BT2 user manual - H-5911-9004-02-B Page | 13
4 Boretrak2 deployments – geo-referencing
4.1 Georeferencing a survey
When using the Boretrak2 system, it is usually the case that the absolute position and orientation of the surveyed
hole will be required. For example, if deviation is detected in the borehole, in which direction is it inclined and how
does this relate to other features above or below the ground?
To establish the position and orientation of the surveyed data, two values are required:
1. The position of the borehole collar.
2. The orientation of the probe during the gyro alignment.
With these two values established, when the Boretrak2 probe is deployed down the borehole, all subsequent
readings can be related back to the starting position and orientation. The surveyed hole can also be referenced to
any other features surveyed on the same coordinate system: for example, a quarry face or an underground tunnel.
4.2 Position of the borehole
The position of the borehole can be established by:
• GPS.
• Traditional survey methods.
• A Carlson Quarryman Pro. The Quarryman Pro is used in quarrying operations to scan a quarry face and
to position borehole collars.
If the collar is very wide and uneven, take care to survey to the exact point from which the deployment is to be
measured.
4.3 Orientation and positioning of the alignment jig
Find a location for the alignment jig. The location must be close enough to the collar so that the Boretrak2 can be
promptly deployed when the alignment is complete.
The location should be solid and not subject to movement or vibrations. Ensure the jig is roughly horizontal (ie.
within 20° of level).
It is important to minimise handling of the Boretrak2 probe between the alignment and deployment. Therefore, if
convenient, keep the deployment device attached to the probe while it is being aligned. This may influence where
you choose to position the alignment jig, particularly if using the push rod system for deployments.
The heading of the Boretrak2 in the jig must be entered into Carlson Boretrak. The heading is that which is defined
by the direction of the Boretrak2 from the rod adaptor to the tip of the nose cone (see Figure 2).
This heading can be established by:
• A direct survey of the jig using traditional survey methods.
• Aligning the jig along a line of known azimuth – eg. along the centre of a tunnel underground, or along a
shotline in a quarry.
• Aligning the jig between two points with known coordinates – eg. between two surveyed hole collars. The
heading between the two holes can be computed in Carlson Boretrak software.
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