Product Manual

Page 18
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8.7.1 Record the ground temperature at a depth of about 300 mm (12 in.), or at the
mid-depth of the test zone.
8.7.2 To determine and record the volume of liquid that is added, maintain a constant
head in the inner ring and annular space during each timing interval by
measuring and reading the site glass the change in elevation of liquid level in
the Mariotte tube. After recording how much water was been siphoned from
the Mariotte tube, move the rubber water height marker to the new water level
position. (Figure 5) Record the temperature of the liquid within the inner ring.
8.7.3 For average soils, record the volume of liquid used at intervals of 15 minutes
for the first hour, 30 minutes for the second hour, and 60 minutes during the
remainder of a period of at least 6 hours (or until after a relatively constant
rate is obtained).
8.7.4 The appropriate schedule of
readings may be determined only
through experience. For high-
permeability materials, readings may be
more frequent, while for low
permeability materials, the reading
intervals may be 24-hours or more. In
any event, the volume of liquid used in
any one reading interval should not be
less than approximately 25 cm
3
.
8.7.5 Place the driving cap, or some
other covering, over the rings during the
intervals between liquid measurements
to minimize evaporation (see 8.2.1).
8.7.6 Upon completion of the test, remove the rings from the soil by
lightlyhammering on the sides with a rubber hammer.
9. Calculations
9.1 Convert the volume of liquid used during each measured time interval into an
incremental infiltration velocity, for both the inner ring and annular space, using the
following equations:
9.1.1 For the inner ring, calculate as follows:
V
1R
= ΔV
1R
/(A
1R
· Δt)
Where:
V
1R
= inner ring incremental infiltration velocity, cm/h
ΔV
1R
= volume of liquid used during time interval to maintain constant head in the
inner ring, cm
3
Figure 5
IN12 - Mariotte Tubes water height marker
is shown