to evaporate any moisture. The soil was placed in an 1-
liter graduated cylinder and the height of the soil was
marked. Then water was added by such that the water level
just coincided with the original soil level. Mixing was
provided to eliminate air pockets.
Porosity = [amount of water added] / 200 (4-1)
Hydraulic conductivity determination. Hydraulic
conductivity of the soil columns was determined by a
constant head permeameter shown in Figure 4-1. Soil
retention screens made of a few layers of glass fiber
supported with a stainless steel mesh were placed both on
top and at the bottom of the soil column. A piece of 3/4
inch tygon tubing was used to feed water from the constant
head reservoir. The frictional head losses from the tubing
and the fixtures were negligible compared to that caused by
the soil column. The hydraulic conductivity (K) was
calculated according to the formula:
K = Q L / dh A (4-2)
where K is the hydraulic conductivity (cm/sec), Q is the
measured flow rate (ml/sec), L is the length of the soil
column (cm), dh is the total head loss through the
permeameter (cm) (which is the difference in elevation
between the inflow and outflow water levels), and A is the
cross sectional area of the soil column (cm2) (McWhorter and
Sunada, 1977).