NUCA Members Working in Trenchless
NUCA contractor Arby Construction, New Berlin, WI is replacing 5/8-inch diameter copper gas services with 1-inch CTS utilizing the trenchless Mini-Grundotugger pipe replacement system from Associate NUCA member TT Technologies, Aurora, Ill.
With numerous, aging copper and plastic service lines in need of replacement, the gas industry is always looking for new replacement techniques that limit disruption and speed installation times. Trenchless equipment manufacturer and associate NUCA member TT Technologies, Aurora, Ill., is working with the Gas Technology Institute (GTI), Naperville, Ill. to develop new techniques and methods for effectively and efficiently replacing these small diameter gas service lines.
NUCA contractor Arby Construction, New Berlin, WI, has partnered with TT Technologies and GTI in order to utilize the latest in trenchless pipe splitting technology to replace numerous copper gas services for Nicor Gas, Naperville, Ill.. Arby crews are using the new Mini-Grundotugger static pipe splitting system (patent pending) to split and replace 5/8-inch diameter copper gas services and replace them with 1-inch CTS.
Contractor & Utility Background
Started in 1956, Arby Construction has grown from a small telephone contractor to one of the largest underground construction contractors in the United States. For the gas industry, Arby Construction offers complete installation services for all sizes of pipe for gas distribution systems.
Nicor’s roots, like Arby Construction’s, date back to the 1950s. Founded in 1954, Nicor Gas is an investor-owned natural gas utility that serves nearly two million customers in northern Illinois, excluding Chicago. Nicor Gas is the largest natural gas distribution company in Illinois and one of the largest in the United States. The company maintains a 29,000-mile distribution system that is connected to seven interstate pipelines. In addition, Nicor Gas transports and stores natural gas for customers that purchase their own gas supplies. These commercial,
With a service area that is growing, a large portion of fieldwork is devoted to upgrading exiting systems and performing new service installations. Nicor contracted Arby Construction to complete a large portion of this service upgrade.
The trenchless pipe replacement system replaces the host pipe by simultaneously splitting the existing service line while pulling in a new PE service line.
TT Technologies Product Specialist Brian Mattson said the trenchless application is ideal for this type of work. He said, “These services are pretty much all main to meter. They’re running under lawns, landscaped areas, driveways, and sidewalks. By using the trenchless splitting system, Arby is able to save a lot of time and money in terms of excavation and restoration. Plus, customers are back up and running the same day.”
Mattson said there are three different models available, for the specific splitting situations. He said, “The Mini-Grundotugger 250 offers 6,000 lbs of pullback and is typically used for host pipe diameters of 1/2- to 5/8-inch, the 313 offers 9,000 lbs of pullback and is used for host pipe diameters of 5/8- to 3/4-inch and model 375 offers 12,000 lbs of pullback and is used for host pipe diameters up to 1-inch. Each machine utilizes a different cable diameter. The 250 uses 1/4-inch cable,
the 313 uses 5/16-inch cable and the 375 uses 3/8-inch diameter cable.
Depending on the existing pipe material, the unit’s specially designed splitting head and expander split the host pipe. Then you can either pull in the new pipe directly behind the expander or retrieve the split service first, then pull in the new service.”
Arby crews try to accomplish 10 service line replacements per day and have all customers back up and running the same day.
Most of the services that the Arby crews encounter are between 30 and 75 feet in length. According to Arby Construction Area Manager Mario Lipira, splitting times vary depending on soil conditions. He said, “The time of year and soil conditions have a lot to do with how fast we can split and replace service. If conditions are wet you can see between 5 and 10 services per day. If soil conditions are dry and hard only 1 to 3 services per day.”
Keyhole Technology
The MiniTugger System can be used for both small-hole (keyhole) and traditional trenchless work for the replacement of copper or plastic service lines. The system replaces the service line by simultaneously splitting the existing service line while pulling in a new PE service line. The existing service line is split and expanded to allow for the subsequent replacement service to be installed. The existing service line can act as a conduit for the replacement service that aids in the installation of the new service line.
The Mini-Grundotugger requires only small entry and exit pits to facilitate the replacement of the existing gas service lines. Restoration is dramatically reduced with the system.
Lipira said, “On a typical job first you identify existing copper or Aldyl-A services for replacement and where the service tee is located in both the parkway as well as under pavement including sidewalks. Then you keyhole by using either a coring rig for pavement or spade or vacuum excavation if it’s on a lawn to expose the service tee.
Once that’s done, the system is set up at the service tap hole. The splitter head with new PE service tubing and tracer wire attached are configured at the service riser tap hole. Once the winch line is pushed through the existing service, the splitter head and replacement service is pulled back. Typical launch and exit pits are 3 feet by 5 feet. We try to get 10 services done per day.”
Trenchless Benefits
Cost-saving opportunities are one of the most attractive benefits of the system, especially when it comes to excavation and restoration requirements. Mattson said, “Not only can this tooling be utilized through a keyhole in pavement applications, but also through a small hole excavation in the parkway, minimizing not only excavation requirements, but also, final restoration needs.
Minimal disruption through the use of the trenchless pipe replacement system has pleased homeowners in Nicor’s service area.
In fact, for crews working in the parkway, they should be able to simply spade out a 15- to 18-inch ‘coupon’ of sod that could be directly placed back into the excavation for restoration. If the crew then simply added some grass seed around the edges of the coupon, similar to grout for a pavement core, this process could eliminate a trip by an L&P contractor, saving even more hard costs. Some of the soft costs should include improved public and municipality appeal due to less disruption of the property.”
Lipira said, “Using the trenchless system has really helped us limit restoration and the associated costs. It has also helped reduce customer complaints and callbacks. When you avoid tearing up sidewalks and driveways, residents are usually very pleased.”
Jim Schill
Technical Writer
Mankato, MN
Utility Contractor, June 2006
