Utility contractor Potelco, Sumner WA, has embraced trenchless equipment. In fact, the company has been using one trenchless tool in particular for almost 20 years, the pneumatic piercing tool. A workhorse of trenchless technology, the piercing tool has become a mainstay at Potelco providing solutions for a wide variety construction applications.
Potelco’s piercing tool arsenal numbers somewhere around 200 tools company wide. For gas work alone crews perform as many as 150 residential service bores in any given month. According to General Foreman Mike Beuslinch, the tool is an important part of daily operations throughout the company. He said, “We couldn’t do our work without them. It would be too costly with restoration, the hauling off and importing of materials. We use them for power, phone and cable, but gas is definitely the area where we use them the most.”
According to Scott Langfeldt, piercing tool specialist from trenchless equipment manufacturer TT Technologies, Aurora, IL, Potelco has been utilizing piercing tool technology for years. He said, “Potelco crews have a long history with the piercing tool. Over that time they’ve really gotten the most of the technology and they continue to grow their services with it.”
Potelco, Inc. (a subsidiary of Quanta Services, Inc., Houston, TX) was established in 1967. The full service utility contracting firm, serves customers throughout the Northwest in Washington, Oregon, Idaho, and Montana. Potelco has been providing overhead power distribution and power transmission services since the company’s inception including everything from street light maintenance and energized system work, to huge overhead construction and mass transit projects.
Their service offerings also include underground power construction and maintenance. The company plays an important role in cable replacement throughout the region. Potelco also performs civil construction and installation, as well as the electrical installation. It is also one of the regions leaders in telecommunications construction having provided both overhead and underground telecom services for decades. The company now has crews specializing in the design, installation, and splicing of fiber optic cable, for last mile operations.
With such a breadth of service and operation, safety is a top concern. Potelco puts employees through extensive safety training. However, according to Potelco Director of Safety Brian Sabari, safety is the first thing every crewmember focuses on when they arrive at the job site. He said, “Everyday, crews, before they get started, are required to do what we call a tailboard meeting which is essentially a daily safety meeting. Crews go through a form specific to the type of work they’re doing. The form raises key questions about, for example, traffic control, excavation, confined spaces and other specific topics crews face at their job site. At that meeting, they basically plan their day for safety on that particular project.”
In addition to safety, many of those projects rely on the capability of the trenchless piercing tool.
Piercing Tool Capabilities
According to Langfeldt, the piercing tool represents one of the most versatile pieces of trenchless equipment ever manufactured. He said, “It’s really incredible if you think about it. The piercing tool itself can be used for a variety of applications. Obviously it is used as a boring tool, but it can also be used as a ramming tool and a pipe bursting tool. It’s extremely capable. For Potelco, it’s mainly a boring tool. And successful boring is a function of accuracy.
“While the Grundomat [piercing tool] basically works on the same principles found in the first piercing tools, the major improvement comes in the reciprocating head. A piston inside of a casing generates power. The piston drives the tool, and air drives the piston. Today’s conventional piercing tools, as well as the Grundomat, operate in this fashion.
“The Grundomat’s reciprocating chisel head assembly, however, moves independently of the main casing, creating a pilot bore for the rest of the tool body to follow. This ultimately leads to greater bore accuracy over conventional tools. The chisel like action helps the tool to power through difficult soils and obstructions without being pushed off course.”
Piercing Tool Projects
Potelco’s crews see a wide variety of soil conditions. Soils types include sandy loam, clay, hard-pan and pit-run. With such a variety of soil types, crews rely on the accuracy and dependability of their piercing tools. Accuracy is necessary to ensure efficiency.
Beuslinch said, “We don’t typically encourage our crews to attempt shots over 75 to 80 feet if possible. The longer the shot the greater the potential is for inaccurate boring. But occasionally, we get in the right soil and the right situation and the crews can pull off a 150- or 200-foot shot. And when they make them, they brag, and rightfully so.”
Gas work performed for Puget Sound Energy, Bellevue, WA, represents the bulk of the piercing tool work done by Potelco. A recent project in Renton, WA highlights the integral role the tool plays in gas distribution installations. According to Beuslinch, the main line replacement was performed for capacity reasons in a commercial district.
Beuslinch said, “The whole area was commercial. When this new customer turned in his application for service, the existing main was no longer sufficient to handle the load requirements, so a new larger main needed to be installed. We typically deal with new service and main installations, but everyone likes main replacement installations.”
For the main replacement project Potelco crews used two 5-inch diameter Grundomat P-130s. But according Beuslinch, the job was originally earmarked for directional drilling. He said, “The project in Renton was approximately 1,100 feet of gas main replacement. It was upgrading from a 2-inch bare steel main to a 4-inch polyethylene main. It was a hard surface job from start to finish with significant portions under concrete sidewalks. When we looked at the job we had 13 services that we had to test-and-tie-over or replace completely and with the other utilities we needed to cross, everything spaced out in 40- to 80-foot shots. It was perfect for a piercing tool. Plus, the soil conditions were ideal. It was basically Class B soil, no rock.”
After successfully boring a section of the project, crews would remove the tool and pull in the new main with a weak link and pulling cable. As work progressed, crews fused the sections of mains together, while other crewmembers attended to connecting services and replacing others. New service installations were also performed with piercing tools.
Beuslinch said, “We used a 2-inch tool, a P-55. We also have the smaller tools, P-45, 1 ¾-inch, for the short shots, but mostly we used the 2-inch and 3-inch diameter tools to install 5/8-inch to 2-inch services lines. Most services were in the 40- and 80-foot range.” The entire project was completed in seven days.
Potelco crews have improved field production and efficiency dramatically under hard surface areas by combining trenchless methods on projects, specifically directional drills and piercing tools.
Beuslinch said, “By combining the tools on a project, we can get done in a day what would normally take two or three days. This works well with specific job layouts. For example, we recently did one on a new main extension and service where we used the piercing tool to install 160 feet of main and the directional drill to install 350 feet. We were in an intersection. We needed to extend the main 160 feet to south, then 350 feet to the east. So, we set up the drill on the 350-foot section and began drilling. Meanwhile the rest of the crew worked from the intersection back to the tie in point with the piercing tool. By the time the piercing tool section was complete, the 350-foot section was already drilled out and pulled back. We had over 500 feet of main and an 80-foot service installed in a day and footage is what pays.”
by Jim Schill
Trenchless Technology, July 2007