When Liner Products LLC was called on to produce tubes for a cured-in-place pipe (CIPP) renewal project within the Minnesota Valley Wildlife Refuge, it did not know that the project would require a house call to the project site.
Lametti & Sons, the contractor and a certified installer of the Inliner Technologies method of CIPP, was tapped to renew 4.66 miles of interceptor sewer pipes within the 14,000-acre protected habitat for migratory birds, bald eagles and a number of unique species, such as prothonotary warblers.
Carefully planning out the project to minimize impact within the refuge meant accounting for factors such as the Eagle Protection easement to cease all work within a 660-ft radius of any eagle nest, as well as the Calcareous Fen, which had an even higher level of restriction than the eagles nest.
The project required 26 segments of CIPP liner in diameters of 12, 36, 42, 60 and 66 in., which were constructed at Liner Products’ manufacturing facility in Paoli, Ind., to ensure compliance with the owner’s structural design requirements.
The smaller liners were wet-out in Lametti’s facility in Hugo, Minn. but the majority of the project consisted of 60-in.-diameter and larger liners requiring over-the-hole wetouts, in which the resin was catalyzed, mixed and pumped into the tubes on the jobsite as the liners were being inverted into the pipe.
Over-the-hole wetouts are performed inside a climate-controlled tent allowing the installers to operate throughout the year with the temperatures ranging from sub-zero to 100°F. The tents were heated in winter and cooled in summer to ensure temperature stability for the catalyzed resin.
The final installation on the project was a 66-in.-diameter pipe more than 1,600 ft long, the shipping height of which alone would have exceeded highway-shipping regulations. As a result, the eight-layer liner was manufactured in two sections, each measuring more than 800 ft in length for transport. Once the two sections arrived at the jobsite, they were spliced together by a team of Liner Products manufacturing technicians, who made the trip from the plant in Indiana to complete the critical task of field splicing, by hand-sewing the tube layers.
Maintaining the integrity and strength of the seam attaching the two sections of this large and heavy liner was critical. The eight layers of heavy-duty felt within the tube were filleted open, and layers were spliced with heavy-duty needle and thread. It was important to distribute the splices of the layers over a distance of more than 100 ft to ensure no two layers were spliced at the same location. The team worked around the clock for 24 hours to complete the field splice.
“This was one of the most complex CIPP installations that our crews have completed,” said Dan Banken, vice president of Lametti & Sons. “After the splice and sewing was complete, the section took about 48 hours to wet out and invert the full length of the pipe, followed by almost four days of circulating heat to ensure the liner reached a full and complete cure.”
