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EPA On-line Tools for Site Assessment Calculation

Transport and Leaching from a Release of Fresh Fuel

One Dimensional Transport Equation

This calculator generates a breakthrough curve* at a receptor and uses a one-dimensional model to determine the

  1. First arrival time for a contaminant (above a specified threshold concentration),
  2. Maximum Concentration, and
  3. Duration of Contaminantion above the specified threshold

*The breakthrough curve is the time history of concentration at a receptor located a specified distance from the contaminant source.

Example breakthrough curve.

See bottom of page for equations solved.>




Water Saturation

Gradient (absolute value) (âˆ'i)

Default Parameters

Percent Mass Fraction
Intermediate Results

Beginning Time of Breakthrough Curve
Breakthrough Curve Through Maximum Concentration

Completion of Breakthrough Curve (for Pulse Sources)

Advective Travel Time

One Dimensional Transport Equation

One-dimensional transport equation

R = retardation factor []
D = dispersion constant [L2/T]
v = seepage velocity [L/T]
μ = first order decay constant [1/T]

with the initial and boundary conditions

Boundary conditions
retardation factor R = 1 + Ï b k d /θ

R = retardation factor
Ï b = bulk density = Ï s (1-θ)
Ï s = solids density
θ = porosity
k d = (soil) distribution coefficient = f o c K o c
f o c = fraction organic carbon
K o c = organic carbon/water partition coefficient

travel time t t r = x R / q s

t t r = advective travel time*
q s = seepage velocity
R = retardation factor
x = distance
* assuming one-dimensional, steady flow, constant gradient

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