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City of Greensboro, North Carolina Pipe Bursting Program Update IV: KRG Utility Completes 30,000 LF using 6-inch and 8-inch Fusible C-900® Pipe

The Greensboro Water Resources Department has been contracting with KRG Utility, Inc. for several years to rehabilitate its sewer collection system, and more recently, its aging 4-inch cast iron water distribution lines. The selected approach for water main rehabilitation was to employ static pipe bursting equipment supplied by TT Technologies to burst the old pipe and pull in a new, fused pipe product. Greensboro’s Robbie Bald, PE, studied the technology and pipe product options and concluded that 6-inch Fusible C-900® pipe was the right material to use, noting the “benefits of Fusible PVC® pipe, including strength, quality of fused joints, and easy connections to our iron mains.”

In 2011, Greensboro decided to expand the pipe diameters replaced via static bursting. The first target was 2-inch cast iron and galvanized steel lines that needed to be upsized to 6-inch. TT Technologies and KRG developed a two-stage method to push smaller rods through the 2-inch pipe while still connecting to a bursting machine with enough power to burst and pullback 6-inch Fusible C-900® pipe. Bald commented: “It doesn’t make a lot of sense to bring in big excavators to replace a 2-inch line with open-cut if you can pipe burst for the same or less money while being less disruptive to the neighborhood.”

Pipeline Details and Project Summary
Project: Greensboro 2-inch, 4-inch and 6-inch Pipe Bursting
Length: 30,000 LF through 2014
Pipe Size: 6-inch & 8-inch DR18 & DR14 Fusible C-900®
Pressure Test: 150 psi for 2 hours
Services: 3/4-inch and 1-inch service taps
Equipment: TT Tech Grundoburst® 400G & 800G

Next in line were neighborhoods that were served by 4-inch and 6-inch mains, with hydraulic modeling showing a need for 8-inch replacement pipe. Greensboro approved the use of 8-inch Fusible C-900® pipe to upsize these mains and KRG was off and running with over 10,000 LF of 8-inch Fusible PVC® installed - mostly double upsizing from 4-inch cast iron. Negligible surface disruption was noted, even with mains as shallow as 30-inches deep. The 2013-14 water main rehabilitation program included 12,000 additional LF of water pipe bursting.

Jeff Greene, President of KRG Utility, Inc., said of his experience, “I see enormous potential for this water pipe bursting process and we continue to refine our methods. On some of the more shallow mains, the double upsize makes it imperative to maintain the minimum OD for the required ID. That makes Fusible PVC® pipe even more attractive. KRG now fuses our own pipe, allowing more control over scheduling.”