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Large Steel Water Main Project Pushes Static Bursting Envelope
The bursting rods are also critical to successful static pipebursting. Holcomb said, "Quicklock style rods are securely linked instead of screwed together like traditional drill stems or other static systems. We’ve found that this system provides the optimum in terms of strength of connection and elimination of rod torque. This style of rod also speeds installation and breakdown because the rods are easily and quickly removed at the exit pit as bursting is in operation. There’s no time wasted screwing and unscrewing rods or having to deal with a potentially dangerous high torsion situation. Plus, in certain situations, you place the bursting unit in the middle of two runs and actually rod the second run by passing the rods through the back of the bursting unit while bursting the first run. Global Underground was able to take advantage of that technique during their project and it saved them a significant amount of time.”
The total length of bursting was 2,529 feet. The main ran under a highly traveled roadway in Colorado Springs. Meadows said, “Galley Road is a major street. I’m not sure exactly what the traffic volume is, but closing that east/west corridor would have been a real problem for the city. It’s normally two lanes of traffic in each direction; we were able to keep one lane open in each direction with the pipebursting application.”
The water main feeds a water tank on the east side of town. Colorado Springs Utilities was able to shut the water main down for the duration of this project by feeding that tank through alternate routes. This eliminated the need for bypass pumping and helped Global Underground and Colorado Springs Utilities crews keep disruption to a minimum.
The 2,500 foot run was divided into five sections. According to Meadows, soil conditions were hard to pin down. “Sections of this main had been dug up so many times over the years, we never knew what we’d encounter. The soil conditions changed constantly. Within a couple of feet you could go from tight clay to sand. For us, the project was remove and replace [the spoil] with select fill, road base.”
Typical launch and exit pits measured 40-feet long and 12-feet wide at depths up to 14 feet. Global crews were aiming for runs over 500 feet, but as Meadows explained, no one knew what to expect, especially when considering the diameter of the pipe and the coal tar coating.