Environmental Engineering Reference
In-Depth Information
Figure 5.14.
(a) Cable tool rig, and (b) cable-tool sampling equipment.
reverse air circulation. These methods provide rapid penetration in medium to very strong
rock but the rock quality must be assessed from penetration rate measurements and log-
ging of sand and gravel sized rock fragments which provide no data on rock structure.
The efficiency of the drilling is affected by excessive groundwater and drilling is slowed if
the bit vents become blocked with clay.
