Question

A soil sample is 10 cm in diameter and 1 m long. The sample is oriented vertically

in a tube. The tube in which the soil resides is 2.5 m tall. The lower 1 m is occupied

by the soil, and there is 1 m of water ponded on top of the soil. A float valve keeps

the amount of water ponded on the soil at 1 m. Water drips out the bottom of the

soil specimen such that the water pressure at the bottom of the soil column is

atmospheric pressure. Assume that the column of soil is completely saturated with

water and that the porosity of this soil (which is fine sand) is 0.4. The hydraulic

conductivity of the soil is 0.0001 cm/sec.

a. A piezometer is inserted at the mid-

point of the soil column (0.5 m above the

base). Show in a sketch to what point the water in the piezometer would rise.

b. A tracer (dye) is instantly mixed into the water located on top of the soil. Assume

that as the dyed w

ater infiltrates into the soil, there is no mixing of dyed water

with remnant soil water. Rather, assume that the infiltrating dyed water fully and

completely displaces the residual soil water. How long will it take for the dyed

water to show up in the eff

luent liquid?

Answer 1