Planning the Bore Path
Before setting up the job site, you need to plan the bore path,
including the following:
Figure 51
1.
Bore entry
4.
Obstacle
2.
Beginning-of-bore-at-depth point
5.
End-of-bore-at-depth point and bore exit
3.
Bore depth
•
Bore entry
This is where you setup the machine and the drill bit
enters the ground. Depending on conditions, this will
typically be set back 9 to 15 m (30 to 50 ft) from the
beginning-of-the-bore-at-depth point.
•
Beginning-of-bore-at-depth point
This is the point where you want the utility line or pipe to
end after installation is complete. It is typically the point at
which the bore levels out and begins to bore horizontally.
This may be the same as the entry point, or you may dig a
separate depth-gauge hole at this point (
•
Bore depth
This the depth at which you want to install the utility
line or pipe. This machine is designed primarily for
installations between 1 and 3 m (3.5 to 10 ft).
•
Obstacles in the path
It is important to know where the known obstacles are
that you will need to steer around or under before starting
so that you can plan where to begin steering prior to
reaching the obstacle.
•
End-of-bore-at-depth point
This is the point where you want the utility line or pipe
to begin after installation is complete. Often, this will
also be the bore exit.
•
Bore exit
This is the location where the drill head will exit the
ground and the point at which you will pull the utility lines
or pipe into the bore. If this point will be at the surface
instead of at installation depth, you will need to determine
the distance from the end-of-bore-at-depth location
needed for steering the drill to the surface, typically 9 to 15
m (30 to 50 ft) from the end-of-the-bore-at-depth point.
Determining the Bore-entry Point
One of the more challenging aspects of planning the bore
path is to determine the entry point of the bore. You need to
take the following traits into account when determining the
location of the entry point:
•
Bore depth
This is the depth at which you want to install the utility
line or pipe. This machine is designed primarily for
installations between 1 and 3 m (3.5 to 10 ft).
•
Pipe and material flexibility
The 3 m (10 ft) pipes used on this machine can flex to
an 8% pitch over the length of the pipe; this equates to
a bend of no more than 20 cm (8 inches) off a straight
path (
Important:
If you steer the pipe to bend sharper
than 20 cm (8 inches) per pipe, you may damage the
pipes and their connections. You must also make
steering changes gradually over the entire length of
each pipe. If you steer the whole 20 cm (8 inches)
in only 25 to 50 cm (1 to 2 ft) of travel, you will
permanently damage the pipes.
51
