During the installation of sprinkler systems or outdoor lighting it is not uncommon to meet up with obstacles that prevent the installer from continuing on.
These obstacles such as driveways or sidewalks can pose a formidable barrier. The expense of digging up concrete, asphalt or even paving bricks and stones and them replacing them can be more than the rest of the project combined.
There are ways to get under the obstacle that are usually much less expensive than digging it up and replacing it.
The technique is called:
Horizontal Boring or Horizontal Drilling
If you are confronted with a sidewalk a 3 to 6 foot obstacle, you can generally manually horizontal bore under the sidewalk using a garden hose and a piece of 1/2 inch steel pipe.
Figure 1 - Trench construction for horizontal boring under a sidewalk
Note: The hole made by the water pressure will be much larger than the 1/2 inch pipe.
Figure 2 - Pipe laid in trench for horizontal boring using water pressure
Figure 3 - 2 inch, schedule 80, PVC pipe in the bore hole under sidewalk
If your obstacle is wide, such as a two car driveway, the aforementioned method may not be suitable due to compacted soil or logistics.
In that case you will need to rent a horizontal boring machine. These machines are available at most rental facilities.
The machines come in a variety of sizes, but for the homeowner a walk-behind machine is usually quite adequate to do the job.
Horizontal boring illustration is supplied courtesy of www.maxbore.com