NUCA contractor Tires ‘n Tracks, Addison, Ill was recently subcontracted to replace an aging sewer main near a high school in Hampshire, Ill. The project was specified as pipe bursting only. Tires ‘n Tracks, like many contractors around the country, has added pipe bursting to its list of capabilities.
Tires ‘n Tracks has been in business since 1981. The mutli-facetted contractor specializes in directional drilling, fiber optics and aerial projects. According to project estimator Dan Carlquist, pipe bursting has been a good addition to their product offering. He said, “We’ve been bursting now for a few years. Every project we do gives us more experience and a competitive edge. Being able to add another method to our list of services makes us a more versatile company.”
The project for the Village of Hampshire called for the replacing an aging 8-inch VCP sewer main with 8-inch High Density Polyethylene (HDPE). After reviewing the project with Tires ‘n Tracks President Chuck Cohen, the decision was made to utilize gave a reversible bursting technique.
Carlquist said, “The stretch of main we needed to replace ran from the back side of Hampshire High School, under a wooded area to a manhole that was located in the curb line of a residential neighborhood. We had no intention of tearing up the neighborhood and disrupting traffic. That’s why we went with a reversible bursting tool to avoid having to dig an exit pit in the residential area.”
To replace the 280 feet of 8-inch VCP, Tires ‘n Tracks used a pneumatic Grundocrack PCG 180 straight barrel reversible bursting tool from associate NUCA member TT Technologies, Aurora, Ill.
Standard pneumatic pipe bursting tools have been used to replace aging infrastructure since the early 1980s. According to TT Technologies pipe bursting specialist Ben Cocogliato, reversible tools have been around since bursting began. He said, “Pipe bursting was developed based on the concepts found in piercing tools, a piston inside a casing, propelled by compressed air. The reversible feature has been a standard on piercing tools for over 35 years. The same holds true for bursting tools.”
Reversible tools, however, are rather specialized when it comes to bursting. Cocogliato said, “A wide majority of the pipe bursting done in North America is done with high production pneumatic bursting tools equipped rear expanders. Straight barrel reversible tools utilize a front expander configuration. This limits their overall capability, but does allow the tool to be placed in reverse after the bursting run is complete and be backed out through the new pipe. The Hampshire project is a good example of a project well suited for using a reversible tool. Larger diameter projects or longer runs are usually best handled with standard high production rear expander tools.”
Residents in the area of the sewer main, as well as the high school itself experienced numerous backups during the months preceding the project. Village officials attempted to video the line to determine the cause of the backups. They soon discovered that the line had been so badly infiltrated by tree roots, it was impossible to run a video camera through the pipe. Carlquist said, “This was one of the things that made the project difficult and challenging. We weren’t sure what we were up against. We knew the major problem was massive tree root infiltration, but we didn’t know what else to expect.”
The Tires ‘n Tracks crew began by assembling a bypass pumping system. A manhole in the back of the school was excavated and removed. Next, the area was shored and ultimately served as the launch pit for bursting operations. Crews then placed a 10-ton constant tension, dual motor, variable speed Grundowinch 280 feet downstream at the manhole in the curb line. The PCG 180 was fused to the new HDPE pipe string, moved to the launch pit and connected to the winch cable. Bursting was ready to begin.
Bursting operations proceeded without problems. Within two hours the existing 280 feet of 8-inch VCP pipe was burst and replaced with 8-inch HDPE. Once the PCG 180 bursting tool reached the downstream manhole, the crew put it in reverse and backed it out through the newly installed pipe. The front expander was detached from the HDPE and removed through the manhole. A new manhole was placed upstream at the launch pit and restored. The entire project took under three days to complete.
Cocogliato said, “The Tires ‘n Tracks crew did an excellent job on this burst. It really serves as a model reversible bursting project.”
Carlquist said, “Everyone associated with the project was very pleased and impressed by the speed and efficiency of how it was completed.”
by Jim Schill
NUCA, October 2003