EPA On-line Tools for Site Assessment Calculation

Notice

The old seepage velocity and travel time calculator determined the advective travel time. This calculation accounted for transport due to advection and sorption only. Because of widespread biodegradation of petroleum hydrocarbons and dispersion in aquifers, the advective travel time can come long after the first arrival time of a contaminant at a receptor. To avoid this situation the one-dimensional transport calculators have been revised to calculate the first arrival times.

Try instead:

Continue below for the seepage velocity calculation.

Seepage Velocity

Seepage Velocity Calculation
See bottom of page for equations solved.

Input Parameters


Site Name
Date
Distance Unit
Time Unit
Chemical
Porosity
Fraction Organic Carbon
Hydraulic Conductivity (K)
Upgradient Location (x₁,y₁)
Downgradient Location (x₂,y₂)
Head unit
Upgradient Water Level (h₁)
Downgradient Water Level (h₂)

Defaults


K_oc

Intermediate Results


Hydraulic Conductivity (K)
Bulk Density (r_b)
k_d
Retardation factor (R)
Gradient (i)

Main Result


Seepage Velocity (q_s = v)
Retarded Seepage Velocity (q_s/R)

seepage velocity q _s = v = -K i / q

q_s = v = seepage velocity [L/T]
K = hydraulic conductivity [L/T]
i = hydraulic gradient [L/L]
q = porosity [L/L]

retardation factor R = 1 + r_bk_d /q

R = retardation factor
r_b = bulk density = r_s(1-q)
r_s = solids density
q = porosity
k_d = (soil) distribution coefficient = f_oc K_oc
f_oc = fraction organic carbon
K_oc = organic carbon/water partition coefficient

Contact Jim Weaver to ask a technical question on this material.