Protocol for the Derivation of Environmental and Human ... - CCME

Appendix G
Table G.1
Equations Used in Vapour Transport Model
Note:
The following equations are in generalized form; actual equations may contain factors to ensure
consistent units.
1. Phase Partitioning
C sw = C s /(K oc × f oc ) Eq.(1)
where:
C s = contaminant concentration adsorbed to soil (mg/kg)
C sw = contaminant concentration dissolved in soil water (mg/L)
K oc = organic carbon partitioning coefficient (ml/g)
= organic fraction of dry soil (g/g)
f oc
C sg = (C sw × H × 10 -3 )/(R × T) Eq.(2)
where:
C sg = contaminant concentration in soil gas (mg/m 3 )
H = Henry's Law constant (atm⋅m 3 /mol)
R = Gas constant (m 3 ⋅atm/mol⋅ 0 K)
T = absolute temperature ( 0 K)
2. Mass Transfer to Building
? p = ? a × g × h (T i - T o ) Eq.(3)
T o × 10 3
where:
? p = pressure difference (kPa)
? a = density of air (kg/m 3 )
g = acceleration due to gravity (m/s 2 )
h = height of neutral pressure = ½ building height (m)
T i = inside temperature ( 0 K)
T o = outside temperature ( 0 K)
Q sg = C (b c 3 × l c × ? p)/(t c × A × µ) Eq.(4)
where:
Q sg = soil gas flow rate through slab (m 3 /m 2 ⋅h)
C = constant including unit conversion factors (unitless) = 3.04 × 10 -4
l c = total length of cracks (m)
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