Conducting Subsurface Environmental Investigations in Urban Watersheds - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 141

tool comprised of two halves of a hollow metal tube. The tube is threaded on each end
where end caps are screwed onto the split spoon to hold it in place while the sample is
collected. The split spoon is lowered down the borehole to the desired sampling depth
through the center of the hollow-stem auger and then is pounded into the ground using
a 64 kg (140 lb) hammer. The number of hammer blows required to drive the split spoon
into the ground 2 ft is recorded to provide geotechnical information concerning soil type
and resistance.
Figure 4.10 is a photograph of a Geoprobe, and Figure 4.11 is a photograph of a hol-
low stem auger drilling rig. Figure 4.12 shows a 5 cm diameter by 1.2 m (4 ft) long soil
sample collected using a Geoprobe being inspected by a geologist. The plastic sleeve has
been sliced in half longitudinally to provide proper access to the sample for inspection.
Figure 4.13 shows a Roto-sonic drilling rig, and Figure 4.14 shows a sample being extracted
from a Roto-sonic drilling rig.

Geoprobe

Borehole location

FIGURE 4.10
Geoprobe. (Photo by Daniel T. Rogers.)

Hollow stem
auger

Center rod

Bottom plug

FIGURE 4.11
Hollow-stem auger drilling rig. (Photo by Daniel T. Rogers.)