NUCA contractor Di Paolo Company, Glenview, IL was recently contracted by Lake County Public Works, Libertyville, IL to replace 600 feet of undersized 15-inch VCP with 20-inch High Density Polyethylene pipe (HDPE) through pneumatic pipe bursting. For the challenging project Di Paolo Company used a 14-inch diameter Grundocrack Koloss from associate NUCA member TT Technologies, Aurora, IL.
Wildwood Subdivision near Gages Lake, IL was constructed prior to the 1970s, before the establishment of clear and enforced restrictions against the use of sanitary sewers for home footing drain and sump pump discharges. For many years residents in low lying areas near Gages Lake and adjacent Valley Lake encountered basement flooding and overflowing neighborhood manholes during heavy rains. Wet-weather sanitary sewer flows were sometimes greater than 20 times normal dry-weather flow. According to Public Works Project Manager Art Malm, engineering studies during the late 1990s identified possible solutions to the areas problems. Malm said, “Video, dye and smoke testing detected some cracked pipes, some leaking manholes, a few gutter and patio drains and several broken lateral connections. Added up however, these defects accounted for less than 30% of measured wet-weather I&I. We concluded that 70% or more of our stormwater flows most likely came from footing drains and sump pumps.” There were two possible solutions to correct this situation. First, the owners of several hundred properties could each voluntarily pay several thousand dollars to correct their home sanitary services. Or, the carrying capacity of the sanitary sewer system could be increased. According to Malm, the appropriate economic and political decision was clear.
Lake County Public Works had successfully used pipe bursting to upsize an 8-inch VCP pipe in a heavily forested neighborhood in 1998 where storm-flow problems similar to Gages Lake were encountered.
At Gages Lake, the interceptor passed under maturing trees and through a new residential neighborhood adjacent to a wetland area. Open cutting would have required loss of wetland woodlands and a considerable effort to obtain construction permits and easements. Pipe bursting eliminated these potential problems. It was an ideal choice for the project.
On The Job
The Di Paolo crew divided the 600-foot run in half and decided to burst from the middle, using the same launch pit for each run. The launch and exit pits measured 10 feet wide by 20 feet long. A 10-ton constant tension Grundowinch was placed at the exit pit, at the end of the first run. After the crew direct bolted the 300 feet of fused HDPE to the 22.5-inch diameter front expander on the Koloss, the tool was lowered in to the launch pit. Bursting was ready to begin.
According to Di Paolo Company Vice President Sal Di Paolo, the biggest challenge during the first run came from an undocumented section of steel casing. He said, shortly after the start of the first run, the progress of the bursting began to slow down. At the end of the run we discovered the section of steel casing. The winch and bursting tool moved 20-foot length of steel casing nearly 200 feet.” In light of the unexpected section of steel casing, the Di Paolo crew opted for a rear expander configuration on the Grundocrack Koloss for the second 300-foot run to provide stability in the host pipe and cracking power if another unexpected point repair was encountered. The second run was completed without any complications.
According to Malm the next phase of interceptor capacity improvement in Gages Lake through bursting will include an 890-foot segment of 15-inch VCP upsizing to 19.4-inch ID HDPE. The upsize work to resolve the remaining capacity problems in this community is scheduled for completion before 2004. Di Paolo sees more bursting in his company’s future as well. He said, “Pipe bursting is a very valuable pipe replacement method. Owners and engineers should take a look at current and future projects and find the areas where pipe bursting would be beneficial. I believe the potential for pipe bursting in our company as well as the market in general is tremendous. It will continue to grow as more and more people become familiar with the method.”
by Jim Schill
NUCA, December 2001