Total station and prisms
The use of a total station and prisms for pit wall monitoring is the most frequently used
measurement technique. Small prisms are installed in potentially unstable zones or
areas of interest. One or more base stations with back-sight prisms installed in stable
ground are established around the rim of the open pit depending on access and visibility
of the pit walls. The number of prisms installed in potentially unstable areas measured
from any one base station may range from 10 to 100 s. To minimise the manual
effort of reading the prism coordinates and to improve the frequency and the accuracy
of the measurements, HVC uses robotic total stations operating from within climatecontrolled
huts. These total stations have wireless technology for transmission of data
to the engineering office for fast data processing and analysis thereby saving time and
reducing human errors. A description of the automated system used by HVC can be
found in various publications [7–10].