[citation needed] A piercing tool uses compressed air to bore through the ground.
Additionally an oiler attachment is used to send oil along with the compressed air, similar to a jackhammer.
This compaction maintains the same diameter as the tool and leaves the borehole through which the product is passed.
The hole also must be deep enough so that, as the tool compacts the ground, the surface remains undisturbed.
The depth of the starting bore pit depends on the type of soil being worked in and how well it compacts.
The operator aims the tool to the desired exit point and allows it to perform its function, creating a borehole under the ground without disturbing the surface.
First, the distance of the drill is limited by the length of the hose that supplies the tool with air.
These hazards make it important for the operator to maintain close observation of the tool.
If the soil is rocky the tool may be deflected or fail to pound forward due to its inability to break the rock.