Compact Directional Drilling:
April 26, 2011As part of its system maintenance program in Colorado, Xcel Energy is in the process of replacing a significant portion of its existing underground electrical conductor and conduit. In addition, the utility is also upgrading and replacing existing gas service line infrastructure in Denver and surrounding areas.
Minnesota-based Q3 Contracting has been using compact directional drilling to install those electrical conduits, conductor and gas services throughout Colorado.
Q3 Contracting general manager Jaeson Osborn says the use of compact HDD units has been quite successful for these installations. “The compact drill works very well in these backyard and rear easement installations. They helped us save time on projects and reduced restoration costs,” he said.
Q3 Contracting has been in business for 20 years and has offices is Minnesota, Colorado, Iowa, North Dakota and Wisconsin. Q3 provides comprehensive services to various utility companies, including gas and electric distribution, directional drilling, streetlight construction, subsurface utility engineering, hard and soft surface restoration, right-of-way restoration, stormwater management, temporary traffic control, permanent sign installation and oil and gas transmission installation and repair. Its labor force totals more than 600 employees nationwide.
For portions of the electrical and gas installation program, Q3 Contracting is using Grundodrill 4X compact directional drills from trenchless equipment manufacturer TT Technologies, Aurora, Ill.
Safety & Training
Q3 Contracting is committed to creating a safe work environment on every project. That begins by establishing standards of performance consistent with the company’s commitment to continuously improve its processes of operation.
“As a company, we constantly strive to achieve a higher standard for the benefit of our employees,
customers and communities,” Osborn said. “Safety and training play a huge roll in that. We try to incorporate mechanisms or routines that improve safety at every level whether it’s daily jobsite safety evaluations, ongoing employee qualification and safety training, or weekly safety meetings. Safety is part of the culture at Q3.”
Q3 Contracting’s Employee Training and Development Program takes that one step further. The program is designed to assist the educational and skill development of employees, with the objective of being a safer more productive work environment.
“We want each employee to meets or exceed our customer’s requirements and expectations. We also want to be sure that all employees have the tools they need, in terms of training, to be safe, as well as efficient in their jobs. Individual accountability is the main component in all training,” Osborn said.
According to TT Technologies compact HDD specialist Bill Brennan while compact style drills have been around for the better part of 15 years, much progress has been made in the function and capability of these machines. “The technology itself has been refined over the years and the machines have a smaller footprint and more power,” he said. “On the 4X, we’ve developed what we call SmartVice technology that simplifies the drilling process by performing different aspects of the vice cycling routine automatically, all under the control of the operator.”
Typically compact rigs are defined by their size. They are relatively lightweight and smaller than standard size drill rigs. They can work in tight, residential areas. They also tend to be about 36 in. in width so they can fit through a standard yard gate. Portability is another factor. Most compact drills can be legally towed behind a 1-ton truck.
According to Brennan, what the drills are used for also can help define compact HDD. “They are usually doing service installations or FTTH projects. For the most part, compact drills are used for pulling in pipe under 6 in. in diameter at lengths under 500 ft,” Brennan said. “Finally, they can be categorized by power, as well. Some consider drills under 20,000 lbs of pullback to be in that compact category, for others it’s under 10,000 lbs. You can even take that a step further and sub-categorize compact drills that offer 5,000 lbs of pullback and less. The Grundodrill 4X offers 9,800 lbs of pullback and thrust.
“The benchmark is 500 ft. That’s usually the maximum distance. Although a lot depends on soil conditions and pipe diameter, so distances may vary. The depth also varies depending on the requirements of the application and what area of the country you’re in and the conditions you’re dealing with.”
For Q3, one of the biggest benefits of the compact drill on utility projects is the ability to operate in tight working conditions. The drill has a small footprint and a low environmental impact. Plus it’s a trenchless application and that further reduces the impact on lawns, sidewalks and roadways.
Electric & Gas
Q3 Contracting’s work with Xcel Energy in Colorado includes electrical distribution conduit and conductor installation, as well as gas service line installation. According to Osborn, using the compact directional drill for these utility installations has been very productive and efficient.
“Basically we have to go in between transformers and replace the span between the transformers and switch cabinets,” Osborn said. “The conductor that was put in 30 to 40 years ago has started to come to the end of its functional life cycle and we’ve been contracted to replace it. The conductor was originally installed underground and its remaining that way. The lines are usually in backyards, rear easements.
The installations Q3 Contracting are performing vary between direct bury and conduit. In either case, crews use a compact directional drill to either pull in the conduit or directly install the conductor in the ground. For projects that include installing the conductor inside the conduct, crews will blow in a string after the conduit is installed, pull in a line and then pullback the conductor with a cable puller. For these projects, Q3 uses a two-person crew for drilling operations. A pothole crew works ahead of the drill crew to excavate pits and pothole adjacent utilities.
Conduit sizes range between 2 and 4 in. in diameter, with typical pull lengths of 300 ft. “Span lengths are closer to 500 or 600 ft, so the 300-ft pull cuts that in half. We’ll set up in the middle of the span, drill out to transformer and pull back,” Osborn said “Then we’ll turn the machine around and drill out to the other and pull back. That allows us to minimize the number of pits. If we’re pulling 2-in. conduit we’ll use a 4-in. reamer. For 4-in. conduit, a 6-in. reamer is used. Total pulling time for one 300-ft pull ranges between three to four hours.”
On the gas side, Q3 is using compact drills for service line installations. According to Osborn, crews are mainly replacing existing steel and PVC services. Typical installations average 40 to 50 ft in length and ¾ in. in diameter. Like the electric work, Q3 uses two-person drill crews to install the new service. Once the new service is installed, the drill crew moves on to the next installation. Another crew follows and completes the service tie-in.
Ground conditions can significantly affect machine operations. Osborn said, “Soil conditions can vary greatly for our projects. We see sand, clay mixture and cobble. The clay is horrible; we have to use a lot of drilling fluid. We use the onboard 225-gal bentonite system and carry another 500 gals of fresh water.”
Jim Schill is a technical writer in Mankato, Minn.
What to Look For In a Compact HDD
According to compact HDD specialist Bill Brennan, there can be quite a few differences between compact directional drills and contractors should look at a variety of things before purchasing or renting these units. “Some undercarriages are not as strong as others. The undercarriage can be considered the frame of the machine. And without a sturdy frame, you’re obviously not going to have a sturdy drill,” Brennan said.
“Thrust power and carriage speed determine the amount of work that can be performed in a given amount of time. In some cases, the thrust power of the machine may determine whether the drill may even complete the job,” he added. “And rotation speed needs to be 200 rpm or greater for the machine to do an adequate job of effectively backreaming. In addition rotational torque should be in excess of 1,000 ft-lbs. in order to have enough power to turn the reamers typically used with compact drills.”
Brennan also said that the drill system should be small enough to tow behind a 1-ton truck and should be small enough to work in tight spaces, on lawns and between structures, without doing damage to turf or pavement. And an appropriate anchor system is essential.
“Power is not of any benefit if it cannot be delivered to the drill head. Lightweight drill frames must be secured to the ground even more so than larger, heavier drills since their power to weight ratio may be greater than the bigger machines,” Brennan said. “Without being adequately anchored to the ground the machine tends to push itself back instead of thrusting the drill head forward when redirecting the drill.”