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with material from other intervals. Drilling has to stop when groundwater is encountered as the hole
quickly becomes clogged with mud.

Surveying A Drill Hole
The deeper the drilling the greater is the need for down-hole surveys. These are important drill holes
can be very off course. A survey will confirm the actual angle and direction of the holes at a specific
depth. Typically, surveys are conducted every 30 metres. However, sometimes there is a need to obtain
surveys every 15 metres, especially when the hole is being deliberately redirected using navigational
drilling techniques. When the surveys are plotted using 3D-modelling software the trajectory of the
drill-hole relative to the target is revealed. Monitoring of the orientation of the hole during drilling allows
the driller to make minor adjustments which can result in some degree of control over the drilling
direction.

Diamond Drill-Hole Drilling

The diamond drill-core drilling is used to obtain oriented and intact rock from hundreds of metres below
the ground’s surface. An experienced geologist then describes core in detail, a process known as
logging. Diamond drilling provides the most detailed geological and geotechnical information available
prior to mining.
Diamond drilling is the result of months, or years of field work and is a significant investment in a
prospect.
Drill site selection is often an iterative process comprising office work together with site visits to
ensure that drilling is physically possible at each site.

HQ drill-core with drill bit and stem

Drill Planning and Logistics

Prior to undertaking any drilling, a
drill-hole plan is designed and a
proposal written. This document
outlines the reasons for drilling, the
expected costs and details of
contracts. Diamond drilling is
expensive, so the proposal is likely to require board of director’s budgetary approval.

Drill site selection is often an iterative process comprising office work together with site visits to ensure
that drilling is physically possible at each site. What might look like a good site on the computer could, on
the ground, be a site fraught with difficulties.
Site inspections by the drilling contractor are also conducted to ensure that all logistics of the proposed
drilling exercise are considered. This may include the inspection of access tracks and selection of camp
sites for personnel.

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