCES AND DISCUSSION

U.S. EPA. 1989. Risk Assessment Guidance for Superfund, Volumel, Human Health Evaluation Manual (Part A). Interim Final. Office of Emergency and Remedial Response. EPA/540/1-
89/002. December.

This document is cited as the reference source document of the exposure duration for adult and child residents. This document is also cited as the reference source document for the averaging
time for carcinogens.

U.S. EPA. 1991. Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. Office of Solid Waste and Emergency Response. OSWER Directive 9285.6-
03. Washington, D.C.

This document is cited as the reference source document of the exposure frequency.

This document is cited as the reference source document of the exposure duration for the subsistence fisher and subsistence farmer.
C-29
-------
TABLE C-l-8
HAZARD QUOTIENT: NONCARCINOGENS
(Page 1 of 3)
Description
This equation calculates the hazard quotient for indirect exposure to noncarcinogenic COPCs. The following uncertainty is associated with this equation.

A chronic RJD is an estimate of a daily exposure level for the human population, including sensitive subpopulations, that is Ukely to be without an appreciable risk of deleterious effects
during a lifetime. Chronic RJDs are specifically developed to be protective for long-term exposure (from 7 years to a lifetime) to a compound. COPC-specific reference doses (RJD) are
unlikely to underestimate a chemical potential for causing adverse effects.
Equation
I: ED' EF
RfD • AT - 365
Daily intake of COPC i from
animal tissue/
mgCOPC/
kg-day
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-l-6. The value for this variable
will vary for each exposure pathway and each exposure scenario location. Uncertainties associated with this variable are
site-specific.
ED
Exposure duration
6,30, or 40
Consistent with U.S. EPA (1994b) and NC DEHNR (1997), U.S. EPA OSW recommends the use of the following default
values.
Exposure Scenario
Subsistence Farmer
Subsistence Farmer Child
Subsistence Fisher
Subsistence Fisher Child
Adult Resident
Child Resident
ED
40 (U.S. EPA 1994a)
6 (U.S. EPA 1989)
30 (U.S.EPA1994a)
6 (U.S. EPA 1989)
30 (U.S. EPA 1989)
6 (U.S. EPA 1989)
Uncertainty associated with this variable includes:

These exposure durations are single values that represent the highest exposure that is reasonably expected to occur at a
site. These values may overestimate ED for some individuals.
C-30
-------
TABLE C-l-8
HAZARD QUOTIENT: NONCARCINOGENS
(Page 2 of 3)
Variable
Description
Valws,
EF
Exposure frequency
days/yr
350
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of site-specific data.
This value is based on U.S. EPA (1991) and is consistent with U.S. EPA (1994b).

Uncertainty associated with this variable includes:

This exposure frequency is a single value that represents the most frequent exposure that is reasonably expected to
occur at a site with two weeks of vacation or travel. This recommended value may overestimate EF for individuals
who are away from their home for more than two weeks each year. On the other had, some individuals such as
subsistence farmers, may remain at their home (or farm) for more than 350 days per year. In either case, the degree of
over- or underestimation is not expected to be significant in most cases.
RfD
Reference Dose
AT
Averaging time
mg/kg-day
Varies
This variable is COPC-specific, and should be determined from the COPC tables in Appendix A-3.

The following uncertainty is associated with this variable:

A chronic RfD is an estimate of a daily exposure level for the human population, including sensitive subpopulations,
that is likely to be without an appreciable risk of deleterious effects during a lifetime. Chronic RfDs are specifically
developed to be protective for long-term exposure (from 7 years to a lifetime) to a compound. COPC-specific RfDs are
unlikely to underestimate a COPC's potential for causing adverse health effects.
6,30, or 40
This variable is site-specific and related to ED. Specifically, the ^rfor noncarcinogens is numerically the same as ED.
This default value is consistent with U.S. EPA (1989), U.S. EPA (1991), and U.S. EPA (1994a).

Uncertainly associated with this variable includes:

The recommendation for averaging time may not accurately represent site-specific time; specifically this single value
may under- or overestimate the length of an average adult lifetime.
C-31
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TABLE C-l-8

HAZARD QUOTIENT: NONCARCJNOGENS

(Page 3 of 3)

REFERENCES AND DISCUSSION

NCDEHNR(1997). Draft North Carolina Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Exposure Risk Assessments for Hazardous Waste Combustion
Units. January.

U.S. EPA. 1989. Risk Assessment Guidance for Superfitnd, Volume I, Human Health Evaluation Manual (Part A).
Interim Final. Office of Emergency and Remedial Response. EPA/540/1-89/002. December.

This document is cited as the reference source document of the exposure duration for adult and child residents. U.S. EPA OSW assumes that the recommended exposure duration for the
child resident may also reasonably be applied to the subsistence farmer child and to the subsistence fisher child.

U.S.EPA. 1991. Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. Officeof Solid Waste and Emergency Response. OSWER Directive 9285.6-
03. Washington, D.C.

This document is cited as a source document for exposure frequency and averaging time.

U.S.EPA. 1994a. Estimating Exposure to Duxdn-like Components - Volume III: Site-Specific Assessment Procedure. Review Draft. Office of Research and Development Washington D.C.
EPA/600/6-88/005CC. June.

This document is cited by U.S. EPA (1994b) as the same document for the recommended default exposure duration (ED) values for the subsistence farmer and subsistence fisher. The ED
value of 40 years recommended for both the subsistence farmer and the subsistence fisher is based on the assumption that "farmers live in one location longer than the general population".

U.S.EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the following:

• An exposure frequency of 350 days per year
• Recepter-specific exposure duration values as presented in U.S. EPA (1994a)—subsistence fisher (40 years) and subsistence farmer (40 years) and U.S. EPA (1989)—adult
resident (30 years) and child resident (6 years)
• Adult and child body weights of 70 kg and 15 kg, respectively
C-32
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TABLE C-l-9
TOTAL CANCER RISK: CARCINOGENS
(Page 1 of 1)
Description
For carcinogens, cancer risks are added across all carcinogenic COPCs. See Appendix A for identification of carcinogens. Uncertainty associated with this equation includes the following:

Total Cancer Risk assumes that different carcinogens affect the same target organ to produce a cancer response, ignoring potential antagonistic or synergistic effects or disparate effects on
different target organs.
Equation
Total Cancer Risk - Cancer Risk.

Total
Cancer
Risk
Individual lifetime cancer risk
through indirect exposure to all
COPC carcinogens
unitless
Cancer
Risk,
Individual lifetime cancer risk
through indirect exposure to COPC
carcinogen i
unitless
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-l-7. The value for this variable
will vary for each exposure pathway.

Uncertainties associated with this variable include the following:

(1) Default factors for exposure frequency and exposure duration are assumed to represent the highest exposure that is
reasonably expected to occur at a site. In practice, intakes are estimated by combining upper-bound (90th to 95th
percentile) values for these exposure variables, but not for other parameters. This assumption is likely to overestimate
intakes and the Cancer Riskf.
(2) Slope factors are used to estimate an upper-bound lifetime probability of an individual developing cancer as a result of
exposure to a particular level of a potential carcinogen; and are accompanied by the weight of evidence classification to
indicate the strength of the evidence that the agent is a human carcinogen. This classification has the potential to over-
or underestimate risk.
(3) Risk at low exposure levels is difficult to measure directly either by animal experiments or by epidemiological studies.
The development of a cancer slope factor generally entails applying a model to the available data set and using the
model to extrapolate from the relatively high doses administered to experimental animals (or the exposures noted in
epidemiological studies) to lower exposure levels expected for human contact in the environment. This approach is
likely to overestimate CSF.

The uncertainties associated with this variable are COPC- and site-specific.
C-33
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TABLE C-l-J
TOTAL HAZARD INDEX: NONCARCINOGENS
(Page 1 of 1)
Description
For non-cancer health effects, hazard quotient for all COPCs, regardless of target organs, are summed to calculate a total hazard index. Uncertainties associated with this equation include the
following:

target organs, may overestimate the total hazard index.
(2) Total hazard index assumes that a single individual in the exposure scenario is exposed to site-related contaminants at estimated exposure concentrations by all pathways that make up the
scenario. It is unlikely, however, that a single individual will be exposed by each pathway in the exposure media. This assumption may overestimate the total hazard index.
Equation
Total Hazard Index = £).
Variable
Total
Hazard
Index
Description
Total individual hazard index for
all COPCs across all exposure
pathways
Hazard Index for exposure
pathway j
Units
unitless
unitless
Value
Varies
This variable is COPC- and site-specific. The value for this variable will vary for each exposure pathway. Uncertainties
associated with this variable are site-specific.
HQ,
Hazard Quotient for COPC i
unitless
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-l-8. The value for this variable
will vary for each exposure pathway. Uncertainties associated with this variable are site-specific.
C-34
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TABLE C-l-11
SEGREGATED HAZARD INDEX FOR SPECIFIC ORGAN EFFECTS: NONCARCINOGENS

(Page 1 of 1)
Description
For non-cancer health effects, hazard quotients are added across COPCs when they target the same organ to calculate a segregated hazard index. See Appendix A-2 for identification of
noncarcinogens and their associated target organ. Since segregation by critical effect requires the identification of all major effects, information in Appendix A-2 may not always represent the
most current and complete information on COPC-specific major effects. Therefore, Appendix A-2 may require supplemental information about COPC-specific major effects. Uncertainties
associated with this equation include the following:

(1) Target organ segregation is dependent upon the critical effect. Segregation by critical effect requires the identification of all major effects, not just those seen at higher doses. The
segregation process may over- or underestimate the hazard index. __^_^^^^
Equation
HI, = E HQi
Variable
Description
Units
HI,
HQ,
Hazard index for exposure pathway 7

Hazard quotient for COPC /
unitless
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-l-8. The value
for this variable will vary for each exposure pathway.

The following uncertainty is associated with this variable:

(1) Default factors for exposure frequency and exposure duration are assured to represent the highest
exposure that is reasonably expected to occur as a site. In practice, intakes are estimated by combining
upper-bound (90th to 95th percentile) values for these exposure variables, but not for other
parameters. This equation is likely to overestimate intakes and///,.
(2) Adverse health effects at low exposure levels are difficult to either directly either by animal
experiments or by epidemiological studies. The development ofRjDs generally entails applying
uncertainty factors to extempolate from the results of studies using high exposure doses to lower
exposure doses expected for human contact hi the environment. This approach is unlikely to
underestimate and likely overestimate ///,.

The uncertainties associated with this variable are COPC- and site-specific and will vary for each exposure
pathway.
C-35
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TABLE C-2-1

INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS

(Page 1 of 8)
Description
This equation calculates the excess lifetime individual cancer risk from the average daily intake via inhalation of a COPC carcinogen. Uncertainties associated with this equation include:

(1) COPC-specific Inhalation CSF values are unlikely to underestimate, and may overestimate, the carcinogenic potential of COPCs because of the choice of mathematical models and the use
of uncertainty factors on the estimation of these values.
(2) COPC-specific URF values are unlikely to underestimate, and may overestimate, the carcinogenic potential of a COPC because of the choice of mathematical models and the use of
uncertainty factors in the estimation of these values.
(3) The uncertainty associated with the variable Ca are largely site-specific.
(4) The uncertainties associated with the remaining variables in the equation in Table C-2-l,/g, ET, EF, ED, BW, and ^JTare not expected to be significant.
Equation
Cancer Risk^ = ADI
ADI =
Ca • IR • ET - EF • ED • 0.001 mg/yg

BW- AT- 365 daylyr
CSF,
URF ' 70
20 m*lday
Variable
Cancer Rish,^
ADI
Individual lifetime cancer risk
through direct inhalation of COPC
carcinogen i
Average daily COPC intake via
inhalation
C-36
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TABLE C-2-1

INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS

(Page 2 of 8)
Variable
Units
Value
Inhalation CSF
Inhalation Cancer Slope Factor
(mg/kg-
day)-'
Varies
This variable is COPC-specific, and should be determined from the COPC tables in Appendix A-3 .

Uncertainty associated with this variable includes:

Inhalation COPC-specific carcinogenic slope factors (Inhalation CSF) are generally estimated by
fitting the results of studies conducted on laboratory animals with a mathematical model. The
model generally recommended by U.S. EPA is the lineraized multistage (LMS) model; U.S. EPA's
position on assessing carcinogenic potential was recently updated (U.S. EPA 1996b). This model
assumes that there is no "safe dose" or threshold below which a COPC causing cancer and higher
doses will no longer cause cancer in exposed individuals. In other words, any exposure to a
carcinogen may, through a series of stages, result in the formation of cancer in an exposed
individual.

Also, before fitting the results with the LMS model, the results are adjusted by the application of a
series of uncertainty factors. The application of uncertainty factors follows the underlying
assumption that humans are, or may be, as sensitive or more sensitive to the carcinogenic effects of
COPCs than the laboratory COPCs that were tested. As a result, of both the choice of models and
the use of uncertainty factors, COPC-specific Inhalation CSF are unlikely to underestimate a
COPC's potential for causing cancer.
C-37
-------
TABLE C-2-1

INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS

(Page 3 of 8)
Variable
Description
Units
Value
URF
Inhalation Unit Risk Factor
Gig/m3)'1
Varies
This variable is COPC-specific, and should be determined from the COPC tables in Appendix A-3.

The following general uncertainty is associated with this variable:

COPC-specific inhalation unit risk factors (USFs) are generally estimated by fitting the results of
studies conducted on laboratory animals with a mathematical model. The model generally
recommended by U.S. EPA is the linearized multistage (LMS) model. U.S. EPA's position on
assessing carcinogenic potential was recently updated (U.S. EPA 1996b). The LMS model assumes
that there is no "safe dose" or threshold below which a COPC causing cancer at higher doses will no
longer cause cancer in expected individuals. In other words, any exposure to a carcinogen may,
through a series of stages, cause cancer in an exposed individual.

Also, before the results are fitted with the LMS model, series of uncertainty factors are applied to
the results. The application of uncertainty factors follows the underlying assumption that humans
are, or may be, as sensitive or more sensitive to the carcinogenic effects of COPCs than the
laboratory animals that were tested. As a result of the choice of models and the use of uncertainty
factors, COPC-specific URFs are unlikely to underestimate a COPC's potential for causing cancer.
Total COPC air concentration
ug/m3
Varies
This variable is COPC- and site-specific, and is calculated using the equation in Table B-5-1.

Uncertainty associated with this variable includes:

Calculated assuming a default ST value for background plus local sources, rather than a ST value for
urban sources. If a specific site is located in an urban area, the use of the letter ST value may be
more appropriate. Specifically, the ST value for urban sources is about one order of magnitude
greater than the ST value for background plus local sources and would result in a lower calculated Fv
value; however, the Fv value is likely to be only a few percent lower.
C-38
-------
TABLE C-2-1

INHALATION CANCER RISK FOR INDIVTOUAL CHEMICALS: CARCINOGENS

(Page 4 of 8)
Variable
> Description
Value
IR
Inhalation rate
m3/hr
0.30 or 0.63
This variable is site-specific. U.S. EPA OSW recommends using default values of 0.63 (adults) and 0.30
(children) in the absence of site-specific information. The recommended adult value is consistent with
U.S. EPA (1991) and U.S. EPA (1994a). The recommended child value is greater than the inhalation rate
proposed on U.S. EPA (1994b)— 0.18 m3/hr based simply on the adult inhalation rate multiplied by the
ratio of child to adult body weight (15 kg/70 kg)—but is consistent with U.S. EPA (1997) and U.S. EPA
(1996c).

Uncertainty associated with this variable includes:

The recommended inhalation rates do not consider individual respiratory or activity differences.
Therefore, based on the individual and the activities that individual is engaged in, the recommended
inhalation rates may under-or overestimate the actual rates. However, the degree of under-or
overestimation is not expected to be significant.
ET
Exposure time
hrs/day
24
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of
site-specific data.

Uncertainty associated with this variable includes:

The recommended ET value assumes that an individual remains at a specific location 24 hours per
day. In reality this is likely to be true only for a minority of the population including young
children, their caregivers, and elderly or other individual who are sick. Therefore, this
recommended value contributes to a degree of overestimation for much of the population. However,
it must be noted that though an individual may not always be at a single location, that individual
may continue to be exposed to emissions at an alternate location.
C-39
-------
I
TABLE C-2-1

INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS

(Page 5 of 8)
Variable
EF
ED
Description
Exposure frequency
Exposure duration
Units
days/yr
F
Value 4 :-* i
350
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of
site-specific data. This value is based on U.S. EPA (1991) and is consistent with U.S. EPA (1994b).
Uncertainties associated with this variable include:
(1) This exposure frequency is a single value that represents the most frequent exposure that is
reasonably expected to occur at a site with two weeks of vacation. This recommended value may
overestimate EF for individuals who are away from their home for more than two weeks each year.
On the other had, some individuals such as subsistence farmers, may remain at their home (or farm)
for more than 350 days per year. In either case, the degree of over- or underestimation is not
expected to be significant in most cases.
6, 30, or 40
This variable is site-specific. Consistent with U.S. EPA (1994b), U.S. EPA OSW recommends the use of
the following default values.
Exposure Scenario ED
Subsistence Farmer 40 (U.S. EPA 1994a)
Subsistence Farmer Child 6 (U.S. EPA 1989)
Subsistence Fisher 30 (U.S. EPA 1994a)
Subsistence Fisher Child 6 (U.S. EPA 1989)
Adult Resident 30 (U.S. EPA 1989)
Child Resident 6 (U.S. EPA 1989)
Uncertainties associated with mis variable include:
(1) These exposure durations are single values that represent the highest exposure that is reasonably
expected to occur at a site. These values may overestimate ED for some individuals.
C-40
-------
TABLE C-2-1

INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS

(Page 6 of 8)
Variable
Description
Units
Value
BW
Body weight
kg
IS or 70
This variable is site-specific. U.S. EPA OSW recommends using default values of 70 (adults) and IS
(children) in the absence of site-specific information. These default values are consistent with U.S. EPA
(1991; 1994b).

Uncertainties associated with this variable include:

(1) These body weights represent the average weight of an adult and child. However, depending on the
site, the body weights may be higher or lower. These default values may overestimate or
underestimate actual body weights. However, the degree of under- or overestimation is not
expected to be significant.
AT
Averaging time
yr
70
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of
site-specific data.

This default value is consistent with U.S. EPA (1989), U.S. EPA (1991), and U.S. EPA (1994b).

Uncertainties associated with this variable include:

(1) The recommendation for averaging time may not accurately represent site-specific time; specifically
this single value may under- or overestimate the length of an average adult lifetime.
C-41
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TABLE C-2-1

INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINO GENS

(Page 7 of 8)

REFERENCES AND DISCUSSION

U.S. EPA. 1989. Risk Assessment Guidance for Superfund, Volume J, Human Health Evaluation Manual (Part A).
Interim Final. Office of Emergency and Remedial Response. EPA/540/1-89/002. December.

This document is cited as the reference source document of the exposure duration for adult and child residents. U.S. EPA assumes that the recommended exposure duration for the child
resident may also reasonably be applied to the subsistence farmer child and to the subsistence fisher child. This document is also cited as reference source document for the averaging time
for carcinogens.

U.S.EPA. 1991. Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. Office of Solid Waste and Emergency Response. OSWER Directive 9285.6-
03. Washington, D.C. March 21.

This document is cited as the reference source document of the exposure frequency and body weight variables.

U.S.EPA. 1994a. Estimating Exposure to Dioxin-like Components - Volume III: Site-Specific Assessment Procedure. Review Draft. Office of Research and Development. Washington D.C.
EPA/600/6-88/005Cc. June.

U.S.EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the following:

• An adult inhalation rate of 20 m'/day (0.83 m3/hr) an a child inhalation rate of 7.2 mVday (0.3 nrVhr)—based on multiplying the adult rate by the ratio of child to adult body
weight (15 kg/70 kg).
• An exposure frequency of 350 days per year
• Receptor-specific exposure duration values as presented in U.S. EPA (1994a)—subsistence fisher (40 years) and subsistence farmer (40 years) and U.S. EPA (1989)—adult
resident (30 years) and child resident (6 years)
• Adult and child body weights of 70 kg and 15 kg, respectively
• An averaging time, AT, of 70 years
U.S.EPA. 1994c. Health Effects Assessment Summary Tables. Annual Update. OHEA-ECAO-CIN-909. Environmental Criteria and Assessment Office, Office of Research and Development
Cincinnati, Ohio.

This document represent U.S. EPA's secondary source of Inhalation CSF values.

U.S.EPA. 1996a. "Integrated Risk Information System (IRIS)". Database on Toxicity Information Network (TOXNET).

C-42
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TABLE C-2-1

INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS

(Page 8 of 8)

This reference represents U.S. EPA's primary source of Inhalation CSF values and other toxicity factors. This reference is updated periodically and should be reviewed prior to preparing a
risk assessment.

U.S.EPA. 1996b. "Proposed Guidelines for Carcinogenic Risk Assessment." Federal Register. 61 FR 31667. Volume 61. Number 120. June 20.

This document proposes new guidelines for assessing the carcinogenicity of COPCs.

U.S. EPA. 1996c. "EPA Region IX Preliminary Remediation Goals (PRGs) ~ 1996." August 1.

This document recommends a reasonable maximum exposure (RME) inhalation rate for children of 10 mVday, citing U.S. EPA (1989) as its source of information.

U.S.EPA. 1997. Exposure Factors Handbook Office of Research and Development. EPA/600/P-95/002F. August.

This document recommends an "average" child inhalation of 7.17 mVday (0.30 mVhr), and an "average" adult inhalation rate of 15.2 m3/day (0.63 m3/hr).
C-43
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TABUS C-2-2

INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCINOGENS

(Page 1 of 5)
Description
This equation calculates the HQ for inhalation exposures to COPCs that have noncancer health effects. Uncertainties associated with this equation bclude the following:
(1) COPC-specific reference concentrations (RfC) are unlikely to underestimate a COPC's potential for causing adverse health effects.
(2) Most of the uncertainties associated with the variables in the equation in Table B-5-1 (used to calculate Ca), specifically those associated with the variables Q, Cyv, and Cyp, are site-
specific.
(3) The uncertainties associated with the remaining variables in the equation hi Table C-2-2, IR, ET, EF, ED, BW, andylfare not expected to be significant.

Variable
HQw>
ADI
ca
Description r ° ^ . .; .. Units
Hazard quotient for direct unitless
inhalation of COPC noncarcinogen
j
Average daily COPC intake via mg COPC
inhalation kg-day
Total COPC air concentration ug/m3
Equation
HO ~mi
"Uum RJD
C'lR'ET'EF-ED- 0.001 mg/pg
BW- AT- 365
D/n _ RfC ' 20 m3/day
70%
Vatae

Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table B-5-1.
e-44
-------
TABLE C-2-2
INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCBVOGENS
(Page 2 of 5)
Variable
Units
Value
RfD
Reference Dose
mg/kg-day
Varies
This variable is COPC-specific, and should be determined from the COPC tables in Appendix A-3.

The following uncertainty is associated with this variable:

A chronic RfD is an estimate of a daily exposure level for the human population, including sensitive subpopulations,
that is likely to be without an appreciable risk of deleterious effects during a lifetime. Chronic RfDs are specifically
developed to be protective for long-term exposure (from 7 years to a lifetime) to a compound. COPC-specific RfDs are
unlikely to underestimate a chemical's potential for causing adverse health effects.
RfC
Reference concentration
mg/m3
Varies
This variable is COPC-specific, and should be determined from the COPC tables in Appendix A-3.

The following uncertainty is associated with this variable:

COPC RfCs are generally estimated by applying a series of uncertainty factors to the results of studies conducted on
laboratory animals. The application of uncertainty factors follows the underlying assumption that humans are, or may
be, as sensitive or more sensitive to the harmful effects of COPCs than the laboratory animals that were tested. RfCs
are designed to ensure that the general public, including sensitive subpopulations, will not experience adverse health
effects as a result of exposure to a COPC at its RfC. As a result, COPC-specific RfCs are unlikely to underestimate a
COPC's potential for causing adverse health effects.
IR
Inhalation rate
mVhr
0.30 or 0.63
This variable is site-specific. U.S. EPA OSW recommends using default values of 0.63 (adults) and 0.30 (children) in the
absence of site-specific information. The recommended adult value is consistent with U.S. EPA (1991) and U.S. EPA
(1994c). the recommended child value is greater than the inhalation rate proposed in U.S. EPA (1994b)— 0.18 mVhr based
simply on the adult inhalation rate multiplied by the ratio of child to adult body weight (15 kg/70 kg)—but is consistent with
U.S. EPA (1997).

Uncertainty associated with this variable includes:

The recommended inhalation rates do not consider individual respiratory or activity differences. Therefore, based on
the individual and the activities that individual is engaged in, the recommended inhalation rates may under-or
overestimate the actual rates. However, the degree of under-or overestimation is not expected to be significant.
C-45
-------
r
TABLE C-2-2

INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCINOGENS

(Page 3 of 5)
Variable
Dwcriptioii
Value
ET
Exposure time
his/day
24
This variable is site-specific. U.S. EPA OSW recommends the use of this default value in the absence of site-specific data.

Uncertainty associated with this variable includes:

The recommended ET value assumes that an individual remains at a specific location 24 hours per day. In reality this
is likely to be true only for a minority of the population including young children, their caregivers, and elderly or other
individual who are sick. Therefore, this recommended value contributes to a degree of overestimation for much of the
population. However, it must be noted that though an individual may not always be at a single location, that individual
may continue to be exposed to combustion emissions at an alternate location.
EF
Exposure frequency
days/yr
350
This variable is site-specific. U.S. EPA OSW recommends the use of this de&ult value in the absence of site-specific data.
This value is based on U.S. EPA (1991) and is consistent with U.S. EPA (1994b).

Uncertainties associated with this variable include:

(1) This exposure frequency is a single value that represents the most frequent exposure that is reasonably expected to
occur at a site with two weeks of vacation. This recommended value may overestimate EF for individuals who are
away from then- home for more man two weeks each year. On the other had, some individuals such as subsistence
farmers, may remain at their home (or farm) for more than 350 days per year. In either case, the degree of over- or
underestimation is not expected to be significant in most cases.
C-46
-------
TABLE C-2-2
INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCINOGENS
(Page 4 of 5)
Variable
ED
BW
365
AT
/. . t Description *. ' ?V
Exposure duration
Body weight
Units conversion factor
Averaging time
' Units '
yr
kg
day/yr
F
-" "*, \ \ .; 1,'A t ;, "^-'"Viito.' , . '*
6, 30, or 40
This variable is site-specific. Consistent with U.S. EPA (1994b) and NC DEHNR (1997), U.S. EPA OSW recommends the
use of the following default values.
Exposure Scenario ED
Subsistence Fanner 40 (U.S. EPA 1994c)
Subsistence Farmer Child 6 (U.S. EPA 1989)
Subsistence Fisher 30 (U.S. EPA 1994c)
Subsistence Fisher Child 6 (U.S. EPA 1989)
Adult Resident 30 (U.S. EPA 1989)
Child Resident 6 (U.S. EPA 1989)
Uncertainty associated with this variable includes:
These exposure durations are single values that represent the highest exposure that is reasonably expected to occur at a
site. These values may overestimate ED for some individuals.
15 or 70
This variable is site-specific. U.S. EPA OSW recommends using default values of 70 (adults) and 15 (children). These
default values are consistent with U.S. EPA (1991; 1994c).
Uncertainty associated with this variable includes:
These body weights represent the average weight of an adult and child. However, depending on the site, the body
weights may be higher or lower. These default values may overestimate or underestimate actual body weights.
However, the degree of under- or overestimation is not expected to be significant.

6, 30, or 40
This variable is site-specific and related to ED. Specifically, the AT for noncarcinogens is numerically the same as the ED.
This default value is consistent with U.S. EPA (1989), U.S. EPA (1991), and U.S. EPA (1994c).
Uncertainty associated with this variable includes:
The recommendation for averaging time may not accurately represent site-specific time; specifically this single value
may under- or overestimate the length of an average adult lifetime.
C-47
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TABLE C-2-2

INHALATION HAZARD QUOTIENT FOR COPCS: NONCARONOGENS

(Page 5 of 5)

REFERENCES AND DISCUSSION

U.S. EPA. 1989. Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part A).
Interim Final. Office of Emergency and Remedial Response. EPA/540/1-89/002. December.

U.S. EPA. 1991. Human Health Evaluation Manual, Supplemental Guidance: Standard Default Exposure Factors. Office of Solid Waste and Emergency Response. OSWER Directive 9285.6-
03. Washington, D.C.

This document is cited as the reference source document of the body weight variables.

U.S. EPA. 1994a. IRIS. Database on the TOXNET.

This document is U.S. EPA's primary source of RJCs and other toxicity fectors. This document is updated periodically and should be reviewed prior to preparing a risk assessment

U.S. EPA. 1994b. Estimating Exposure to Dioxin-like Components -Volume III:"Site-Specific Assessment Procedure. Review Draft. Office of Research and Development Washington D.C.
EPA/600/6-88/005Cc. June.

This document is cited by U.S. EPA (1994b) as the same document for the recommended defeult exposure duration (ED) values for the subsistence farmer and subsistence fisher. The ED
ion".

U.S. EPA. 1994c. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the following:

• An adult inhalation rate of 20 mVday (0.83 m3/hr).
• An exposure frequency of 350 days per year
• Receptor-specific exposure duration values as presented in U.S. EPA (1994a)—subsistence fisher (40 years) and subsistence farmer (40 years) and U.S. EPA (1989)—adult
i resident (30 years) and child resident (6 years)
• Adult and child body weights of 70 kg and. 15 kg, respectively

U.S. EPA. 1995. Health Effects Assessment Summary Tables. Annual Update. OHEA-ECAO-CIN-909. Environmental Criteria and Assessment Office. Office of Research and Development.
Cincinnati, Ohio.

This document is U.S. EPA's secondary source of RfCs and other toxicity factors. This document is updated periodically and should be reviewed prior to preparing a risk assessment.

U.S. EPA. 1997. Exposure Factors Handbook. Office of Research and Development. EPA/600/P-95/002F. August.
C-48
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TABLE C-2-3
TOTAL INHALATION CANCER RISK: CARCINOGENS
(Page 1 of 1)

This document recommends an "average" child inhalation of 7.17 m3/day (0.30 m3/hr), and recommends an "average" adult inhalation rate of 15.2 m'/day (0.63 mVhr).
Description
Cancer risk to the individual via inhalation are added across all COPCs that are carcinogenic via the direct inhalation route of exposure.

Uncertainties associated with this equation include the following:

(1) Total Cancer Risk assumes that different carcinogens affect the same target organ to produce a cancer response, ignoring potential antagonistic or synergistic effects or disparate effects on
different target organs. This assumption may overestimate Total Cancer Risk.
(2) The summation of cancer risks across multiple COPCs means that the uncertainties associated with estimating cancer risk for each COPC are also summed. This means Total Cancer
Risk, as defined below, is unlikely to be overestimated.
Equation
Total Cancer Riskjnh = ^ Cancer Risk
Variable
Description
^•^'•/i^:5/^
Total
Cancer
RiskM
Total individual lifetime cancer risk
through direct inhalation of all
COPC carcinogens
unitless
Cancer
Individual lifetime cancer risk
through direct inhalation for COPC
carcinogen i
unitless
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-2-1. The equation in Table C-2-
2 is used if the carcinogenic slope factor is available for the COPC.

Uncertainties associated with this variable include the following:

(1) COPC-specific URF values are unlikely to underestimate, and may overestimate, the carinogenic potential of COPCs
because of the mathematical models and the use of uncertainty factors in the estimation of these values.
(2) Most of the uncertainties associated with the variables used to calculate Ca, specifically Q, Cyv, and Cyp, are
site-specific.
C-49
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TABLE C-2-4
HAZARD INDEX FOR INHALATION: NONCARCINOGENS
(Page 1 of 1)
Description
For non-cancer health effects, HQs for inhalation exposures are added across COPCs when they target the same organ to obtain an HI for the target organ. See Appendix A-2 for target organs
and Appendix A-3 for COPC-specific inhalation RfCs and for identification of COPCs that cause noncarcinogenic effects via the inhalation route of exposure and their associated target organs.
Uncertainties associated with this equation include the following:

(1) The summation of noncarcinogenic hazards across multiple COPCs means that the uncertainties associated with estimating hazards for each COPC (see HQ below) are also summed. This
means that the total noncarcinogenic hazard, as defined below, is unlikely to be overestimated.
(2) As defined below, the HI sums the HQs for all COPCs to which a receptor is potentially exposed. Ideally, HQs should be summed only for COPCs that affect the same target organs and
systems. To the extent that COPCs affect different target organs, summing their associated HQs will overestimate the actual HI.
Equation
- E
Variable
Him
Description
Hazard index for target organ effect
j through direct inhalation of all
COPCs
Hazard quotient for direct
inhalation of COPC i
Units
unitless
unitless
Value
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-2-3.

Uncertainties associated with this variable include the following:

(1) COPC-specific RfCs are unlikely to underestimate a COPC's potential for causing adverse health effects.
2) Most of the uncertainties associated with the variables used to calculate Ca, specifically Q, Cyv, and Cyp, are
site-specific.
C-50
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TABLE C-3-1
CONCENTRATION OF DIOXINS IN BREAST MILK
(Page 1 of 4)
Description
This equation calculates the concentration of dioxins in milkfat of breast milk. Uncertainties associated with this equation include the following:

(1) The most significant uncertainties associated with this equation are those associated with the variable m. Because m is calculated as the sum of numerous potential intakes, estimates of
m incorporate uncertainties associated with each exposure pathway. Therefore, m may be under- or overestimated. Every effort should be made to limit and characterize the uncertainties
associated with this variable.
(2) This equation assumes that the concentration of dioxin in breast milkfat is the same as in maternal fat. To the extent that this is not the case, uncertainty is introduced.
Equation
m • IxlO9 • h -/i
0.693 • /,
Variable
Description
-mlllifat
m
Concentration of dioxin in milk fat
of breast milk for a specific
exposure scenario
Average maternal intake of dioxin
for each adult exposure scenario
mgCOPC/kgBW-
day
Varies
This variable is COPC- and site-specific and is equal to the total daily intake of dioxin (7), which is calculated using
the equation in Table C-l-6 for each adult exposure scenario.

The following uncertainty is associated with this variable:

(1) The uncertainty associated with this variable may be significant, because this uncertainty represents the sum
of all uncertainties associated with each of the potential exposure pathways. To gauge the potential
magnitude of the uncertainty associated with this variable, estimated m values should be compared to values
reported in the literature.
C-51
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TABLE C-3-1

CONCENTRATION OF DIOXINS IN BREAST MILK

(Page 2 of 4)
Variable
JEtescrtpttoB
Units
Value
Half-life of dioxin in adults
days
2,555
This variable is COPC- and site-specific. U.S. EPA OSW recommends the use of this default value, consistent with
U.S. EPA (1994a) and U.S. EPA (1994b).

The following uncertainty is associated with this variable:

As discussed in U.S. EPA (1994a), the half-life may vary from about 5 to 7 years for 2,3,7,8-TCDD. Use of
the upper end of the range is conservative. Based on the work of Schecter (1991), and Schlatter (1991), as
discussed hi U.S. EPA (1994a), the value ofh may vary by almost one order of magnitude (1.1 to 50). for
different dioxin and furan congeners around die value of 7 proposed for 2,3,7,8-TCDD. The differences are
largely the result of differences in absorption. However, if the average material intake of dioxin is calculated
in terms of TEQs, the use of a single h value based on 2,3,7,8-TCDD is assumed to be reasonable.
Fraction of ingested dioxin that is
stored in fat
unitless
0.9
This variable is COPC- and site-specific. U.S. EPA OSW recommends the use of this default value, consistent with
U.S. EPA (1994b). The source of this value is U.S. EPA (1994a).
Fraction of mother's weight that is
fat
unitless
0.3
This variable is COPC-specific. U.S. EPA OSW recommends the use of this default value, consistent with U.S.
EPA (1994a) and U.S. EPA (1994b). The source of this value is U.S. EPA (1994a).

The following uncertainty is associated with this variable:

Although this single value clearly does not adequately represent all potentially exposed women of
childbearing age, the average uncertainty associated with this value is assumed to be minimal.
C-52
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TABLE C-3-1

CONCENTRATION OF DIOXINS IN BREAST MILK

(Page 3 of 4)

REFERENCES AND DISCUSSION

Schecter, A. 1991. "Dioxins and Related Chemicals in Humans and in the Environment." In: Biological Basis for Risk Assessment ofDioxins and Related Compounds: Gallo, M.; Schenplein, R;
Van Der Heijden, K. Eds; Banbury Report 35, Cold Spring Harbor Laboratory Press.

This document is cited by U.S. EPA (1994a) as the source of information related to the metabolism of dioxin and related compounds, in addition to concentrations of various congeners in
adipose tissue.

Schlatter, C., 1991. "Data on Kinetics of PCDDs and PCDFs as a Prerequisite for Human Risk Assessment." In: Biological Basis for Risk Assessment ofDioxins and Related Compounds; Gallo,
M; Schenplein, R; Van Der Heijder, K., eds. Banbury Report 35, Cold Spring Harbor Laboratory press.

This document is cited by U.S. EPA (1994a) as a source of a method of estimating the half-life of dioxin-related compounds, based on uptake data relative to 2,3,7,8-TCDD. U.S. EPA
(1994a) proposed the following equation, based on this document:
i/2»
•TCDD
In2
where

CTCDD = Concentration of TCDD in body
DTCDD = Daily intake of TCDD
tl/2,TCDD = Half-life of TCDD in body
V = Volume of body compartment

Smith, A.H. 1987. "Infant Exposure Assessment for Breast Milk Dioxins and Furans Derived from Waste Incineration Emissions." Risk Analysis. 7(3)347-353.

This document is cited by U.S. EPA (1994a) as the source of the equation in Table C-3-1 and the recommended values for h (2,555 days),// (0.9), andf2 (0.3). This document assumes that
the concentration of dioxins in breast milkfat is the same as in maternal fat.

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Volume II: Properties, Sources, Occurrence, and Background Exposures. Review Draft. Office of Research and
Development. EPA/600/6-88/0055Cb. Washington, D.C. June.

This document cites Smith (1987) as the source for half of the recommended values for the life of dioxin for adults (h), proportion of ingested dioxin that is stored in fat (/}), and proportion
of mother's milk that is fat (f2).
C-53
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TABLE C-3-2

AVERAGE DAILY DOSE TO THE EXPOSED INFANT

(Page 4 of 4)

U.S. EPA. 1994b. RevisedDraft Guidancefor Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste, Attachment C, Draft Exposure Assessment
Guidance for RCRA Hazardous Waste Combustion Facilities. Office of Emergency and Remedial Response. Office of Solid Waste. December 14.

This document recommends the use of the equation in Table C-3-1 and values for the variables in this equation: h (2,555 days),./) (0.9), wdf, (0.3).
C-54
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TABLE C-3-2
AVERAGE DAILY DOSE TO THE EXPOSED INFANT
(Page 1 of 4)
Description
This equation calculates the average daily dose for an infant exposed to contaminated breast milk. Uncertainty associated with this equation includes the following:

The most significant uncertainty associated with this equation is the selection of a value for averaging time (AT). As stated in U.S. EPA (1994a), "Little agreement exists regarding the
appropriate choice of an averaging time for less than lifetime exposures. This is especially true for cases where exposure is occurring in a particularly sensitive developmental period."

Use of an averaging time (AT) of 1 year is appropriate for assessing noncarcinogenic effects. However, use of this value may overestimate a lifetime average appropriate for assessing
carcinogenic risk by almost two orders of magnitude (70/1). _^____
ADD
Equation

' /3 • /4 '
infant
BWinfant ' AT
Average daily dose for infant
exposed to contaminated breast
milk
Concentration of COPC in milk fat
of breast milk for a specific
exposure scenario
pg COPC/kg
milkfat
%?5£M^^
Varies
This variable is COPC- and site-specific, and is calculated by using the equation in Table C-3-1.

The following uncertainty is associated with this variable:

The most significant uncertainties associated with the calculation of this variable are those associated with the
variable m and the estimate ofC^-a- Uncertainties associated with m represent a sum of the various uncertainties
associated with each of the potential exposure pathways (see the equation in Table C-l-6).
Fraction of mother's breast milk
that is fat
unitless
0.04
This variable is COPC- and site-specific. U.S. EPA OSW recommends the use of this default value, consistent with -
U.S. EPA (1994a) and U.S. EPA (1994b). As cited in U.S. EPA (1994a), the source of this variable value is Smith
(1987).

The uncertainty associated with this value is assumed to be minimal.
C-55
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TABU; c-3-2
AVERAGE DAILY DOSE TO THE EXPOSED INFANT
(Page 2 of 4)
Variable
DtacriptioB
Fraction of ingested COPC that is
absorbed
Units
unitless
0.9
This variable is COPC- and site-specific. U.S. EPA OSW recommends the use of this default value consistent with
U.S. EPA (1994a),and U.S. EPA (1994b). As cited in U.S. EPA (1994a), the source of this variable value is Smith
(1987).

The uncertainty associated with this value is assumed to be minimal.
Ingestion rate of breast milk by the
infant
kg/day
0.8
This variable is COPC- and site-specific. U.S. EPA OSW recommends the use of this default value, consistent with
U.S. EPA (1994a) and U.S. EPA (1994b). As cited in U.S. EPA (1994a), the source of this variable value is Smith
(1987).

The following uncertainty is associated with this variable:

As reported in U.S. EPA (1994a), Smith (1987) reports that breast milk ingestion for 7- to 8-month-old infents
ranged from 677 to 922 mL/day. Assuming a density of breast milk of slightly more than 1.0, the recommended
value is about the midpoint of the reported ingestion rate, converted from milliliters per day to kilograms per day.
Based on the reported ingestion range, the ingestion rate could vary by about 12 percent from the recommended
value. This possible variance is not considered especially significant.
ED
Exposure duration
1.0
This variable is COPC- and site-specific. U.S. EPA OSW recommends the use of this default value, consistent with
U.S. EPA (1994a) and U.S. EPA (1994b).

The following uncertainty is associated with this variable:

Some infants may nurse for more or less than the recommended 1 year. However, the average uncertainty
associated with mis variable value is not expected to be large.
BWt
infant
Body weight of infant
10
U.S. EPA OSW recommends the use of this defimlt value. As cited in U.S. EPA (1994a), this value is based on
information presented by the National Center for Health Statistics (1987).

The following uncertainty is associated with this variable:

As reported in U.S. EPA (1994a), the National Center for Health Statistics (1987) reported mean body weights of
6- to 11-month-old and 1 year-old infants of 9.1 and 11.3 kilograms, respectively. Based on this information and
an assumed 1-year ED, the uncertainty associated with this variable value is expected to be minimal.
C-56
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TABLE C-3-2
AVERAGE DAILY DOSE TO THE EXPOSED INFANT
(Page 3 of 4)
Variable
Value
AT
Averaging time
This variable is COPC- and site-specific. U.S. EPA OSW recommends the use of this default value, consistent with
U.S. EPA (1994a) and U.S. EPA (1994b).

The following uncertainty is associated with this variable:

The uncertainty associated with this variable value is significant, as stated in U.S. EPA (1994a): "Little agreement
exists regarding the appropriate choice of an averaging time for less than lifetime exposures. This is especially
true for cases where exposure is occurring in a particularly sensitive developmental period." Use of an averaging
time of 1 year is appropriate for assessing noncarcinogenic effects. However, use of this value may overestimate a
lifetime average, appropriate for assessing carcinogenic risk, by almost two orders of magnitude (70/1).
C-57
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TABLE C-3-2

AVERAGE DAILY DOSE TO THE EXPOSED INFANT

(Page 4 of 4)

REFERENCES AND DISCUSSION

National Center for Health Statistics, 1987.

Cited in U.S. EPA (1994a) as the source of the recommended BW,^, value of 10 kilograms. However, that document does not provide a complete reference for this document

Smith., A.H. 1987. "Infant Exposure Assessment for Breast Milk Dioxins and Furans Derived from Waste Incineration Emissions." Risk Analysis. 7(3)347-353.

This document is cited by U.S. EPA (1994a) as the source of the recommended values for the variables in the equation in Table C-3-2.

U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds. Review Draft. Office of Research and Development. EPA/600/6-88/0055Cc. Washington ,D.C. June.

This document is cited as the original source of the fraction of fat in breast milk, fraction of ingested COPC that is absorbed, ingestion rate of breast milk, exposure duration, and body weight
of infant.

This document recommends the use of the equation in Table C-3-2 and values for the variables in this equation: f3 (0.04), /, (0.9), IRmllk (0.8 kg/day), ED (1 year), BW, fml (10 kg) and AT (1
year). J
C-58
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TABLE C-4-1
ACUTE HAZARD QUOTIENT

(Page 1 of 1)
Description
This equation calculates the acute hazard quotient AHQ for short term inhalation exposures to COPCs. Uncertainties associated with this equation include the following:

(1) Uncertainties may be associated with development components of COPC-specific acute inhalation exposure criteria (AIECs), including exposure group protected, exposure duration, and
toxicity endpoint. Uncertainties are specific to each COPC's AIEC, and may under or overestimate the potential for causing adverse health effects.
(2) Most of the uncertainties associated with the variables in the equation in Table B-6-1 (used to calculate Cacwe), specifically those associated with the variables Q, Chv, and Chp, are
site-specific.
Equation
o.ooi
Variable
"'<',,' »esciiB«
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