Contractor Spotlight: R Directional Drilling & Underground Technology Inc.
September 21, 2011There’s rock, and then there’s caliche. Add cobble to the formula and 905 ft of 12-in. steel pipe — weighing in at nearly 28 tons — and if you’re the installation contractor, you may want to prepare for a few challenges — unless you happen to be Phoenix-based R Directional Drilling & Underground Technology Inc.
Established in 2006 by the Ruiz brothers, Jose and Aurelio, R Directional Drilling & Underground Technology Inc. is a professional horizontal directional drilling (HDD) contractor specializing in highly technical underground construction services. The company has emerged from its humble beginnings — one drill and a skeleton crew — to become one of the leading trenchless installers in the Southwest, due in large part to the combined HDD experience of its founders and crew, and an operational philosophy that focuses on excellence.
“We believe that exceptional service builds long-lasting relationships,” say the Ruiz brothers, owners of R Directional Drilling and Underground Technology Inc. “Our clients have come to expect excellence, from initial contact through project completion, and our company has been built on this core value. We feel a great sense of pride having earned a reputation based on dependability, even in the most challenging situations.”
The success of R Directional Drilling is documented by consistent growth. Currently, the company has 36 staff members, six drills and a reference list of loyal, satisfied clients who repeatedly call on the underground expertise of the Ruiz brothers and their crew to complete challenging gas, water, sewer, electric, telecommunications, cable and related underground utility installations. Among its many repeat clients is Southwest Gas Corp., an investor-owned utility serving more than 1.8 million customers in Arizona, New Mexico and portions of California. At the recommendation of Matt Godfrey, Jim Gardner and Gene Kirkland, representing subcontractor Northern Pipeline, Southwest Gas recently turned to R Directional Drilling to complete an expansion job of an existing gas pipeline situated in an area that includes a variety of challenging conditions.
Given that the location of the job was in largely rural, non-urbanized area void of existing infrastructure, one would expect the project to have been completed using open-cut. But environmental sensitivities along with the potential for drainage diversion that would have likely resulted from tampering with two existing 20-ft wide wash areas, trenchless surfaced as the only installation option.
The Ruiz brothers and crew began by walking the jobsite, surveying the surface terrain and capturing measurements of the varying elevations. This was important for determining the capacity of the drill rig selected to complete the job, along with identifying parameters of the potential stress that would likely be inflicted on the material during pullback, especially given the immense weight of the steel pipe.
“First, we needed to identify and evaluate if we would be able to maintain a level of elevation that was within 1 degree per 10 ft of pipe,” Ruiz explained. “It was critical to make sure the elevation wouldn’t deviate much more than that as this would result in placing undue stress on the steel pipe as we were pulling it back through. We also needed to calculate entry and exit locations that would allow us to achieve the mandated 6-ft minimum cover through the wash areas. We wanted to make sure we were well covered, so we calculated the bore plan at 14 to 15 ft beneath the wash areas.”
After walking the site, completing the calculations and finalizing the bore plan, Ruiz’ crew — including accomplished HDD operators Jim Kirkland with Northern Pipeline and Aurelio Ruiz — were anxious to conquer the rock-filled terrain. They selected a Vermeer D36x50 Series II NAVIGATOR horizontal directional drill with its 4,995-ft-lb rotational torque capabilities and 36,000 lbs of thrust/pullback, to navigate the caliche/cobble conditions.
Cobble can exist in many different forms and in different conditions. It may be a loose conglomerate of stones or glacial till sized from pea to basketball diameter, either mixed with sand and soils or packed tightly — resulting from thousands of years of compression — referred to as cemented cobble. In another form, cobble can be a conglomerate of broken or fractured sandstone, limestone or other rock that has been reclaimed, replaced or used for fill in construction or other similar applications.
Concerned that the nearly 57,000-lbs weight of the steel pipe would likely encounter some resistance when pulled back through, Ruiz’ crew was acutely aware of the importance of keeping the bore path as straight as possible. They implemented a multiple-pass reamer approach, attaching a 5-in. bear claw tool to the bore head for the initial pass, a diameter that would help minimize the resistance often encountered by the cobble/caliche rock formations.
Another critical component of successfully navigating through cobble and caliche is drilling fluid. Having much prior experience drilling in these conditions, the crew used a proven drilling fluid recipe of bentonite treated with a touch of soda ash to restore the mud mixture to the proper pH after years of calcium and related deterrent buildup.
“The entire 905 ft were initially shot at 5 in. using the bear claw tool and then we came back and used a 14-in. reamer to open up that hole,” Ruiz explains. “We attached a 20-in. reamer after that. We then pulled back with a 20-in. reamer all the way through with the pipe attached, all along making sure that the mud consistency in the mix was correct for the ground conditions and the cobble/rock spoil was coming out of the bore path as intended.”
As the Ruiz brothers explain, consistent mud flow is critical during the reaming process to facilitate removal of spoil and help secure the bore hole from cave-ins and displacement. Increasing the size of the bore to 20 in. — well beyond the 12-in. diameter of the material installed — was an intentional strategy that allowed the crew to infuse adequate drilling fluid in the bore path to mitigate the excessive weight of the steel pipe by suspending the steel pipe somewhat, and serve as a lubricant that helped minimize stress as the material was pulled back through.
After 11 hours of patiently drilling through the cobble-caliche concoction, the pilot bore was completed, paving the way for the reaming process, which was completed in the next day and a half. The job concluded after another six and a half hours, the amount of time it took for the R Directional Drilling crew to pull back the pipe. Jose Ruiz credits the experience and instincts of his drill operators, Jim Kirkland and Aurelio Ruiz, along with a well-conceived plan for completing the bore successfully.
“It went just like we had hoped,” Ruiz says. “We didn’t need to adjust our drill plan at any point, mainly because our plan was solid and our drill operators have experience with these conditions. One of the most important qualities an operator should have when drilling through cobble is patience. With a bore of this length and all the resistance on the head created by the cobble, the process just can’t be rushed. Excessive pressure on the drill head can result in a costly amount of lost tooling or a frac-out, resulting in a lost bore. These two operators know this better than most.”
Ruiz went on to reiterate the importance of keeping the pilot bore as straight as possible, including minimal vertical deviation, cannot be overemphasized, especially given the weight of the material and the length of the bore.
“To keep things on the straight and narrow our guys took measurements at every 10-ft interval,” Ruiz explains. “They’re also looking at the pitch of where the bore is heading directionally. This allows them to detect if there was any deviation on the rod that needed to be corrected. The weight alone was enough to cause stress on the material during pullback. Having a bore path with deviations, regardless of how slight, will jeopardize the success of the pullback by adding stress on the material.”
Randy Happel is a features writer with Two Rivers Marketing, Des Moines, Iowa.