CS650 and CS655 Water Content Reflectometers
25
5.
Repeat steps 3 and 4 three or four times.
6.
Add water to top of the container.
7.
Cover the container to prevent evaporation.
8.
Frequently observe the CS650 permittivity output, waiting for the
permittivity to be constant. This indicates equilibration. The time required
for equilibration depends on the amount of water added and the hydraulic
properties of the soil.
9.
Record the CS650 permittivity.
10.
Repeat steps 6 through 9.
11.
Remove the CS650.
12.
Take core samples of soil using this process:
a.
Evenly push copper tubing into the soil where the sensor rods were
inserted.
b.
Remove the tube containing the sample and gently trim the ends of
excess soil.
c.
Remove excess soil from outside of the tube.
d.
Transfer the soil from the tube to the oven or microwave safe
container.
e.
Weigh the container holding the wet soil, and subtract the container
weight from this value to get the wet soil mass.
f.
Record the wet soil mass.
g.
Use oven or microwave to remove water from soil. Oven drying
requires 24 hours at 105 °C. Microwave drying typically takes 20
minutes depending on microwave power and sample water content.
ASTM Method D4643-93 requires heating in microwave for 3
minutes, cooling in desiccator then weighing and repeating this
process until measured mass is constant (Section
(p. 30)
).
h.
Weigh the container holding the dry soil, and subtract the container
weight from this value to get the dry soil mass.
i.
Record the dry soil mass.
j.
Repeat process to take replicate samples. Three carefully handled
samples provide good results.