Directional Loop Installation
Directional boring is a valuable tool for getting pipes under an obstruction without damage to landscape. It is widely used to cross driveways or sidewalks, bore under barns or outbuildings, and even bore into buildings when necessary. It is not an efficient tool for installation of horizontal loop fields. This is the reason for a higher cost on directional loop fields than other horizontal fields.
Directional boring requires less ground area than most other horizontal methods, but requires more on site setup area than others. Here is how a directional field is installed:
- A bucket trench 3’-4’ deep and 30” wide is dug from the building to the desired header location.
- The boring machine is set up perpendicular to the trench, 15’-20’ behind the trench. The machine is 17’long. This means you need almost 40’ of operating room on the opposite side of the trench as you plan to put the loop field.
- The machine bores into the trench and out the other side on the bottom. The machine will continue to bore down and out until the desired depth is reached and then bore outward and level until the desired length is met. The most common length is 200’ per shot. One shot per ton of unit capacity.
- The machine will bore up and outward until the bore head comes to the ground surface. At 12’-18’deep at level, this usually takes 30’-50’ of bore beyond the desired length. This makes a total of 270’-300’ of working area. The extra bore distance is considered waste and left to collapse after the loop is pulled back through the bore. Exit holes resemble gopher holes.
- The loop u-bend pipes are hooked onto the bore head and pulled back into the header trench.
- When the pipes reach the trench, the head is disconnected, and pulled back to the machine so it can be aimed at another shot.
- Repeat steps 2-6 keeping 12’-18’ minimum separations between shots.