Environmental Engineering Reference
In-Depth Information
PVC. The cap was equipped with a three-way plastic stopcock purchased
from Cole-Parmer
®
. Tubing attached to a portable, infrared gas analyzer
has a fitting for the stopcock valve. The pump of the gas analyzer with-
draws and analyzes an air sample. The probe remains in the ground
between sample events. Construction details are supplied in Nestler et al.
(2001b).
7.3.10 Pilot-scale methods
7.3.10.1 Sampling design
Each LTU was subdivided into 20 equal sections (Figure 7.14). A sampling
grid sized to fit the sections was constructed from Plexiglas and drilled with
36 equidistant holes for the soil corer. The grid for LTU 1 was designed to
fit around the soil gas probes so they did not have to be removed. At each
sampling interval, five randomly selected cores were collected from each of
the 20 sections. The five soil cores for each single grid were combined in a
950-cc amber jar and manually homogenized into a single sample. A random
number-generating computer program selected 7 of these 20 grids for anal-
ysis. The remaining 13 samples were archived at 4˚C in their original collec-
tion jars. The sampling holes in LTU 1 were filled by raking lightly across
the soil surface. Water was added, if necessary. LTU 2 was tilled, and the gas
LT U
Each LTU had 20 sampling zones from which 7
were randomly selected for analysis.
Sampling grid (enlarged)
showing 7 randomly-selected
subsamples of 36 potential samples
Figure 7.14
Design of random sampling process for the LTUs.
