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

Appendix D
R = recharge, m/yr
A = area of contaminated site, m 2
Neglecting lateral dispersion, the horizontal contaminant flux in groundwater is approximated by
Q ch = C gw [(W × B × q) + (R × A)] [2]
where
Q ch = horizontal contaminant flux, mg/yr
C gw = concentration of contaminant in groundwater, mg/m 3
W = width of contaminated zone, m
B = effective mixing depth in aquifer, m
q = Darcy velocity of aquifer, m/yr
Applying mass balance considerations, contaminant transport in the vadose and saturated zones is set
equal:
C sw × R × A = C gw [(W × B × q) + (R × A)] [3]
And a dilution factor (DF) may be defined as:
Which reduces to
By definition
DF = C sw /C gw = [(W × B × q) + (R × A)]/R × A [4]
DF = (W × B × q/R × A) + 1 [5]
A = W × L [6]
where
L = length of contaminated site, m
Substituting [6] into [4] yields
DF = (B × q/R × L) + 1 [7]
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