Parameter Estimation Guidelines for Risk-Based Corrective Action ...

Groundwater Services, Inc.
Equation CM-1: Surface Soil Volatilization Factor (VFss)
Uair
breathing zone
d affected surficial soils
W
δ air
diffusing
vapors
CM-1a:
VF
ss
( )
3
⎡
eff
mg / m − air ⎤ 2W
s
Ds
H
⎢
⎥
⎣⎢
( mg / kg − soil)
⎦⎥ = ρ
Uairδair
πτ θ + k ρ + Hθ
or CM-1b:
VF
whichever is less
Equation CM-2: Soil Particulate Emission Factor (PEF)
ss
( )
3
⎡ mg / m − air
⎢
⎣⎢
mg / kg − soil
( )
( ) ×
ws s s as
⎤ Wρsd
⎥ = × 10
⎦⎥
Uairδairτ
3
10
3
Uair
d
P e
breathing zone
affected surficial soils
δ air
diffusing
vapors
( )
3
⎡ mg / m − air
PEF⎢
⎣⎢
mg / kg − soil
( )
⎤ PW
e
⎥ = × 10
⎦⎥
Uairδ
air
3
W
Equation CM-3: Subsurface Soil Volatilization Factor (VFsamb)
L s
U air
breathing zone δair
vadose zone
d i f f u s i n g v a p o r s
affected subsurface soils
W
CM-3a:
⎡ 3
( mg / m − air)
⎤
H
VF ⎢
⎥
s
samb
⎢( mg / kg − soil)
⎥ = ρ
⎡
⎣
⎦ θws + ksρs + Hθas
⎢1
⎣⎢
or CM-3b:
whichever is less
[ ] +
( )
⎡ 3
mg / m − air
VF ⎢
samb
⎢ mg / kg − soil
⎣
( )
3
x10
Uairδair L ⎤
s
Ds eff ⎥
W ⎦⎥
⎤
⎥ W sds
3
10
⎥ = ρ
Uairδairτ x
⎦
Equation CM-4: Subsurface Soil to Enclosed Space Volatilization Factor (VFsesp)
ER: air
exchange
rate
L s
enclosed-space
foundation cracks
,,,,,,,,,,,,,,
d i f f u s i n g
affected subsurface soils
W
v a p o r s
L
b
: Vol. / Infil. Area Ratio
L crack : Foundation
Thickness
vadose zone
CM-4a:
Hρ
⎡
s Ds eff / L ⎤
s
⎡ 3
( mg / m − air)
⎤
⎢ ⎥
ws ks s H as ER LB
VF ⎢
⎥
[ 3
sesp
10
⎢( mg / kg − soil)
⎥ = θ + ρ + θ ] ⎣⎢
⎦⎥
x
⎣
⎦ Ds eff / Ls
Ds eff / L
1 + ⎡ s
ER L eff
⎣ ⎢ ⎤
⎡
⎤
⎥
⎢ B ⎦⎥ + ⎢
⎥
( Dcrack
/ L
⎣⎢
crack ) η
⎦⎥
or CM-4b:
whichever is less
( )
⎡ 3
mg / m − air
VF ⎢
sesp
⎢ mg / kg − soil
⎣
( )
⎤
⎥ sds
3
10
⎥ = ρ LBERτ x
⎦
FIGURE 2. CROSS-MEDIA PARTITIONING EQUATIONS IN THE RBCA SPREADSHEET SYSTEM
Continued
NGWA Petroleum Hydrocarbons Conference 4 Parameter Estimation Guidelines
Houston, Texas, November 1996
for RBCA Modeling